WO2012107663A1

WO2012107663A1 - System for detecting a longitudinal movement threshold and for determining the rotational speed of a cylindrical element, and starter provided with such a system

Info

Publication number: WO2012107663A1
Application number: PCT/FR2012/050142
Authority: WO
Inventors: Marc UNTERNAHRER
Original assignee: Peugeot Citroen Automobiles Sa
Priority date: 2011-02-11
Filing date: 2012-01-23
Publication date: 2012-08-16
Also published as: FR2971557B1; FR2971557A1

Abstract

The invention relates to a system for detecting a longitudinal movement threshold and for determining the rotational speed of a cylindrical element translating along the central axis thereof and rotating about said axis, characterized in that it includes a single sensor (13) connected to a means for acquiring and processing the signal, and a target (14) arranged on the outer surface of the cylindrical element and capable of interacting with the sensor (13) so as to produce said signal, said target (14) comprising a first area (20) and a second area (21) that extend around the element, the second area (21) being contiguous with the first area (20), and in that the first area (20) is intended for determining the rotational speed of the element, and both areas are intended for detecting the movement threshold. The invention also relates to a starter including such a system.

Description

SYSTEM FOR DETECTING A LONGITUDINAL DISPLACEMENT THRESHOLD AND DETERMINING THE ROTATION SPEED OF A CYLINDRICAL ELEMENT AND

STARTER EQUIPPED WITH SUCH A SYSTEM

Technical field of the invention

The present invention relates to the field of displacement and speed measuring systems and more particularly to a starter equipped with such a system.

Technological background

This invention is in the context of the current automotive technology, particularly in the context of thermal engine starters possessing the functionality commonly known as "Stop & Start". This feature is to automatically shut down the engine when the vehicle speed is at zero, for example when stopped at a red light or in any other situation requiring the vehicle to stop, the engine is then restarted automatically when the user requests it again. This is to reduce the fuel consumption of the vehicle and the pollution it generates. To achieve this function "Stop & Start" still called STT on a vehicle with a combustion engine, especially on a car, there are mainly two possibilities based on electromagnetic automotive starting devices. Either a starter alternator is used which is a reversible machine placed on the motor belt, or a starter adapted to the STT function is used. This kind of starter ensures, during the starting phase up to the autonomy of the engine by the combustion cycles, driving the crankshaft of the engine by means of a pinion which meshes with the toothing of a toothed crown mounted on the periphery of the flywheel, the engagement of the pinion being controlled by a solenoid arranged in the starter.

Currently, car manufacturers are still seeking to improve this kind of STT starter, particularly since it would be desirable to have in addition to the possibility of restarting the engine by the starter member while the crankshaft of the engine, unlike the case of a usual start, did not stop. This kind of situation can for example occur if the driver unexpectedly wants to accelerate at low speed.

Document FR2925615 and FR2925615 disclose an STT starter whose pinion can be rotated before it is engaged in the ring gear of the heat engine. However, an engagement operation of the pinion, which is then driven by both a rotational and translational movement, on a rotating crown risks to produce a rebound of the teeth of the pinion against the teeth of the crown with sound effects and wear or even breakage of the teeth, which is unacceptable. In addition, the level of engagement of the pinion in the toothing of the flywheel is not known with certainty, which penalizes the choice of the right moment to trigger a start order.

Document EP1051275 discloses a starting device for starting an internal combustion engine. This starter is equipped with a starter motor and a pinion that can be driven by an armature shaft, which pinion can engage in a ring gear. The starter comprises a first rotation speed sensor and a second displacement sensor, the two sensors being arranged at the pinion. However, such a configuration with two sensors is penalizing from the point of view of compactness, in an environment where the space available for the implantation of the sensors is restricted. Furthermore in this configuration these sensors must be sufficiently far from the pinion not to be affected when moving the freewheel adjacent to the pinion, because of the larger diameter of the freewheel relative to that of the pinion. This distance between the sensor and the pinion does not guarantee a sufficient signal quality of the sensor, which is an important prerequisite for good information processing.

There is therefore a need for a compact system to inform us of the good position of engagement of the starter gear and its rotational speed, with guaranteed signal quality.

The invention thus relates to a system for detecting a predetermined longitudinal displacement threshold and for determining the rotational speed of a cylindrical element driven by a translation movement along its central axis and of rotation about said axis. central, characterized in that it comprises a single sensor connected to means for acquiring and processing an output signal of the sensor, a target disposed on the outer surface of the cylindrical element adapted to cooperate with the sensor to produce the output signal, said target having a first area and a second area extending all around the cylindrical member, the second area being contiguous with the first area, and in that the first area is dedicated to determining the rotational speed of the cylindrical element and the two zones are dedicated to detecting the predetermined longitudinal displacement threshold. Thus, thanks to the specific configuration of the target in cooperation with the sensor, these two pieces of information are reliably known.

Preferably, the first zone comprises a plurality of a first pattern extending parallel to the central axis, each of the first patterns being spaced by an identical interval, in order to produce a cyclic signal whose rotation speed can be deducted.

More preferably, the second zone comprises a second single pattern, for the purpose of producing an output signal of the continuous sensor whose committed positron state can be confirmed.

Preferably, the sensor is arranged to appear opposite the transition between the first zone and the second zone when the cylindrical element has moved from the predetermined longitudinal displacement threshold.

In a variant, the sensor is a proximity sensor.

In another variant, the sensor is an optical sensor.

In another variant, the proximity or optical sensor cooperates with a target whose first pattern is a groove formed in the thickness of the cylindrical element.

In yet another variant, in the case where the sensor is an optical sensor, the first pattern and the second pattern appear as a color marker. Indeed, the color change causes a change in light intensity received by the optical sensor.

The invention also relates to an internal combustion engine starter equipped with a launcher drivable longitudinally along its central axis and being able to be rotated about said central axis, characterized in that it comprises a system of the invention adapted to detect a predetermined critical displacement threshold of the launcher and determine the rotational speed of said launcher.

Preferably, in the case where the launcher comprises a freewheel cage, the target is disposed on the outer surface of the freewheel cage. Preferably, the predetermined critical displacement threshold corresponds to a critical engagement threshold of a launcher pinion in a flywheel toothing.

Brief description of the drawings

Other features and advantages will appear on reading the following description of a particular embodiment, not limiting of the invention, with reference to the figures in which:

FIG. 1 is a schematic representation of a motor starter for an instrumented motor vehicle of the system of the invention.

- Figure 2 is a schematic representation of a starter launcher in the position not engaged in the flywheel.

- Figure 3 is a schematic representation of the starter starter being engaged in the flywheel.

- Figure 4 is a schematic representation of the starter launcher fully engaged position.

- Figure 5 is a timing chart showing the evolution of the sensor output signal as a function of time during the engagement phase of the pinion in the flywheel.

detailed description

FIG. 1 diagrammatically shows a starter 1 intended to equip an internal combustion engine of a motor vehicle and in particular having the functionality commonly known as "Stop & Start" or STT. We will still name such a starter, an STT starter.

The starter 1 comprises an electric motor of which only the armature 2 is shown in FIG. The electric motor is intended for driving in rotation a shaft 3 of central axis XX integral with the armature 2. The shaft 3 slidably carries a launcher 4 starter. The launcher 4 carries a starter gear 5 connected to a free wheel whose internal structure is not visible in FIG. A metal cage 6 protects the freewheel. The freewheel has as axis of rotation the central axis XX of the shaft 3 to which it is connected. Thus the freewheel transmits the rotation of the armature 2 to the pinion 5 while it does not allow the starter motor to be driven by the motor. The starter gear 5 comprises teeth 7. The set of starter elements is protected by a housing 8. The launcher is thus drivable longitudinally along its central axis XX and can be rotated about said central axis XX. The starter 1 is driven by control means. The control means are capable of rotating the launcher 4, trigger the engagement of the launcher 4, trigger the start or restart of the engine by driving the flywheel. The triggering of the engagement of the launcher 4 may be conditional, one of the conditions being a range of rotational speed of the flywheel, for example between 80 and 200 rev / min which allows to consider restarting the engine by the starter 1 when the vehicle is at low speed.

The launcher 4 is shown in Figure 1 in the rest position, when the starter 1 is not electrically activated.

During an engagement operation, for example to start the motor vehicle, the launcher 4 is moved from its rest position to an active position (not shown in Figure 1) in which the teeth 7 come into mesh with the teeth of a ring gear (not shown in Figure 1) belonging to the flywheel of the internal combustion engine of the vehicle.

The launcher 4 is brought into active position by translation along the shaft 3, until it comes into contact with a stop 9 formed at the end of the shaft 3. The launcher 4 moves under the action of an electromagnetic contactor (not shown in FIG. 1),

The launcher 4 of an STT starter can be further rotated about the central axis XX by the electric motor before being launched to be brought into the active position. In this case, during the engagement operation, the launcher 4, thus also the pinion 5 is driven both the rotational movement about the axis XX and the translational movement along the axis XX in the direction of the stop 9. During an engagement operation, the launcher 4 moves with a stroke C, for example 10 mm, between its rest position and its active position against the stop 9.

However, such an engagement operation of the starter gear 5 on a ring gear which may further itself be rotated may produce one or more rebounds of the pinion teeth 5 against the crown toothing before meshing. be effective.

In order to improve our knowledge of the phenomena responsible for rebounds, it is planned to detect a threshold of critical engagement of the pinion and the speed of rotation of the launcher 4. To do this, in a preferred embodiment, the starter 1 is instrumented with an optical system.

In this preferred embodiment, the system comprises an incident light source 10 comprising a light-emitting optical fiber, reflected light receiving means 11 such as an optical fiber for receiving light, acquisition means 12 and signal processing connected to the receiving fiber 1 1. The processed signal being in this case the output signal of the sensor, in other words the intensity of the reflected light.

For reasons of compactness, the transmitting optical fiber 10 and the receiving optical fiber 11 are preferably included in the same optical sensor 13.

The means 12 for acquiring and processing the signal are configured to detect whether a predetermined critical engagement threshold of the pinion 5 is reached and to determine a rotational speed, V of the launcher 4, and therefore of the pinion 5 which is connected to it, from the time record of the intensity of the reflected light signal. The critical predetermined engagement threshold corresponds to the minimum physical engagement required between the pinion gear and the flywheel, not shown, guaranteeing their mechanical strength and avoiding a risk of breakage of the teeth 7. A S indicator, two-state for example of the Boolean type indicates whether the predetermined critical commitment threshold is considered reached by the acquisition and processing means 12 or not.

To complete the optical system, there is provided a target 14 on which is directed the incident light and to produce during the movement of the launcher 4 variations of reflected light intensity.

The optical sensor 13 is fixed to the housing 8. The optical sensor 13 is positioned with respect to the freewheel cage 6 so as to place the emitting optical fiber 10 and the receiving optical fiber 1 1, relative to the direction of launch indicated by the arrow referenced E in Figure 1, at the downstream end of the target 14. The incident light is directed by the optical fiber 10 on the target 14, the outer surface of the cage 6, radially thereto. The reflected light is collected by the optical reception fiber 1 1 to be transmitted to the acquisition and processing means 12.

FIG. 2 now shows in more detail the launcher 4 equipped with its target 14. FIG. 2 shows the launcher 4 in the rest position, that is to say in its state before a order of engagement with a flywheel 15. The target 14 is disposed outer surface of the cage 6 freewheel. The optical sensor 13 is disposed opposite the target 14, radially thereto. In this arrangement, the sensor can be positioned very close to the target, which makes it possible to improve the quality of the output signal of the sensor 13 and therefore the quality of the post-processing.

The target 14 comprises a first zone 20 and a second zone 21 extending in a band all around the cage 6 freewheel. The second zone 21 is contiguous with the first zone 20, in other words the two zones 20 and 21 are in contact. In relation to the direction of launch indicated by the arrow referenced E in FIG. 1, the second zone 21 is upstream of the first zone 20. The first zone 20, relative to the direction of launch indicated by the arrow referenced E in FIG. is downstream of target 14.

The first zone 20 comprises a plurality of a first pattern 22 in the form of a color marker on the outer surface of the cage 6, for example of black color, extending parallel to the central axis XX, each of the first patterns 22 being spaced an identical interval 23. For the sake of clarity in Figure 2, only a pattern 22 and a gap 23 are referenced. The color may be deposited on the outer surface of the cage 6 using a high temperature paint, that is to say here a temperature resistance paint typically seen by an internal combustion engine starter. Preferably, the width of the first pattern 22 and the gap 23, taken in the circumferential direction of the target 14 are equal, to ensure a good accuracy of acquisition and processing. In addition, it has been found that good measurement accuracy is obtained for a number of patterns of at least 8.

The second zone 21 comprises a second single pattern 24 in the form of a color marker on the outer surface of the cage 6, for example of black color, in other words in this case the entire second zone is black in color.

During an engagement operation, the launcher 4 moves a total stroke C, for example 10 mm, between its rest position and its active position against the stop 9.

In Figure 3 is shown the launcher 4 equipped with its target 14 with a pinion 5 being engaged in the flywheel 15, more precisely, at a time when the predetermined critical engagement threshold of the pinion is reached. The threshold of critical engagement is materialized on the target 14 by the transition between the first zone 20 and the second zone 21. At this moment, the launcher 4 has traveled a predetermined longitudinal displacement threshold L representing a fraction of its total travel C, and the optical sensor 13 is opposite this transition. At this time again the teeth 7 of the pinion 5 are considered to have a sufficiently intermeshed part with those of the flywheel 15 to ensure the mechanical strength of the teeth in case of start order.

FIG. 4 shows the launcher 4 equipped with its target 14 in its active position, in other words in its engaged position with the flywheel 15 after the launcher 4 has traveled all of its stroke C. In this position, the optical sensor 13 is opposite the second zone 21 relative to the direction of launch indicated by the arrow referenced E in FIG. 1, more precisely at the upstream end of the target 14.

The operation illustrated by the timing diagram of FIG. 5 is as follows:

Before the instant t0 the launcher 4 is stationary, the same is true for the target 14 facing the optical sensor 13 at the first zone 20 (FIG. 2), at the downstream end of the target 14.

At the time t0, the control means trigger the rotation of the launcher 4. Therefore, the color patterns 22 and the intervals 23 scroll successively opposite the optical sensor 13. When the sensor 13 is facing a pattern 22 of black color, the reflected light intensity is, l _min , minimum, whereas when the sensor 13 is opposite a colorless interval, the reflected light intensity is l _max , maximum. The rotational scrolling of the first zone 20 thus generates a niche type sensor output signal as shown in FIG. 5. The acquisition and processing means 12 can then determine the rotation speed of the target 14, for example from the ratio between the width, taken in the circumference of the target of the color pattern 22 and the time T in the low state of the output signal of the optical sensor 13.

At time t1, the control means trigger the engagement of the launcher 4. The launcher 4 initiates its movement in translation towards the stop 9, in the direction of the arrow E (Figure 1). The acquisition and processing means 12 always control the rotational speed of the target 14. The sensor 13 is always facing the first zone 20, which makes it possible to deduce that the threshold of critical engagement is not reached. . The indicator S remains in the state which indicates this fact. At time t2 the launcher has moved so that the optical sensor 13 is now at the transition between the first zone 20 and the second zone 21 (FIG. 3). The predetermined critical commitment threshold is physically reached. In order to be certain that the critical engagement threshold is reached, the acquisition and processing means 12 verify by the coherence in time of the rotation speed of the target 14. Indeed, since the commitment critical is reached and exceeded, the launcher 4 is now in a position where the optical sensor 13 is next to the second zone 21. The output signal remains continuously low. It can therefore be considered that in the absence of a new rising edge beyond a delay, d, determined the sensor 13 is no longer opposite the first zone 20, which is therefore opposite the second zone 21 and therefore that the critical commitment is reached.

At time t3, the time el has elapsed without new appearance of a rising edge, the acquisition and processing means 12 considers that the pinion 5 is sufficiently engaged with the flywheel 15. The indicator S takes the value which indicates that the critical threshold of commitment is reached. Starting or restarting can then be safely authorized for the mechanical resistance of the teeth 7. The state remains low as long as the pinion is engaged.

Thus, according to the invention, the first zone 20 is dedicated to determining the rotational speed V of the launcher 4 and the two zones 20, 21 are dedicated to the detection of the predetermined longitudinal displacement threshold. The first zone 20 makes it possible to indicate that the predetermined longitudinal displacement threshold and therefore the critical engagement threshold is not reached while the second zone makes it possible to indicate that the predetermined longitudinal displacement threshold and therefore the threshold of critical engagement is achieved.

The described embodiment is not limiting of the invention. Indeed, in a variant the patterns may be in the form of grooves formed in the thickness of the cage 6 freewheel. In this case an optical sensor can still be used because the variation in thickness induces a variation in light intensity.

In another variant, the optical sensor may be replaced by a proximity sensor, for example a Hall effect sensor or a capacitive sensor. In this case the proximity sensor cooperates with patterns in the form of grooves, the variation in thickness inducing a variation in proximity of the outer surface to the sensor and therefore an output signal intensity variation. In addition, the system of the invention is suitable for determining, by means of a single sensor, two pieces of information which are a predetermined longitudinal displacement threshold and the rotational speed of any cylindrical machine element, such as a shaft, driven at the same time by a rotational movement about an axis and a translational movement along the same axis.

Claims

claims

1. System for detecting a predetermined longitudinal displacement threshold and for determining the rotational speed (V) of a cylindrical element driven by a translation movement along its central axis (XX) and of rotation around said central axis (XX), characterized in that it comprises a single sensor (13) connected to means for acquiring and processing (12) an output signal of the sensor, a target (14) disposed on the outer surface the cylindrical element adapted to cooperate with the sensor (13) to produce the output signal, said target (14) having a first zone (20) and a second zone (21) extending around the cylindrical element , the second zone (21) being contiguous with the first zone (20), and in that the first zone (20) is dedicated to determining the rotational speed (V) of the cylindrical element and the two zones ( 20, 21) are dedicated to the detection of the longitudinal displacement threshold predetermined tudinal.

2. System according to claim 1, characterized in that the first zone (20) comprises a plurality of a first pattern (22) extending parallel to the central axis (XX), each of the first patterns being spaced apart by a interval (23) identical.

3. System according to claim 1 or claim 2, characterized in that the second zone (21) comprises a second unit (24) single.

4. System according to one of claims 1 to 3, characterized in that the sensor (13) is arranged to appear opposite the transition between the first zone (20) and the second zone (21) when the cylindrical element has moved from the predetermined longitudinal displacement threshold.

5. System according to any one of claims 1 to 4, characterized in that the sensor is a proximity sensor.

6. System according to any one of claims 1 to 4, characterized in that the sensor is an optical sensor.

7. The system of claim 5 or claim 6 in its dependence on claim 2, characterized in that the sensor cooperates with a target (14) whose first pattern (22) is a groove made in the thickness of the cylindrical element.

8. System according to claim 6 in its dependence on claims 2 and 3, characterized in that the first pattern (22) and the second pattern (24) are presented as a color marker.

9. A starter (1) for an internal combustion engine equipped with a launcher (4) drivable longitudinally along its central axis (XX) and able to be rotated about said central axis (XX), characterized in that comprises a system according to any preceding claim adapted to detect a predetermined critical displacement threshold of the launcher (4) and determine the speed (V) of rotation of said launcher (4).

10. Starter (1) according to claim 9, characterized in that the launcher (4) comprising a cage (6) freewheel, the target (14) is disposed on the outer surface of the cage (6) freewheel .

1 1. Starter (1) according to claim 9 or claim 10, characterized in that the predetermined critical displacement threshold corresponds to a critical engagement threshold of a pinion (5) of the launcher (4) in a flywheel toothing.