JPH0716531Y2 - Clutch mechanism for motor retractor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a clutch mechanism used in a motor retractor which is provided in a seat belt device and winds a webbing by a driving force of a motor.

[Prior Art] In a motor retractor in which the driving force of a motor is used to wind up the webbing, the motor starts to drive when an occupant releases the wearing of the webbing, and the rotation of the motor is decelerated via a plurality of gears. By being transmitted to the winding shaft,
The webbing take-up shaft is adapted to wind up the webbing.

In such a motor retractor, a clutch is used because the motor and the webbing take-up shaft need to be disengaged from each other when the motor is not driven.

As shown in FIG. 7, the clutch mechanism has a clutch piece 68 supported by a return spring 66 so as to be movable along a guide portion 70 on the first rotating body 14 on the motor side. The clutch piece 68 is attached to the second rotating body 52 on the shaft side.
And an engaging protrusion 71 for engaging with. When the clutch piece 68 is driven by the motor and the first rotating body 14 starts rotating to reach a predetermined rotation speed, the return spring 66 is elastically extended by centrifugal force to advance in the diameter direction of the first rotating body 14. And engages with the engagement protrusion 71 to rotate the first rotating body 14 to the second position.
It is adapted to be transmitted to the rotating body 52.

However, in such a clutch mechanism, since it takes some time for the first rotating body 14 to reach a predetermined rotation speed in relation to the start-up characteristics of the motor, the mounting of the webbing and the start of the winding of the webbing are started. There was a problem that a noticeable time lag was generated and the passengers felt uncomfortable.

[Problems to be Solved by the Invention] In view of the above, the present invention provides a clutch mechanism for a motor retractor capable of quickly advancing the clutch piece to reduce the time lag between the dismounting of the webbing and the start of winding the webbing. Is an issue.

[Means for Solving the Problems] In the present invention, a clutch piece disposed so as to be capable of advancing and retracting along a guide portion on a first rotating body on a motor side advances by centrifugal force due to rotation of the first rotating body to wind up a webbing. In the clutch mechanism for the motor retractor that engages with the second rotating body on the shaft side, the guide portion tilts the advancing of the clutch piece in the direction opposite to the rotational direction of the first rotating body with respect to the diameter direction of the first rotating body. It has a structure to guide you to.

[Operation] In the present invention, which is the above means, in addition to the centrifugal force generated by the clutch piece, a part of the inertial force generated by the clutch piece causes the clutch piece to advance. Become.

[Embodiment] FIGS. 2 and 3 show a motor retractor to which an embodiment of the clutch mechanism according to the present invention is applied.

The frame 26 fixed to the vehicle body has a take-up shaft 28 pivotally supported between its leg plates 26A and 26B, and a webbing 30 is taken up at an intermediate portion of the take-up shaft 28. Inside the cover 31 attached to the outside of the leg plate 26A, an inertia locking mechanism interposed between the cover 31 and the winding shaft 28 is housed.
This inertia lock mechanism has a generally used structure, and detects the vehicle body acceleration or the withdrawal speed of the webbing 30 to instantly stop the rotation of the winding shaft 28 in the webbing withdrawal direction in case of an emergency of the vehicle.

A spring seat 32 is attached to the outside of the leg plate 26B, and a spring spring 34 for slightly tensioning the webbing 30 worn by an occupant is attached to the recess of the spring seat 32. The motor 36, which is the main driving force, penetrates the motor shaft 10 and the helical gear 12 attached to the tip thereof into the hole 40 of the spring seat 32, is housed in the motor case portion 41, and is fitted into the motor case portion 41. The motor cover 43 is fixed. The mainspring spring 34 has an outer end locked in the groove 44 of the spring seat 32, and an inner end engaged and connected to one end of the winding shaft 28 so as to pass through the hole 46 of the spring seat 32.
It is locked in the groove 48 of 20.

The mainspring 34 is covered with the spring seat 32 by the housing 50, and in the recess of the housing 50, the helical gear 12 for transmitting the rotation of the motor 36 to the winding shaft 28, the helical gear 14 as the first rotating body, and the first gear. The wheel 52 and the helical gear 18 as the two rotating bodies are housed. The helical gear 14 has its one side shaft supported by the hole 54 of the housing 50.
The shaft 56 on the other side penetrates the shaft center of the wheel 52 and the gear base 58.
Is rotatably driven by being engaged with the helical gear 12 protruding from the hole 62 of the housing 50.

As shown in FIG. 4, the helical gear 14 has a cylindrical space portion in the axial direction, and the wheel 52 is axially supported by the shaft 56 and is fitted into the cylindrical space portion. When the wheel is not rotating, the wheel 52 is rotatable with respect to the helical gear 14. Inside the helical gear 14, a metal clutch plate 68 as a clutch piece having a tip claw portion 68A is arranged.

As shown in FIG. 1, the clutch plate 68 is fitted in a recess 70 as a guide portion formed in the helical gear 14, and can slide back and forth between a pair of parallel guide walls 50A, 50B. Has become. The guide walls 50A and 50B are parallel to a directional line B which is inclined with respect to the diametrical line A of the helical gear 14 in the counter-rotational direction of the helical gear 14 (counter arrow direction in the figure). The inclination angle of the direction line B with respect to the diametrical direction line A is the centrifugal force (indicated by the vector C) generated in the clutch plate 68 by the rotation of the helical gear 14 and the inertial force generated in the clutch plate 68 (in this embodiment). The line of action of the resultant force (shown by vector E) (shown by vector D) and the direction line B coincide with each other.

The clutch plate 68 has a return spring whose one end is hooked on the protrusion 64 and whose middle portion extends parallel to the direction line B.
The other end of 66 is hooked. As a result, the clutch plate 68 is supported so as to be positioned at the limit of movement in the retreat direction when the helical gear 14 is not rotating.

On the other hand, on the inner circumference of the wheel 52, four engaging projections 71 that engage with the tip claw portions 68A of the clutch plate 68 are provided at equal intervals. When the helical gear 14 is not rotating, the engagement protrusion 71 is in a state of being separated from the tip claw portion 68A of the clutch plate 68, and the wheel 52 is rotatable with respect to the helical gear 14, but when the helical gear 14 rotates. The clutch plate 68 expands the return spring 66 by the centrifugal force and the inertial force and advances, and the tip claw portion 68A of the clutch plate 68
Is engaged with the engagement protrusion 71, and the rotation of the helical gear 14 is transmitted to the wheel 52.

The helical gear 18 meshes with the helical gear 16 that is coaxially fixed to the wheel 52, rotates about the shaft 20 that penetrates the hole 72 of the housing 50 as an axis, and the C-shaped spring 22 installed inside the helical gear 18. The rotation can be transmitted to the shaft 20 via the C-shaped spring fitting 24.

This will be described in detail. As shown in FIG. 5, the helical gear 18 has an axially deformable cylindrical space inside, and the inner wall has two locations so that the radius from the axial center becomes small. The raised portions 18A and 18B are formed. Meanwhile, the fixture 24
Is a C-shaped spring 2 having elastic pieces 22A, 22B which are non-rotatably engaged with the elliptical axis of the shaft 20 and undulate in the same rotational direction.
2 has one end locked in the groove 25 and fitted into the fixture 24, and the ridges 18A, 1 of the helical gear 18 are attached to the elastic pieces 22A, 22B.
8B is engaged to give a rotational force. The elastic pieces 22A, 22B and the raised portions 18A, 18B have a helical gear shape.
When the webbing 18 is rotated in the webbing take-up direction (arrow A), the raised portions 18A, 18B of the helical gear 18 elastically abut and engage the elastic pieces 22A, 22B, and the webbing is pulled out to rotate in the reverse direction (counterclockwise). When a certain amount of force is applied to the elastic pieces 22A, 22B by the force indicated by the arrow A), the elastic pieces 22A, 22B are bent and disengaged from each other so that the elastic pieces 22A, 22B rotate freely. The raised portions 18A and 18B are gently inclined from the top toward the webbing pull-out rotation direction so as to suppress the sound generated when the elastic pieces 22A and 22B idle.

The helical gear 12, the helical gear 14, the wheel 52, and the helical gear 18 are covered by a gear base 58 for a webbing winding state detecting device, and the webbing winding state detecting device is arranged on the gear base 58. That is, the shaft 76 engaged and connected to the winding shaft 28 projects from the hole 74 of the gear base 58, and the rotation of the small gear 77 fixed to the tip of the shaft 76 is internally transmitted via the inner gear 80 pivotally supported by the pin 78. It is adapted to be transmitted to the tooth gear 82. The internal gear 82 is axially supported by a notched annular guide 84 provided on the gear base 58 so that its tooth tips slide. The contact 86 protruding from the outer periphery of the internal gear 82 abuts the contact 88 in the full webbing winding state, and stops the motor 36 via a circuit (not shown).

The spring seat 32 and the housing 50 are attached to the leg plate 26B with screws 90 and 92, and the gear base 58 and the cover 94 are attached.
Is attached to the housing 50 by screws 96,98.

Next, the operation of this embodiment will be described.

When the occupant pulls out the webbing 30 for mounting, the winding shaft 28
Rotates against the urging force of the mainspring 34, and the shaft 20 rotates with this, and the rotation of the shaft 20 is transmitted to the wheel 52 via the C-spring mount 24, the C-spring 22, and the helical gear 18. However, since the motor 36 is stopped, the clutch plate 68 arranged on the helical gear 14 is disengaged from the engaging protrusion 71 formed on the wheel 52, and the rotation of the wheel 52 is prevented from rotating. Therefore, no rotational force is transmitted to the motor 36. Further, the rotation of the shaft 20 causes the internal gear 82 to rotate via the small gear 77 and the internal gear 80, so that the contact 86 pivots to a position corresponding to the webbing winding state.

When the occupant is wearing the webbing 30, a slight tension is generated on the webbing 30 by the urging force of the mainspring 34. When the occupant releases the wearing of the webbing 30,
This operation is detected by, for example, a bag switch, the motor 36 starts driving, and the driving force of the motor 36 winds the webbing 30 at a stretch. That is, the rotation of the motor 36 is
When the helical gear 12 is transmitted to the helical gear 14, and the helical gear 14 rotates, the clutch plate 68 advances and engages with the engaging protrusion 71 to rotate the wheel 52,
Is rotated by helical gear 18, C-shaped spring 22, C-shaped spring fitting 2
The webbing 30 is wound up by being transmitted to the winding shaft 28 via the shaft 20.

Here, since the clutch plate 68 is guided in the direction of the resultant force of the centrifugal force and the inertial force generated by the clutch plate 68,
The clutch plate 68 will advance not only by centrifugal force but also by inertial force, and will start advancing rapidly even when the rotation speed of the motor 36 is low due to the rise of the motor 36. Therefore, the time lag from when the wearing of the webbing 30 is released to when the winding of the webbing 30 is started is shortened, and the occupant does not feel discomfort.

In the case where the clutch plate 68 slides and moves as in the present embodiment, the sliding resistance of the clutch plate 68 decreases due to the movement of the clutch plate 68 in the above direction. The Clutch Plate 68 will start moving faster.

If the occupant suddenly pulls the webbing 30 during the winding operation, the C-shaped spring 22 and the gear 18 run idle to prevent an excessive load on the motor drive system.

The rotation of the take-up shaft 28 during the take-up of the webbing is simultaneously transmitted to the webbing take-up state detecting device, and when the webbing 30 is completely taken up, the contact 86 of the detecting device comes into contact with the contact 88 and the motor 36. To stop.

In addition, as schematically shown in FIG. 6, the first rotating body 10
If 0 is fixed to the motor shaft of the motor 36, the first rotating body 100 can be rotated at a high rotation speed before deceleration, and the centrifugal force generated by the clutch plate 68 can be increased, so that the time lag can be further shortened. can do.

[Effects of the Invention] As described above, in the clutch mechanism for a motor retractor according to the present invention, the guide portion inclines the advancing of the clutch piece toward the opposite rotational direction side of the first rotating body with respect to the diameter direction of the first rotating body. Since the guide piece is guided in the opposite direction, the clutch piece can be quickly advanced to shorten the time lag between the dismounting of the webbing and the start of winding the webbing.

[Brief description of drawings]

1 is a front sectional view showing an embodiment of a clutch mechanism for a motor retractor according to the present invention, and FIG. 2 is a schematic side sectional view of a motor retractor to which the clutch mechanism of the embodiment is applied.
3 is an exploded perspective view of FIG. 2, FIG. 4 is a partially detailed side sectional view of FIG. 2, and FIG. 5 is a partially detailed front sectional view of FIG.
FIG. 6 is a schematic side view of a motor retractor in which a clutch is provided in a portion different from the embodiment, and FIG. 7 is a front sectional view showing a conventional clutch mechanism corresponding to FIG. 14 ... Helical gear (first rotating body), 30 ... Webbing, 36 ... Motor, 52 ... Wheel (second rotating body), 66
...... Return spring, 68 …… Clutch plate (clutch piece), 70 …… Recess (guide section), 71 …… Engagement protrusion.

Claims (1)

[Scope of utility model registration request] 1. A clutch piece, which is arranged on a motor-side first rotating body so as to be able to move back and forth along a guide portion, advances by a centrifugal force generated by the rotation of the first rotating body to advance to a second rotating body on the webbing take-up shaft side. In the clutch mechanism for the motor retractor that engages with
A clutch mechanism for a motor retractor, characterized in that the guide portion has a structure for guiding the advancing of the clutch piece in a direction inclined in the direction opposite to the rotational direction of the first rotating body with respect to the diameter direction of the first rotating body.