JP4247683B2 - Planetary gear mechanism reduction starter - Google Patents

Description

  The present invention relates to a planetary gear mechanism reduction starter.

  In the starter motor, as an excessive torque absorbing mechanism for generating various excessive torques such as a meshing impact generated when the pinion meshes with the engine, Patent Document 1 below discloses that an outer cylinder is fitted to an internal gear, A pair of anti-rotation projections provided symmetrically on the outer peripheral surface of the cylinder are provided, and the pair of locking projections are fitted into the groove of the machine frame to fix the outer cylinder to the machine frame so that it cannot rotate. Furthermore, an excessive torque absorbing mechanism is proposed in which the inner peripheral surface of the outer cylinder and the outer peripheral surface of the internal gear are frictionally fitted so as to start relative rotation at a predetermined slip torque or more. Hereinafter, this mechanism is abbreviated as an outer cylinder fitting type shock absorbing mechanism.

According to this mechanism, since the precise manufacture of the clearance between the outer cylinder and the internal gear can be facilitated by adding the outer cylinder, a predetermined slip torque generated on the inner peripheral surface of the internal gear is obtained. Torque can be transmitted to the machine frame satisfactorily through the outer cylinder, and if a torque greater than the slip torque value occurs on the inner peripheral surface of the internal gear, the internal gear By rotating, the generation of excessive torque can be prevented.
Japanese Patent No. 3499177

  However, in the planetary gear mechanism decelerating starter having the outer cylinder fitting type shock absorbing mechanism described in Patent Document 1, when the thickness of the outer cylinder decreases, the internal gear starts to slide relative to the outer cylinder. The slip torque value (also simply referred to as the slip torque) is a deviation from the initial setting value, and the uneven wear occurs due to elliptical deformation between the outer cylinder and the internal gear. It was found that the problem of lubrication was difficult. These problems are alleviated by increasing the thickness of the outer cylinder, but in order to make the above problem within the practically acceptable range, for example, in the case of an outer cylinder that generates a slip torque at the normal use level, the thickness (locking) It is difficult to put the device into practical use because the portion having no projecting projections) must be 7 mm or more, and the physique weight and manufacturing cost of the device are inevitably increased.

  In addition, at the beginning of the mating operation between the internal gear and the outer cylindrical body, which have the same axial width and a small mating gap, the mating surface is damaged from the mating end surface and the lubricity of the mating surface deteriorates. However, there is a problem that the possibility of seizure increases.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is an outer cylinder fitting type shock absorbing mechanism type that is compact and lightweight, can be simplified in structure or manufacturing process, and has excellent lubrication reliability while ensuring high torque transmission. It is an object of the present invention to provide a planetary gear mechanism decelerating starter.

To achieve the above object, one reference invention and two independent inventions 1 and 2 are described and explained below. The reference invention and the independent inventions 1 and 2 are respectively a motor having a motor rotation shaft, a one-way clutch for driving an output shaft disposed in front of the motor in the axial direction, an outer peripheral side of a front end portion of the motor rotation shaft, And a planetary gear mechanism disposed behind the one-way clutch for transmitting torque from the motor rotating shaft to the one-way clutch, the motor rotating shaft and the output shaft are rotatably supported, and the one-way clutch And a center case surrounding the planetary gear mechanism, the planetary gear mechanism comprising: a sun gear provided on the motor rotation shaft; a planetary gear meshing with the sun gear; and an internal gear meshing with the planetary gear. Corresponding to the center case and having a locking projection or a locking groove on the outer peripheral surface to be locked to the center case. And a cylindrical outer cylinder that is frictionally coupled to the outer peripheral surface of the null gear at a predetermined impact torque or less.

The starter of the reference invention is a planetary gear mechanism decelerating starter with an outer cylinder-fitting type impact absorbing mechanism, wherein the outer cylinder has the number of the locking protrusions more than twice the number of the planetary gears. On the outer peripheral surface at a constant pitch in the circumferential direction. However, it is assumed that at least three planetary gears are provided as in the case of a normal planetary gear mechanism reduction starter. In this way, it is possible to realize a planetary gear mechanism decelerating starter of an outer cylinder fitting type shock absorbing mechanism type that is small and light and excellent in reliability.

The effects of this reference invention will be described below.

  The present inventors examined the planetary gear mechanism decelerating starter of the outer cylinder fitting type shock absorbing mechanism of Patent Document 1. As a result, it was found that the sliding torque fluctuates and the uneven wear occurs on the fitting surface when the thickness of the outer cylinder described above is small because of the following reason.

  In the planetary gear mechanism reduction type starter, a small number of planetary gears that mesh with the internal teeth of the internal gear radially inward of the internal gear exchange torque with the internal gear. That is, of the internal teeth of the internal gear, the internal teeth that actually transmit and receive torque to and from the planetary gear (hereinafter referred to as torque transfer internal teeth) are only a part of the internal gear, and as a result, the circumferential portions of the internal gear It can be seen that only a small part of is involved in torque transfer. On the other hand, in Patent Document 1, the outer cylindrical body fitted to the internal gear so as to be capable of relative rotation at a predetermined slip torque or higher finally transmits torque to the center case by the locking projection.

  Now, the state of torque transmission from the planetary gear through the internal gear and the outer cylinder to the center case will be described with reference to FIGS. FIG. 9 is a schematic view showing an example of a conventional anti-rotation protrusion, and FIG. 10 is an example of an anti-rotation protrusion of the present invention.

  100 is a planetary gear, 101 is an internal gear, 102 is an outer cylinder, 103a and 103b are locking protrusions of the outer cylinder 102, 104 is a center case, and 105 is a groove for preventing rotation of the center case 104. . For simplification, only one planetary gear 100 is shown at an intermediate position between the pair of locking projections 103a and 103b. The planetary gear 100 urges the internal gear 101 in the circumferential direction, that is, the y direction, at a point x indicating the torque transmission / reception internal teeth of the internal gear 101. Then, by this urging force, the arc portion between the planetary gear 100 and the locking projection 103a in each circumferential portion of the outer cylinder 102 is urged so as to swell in the radially outward direction A. And the locking projection 103b are urged so as to be recessed in the radially inward direction B. This is because the roundness of the outer cylindrical body 102 decreases, and as a result, the surface pressure between the internal gear 101 and the outer cylindrical body 102 fluctuates due to elliptical deformation, and finally the variation in slip torque and It means that uneven wear occurs on the inner peripheral surface of the outer cylinder.

  In other words, when this outer cylinder-fitted shock absorbing mechanism is employed in a planetary gear mechanism, particularly a planetary gear mechanism for a starter that generates a large impact torque, there are few torque transfer points on the internal gear. Bending stress in the radial direction is generated in the body. The sliding torque of this outer cylinder fitting type shock absorbing mechanism is proportional to the surface pressure between the internal gear and the outer cylinder x frictional joint area. The obtained slip torque value cannot be obtained.

  In other words, the present inventors have found that the cause of slip torque fluctuation and uneven wear in the conventional outer cylinder-fitted shock absorbing mechanism is the number of locking projections 103a and 103b between the outer cylinder and the center case. Since the angle between the torque transmitting / receiving internal tooth that is the torque generation point x and the locking projections 103a and 103b is large, it is necessary to largely change the direction of the force received by the outer cylinder. For this reason, it has been found that the outer cylindrical body is bent radially outward and inward to reduce its roundness.

The reference invention is made on the basis of the above problem recognition, and the protrusions for locking the outer cylindrical body are provided at a constant pitch in the circumferential direction or more than the number of planetary gears. In this way, as shown in FIG. 10, the angle between the torque receiving point that is the position of the locking projection 103c and the torque generating point x that is the position of the torque transfer internal teeth is small, and torque generation The torque transmitted from the planetary gear 100 to the outer cylinder 102 through the internal gear 101 at the point x is a pair of locking points as torque receiving points that are close to the torque generation point x with the torque generation point x in the circumferential direction. The outer cylinder 102 receives almost no bending force in the radial direction by being distributedly received by the protrusion 103c.

  This is because the torque generation point x and the locking projection 103c are close to each other, so that the angle θ between them is small, and the direction of the force Y at the torque generation point x and the force at the locking projection 103c. This is because the direction becomes substantially equal.

In addition, according to this reference invention, the thickness of the outer cylindrical body can be reduced because the outer cylindrical body has a large number of locking projections at a constant pitch while suppressing the above-described variation in slip torque and uneven wear. Therefore, it is possible to reduce the size and weight of the outer cylinder-fitted impact absorbing mechanism and reduce the manufacturing cost.

Furthermore, according to this reference invention, since the torque borne by one locking projection can be reduced as the number of locking projections increases, the radial height of the locking projection is shortened. Accordingly, the planetary gear mechanism having the outer cylinder-fitting type shock absorbing mechanism can be reduced in size and weight.

  In a preferred aspect, the locking protrusions of the outer cylinder are formed on the outer peripheral surface of the outer cylinder at a pitch substantially equal to the internal gear pitch of the internal gear. Here, “substantially equal” means 0.5 to 2.0 times. In this way, since the outer cylinder has the same number of locking projections as the internal gear, no matter which internal tooth of the internal gear becomes the torque transfer internal tooth, Because the torque can be received by the locking projections that substantially coincide with the circumferential direction, the above problems derived from the bending of the outer cylinder can be almost eliminated, and the thin, small, and lightweight outer cylinder is excellent in reliability. A body fitting type shock absorbing mechanism can be realized.

  In a preferred aspect, the locking projection of the outer cylinder has a gear shape. By doing so, the locking projection of the outer cylinder can be manufactured by the same gear cutting device as the internal teeth of the internal gear, so that the manufacturing process can be simplified.

  In a preferred embodiment, after forming the locking projection on the outer cylinder, a heat treatment process for curing the inner peripheral surface of the outer cylinder is performed. In this way, in addition to improving the wear resistance of the inner peripheral surface of the outer cylindrical body, the bending rigidity of the outer cylindrical body can be improved, and the strength of the locking projection can also be improved. Furthermore, in this aspect, in the heat treatment, a non-heat treatment layer having a thickness of 1 to 2 times the thickness of the heat treatment layer for curing formed on both peripheral surfaces of the outer cylinder is provided in the outer cylinder. Leave inside. If it does in this way, tenacity, ie, toughness, can be ensured, ensuring the bending strength and abrasion resistance of the above-mentioned outer cylinder, without unnecessarily increasing the radial thickness of the outer cylinder. Further, by reducing the thickness of the outer cylindrical body, it is possible to increase the tightening margin for obtaining a predetermined slip torque (for example, increase the polishing tolerance), so that the outer cylindrical body can be easily manufactured. For example, in order to obtain a sliding torque of 150 Nm, if the depth of the heat treatment layer for hardening of the outer cylinder (in this case, the carburization depth) is set to 0.8 mm, the outer cylinder has a portion without a locking projection. The thickness To is 0.8 × 3 = 2.4 to 3.2 mm, and a fitting tolerance width of 60 to 70 μm can be secured.

  In a preferred aspect, the front end portion of the outer cylindrical body extends radially inward along the front end surface of the internal gear, and serves as an internal gear retaining member forward in the axial direction of the internal gear. It is characterized by having an inner flange that restricts the movement of the inner wall. As a result, it is possible to prevent the internal gear from coming off, and it is possible to reduce the thickness of the outer cylindrical body while suppressing a decrease in rigidity of the outer cylindrical body.

  In a preferred aspect, the front end portion of the internal gear extends radially outward along the front end surface of the outer cylindrical body, and is fitted into the groove portion of the center case so as not to be displaced forward in the axial direction. It is characterized by having a ring plate-like outer flange. As a result, it is possible to prevent the internal gear from coming off, and it is possible to reduce the thickness of the outer cylindrical body while suppressing a decrease in the rigidity of the internal gear.

The planetary gear mechanism decelerating starter having the outer cylinder-fitting type impact absorbing mechanism of the first invention that achieves the above object is characterized in that the inner peripheral surface of the outer cylindrical body or the outer peripheral surface of the internal gear is an axially central portion. A contact surface portion that is frictionally coupled to each other, and a fitting guide surface portion that is chamfered in a tapered shape from the end of the contact surface portion toward the inner peripheral surface or the axial end of the outer peripheral surface, The contact surface portion and the fitting guide surface portion are covered with a solid lubricating film. However, the fitting guide surface portion is provided at least 1 mm or more in the axial direction, and the radial chamfer dimension of the fitting guide portion is at least the thickness of the solid lubricating film (usually 10 to 30 μm).

That is, in the first invention, a solid lubricating film made of an inorganic material or an organic material such as molybdenum disulfide or organic molybdenum is formed on the fitting surface, that is, the inner peripheral surface of the outer cylinder or the outer peripheral surface of the internal gear. Preferably, the solid lubricant film is coated after the fitting guide surface portion and the contact surface portion are subjected to a chemical conversion film treatment to roughen the surface to hold the solid lubricant. As a result, various mechanisms for supplying or holding the lubricant in the conventional grease lubrication can be omitted, so that it is possible to realize a small and easy to manufacture outer cylinder fitting type shock absorbing mechanism.

  It is a known technique to coat the sliding surface with the above-described solid lubricating film. However, in the planetary gear mechanism decelerating starter outer shock absorption mechanism to which the present invention is applied, the fitting clearance between the outer cylinder and the internal gear is very narrow in order to secure the sliding torque. Therefore, at the time of fitting both, the corner portion between the outer peripheral surface and the end surface of the internal gear, which is a radially inner member (inserting member), is a radially outer member (fitting member) of the outer cylindrical body There is a problem that the inner peripheral surface is damaged, or conversely, the corner portion between the inner peripheral surface and the end surface of the outer cylindrical body damages the outer peripheral surface of the internal gear. In such a case, if there is a solid lubricating film on these peripheral surfaces, the solid lubricating film will be damaged, and the damage of the solid lubricating film will expand from this part. In the planetary gear mechanism decelerating starter having a solid lubricant film, it is difficult to use the solid lubricant film between the internal gear and the outer cylinder.

Therefore, in the first aspect of the invention, the corners of the outer peripheral surface of the internal gear and the inner peripheral surface of the outer cylinder are chamfered into a fitting guide surface portion, and these corner portions are fitted on the other side when mating. We are trying to prevent the surface from being damaged. As a result, even in a planetary gear mechanism decelerating starter having an outer cylinder-fitted shock absorbing mechanism, a solid lubricating film can be employed on the mating surface between the outer cylinder and the internal gear. Therefore, it is possible to omit the holding and replenishment mechanism, and to simplify the structure and facilitate manufacturing and maintenance.

  The fitting guide surface portion of the present invention may be provided on either the outer peripheral surface of the internal gear or the inner peripheral surface of the outer cylindrical body, but the outer peripheral surface of the internal gear and the inner peripheral surface of the outer cylindrical body. If both are provided, the effect of preventing scratches during fitting can be further improved. In addition, when these fitting guide surface portions are provided on both the outer peripheral surface of the internal gear and the inner peripheral surface of the outer cylinder, the surface alignment becomes unnecessary at the time of manufacturing, which facilitates manufacturing.

  In a preferred embodiment, the axial width of the fitting guide portion is changed in order to give different sliding torque. That is, when changing the slip torque value for each model of planetary gear mechanism reduction starter, keep the diameter and shaft dimensions of the internal gear and outer cylinder constant, and change the axial width of the fitting guide surface. Thus, it is possible to easily cope with the change of the sliding torque, and substantially reduce the types of parts or semi-finished products thereof.

The planetary gear mechanism decelerating starter having the outer cylinder fitting type shock absorbing mechanism of the second invention is characterized in that the front end surface of the outer cylinder and the front end surface of the internal gear are connected to the center case via a first washer. The rear end surface of the outer cylinder and the rear end surface of the internal gear are supported by at least a second washer on the end surface of the motor yoke, and the yoke is connected to the center case by a through bolt. It is characterized by being fastened to.

That is, in the second invention, the outer cylinder is sandwiched between the end surface of the motor yoke and the step surface of the center case, and is fixed when the yoke and the center case are fastened by the through bolts. Further, a washer is extended radially inward while being in contact with both end faces of the outer cylinder, and the axial displacement of the internal gear is prevented by the pair of washers. Since the structure for axial displacement of the internal gear can be substantially omitted, simplification of the structure and reduction in size and weight of the apparatus can be realized. Further, since the outer cylindrical body can be made into a simple cylindrical shape, the surface pressure of the fitting portion can be made uniform, and the lubrication life of the fitting portion can be extended.

  A preferred embodiment of the starter of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following embodiments, and it is a matter of course that the technical idea of the present invention can be configured by combining other known techniques or other techniques having the same functions as those of other known techniques.

(Overall structure)
The starter of this embodiment has the same structure as an ordinary planetary gear mechanism reduction starter that is basically well-known except for a cylindrical body to be described later. Therefore, the entire starter structure is simplified without using the drawings. Only the main part will be described with reference to the main part axial sectional view shown in FIG. 1 and the main part enlarged axial sectional view of FIG.

  The starter includes a motor 2, an output shaft 3, a pinion gear 4, a magnet switch 5, a planetary gear mechanism 6, a one-way clutch 7, and a shift lever 8, and the pinion gear 4 is disposed in proximity to the engine-side ring gear 9.

(housing)
The starter housing that accommodates these components includes a front frame 11 that is a substantially bowl-shaped member having an open rear end, a center case 12, a cylindrical partition plate 13 with a hook, and a cylindrical yoke having both ends opened. 14. It is comprised by the end frame which is a substantially bowl-shaped member by which the front end was opened, and is arrange | positioned sequentially from an axial direction front side to a back side in the above-mentioned order. The center case 12 has a switch housing chamber with a rear end opening for housing the magnet switch 5 on the upper side, and a torque transmission mechanism housing with a rear end opening for housing the planetary gear mechanism 6 and the one-way clutch 7 on the lower side. It has chamber S. The yoke 14 and the end frame 15 have a motor chamber M for accommodating the motor 2 therein. The front frame 11 has a shift lever chamber C inside.

  The front frame 11 and the end frame 15 are fixed by through bolts 16 with the center case 12 and the yoke 14 sandwiched in the axial direction. Thereby, the partition plate 13 is clamped in the axial direction by the center case 12 and the yoke 14 to block the above-described torque transmission mechanism accommodation chamber S of the center case 12 and the above-described motor chamber M of the yoke 14. .

  The shift lever chamber C of the front frame 11 has a shift lever 8, the torque transmission mechanism housing chamber S of the center case 12 has a planetary gear mechanism 6 and a one-way clutch 7, and the switch chamber of the center case 12 has a magnet switch 5. However, the motor 2 is housed inside the yoke 14 and the end frame 15, respectively.

(Motor 2)
The motor 2 is a DC motor having a motor rotating shaft 20. The motor rotating shaft 20 is rotatably supported by the partition plate 13 and the end frame 15 via bearings. The yoke 14 contains a field coil and an armature, and the end frame 15 contains a commutator, a brush, and the like. However, the yoke 14 constitutes a part of the magnetic circuit of the motor 2 as a stationary yoke member of the motor 2. The armature and the commutator are fixed to the motor rotating shaft 20, and the tip of the motor rotating shaft 20 passes through the partition plate 13 and projects into the torque transmission mechanism accommodation chamber S of the center case 12. The motor 2 itself is well known and further description is omitted.

(Planetary gear mechanism 6)
The planetary gear mechanism 6 is accommodated in the lower part of the center case 12 adjacent to the partition plate 13. The planetary gear mechanism 6 includes a sun gear 61 formed at the tip of the motor rotating shaft 20, a ring-shaped internal gear 62, a plurality of planetary gears 63 that mesh with both gears 61, 62, and a planetary gear 63. The planetary gear pin 64 is rotatably supported via the carrier, the carrier 65 to which the planetary gear pin 64 is fixed, and the outer cylindrical body 66 fitted into the center case 12 and fitted into the internal gear 62. Then, the rotational speed of the motor rotating shaft 20 is reduced to the revolution speed of the planetary gear 63. The planetary gear pin 64 is press-fitted into the hole of the carrier 65 and fixed. In this embodiment, the carrier 65 is integrated with a clutch outer 71 of the one-way clutch 7 described later. The outer cylindrical body 66 will be described in detail later in order to make the feature of this embodiment.

(One-way clutch 7)
The one-way clutch 7 includes a clutch outer 71 that is integrated with the carrier 65 of the planetary gear mechanism 6, a substantially cylindrical tube 72 that is disposed on the radially inner side of the clutch outer 71 to form a so-called clutch inner, and a clutch outer. The clutch cam 73 is accommodated in a wedge-shaped cam chamber formed on the inner peripheral surface of 71 together with a roller spring (not shown). The clutch roller 73 transmits the torque transmitted from the inner peripheral surface of the clutch outer 71 to the outer peripheral surface of the tube 72.

  The clutch outer 71 is fitted to the tip of the motor rotating shaft 20 via a bearing so as to be relatively rotatable. The clutch outer 71 is a bowl-shaped member having a recess opening forward, and the bottom of the clutch outer 71 constitutes the carrier 65 described above. The clutch outer 71 is provided with a thrust washer (not shown) on the surface facing the rear end surface of the output shaft 3 in the axial direction, but the rear end surface of the output shaft 3, the front end surface of the motor rotating shaft 20, and the like. A gap is secured between them to prevent thrust transmission.

  The tube 72 has a bearing portion 72a that protrudes toward the front end side in the axial direction. The bearing portion 72 a is rotatably supported by the front end portion of the center case 12 via a ball bearing 74. The ball bearing 74 is provided integrally with the tube 72 by using the bearing portion 72a as an inner ring.

  The front end opening of the clutch outer 71 is closed by a washer 75 to prevent the clutch roller 73 from escaping, and the washer 75 is fixed by a cover 76.

(Output shaft 3)
The rear end portion of the output shaft 3 is fitted in the tube 72 so as to be able to advance and retract in the axial direction, and the bearing portion 72a of the tube 72 supports the output shaft 3 so that it can advance and retract in the axial direction and is relatively rotatable in this embodiment. Yes. A female helical spline 72 c is formed on the inner peripheral surface of the tube 72 from the bearing portion 72 a to the rear end of the tube 72. However, the female helical spline 72c is not formed from the front end portion of the bearing portion 72a to the front end portion of the female helical spline 72c, so that the output shaft 3 is located on the engine side (the left side in FIG. 1) of the front end portion of the female helical spline 72c. ) To function as a front end stopper for restricting the movement of the output shaft 3. Of course, the front end stopper function may be provided at another location. The front end portion of the output shaft 3 is supported by the front frame 11 via a bearing so as to be rotatable and slidable. A male helical spline 3 a that fits into the female helical spline 72 c of the tube 72 is formed on the outer peripheral surface of the rear end portion of the output shaft 3.

  13 a is a thrust washer that extends in the radial direction while contacting the front end surface of the partition plate 13, and receives the reverse thrust of the output shaft 3 through the planetary gear pin 64. The thrust washer 13a may be further extended radially outward and sandwiched between an outer cylinder 66 and a partition plate 13 which will be described later. The thrust washer 13a is a wear-resistant member formed in the shape of a ring plate, and when the output shaft 3 is moved backward by the shift lever, it is finally transmitted to the planetary gear pin 64 from the output shaft 3. Can be received by the thrust washer 13a. As a result, the inertial rotational energy of the output shaft 3 can be satisfactorily consumed by the friction between the planetary gear pin 64 and the thrust washer 13a, and the rotation of the output shaft 3 can be stopped quickly.

(Pinion gear 4)
The pinion gear 4 is spline-fitted to the front end portion of the output shaft 3 protruding forward from the front frame 11 so as to be relatively movable in the axial direction and non-rotatable, and is disposed between the pinion gear and the output shaft 3. The output shaft 3 is biased forward by being biased by a spring. A collar that restricts the forward movement of the pinion gear 4 is attached to the tip of the output shaft 3.

(magnetic switch)
The center case 12 separates the magnet switch 5 from the one-way clutch 7 and the planetary gear mechanism 6 below. The front end portion of the plunger of the magnet switch 5 protrudes into the front frame 11. The magnet switch 5 includes an exciting coil energized from the battery by closing the engine start switch, a plunger attracted by the magnetic force generated by the exciting coil, and a plunger when the energization to the exciting coil is stopped and the magnetic force disappears. However, the description is omitted because it is the same as a well-known normal one.

(Shift lever 8)
The shift lever 8 is swingably supported by a lever holder fixed to the center case 12, and the upper end portion of the shift lever 8 is connected to the front end portion of the plunger of the magnet switch 5 with a hook. The part is engaged between a pair of washers provided on the output shaft 3 to transmit the movement of the plunger to the output shaft 3, thereby moving the output shaft 3 forward and backward.

(Description of operation)
When the exciting coil of the magnet switch 5 is energized by closing the engine start switch, the plunger is attracted backward, and the plunger pushes the output shaft 3 forward via the shift lever 8.

  When the pinion gear 4 meshes smoothly with the ring gear 9 of the engine, the movable contact of the magnet switch 5 comes into contact with a set of fixed contacts, the motor 2 is energized and the motor 2 rotates. When the pinion gear 4 collides with the ring gear 9 without meshing with the ring gear 9, only the output shaft 3 further moves forward while pressing and contracting the pinion spring, whereby the pinion gear 4 relatively moves back on the output shaft 3. At this time, the pinion gear 4 rotates to a position where it can mesh with the ring gear 9 as the output shaft 3 moves, and the pinion gear 4 is pushed out and meshed with the ring gear 9 by the reaction force of the pinion spring, and then the magnet switch 5 is fixed. The contact is brought into contact with the movable contact, and the motor 2 generates a rotational force. When the meshing between the pinion gear 4 and the ring gear 9 is completed, the rotational force is transmitted from the pinion gear 4 to the ring gear 9 to crank the engine.

  When the engine start switch is opened after the engine is started, the magnetic force disappears due to the energization stop of the magnet coil 5 exciting coil, so that the plunger is pushed back by the reaction force of the return spring, and the movable contact of the magnet switch 5 becomes the fixed contact. Away from the power supply to the motor 2 is stopped. Further, when the plunger is pushed back, the output shaft 3 is returned via the shift lever 8, so that the rear end surface of the output shaft 3 comes into sliding contact with the clutch outer 71 and stops.

(Outer cylinder 66)
The outer cylinder 66 that characterizes this embodiment will be described below with reference to FIGS. FIG. 3 is a partially enlarged radial direction sectional view of the outer cylindrical body 66.

  As shown in FIGS. 1 and 2, the outer cylindrical body 66 is a cylindrical member having openings at both ends, and has a cylindrical shape that is fitted to the internal gear 62 and fitted to the outer peripheral surface of the internal gear 62. The main cylindrical portion 661 includes a rotation preventing projection 662 protruding from the outer peripheral surface of the main cylindrical portion 661 at a predetermined pitch in the circumferential direction. Each anti-rotation protrusion 662 extends in the axial direction, but may be formed in a spiral shape. The inner peripheral surface of the main cylinder portion 661 is frictionally coupled to the outer peripheral surface of the internal gear 62.

  As shown in FIG. 3, the rotation prevention protrusion 662 is formed in a gear shape in the radial direction, and meshes with a rotation prevention groove 121 that is recessed in the inner peripheral surface near the rear end opening of the center case 12. . Therefore, the number of the non-rotating groove portions 121 is equal to the number of the non-rotating protrusions 662. In addition, the radial shape of the anti-rotation protrusion 662 is not limited to the gear shape.

  8 is a ring-shaped retaining washer that restricts the axial displacement of the internal gear 62, and extends along the front end surface of the outer cylinder 66. The outer peripheral portion of the retaining washer 8 is clamped and fixed by the front end surface of the main cylindrical portion 661 of the outer cylindrical body 66 and the back end surface of the non-rotating groove portion 121. Thereby, the retaining washer 8 can restrict the movement of the internal gear 62 forward. It is preferable that the radially inner end of the retaining washer 8 is located radially outside the crest of the planetary gear 63.

  The rear end surface of the outer cylindrical body 66 is in contact with the front end surface of the thrust washer 13a. Specifically, the retaining washer 8, the outer cylindrical body 66, the thrust washer 13a and the partition plate are secured by fastening through bolts (not shown). 13 is clamped and fixed in the axial direction by the yoke 14 and the center case 12. As a result, the rear end surface of the internal gear 62 contacts the thrust washer 13a, so that the partition plate 13 is not worn even if the internal gear 62 rotates. The thrust washer 13a that receives the reverse thrust of the output shaft 3 through the planetary gear pin 64 is clamped and fixed by a through bolt together with the outer cylinder 66 and the washer 8, so the outer cylinder 66, the washer 8, and the thrust washer 13a. The groove processing on the center case 12 side for fixing can be easily performed. It should be noted that an anti-rotation projection similar to the anti-rotation projection 662 of the outer cylindrical body 66 can be provided on the outer peripheral portion of the washer 8. Thereby, rotation of the washer 8 by the accompanying rotation with the internal gear 62 can be regulated. Similarly, an anti-rotation projection similar to the anti-rotation projection 662 of the outer cylindrical body 66 can be provided on the outer periphery of the thrust washer 13 a or the partition plate 13.

  Hereinafter, important points in this embodiment will be described sequentially.

(Number of locking protrusions 662)
First, in this embodiment, the number of the rotation-preventing protrusions 662 provided on the outer peripheral surface of the outer cylindrical body 66 is at least twice the number of the planetary gears 63, and the number of the planetary gears 63 is three or more. ing. More preferably, the number of anti-rotation protrusions 662 of the outer cylindrical body 66 is 0.5 to 2.0 times the internal tooth pitch of the internal gear 62. In this way, as described above, even when a large torque is input to the internal gear 62, the internal teeth that receive the torque from the planetary gear 63 are applied to the rotation-preventing protrusion 662 of the outer cylindrical body 66 that is adjacent in the circumferential direction. Since torque can be transmitted, it is possible to prevent a decrease in the roundness due to the bending of the outer cylinder 66 described above. As a result, the surface pressure between the inner peripheral surface of the outer cylindrical body 66 and the outer peripheral surface of the internal gear 62 varies, causing uneven wear due to elliptical deformation, and the slip torque value fluctuating. It can be suppressed well. Moreover, since the minimum radial thickness of the outer cylinder 66 and the internal gear 62 can be reduced, the planetary gear mechanism 6 and the center case 12 surrounding the planetary gear mechanism 6 can be reduced in size and weight. In the above description, the number of the rotation-preventing protrusions 662 is set to be twice or more the number of the planetary gears 63, but may be the same as or more than the planetary gears 63.

(Thickness of outer cylinder 66)
According to this embodiment, the provision of a large number of anti-rotation protrusions 662 of the outer cylinder 66 as described above can reduce local stress concentration and deformation on the outer cylinder 66, so that the outer cylinder The radial thickness of 66 can be remarkably reduced as compared with the prior art. The thickness of the outer cylindrical body 66 referred to here is the distance between the outer diameter and the inner diameter at a portion where the anti-rotation protrusion 662 is not present. In this embodiment, the thickness means the root thickness To shown in FIG. To do.

  The fact that the thickness of the outer cylindrical body 66 can be reduced means that the tolerance of the inner diameter of the outer cylindrical body 66 can be increased in manufacturing, so that the manufacturing and assembly (assembly) of the outer cylindrical body 66 are markedly significant. The effect that it becomes easy is produced. This will be further described below.

  This phenomenon will be described in more detail.

  In the frictional contact between the outer cylindrical body 66 and the internal gear 62 in this embodiment, the sliding torque is proportional to the surface pressure × the frictional contact area × the diameter (the distance from the central axis to the frictional cylindrical surface). That is, it is easily understood that the sliding torque is proportional to the surface pressure, and this surface pressure depends on the tightening margin between the inner peripheral surface of the outer cylindrical body 66 and the outer peripheral surface of the internal gear 62. The outer cylindrical body 66 is fitted onto the outer peripheral surface of the internal gear 62 by press fitting. However, if the outer cylindrical body 66 is thin, elastic deformation in the radial direction of the outer cylindrical body 66 is facilitated. The range of the fitting tightening margin in the allowable surface pressure change range becomes large. In addition, the fitting interference | tightening allowance said here shall mean the tolerance | permissible_tolerance of the diameter of the internal peripheral surface of the outer cylinder body 66. FIG. This predetermined permissible surface pressure change range corresponds to a predetermined permissible slip torque range because the above-described slip torque is proportional to surface pressure × friction contact area × diameter. The allowable range of slip torque in this embodiment is predetermined. After all, the fitting tightening allowance under the condition of maintaining a constant slip torque allowable range can be increased as the minimum wall thickness To (also referred to as the minimum diameter width or the root width) To of the outer cylindrical body 66 decreases. .

  This is illustrated using the slip torque fitting tightening characteristic diagram of FIG. In FIG. 4, the vertical axis represents the value of the sliding torque T, and the horizontal axis represents the amount of the fitting tightening allowance. T1, T2, T3, and T4 are values (ratio) obtained by dividing the minimum diameter width To of the outer cylindrical body 66 by the thickness of the heat-treated hardened layer (for one surface). This ratio is used because it is convenient to indicate the minimum diameter width of the outer cylindrical body 66 on the basis of the heat-treated and hardened layer since the thickness of the heat-treated and hardened layer is required at a minimum. T1 is 2.4, T2 is 3.2, T3 is 4.8, and T4 is 5.6. δ1 indicates a fitting tightening allowance range when the ratio Ti of the minimum wall thickness To of the outer cylindrical body 66 is T1 (= 2.4) and the sliding torque is within the allowable sliding torque range, and δ5 indicates the outer cylinder. The range of the fitting tightening margin when the ratio Ti of the minimum wall thickness To of the body 66 is 5.6 and the sliding torque is within the allowable sliding torque range is shown.

  It is clear that a predetermined fastening allowance is required in the actual manufacturing, particularly in the manufacturing and fitting processes of the outer cylinder 66 and the internal gear 62. A fitting fastening allowance suitable for manufacturing is assumed to be δ1. On the other hand, the allowable slip torque T range ΔT between the outer cylinder 66 and the internal gear 62 is also a value determined in advance in the starter specification. The minimum diameter width ti of the outer cylinder 66 is the sum of the thickness of the heat treatment layer on the inner peripheral surface side, the thickness of the heat treatment hardened layer on the outer peripheral surface side, and the thickness of the internal non-heat treatment layer. It is necessary to set the minimum value of the thickness of the non-heat treatment layer to be equal to or greater than the thickness of the heat treatment cured layer. The thickness of the heat-treated cured layer needs to exceed a certain minimum value.

  From these conditions, the present inventors set the thickness of the non-heat-treated layer to 1 to 2 times the thickness of the heat-treated cured layer, thereby satisfying each of the above conditions, and the desired allowable slip torque T It has been found that an outer cylinder-fitting type impact absorbing mechanism having the following range can be manufactured without requiring high manufacturing conditions.

  Eventually, by providing a large number of anti-rotation protrusions 662 and reducing the minimum wall thickness To of the outer cylindrical body 66, the fitting tightening margin can be greatly increased, so that the internal gear 62 is press-fitted into the outer cylindrical body 66. It is understood that the mating can be very easy.

  More specifically, in the case of T1 in FIG. 4 and in the case of T4, the contact protrusion 5 is compared, so that the fitting tightening allowance is greatly increased as shown in FIG. And the manufacturing ease resulting from it can be realized. In other words, an increase in the minimum diameter width of the outer cylindrical body 66 causes a significant reduction in the fitting tightening allowance, which makes it extremely difficult to manufacture and fit the outer cylindrical body 66. In manufacturing, the fact that this fitting tightening margin can be secured large means that the polishing tolerance in the polishing process after the surface hardening process of the outer cylinder 66 described later can be increased. Further, as will be described later, when a solid lubricating film is formed on the inner peripheral surface of the outer cylindrical body 66, a surface roughening treatment (which is performed on the inner peripheral surface of the outer cylindrical body 66 before coating the solid lubricating film) ( It also means that the tolerance of the surface treatment for retaining the lubricant can be increased.

(Surface treatment of outer cylinder 66)
According to this embodiment, although the outer cylinder 66 can be thinned as described above, the inner peripheral surface of the outer cylinder 66 is a friction surface, so it is necessary to provide wear resistance. Carburizing treatment is the most productive technique for imparting wear resistance. Moreover, it is normal that the same heat treatment hardening layer is formed simultaneously also on the outer peripheral surface side of the outer cylinder body 66 for reasons such as wear prevention. However, as is known, when a heat treatment hardened layer is formed on the surface of the outer cylindrical body 66 by carburizing, the toughness of the outer cylindrical body 66 decreases. In order to ensure the toughness of the outer cylinder 66, it is necessary to leave at least an unheat-treated cured layer having a thickness equal to or greater than the heat-treated cured layer on the surface inside the outer cylinder 66. This indicates that when the thickness of the heat-treated cured layer is 1, the minimum thickness To of the outer cylindrical body 66 needs to be 3 or more. Preferably, the minimum thickness To of the outer cylinder 66 is preferably 3 to 5 times the heat treatment hardened layer (carburization depth), more preferably 3 to 4 times. As a result, the outer cylinder 66 can be made to the minimum practical thickness, so that the manufacturing tolerance (fitting tightening allowance) is increased, the fitting work is facilitated, and the one-way clutch 7 is downsized. can do.

  As the material of the outer cylinder 66, chrome molybdenum steel (SCM415) suitable for carburizing treatment is adopted, but is not limited to this, and other steel materials are adopted as long as surface hardening heat treatment such as carburizing is possible. It is also possible to do. When carburizing is performed in this way, the surface is usually polished by a predetermined amount. However, the allowable tolerance in this polishing processing is the allowable slippage due to the installation of the above-mentioned many non-rotating protrusions 662. The torque T can be greatly increased while maintaining the range ΔT.

  In this embodiment, in order to obtain a sliding torque of 150 Nm, the depth of the heat treatment layer for hardening of the outer cylindrical body 66 (here, the carburized depth) is 0.8 mm, and the minimum thickness To of the outer cylindrical body 66 is 2.4. By this, it was possible to secure a fitting tightening margin of about 70 μm. This manufacturing condition can also be applied to the internal gear 62.

(Solid lubricant film coating)
According to this embodiment, the inner peripheral surface of the outer cylindrical body 66 is coated with the solid lubricating film. By forming this solid lubricating film, it is possible to eliminate problems related to retention and replenishment of fluid lubricants such as grease and changes in fluidity due to temperature. The formation of the solid lubricating film is performed by first performing a surface treatment for retaining a lubricant (eg, tobbon bondeling) after the carburizing process and the subsequent polishing process, and then performing a coating process of molybdenum disulfide. As the coating process, a tumbler process, a spraying process, an immersion process or the like may be employed as appropriate. The film thickness of the solid lubricating film is preferably 10-30 μm. This solid lubricating film may be provided on the outer peripheral surface side of the internal gear 62.

  Eventually, in the manufacture of the fitting surface between the outer cylindrical body 66 and the internal gear 62, a tolerance including the above-described polishing process tolerance, lubricant holding surface process tolerance, and solid lubricant film thickness tolerance is generated. In addition, normally, since both the inner peripheral surface of the outer cylindrical body 66 and the outer peripheral surface of the internal gear 62 are subjected to heat treatment, the polishing process tolerance needs to be doubled. In order to secure such a total tolerance, that is, a fitting tightening allowance, it is necessary to reduce the thickness of the outer cylindrical body 66, and for this purpose, a large number of anti-rotation protrusions 662 of the outer cylindrical body 66 are provided as far as manufacturing costs allow. It is essential. Such an understanding of the problem is lacking in the conventional planetary gear mechanism decelerating starter having the outer cylinder fitting type shock absorbing mechanism.

(Fitting of outer cylinder 66)
However, when the above-described solid lubricating film is provided on the inner peripheral surface of the outer cylindrical body 66 or the outer peripheral surface of the internal gear 62, the corner portion of the inner peripheral surface of the outer cylindrical body 66 or the outer peripheral surface of the internal gear 62 is fitted. There is a possibility that the corner portion of the contact portion contacts the other side obliquely at the initial stage of fitting, and the solid lubricating film is damaged. When such a scratch is attached to the solid lubricating film, the solid lubricating film is easily peeled off from the site of the scratch, and there is a possibility that seizure or the like occurs. Therefore, in this embodiment, as shown in FIG. 5, fitting guide surface portions having a taper are provided at both axial end portions of the outer peripheral surface of the internal gear 62 and both axial end portions of the inner peripheral surface of the outer cylindrical body 66. I made the ingenuity.

  This fitting guide surface portion will be described in more detail with reference to FIG.

  The inner peripheral surface of the main cylindrical portion 661 of the outer cylindrical body 66 is divided into a contact surface portion 6610 and fitting guide surface portions 6611 and 6612 on both sides thereof. Similarly, the outer peripheral surface of the internal gear 62 is divided into a contact surface portion 6200 and fitting guide surface portions 6201 and 6202 on both sides thereof. The two contact surface portions 6610 and 6200 are in frictional contact. The fitting guide surface portions 6201 and 6202 of the internal gear 62 have tapered surfaces that become smaller in diameter as the distance from the contact surface portion 6200 increases. Similarly, the fitting guide surface portions 6611 and 6612 of the outer cylindrical body 66 also extend from the contact surface portion 6610. The taper surface becomes larger in diameter as it goes away. The taper angle is θ. However, the axial length of the fitting guide surface portions 6611, 6612, 6201, and 6202 is 1 mm or more, and the taper angle θ is 15 to 30 degrees. Further, as described above, at least the inner peripheral surface of the outer cylindrical body 66 and at least the outer peripheral surface of the internal gear 62 are subjected to thermosetting treatment such as carburization, and either is coated with a solid lubricating film.

  In this way, in the manufacture of the planetary gear mechanism reduction type starter having the outer cylinder fitting type shock absorbing mechanism, the solid lubricant film and the slide during the precise fitting operation of the outer cylinder 66 and the internal gear 62 are performed. In order to reduce the risk of deterring damage to the contact surface, it is possible to inhibit the lubricity from being lowered due to this flaw. In other words, the adoption of the taper fitting guide surface portion can prevent scratches when the solid lubricant film is fitted, so that it is possible to omit the lubricant holding and replenishment mechanism, which has been a problem of conventional grease lubrication, and to reduce the taper. By adjusting the axial length of the fitting guide surface portion, it is possible to cope with changes in the slip torque for each model without changing the axial length and diameter of the outer cylinder 66 and the internal gear 62.

(Modification)
A modification will be described with reference to FIG. In this embodiment, an inner flange 663 extending radially inward is provided at the front end of the outer cylinder 66 in the embodiment shown in FIG. By providing the inner flange 663, it is possible to prevent the internal gear 62 from deviating forward in the axial direction.

(Modification)
A modification will be described with reference to FIG. In this embodiment, in the embodiment shown in FIG. 2, a ring-shaped outer flange portion 666 extending radially outward is provided at the front end portion of the internal gear 62. The outer flange portion 666 is fitted into the rotation prevention groove portion 121 of the center case 12 and is in contact with the back end surface of the rotation prevention groove portion 121. Thereby, the deviation of the internal gear 62 in the axial direction can be prevented.

(Modification)
Instead of providing a locking projection on the outer peripheral surface of the outer cylindrical body 66, a locking groove may be provided, and a locking projection fitted to the locking groove on the center case side 12 may be provided. Of course.

(effect)
When torque exceeding the frictional force between the outer peripheral surface of the internal gear 62 and the inner peripheral surface of the main cylindrical portion 661 of the outer cylindrical body 66 is transmitted to the internal gear 62, the internal gear 62 rotates relatively. Thereby, even if an excessive torque is input to the internal gear 62, it can be absorbed well. The other effects have already been described in the previous section, so duplicate descriptions are omitted.

It is an axial sectional view showing a planetary gear mechanism decelerating starter having an outer cylinder fitting type shock absorbing mechanism of an embodiment. FIG. 2 is a cross-sectional view of the main part enlarged axis direction of FIG. 1. It is a partial enlarged front view of an outer cylinder. It is a characteristic view which shows the relationship between sliding torque, fitting interference, and the minimum thickness of an outer cylinder. It is principal part expansion axial direction sectional drawing which shows a deformation | transformation aspect. FIG. 6 is a partially enlarged axial direction sectional view of FIG. 5. It is principal part expansion axial direction sectional drawing which shows a deformation | transformation aspect. It is principal part expansion axial direction sectional drawing which shows a deformation | transformation aspect. It is explanatory drawing explaining distortion of the outer cylinder of the planetary gear mechanism decelerating starter which has the conventional outer cylinder fitting type impact absorption mechanism. It is explanatory drawing explaining the distortion of the outer cylinder of the planetary gear mechanism decelerating starter which has an outer cylinder fitting type impact absorption mechanism of this invention.

Explanation of symbols

C Shift lever chamber M Motor chamber S Torque transmission mechanism storage chamber To Minimum outer wall thickness (tooth thickness)
θ taper angle 2 motor 3 output shaft 3a male helical spline 6 planetary gear mechanism 7 one-way clutch 8 washer 11 front frame 12 center case 13 partition plate 13a thrust washer 14 yoke 15 end frame 20 motor rotating shaft 61 sun gear 62 internal gear 63 Planet gear 64 Planet gear pin 65 Carrier 66 Outer cylinder 71 Clutch outer 72 Tube 72a Bearing portion 72c Female helical spline 73 Clutch roller 74 Ball bearing 75 Washer 76 Cover 121 Center case non-rotation groove 6200 Contact surface portion 6201 Fitting guide surface portion 6202 Fitting guide surface portion 661 Main tube portion 6610 Contact surface portion 6611 Fitting guide surface portion 6612 Fitting guide surface portion 662 Anti-rotation protrusion 663 Inner flange 666 Outer flange

Claims (4)

A motor having a motor rotation shaft, a one-way clutch for driving an output shaft disposed in front of the motor in the axial direction, an outer peripheral side of a front end portion of the motor rotation shaft, and rearward of the one-way clutch; A planetary gear mechanism that transmits torque from a motor rotation shaft to the one-way clutch; and a center case that rotatably supports the motor rotation shaft and the output shaft and that surrounds the one-way clutch and the planetary gear mechanism. ,
The planetary gear mechanism includes a sun gear provided on the motor rotation shaft, a planetary gear meshing with the sun gear, an internal gear meshing with the planetary gear, and the center case, and is locked to the center case. A planetary gear mechanism having a locking projection or a locking groove on the outer peripheral surface and a cylindrical outer cylinder that is frictionally coupled to the outer peripheral surface of the internal gear at a predetermined impact torque or less. A decelerating starter,
The inner peripheral surface of the outer cylindrical body or the outer peripheral surface of the internal gear is a contact surface portion that is located in the axially central portion and is frictionally coupled to each other, and the inner peripheral surface or the shaft of the outer peripheral surface from the end of the contact surface portion. A planetary gear mechanism reduction mechanism comprising: a fitting guide surface portion chamfered in a tapered shape toward a direction end, wherein the contact surface portion and the fitting guide surface portion are covered with a solid lubricating film. Formula starter. In the manufacturing method of the planetary gear mechanism reduction type starter according to claim 1 ,
A method of manufacturing a planetary gear mechanism decelerating starter, characterized in that the axial width of the fitting guide portion is changed in order to give different sliding torques. A motor having a motor rotation shaft, a one-way clutch for driving an output shaft disposed in front of the motor in the axial direction, an outer peripheral side of a front end portion of the motor rotation shaft, and rearward of the one-way clutch; A planetary gear mechanism that transmits torque from a motor rotation shaft to the one-way clutch; and a center case that rotatably supports the motor rotation shaft and the output shaft and surrounds the one-way clutch and the planetary gear mechanism. ,
The planetary gear mechanism corresponds to a sun gear provided on the motor rotation shaft, a planetary gear meshing with the sun gear, an internal gear meshing with the planetary gear, and the center case, and is locked to the center case. A planetary gear mechanism having a locking projection or a locking groove on the outer peripheral surface and a cylindrical outer cylinder that is frictionally coupled to the outer peripheral surface of the internal gear at a predetermined impact torque or less. A decelerating starter,
The front end surface of the outer cylinder and the front end surface of the internal gear are supported on the step end surface of the center case via a first washer,
The rear end surface of the outer cylindrical body and the rear end surface of the internal gear are supported on the end surface of the yoke of the motor via at least a second washer,
A planetary gear mechanism decelerating starter characterized in that the yoke is fastened to the center case by through bolts. The planetary gear mechanism reduction starter according to claim 3 ,
The second washer is
A planetary gear mechanism characterized in that a reverse thrust of the output shaft is received through a rear end surface of a planetary gear pin that extends axially rearward from the outer of the one-way clutch and rotatably supports the planetary gear. Deceleration starter.

Images