STARTER FOR MOTOR VEHICLE

Description

[0001] The present invention relates in particular to an electric starter for an internal combustion engine, more particularly to a starter for an internal combustion engine of a motor vehicle.

[0002] French patent application FR 2 872 551 describes a motor vehicle starter having a lever end surface opposite the front face of the movable starter shaped like a cam. Other starters are described in FR2872551A1 and WO2013 / 014385A2.

[0003] The present invention aims to improve this type of starter.

[0004] The invention thus relates to an electric starter for an internal combustion engine according to the characteristics of the attached claim 1.

[0005] The invention allows, with regard to the gap required to electrically deactivate a starter contactor in the event of a starter solenoid jamming in the active position, for this gap to be distributed between the movement of the pivot axis and the movement of the pad. The variable pad clearance between the pad and the starter solenoid reduces the amplitude of the control lever's pivot axis movement, without completely replacing it. It is important for the contactor's moving core to accumulate kinetic energy to prevent any risk of the Z function jamming when cold.

[0006] It is important to remember that the Z-function allows the starter pinion, or the starter pinion itself, to move axially so that it engages with the internal combustion engine's ring gear during starting, and to disengage the pinion from the engine ring gear once the engine has started. The Z-function consists of the contactor, the moving core that slides within the contactor, and the lever attached to the moving core and mounted in the starter pinion, which slides along the rotor axis. Grease is applied between the moving core and the contactor to ensure smooth operation and the long-term durability of the moving core. However, at low temperatures, the grease tends to solidify, which slows the movement of the moving core or even blocks it. Therefore, it is crucial for the contactor's moving core to accumulate kinetic energy to prevent any risk of jamming.

[0007] Thus, in the rest position of the control lever and the starter, the variable play between the runner and the starter is minimal, resulting in a shorter free travel for the contactor's moving core before the starter is engaged. The kinetic energy accumulated by the moving core is therefore lower, and consequently, its energy dissipation in the tooth-to-tooth spring—the spring that pushes the starter toward meshing with the combustion engine's ring gear—is also reduced. The tooth-to-tooth spring is less compressed. The pinion's kinematics are thus increased; that is, the distance traveled by the starter before the contactor electrically closes is increased without requiring any change in the electrical current drawn by the contactor during tooth-to-tooth contact.

[0008] In one example of an implementation of the invention, during the operation of the starter and in the event of the starter being blocked in the active position, in particular in the event of the starter being blocked in a ring gear of the internal combustion engine, said variable pad play is arranged at the front of the pad, on the side of the starter where the starter is located.

[0009] Preferably, during starter operation and in case of starter blockage in active position, in particular in case of starter blockage in an internal combustion engine ring gear, when said variable pad play is generated, the pad is in contact with the starter at the rear of the pad, on the side opposite to the side of the starter where the starter is located.

[0010] As stated in claim 1, the skate has a shape arranged to obtain a lever ratio of the control lever on the launcher, a ratio which is constant or increasing over at least a portion of the launcher's movement from the rest position to the active position.

[0011] In one example of an implementation of the invention, on the portion of the launcher's movement from the rest position to the active position, the control lever and the launcher are arranged so that the lever ratio varies by passing through an inflection point.

[0012] The leverage ratio is preferably between 1 and 1.7.

[0013] In the rest position of the pivot axis and the control lever, the distance between a front facet of the skate and a front support facet of the launcher is notably zero in the case where the chain of ribs of this set is minimum and has a positive play in the case where the chain of ribs of this set is maximum.

[0014] In one embodiment of the invention, during a recoil phase of the pivot axis corresponding to the recoil of the control lever's pivot axis from the rest position to the lever support position without sliding the launcher, the variable pad clearance increases but does not reach the clearance necessary to obtain the cut-off clearance required to interrupt the motor's power supply. Then, during a pivot phase of the lever around its pivot axis in contact with the lever support, the variable pad clearance increases as the launcher slides forward, reaching its maximum once the pinion is in the active position. It is only when the pinion is in the active position, and the variable pad clearance is at its maximum, that the cut-off clearance is sufficient to interrupt the motor's power supply.

[0015] Preferably the front facet of the control lever's skid has a front cam arranged to bear against a front support facet of the launcher, this cam being arranged to come into contact with the front support facet of the launcher in a contact zone which is at a distance from the pivot axis, a distance which is variable, notably increasing, when the control lever pivots to bring the launcher into the active position.

[0016] Advantageously the front cam has a profile observed along the pivot axis, a profile which includes at least one bulge, in particular a profile in at least one arc of a circle, preferably in several arcs of a circle with different radii of curvature.

[0017] The rear face of the skate includes in particular a rear cam having a profile observed along the pivot axis, a profile which includes at least one bulge, in particular a profile in at least one arc of a circle, preferably in several arcs of a circle with different radii of curvature.

[0018] The circular arcs of the profiles of the front and rear cams of the skate are advantageously eccentric.

[0019] In one example of an implementation of the invention, the crown, in particular the arc of the circle, of the rear cam is further from the pivot axis of the control lever than the crown, in particular the arc of the circle, of the front cam.

[0020] The cam provides the control lever with a virtually constant or even increasing ratio over its operating range, ensuring that the available force on the skid is at its maximum at the beginning of its stroke. This helps to better overcome the inertia of the starter and increases the pressure exerted by the starter against the combustion engine's ring gear, thus reducing the risk of milling.

[0021] In one example of an implementation of the invention, the variable pad clearance is between 0.1 and 4 mm.

[0022] Advantageously the translation of the pivot axis of the control lever in the recoil phase is between 0.5 and 2 mm.

[0023] Preferably, the cut-off clearance between the fixed and moving cores of the contactor, obtained with the combination of the variable pad clearance and the translation of the pivot axis of the control lever in the advance phase, is between 2 mm and 5 mm.

[0024] The control lever, for example, includes studs that form the pivot axis.

[0025] If desired, the control lever can be made from a single piece.

[0026] The starter may include a slide in which the pivot axis of the control lever can move in translation.

[0027] This slide may include a stop arranged to stop the control lever in its lever support position.

[0028] In one example of an implementation of the invention, this stop is formed on an insert attached to the starter, in particular a plastic insert.

[0029] If necessary, the starter is designed to be able to start a number of cycles greater than 100,000, in particular 200,000. The starter can, for example, perform a Stop-Start function.

[0030] The invention will be better understood upon reading the detailed description that follows, a non-limiting example of an implementation of the invention, and upon examination of the accompanying drawing, in which: there figure 1 represents, schematically and partially, a motor vehicle starter conforming to an example of an implementation of the invention, the figures 2 to 4 represent, schematically and partially, a detail of the starter of the figure 1 , respectively in three different operating positions, and the figure 5 schematically illustrates the variation of the lever ratio as a function of the displacement of the moving core of a starter contactor. figures 1 to 4 .

[0031] We have represented on the figure 1 a rotating electrical machine forming a starter 1 of a motor vehicle.

[0032] This starter 1 comprises, on the one hand, a rotor 2, also called armature, which can rotate around a longitudinal axis X in order to drive a rotor shaft 6, and on the other hand, a stator 3, also called inductor, around the rotor 2.

[0033] The stator 3 includes a yoke 4 carrying a plurality of permanent magnets 5.

[0034] The rotor 2 comprises a rotor body 7 arranged opposite the magnets 5 of the stator 3, and a winding 8 wound in slots of the rotor body 7.

[0035] The winding 8 comprises a plurality of conducting wires forming, on either side of the rotor body 7, a front bun 9 and a rear bun 10.

[0036] The stator 3 and the rotor 2 are part of an electric motor 45.

[0037] The rotor 2 is provided, at the rear, with a commutator 12 comprising a plurality of contact pieces electrically connected to the winding 8.

[0038] A group of brushes 13 and 14 is provided for the electrical supply of the winding 8, one of the brushes 13 being connected to the ground of the device 1 and another of the brushes 14 being connected to an electrical terminal 15 of a contactor 17 via a wire 16.

[0039] Brushes 13 and 14 rub against the commutator 12 when the rotor 2 is rotating.

[0040] The contactor 17 includes, in addition to the terminal 15 connected to the brush 14, a terminal 29 connected via an electrical linking element, in particular a wire 30, to an electrical supply of the vehicle, in particular a battery, not shown.

[0041] The contactor 17 is capable of actuating a control lever 27 to move a starter 19 from a rest position, in which the starter 19 is located near the rotor 2, to an active position for driving the combustion engine. In this active position, the starter 19 is able to mesh with a ring gear of the combustion engine to drive it in rotation.

[0042] The launcher 19 includes, for example, a free wheel 22 and a washer 23 defining between them a groove 24 to receive the pad 25 of the control lever 27.

[0043] Skate 25 is split in such a way as to form a fork cooperating with the launcher.

[0044] The launcher 19 has a front support facet 51, for example on the free wheel 22, and a rear support facet 52, for example on the washer 23.

[0045] Of course, launcher 19 can be made in another way.

[0046] The launcher 19 is mounted in a sliding and rotating manner on a drive shaft 18.

[0047] The starter 19 also includes a drive element formed by a toothed pinion 21 and intended to engage with a drive component of the internal combustion engine, not shown. This drive component is, for example, a ring gear.

[0048] A speed reducer 20 is interposed between the rotor 2 and the drive shaft 18 in order to adapt the speed of the rotor 2 to the drive of the combustion engine.

[0049] This speed reducer 20 comprises an assembly including a toothed ring in which solar and satellite pinions are arranged in a manner known per se.

[0050] Contactor 17 is arranged to allow: When the starter is stopped, not in operation, a spring 40 of the contactor 17 pushes the control lever forward, namely towards the side of the starter where the starter 19 is located. When the vehicle's ignition key is turned, an electromagnet moves a movable core 41 of the contactor 17, which core 41 pulls the control lever 27 backward, this lever 27 being linked to the core 41 by a joint 42; during this recoil phase, the starter 19 is stationary. When the movable core 41 continues to recoil, the control lever 27, via the pad 25, pushes the starter 19 towards the ring gear to be driven; the movable core continues its travel until it is against a fixed core of the contactor 17.

[0051] In the illustrated example, the control lever 27 is arranged to axially move the launcher 19, the control lever being able to pivot about a pivot axis 50, this pivot axis 50 being movable over a predetermined linear stroke from a rest position to a lever support position in which the lever can pivot to bring the launcher 19 into the active position.

[0052] The control lever 27 has studs 54 forming the pivot axis 50, as illustrated in the figure 2 .

[0053] In the example described, the control lever 27 is made in one piece.

[0054] The starter includes a slide 55 in which the pivot axis 50 of the control lever can move in translation.

[0055] This slide 55 may include a stop 56 arranged to stop the control lever in its lever support position.

[0056] This stop is formed on an insert 57 attached to the starter, in particular a plastic insert.

[0057] During starter operation and in case of starter blockage in active position, in particular in case of starter blockage in the internal combustion engine ring gear, the electrical cut-off of the starter electric motor 45 is achieved by the movement of the pivot axis 50 over a distance Ja from its lever support position to its rest position and by the movement of the pad over a distance Jp from its position on the front support facet of the starter 51 to the rear facet of the starter 52, allowing the control lever 27 to pivot so as to obtain a cut-off clearance between the contactor plate and the terminals 29 and 15, which results in the axial displacement forward of the coupling axis by the value of the cut-off clearance.

[0058] Skate 25 has a shape arranged to obtain a lever ratio of the control lever on the launcher, a ratio which is constant or increasing over at least a portion of the launcher's movement from the rest position to the active position.

[0059] The leverage ratio represents the ratio b / a between distances a and b, where "a" is the vertical projection of the distance between the pivot axis 50 and the joint 42, and "b" is the vertical projection of the distance between the skate 25 and the pivot axis 50, as illustrated in the figure 3 .

[0060] On the portion of the launcher's movement from the rest position to the active position, the control lever and the launcher are arranged so that the leverage ratio b / a varies by passing through one or more inflection points.

[0061] This evolution can be seen on the figure 5 .

[0062] To the right of this curve of the figure 5, the moving core 41 is at its maximum distance from the fixed core, and the control lever and the launcher are in the rest position.

[0063] To the left of this curve, there is magnetic contact in the contactor 17, the moving core 41 being at the end of its travel.

[0064] We can see on this curve that the leverage ratio b / a has an inflection point.

[0065] The leverage ratio is preferably between 1.0 and 1.7.

[0066] During the recoil phase of the pivot axis, corresponding to the recoil of the control lever's pivot axis from its rest position to the lever support position without sliding the starter, the variable pad play increases but not enough to achieve the cutoff clearance required to interrupt the motor's power supply. Then, during the pivot phase of the lever around its pivot axis while in contact with the lever support, the variable pad play increases as the starter slides forward, reaching its maximum once the pinion is in the active position. Only when the pinion is in the active position, and the variable pad play is at its maximum, is the cutoff clearance sufficient to interrupt the motor's power supply.

[0067] The front facet 61 of the control lever skate has a front cam 62 arranged to bear against a front support facet 51 of the launcher, this cam being arranged to come into contact with the front support facet 51 of the launcher according to a contact zone which is at a distance from the pivot axis, a distance which is variable, notably increasing, when the control lever 27 pivots to bring the launcher into the active position.

[0068] Advantageously the front cam 62 has a profile observed along the pivot axis 50, a profile which includes at least one bulge, in particular a profile in at least one arc of a circle.

[0069] The rear facet 60 of the skate has a rear cam 63 having a profile observed along the pivot axis, a profile which has several arcs of circles with different radii of curvature.

[0070] The arcs of the profiles of the front 63 and rear 62 cams of the skate are advantageously eccentric.

[0071] In one example of an implementation of the invention, the arc of the rear cam 63 is further from the pivot axis of the control lever than the arc of the front cam 62.

[0072] The 63 cam provides the control lever with a virtually constant or even increasing ratio over its operating range, ensuring that the available force on the skid is at its maximum at the beginning of its stroke. This helps to better overcome the inertia of the starter and increases the pressure exerted by the starter against the combustion engine's ring gear, thus reducing the risk of milling.

[0073] In one example of an implementation of the invention, the variable pad clearance is between 0.1 mm and 4 mm.

[0074] Advantageously the translation of the pivot axis of the control lever in the recoil phase is between 0.5 mm and 2 mm.

[0075] The cut-off clearance between the fixed and moving cores of the contactor, obtained with the combination of the variable pad clearance and the translation of the pivot axis of the control lever in the advance phase, is between 2 mm and 5 mm.

Claims

1. Electric starter (1) for an internal combustion engine, more particularly a starter for an internal combustion engine of a motor vehicle, this starter comprising: - a starter drive assembly (19) able to move between a rest position and an active position in which the starter drive assembly is capable of starting the internal combustion engine, - an electric motor (45) capable of driving the starter drive assembly in rotation about an axis of rotation (X), - a control lever (27) arranged to move the starter drive assembly axially, the control lever being capable of pivoting about a pivot pin (50), this pivot pin being movable over a predetermined linear travel (Ja) from a rest position to a lever-pressing position into which the lever can pivot to bring the starter drive assembly into the active position, this control lever comprising at least one pad (25) arranged to cooperate with the starter drive assembly, - a contactor (17) arranged so as to enable, when the ignition key of the vehicle is turned, an electromagnet to cause a mobile core (41) of the contactor (17) to move, which core (41) pulls the control lever (27) backwards, this lever (27) being connected to the core (41) by an articulation (42), the pad (25) having a shape arranged to obtain a lever ratio of the control lever acting on the starter drive assembly (19), which ratio is constant or increasing over at least a portion of the movement of the starter drive assembly (19) from the rest position to the active position, the lever ratio representing the ratio b / a between distances a and b, "a" being the vertical projection of the distance between the pivot axis (50) and the articulation (42) and "b" being the vertical projection of the distance between the pad (25) and the pivot pin (50), the starter drive assembly comprising a guideway (55) in which the pivot pin (50) of the control lever can move in translation, characterized in that during operation of the starter and if the starter drive assembly should become jammed in the active position, in particular if the starter drive assembly should become jammed in a ring gear of the internal combustion engine, the electrical power to the electric motor of the starter is cut off by the movement of the pivot pin from its lever-pressing position toward its rest position and by the movement of the pad relative to the starter drive assembly in an opposite direction to the movement of the pivot pin from its lever-pressing position to its rest position.

2. Starter according to the preceding claim, characterized in that during operation of the starter and if the starter drive assembly should become jammed in the active position, in particular if the starter drive assembly should become jammed in a ring gear of the internal combustion engine, said variable pad clearance (Jp) is arranged at the front of the pad, on the same side of the starter as the starter drive assembly.

3. Starter according to one of the preceding claims, characterized in that during operation of the starter and if the starter drive assembly should become jammed in the active position, in particular if the starter drive assembly should become jammed in a ring gear of the internal combustion engine, when said variable pad clearance (Jp) is generated, the pad is in pressing contact with the starter drive assembly at the rear of the pad, on the opposite side of the starter to the starter drive assembly.

4. Starter according to any one of the preceding claims, characterized in that, on the portion of the travel of the starter drive assembly from the rest position toward the active position, the control lever and the starter drive assembly are arranged such that the lever ratio varies, passing through one or more points of inflection.

5. Starter according to one of the preceding claims, characterized in that, in a phase of recoil of the pivot pin (50) corresponding to recoil of the pivot pin of the control lever from the rest position to the lever-pressing position without causing the starter drive assembly to slide, the variable pad clearance increases.

6. Starter according to one of the preceding claims, characterized in that the front facet (61) of the pad of the control lever comprises a front cam (62) arranged to come to bear against a front bearing facet of the starter drive assembly, this cam being arranged so as to come into contact with the front bearing facet of the starter drive assembly along a contact zone which is at a distance from the pivot pin, which distance is variable, in particular increasing, when the control lever pivots in order to bring the starter drive assembly into the active position.

7. Starter according to one of the preceding claims, characterized in that the front cam (62) has a profile observed along the pivot pin, which profile comprises at least one bulge, in particular a profile in at least one arc of a circle, preferably in several circular arcs with different radii of curvature.

8. Starter according to one of the preceding claims, characterized in that the rear facet (60) of the pad comprises a rear cam (62) having a profile observed along the pivot pin, which profile comprises at least one bulge, in particular a profile in at least one arc of a circle, preferably in several circular arcs with different radii of curvature.

9. Starter according to one of Claims 6 to 8, characterized in that the circular arcs of the profiles of the front (62) and rear (63) cams of the pad are eccentric.

10. Starter according to the preceding claim, characterized in that the bulge, in particular the circular arc, of the rear cam is further away from the pivot pin of the control lever than the bulge, in particular the circular arc, of the front cam.

11. Starter according to one of the preceding claims, characterized in that the variable pad clearance (Jp) is comprised between 0.1 mm and 4 mm.