Seat belt retractor

Abstract

To adjust take-up force of a seat belt without impairing a function as a seat belt retractor with a motor for taking up a belt by force of the motor.SOLUTION: A seat belt retractor 1 includes: a spindle 10; a motor 20; a power transmission mechanism 30; a first rotation gear 33; a clutch mechanism 34; a return spring 40 which energizes take-up force to the spindle 10 in a direction for taking up a seat belt 2; a take-up force adjustment spring 50 which can accumulate force against take-up for reducing a magnitude of take-up force applied from the return spring 40 to the spindle 10; a housing 51 which can accumulate force against take-up in the take-up force adjustment spring 50 by rotation; and a connection mechanism 60 which connects the first rotation gear 33 to the housing 51 when the first rotation gear 33 rotates in a prescribed direction accompanying rotation of the motor 20 in a second direction opposite to a first direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a seat belt retractor. [Background technology]

[0002] Conventionally, retractors have been proposed or used as retractors for use in vehicle seat belt devices, which retract the seat belt by rotating a spindle and are configured to lock the rotation of the spindle using a locking mechanism to prevent the seat belt from being pulled out in the event of a vehicle collision (see, for example, Patent Documents 1 to 4).

[0003] As a retractor with a motor for a motorized seat belt (hereinafter sometimes referred to as "PP" (Pre-Pretensioner)) that winds up the seat belt by the force of a motor, there is known a retractor that rotates a spindle in the winding direction by the motor when a sudden vehicle deceleration state (for example, when there is a possibility of a collision) is detected by a sensor, winds up the seat belt by a certain amount to lightly restrain the occupant, and activates a pyrotechnic pretensioner to forcibly wind up the seat belt to securely restrain the occupant when a vehicle collision is detected. Furthermore, it is also known to assist the winding of the seat belt by a motor in order to eliminate slack when the seat belt is fastened and to improve the storability when the seat belt is released. In general, the former, lightly winding the seat belt when a sudden vehicle deceleration state is detected, is called "pre-crash operation", and the latter, auxiliary winding of the seat belt, is called "comfort operation". In addition, a device that weakens the winding force when the belt is fastened and strengthens the winding force when the belt is released is called a tension reducer, etc.

[0004] In such a motorized retractor, a clutch is interposed in the power transmission mechanism that transmits the power from the motor to the spindle. When performing the pre-crash operation and the comfort operation, the motor is rotated forward to engage the clutch and retract the seat belt. After the pre-crash operation and the comfort operation are completed, the motor is rotated backward to disengage the clutch, allowing the seat belt to be retracted and withdrawn normally.

[0005] As described above, in a motorized seat belt (Pre-Pretensioner) that winds up the belt using the power of a motor, the belt storage assist is performed by the motor, so there is an advantage that the winding force of the return spring (the biasing means that applies a biasing force for winding up the seat belt) can be set low.

[0006] Recently, a device has been proposed that is equipped with a spring force adjustment mechanism, which includes a spring for adjusting the winding force (sometimes called an FA spring, etc.) connected to the spindle in parallel with the return spring. The spring for adjusting the winding force is used to strengthen or weaken the force of the return spring, and is configured, for example, to adjust the winding force by rotating the housing of the spring for adjusting the winding force to change the number of turns. Incidentally, in the case of a configuration in which the housing is rotated by the final gear of a PP (Pre-Pretensioner) using an inertia clutch, the motor rotates at high speed to engage the clutch and transmit torque to the spindle when winding by the PP, while the motor rotates slowly to not engage the clutch when adjusting the winding force, so that the torque of the motor is not transmitted to the spindle. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2009-514731 A [Patent Document 2] JP 2005-035539 A [Patent Document 3] JP 2013-173515 A [Patent Document 4] DE 102021102381 A1 Summary of the Invention [Problem to be solved by the invention]

[0008] However, it is believed that each of the above-mentioned conventional mechanisms and devices has the following problems.

[0009] First, although tension reducers are devices that weaken the winding force when the belt is fastened and strengthen it when released, the force with which the user pulls out the belt is the same as with a normal seat belt, so conventional tension reducers cannot weaken the force required by the user when pulling out the belt.

[0010] Next, in the case of PP (a motorized seat belt that retracts the seat belt using the power of a motor), the seat belt retracting action by the motor may conflict with the user's operation, which may give the user a strange impression.

[0011] In addition, when the device equipped with the spring force adjustment mechanism uses an inertia clutch as described above, it is not suitable for operations such as winding the belt slowly with a high load. For example, when assuming that a belt extension suppression operation is performed to hold the occupant's body when driving on a curve where lateral G is applied, the belt needs to be wound slowly so as not to cause discomfort to the user until the belt fits the body, and at the same time, a high winding force is required to support the occupant's body. In this respect, a spring force adjustment mechanism using an inertia clutch is not suitable for such operations because it is difficult to wind the belt slowly, and even so, the spring force alone cannot exert a winding force sufficient to support the occupant.

[0012] Therefore, an object of the present invention is to provide a seat belt retractor having a structure that enables adjustment of the seat belt winding force without impairing the function of the motor-equipped seat belt retractor that winds up the belt using the force of the motor. [Means for solving the problem]

[0013] One aspect of the present invention is a seat belt retractor configured to retract a seat belt for a vehicle, comprising: A spindle for winding up the seat belt; A motor that generates power to rotate the spindle; a power transmission mechanism capable of transmitting power from the motor to the spindle; A first rotary gear that constitutes a power transmission mechanism and is rotatably disposed on a central axis of the spindle; a clutch mechanism provided in the power transmission mechanism that enables transmission of power from the motor to the spindle when the motor rotates in a first direction; A return spring that applies a winding force to the spindle in a direction in which the seat belt is wound up; a winding force adjusting spring connected to the spindle and capable of storing a counter winding force that reduces the magnitude of the winding force acting on the spindle from the return spring; a housing that is rotatably disposed on a central axis of the spindle and that is capable of storing a counter winding force in the winding force adjustment spring by rotating; a coupling mechanism that couples the first rotary gear to the housing when the first rotary gear rotates in a predetermined direction as the motor rotates in a second direction opposite to the first direction; The seat belt retractor is provided with:

[0014] In such a seat belt retractor, by adjusting (specifically, increasing) the magnitude of the counter-winding force provided by the winding force adjustment spring, which is capable of storing the counter-winding force, it is possible to reduce the magnitude of the winding force acting on the spindle from the return spring, thereby weakening the pulling force required by the user when pulling out the belt.

[0015] In addition, in such a seatbelt retractor, by adjusting the magnitude of the counter winding force by the winding force adjustment spring capable of storing the counter winding force, the seatbelt can be wound with an appropriate force by the return spring alone. Therefore, with this retractor, while being provided with a PP (a motorized seatbelt that winds up the seatbelt with the force of the motor) mechanism, it is possible to reduce the odd impression given to the user (for example, the odd impression that the user may have when the operation of winding up the seatbelt by the motor conflicts with the user's operation as described above).

[0016] Furthermore, in this seatbelt retractor, by using a clutch mechanism that does not utilize inertia, such as a one-way clutch, it is possible to slowly wind the belt with a high load, unlike conventional devices. Therefore, when performing a belt extension suppression operation to hold the occupant's body in place while driving on a curve where lateral G forces are applied, it is possible to slowly wind the belt and make it fit the body without giving the user any discomfort.

[0017] In the seatbelt retractor as described above, when the first rotary gear rotates in a predetermined direction, the predetermined direction may be a direction opposite to the direction in which the seatbelt is wound up.

[0018] In the above-described seat belt retractor, the connecting mechanism may be configured as a latch mechanism that is engaged when the first rotating gear rotates in a direction opposite to the direction in which the seat belt is retracted, connecting the first rotating gear to the housing.

[0019] In the seat belt retractor as described above, the latch mechanism may include a ratchet gear formed in the housing, and a pawl rotatably attached to the first rotating gear and engaging its toe with the ratchet gear only when the first rotating gear rotates in a direction opposite to the direction in which the seat belt is retracted.

[0020] In the seat belt retractor as described above, the latch mechanism may further include a pawl return spring that urges the tip of the pawl in a direction away from the ratchet gear, and a guide that brings the tip of the pawl closer to the ratchet gear when the first rotating gear rotates in a direction opposite to the direction in which the seat belt is wound up.

[0021] In the seat belt retractor as described above, the guide may be formed on a co-rotating ring that rotates together with the first rotary gear.

[0022] In the seat belt retractor as described above, a long hole may be formed in the co-rotating ring with which the protrusion of the first rotating gear engages, and the co-rotating ring may be capable of rotating relative to the first rotating gear with a stroke width corresponding to this long hole.

[0023] In the seat belt retractor as described above, when the first rotating gear rotates in the direction of winding up the seat belt by at least an amount that exceeds the stroke width, the pawl return spring may be configured to move the tip of the pawl, which has disengaged from the ratchet gear, away from the ratchet gear.

[0024] In the seat belt retractor as described above, the return spring may be formed of a spiral spring wound around the spindle.

[0025] In the seat belt retractor as described above, the winding force adjusting spring may be formed of a spiral spring wound around the spindle in the opposite direction to the return spring.

[0026] In the seat belt retractor as described above, the winding force adjusting spring may have its inner end fixed to the spindle and its outer end fixed to the housing.

[0027] In the seat belt retractor as described above, the winding force adjusting spring may be accommodated in a housing.

[0028] In the seat belt retractor as described above, the first rotary gear may be a final gear arranged at the end of a gear train that constitutes the power transmission mechanism.

[0029] In the seat belt retractor as described above, a clutch mechanism may be provided between the first rotary gear and the spindle.

[0030] The clutch mechanism in the above-mentioned seat belt retractor may include a one-way clutch. Effect of the Invention

[0031] According to the present invention, it is possible to provide a seat belt retractor having a structure that makes it possible to adjust the winding force of the seat belt without impairing the function of the motor-equipped seat belt retractor that winds up the belt using the force of the motor. [Brief description of the drawings]

[0032] [Figure 1] 1 is a perspective view showing a seat belt retractor according to an embodiment of the present invention; [Diagram 2] FIG. 2 is an exploded perspective view of the seat belt retractor. [Diagram 3] 2 is a cross-sectional view of the seat belt retractor taken along a cross section passing through the central axis of the spindle. FIG. [Figure 4]4 is an enlarged view of the final gear (first rotating gear), return spring, FA spring (winding force adjustment spring) and the surrounding areas in FIG. 3. FIG. [Diagram 5] 1 is an overall view of a seat belt retractor as viewed along the central axis of a spindle from the side where a return spring etc. are located. [Figure 6] FIG. 13 is a diagram showing a state in which the final gear is in an initial position. [Figure 7] 13 is a diagram showing a state in which the final gear has rotated in the winding direction from the initial position. FIG. [Figure 8] 13 is a diagram showing a state in which the final gear has rotated from the initial position in the clutch release direction. FIG. [Figure 9] 9 is a diagram showing a state in which the final gear in FIG. 8 has further rotated in the clutch release direction. [Figure 10] 13 is a diagram showing a state in which the final gear rotates in the clutch release direction and then rotates in the winding direction halfway through. FIG. [Figure 11A] FIG. 2 is an exploded perspective view of a friction ring, a coil spring, and a clutch housing. [Figure 11B] FIG. 2 is a side view of the friction ring, the coil spring, and the clutch housing in an assembled state. [Figure 12] 4 is a flowchart showing, for reference, an example of control in an existing motorized seat belt retractor when a user undoes his or her seat belt. [Figure 13] (A) A flowchart showing an example of control in an existing motorized seat belt retractor when a user unfastens the seat belt. (B) (C) A graph showing the change in the torque (counter-winding force) of the FA spring during the operation of the <c>1 is a graph showing changes in torque (counter-winding force) of the FA spring during operation. [Figure 14] FIG. 2 is an exploded perspective view of a motor, a power transmission mechanism, a file gear, a spindle, etc. [Figure 15] FIG. 2A is a diagram showing the initial state of the one-way clutch, and FIG. 2B is an enlarged diagram showing the periphery of a pawl for the one-way clutch. [Figure 16] 16A is a diagram showing the one-way clutch in a state in which the final gear has rotated a predetermined amount from the state in FIG. 15, and FIG. 16B is an enlarged view of the periphery of a pawl for the one-way clutch. [Figure 17] 17A is a diagram showing the one-way clutch in a state in which the final gear has rotated further from the state shown in FIG. 16, and FIG. 17B is an enlarged view showing the periphery of a pawl for the one-way clutch. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Hereinafter, the configuration of the present invention will be described based on an example of an embodiment shown in the drawings (see FIGS. 1 to 14).

[0034] <Configuration of seat belt retractor> A seat belt retractor 1 according to the present invention is a device for a vehicle configured to retract a seat belt 2. The seat belt retractor 1 of this embodiment is configured with a spindle 10 provided in a housing 3, a motor 20, a power transmission mechanism 30, a final gear (first rotary gear) 33, a clutch mechanism 34, a return spring 40, an FA spring (winding force adjustment spring) 50, an FA housing 51, a latch mechanism (connecting mechanism) 60, and the like (see Figs. 1 and 2, etc.).

[0035] The spindle 10 is a member that winds up the seat belt 2, and is provided in the housing 3 in a state that allows it to rotate forward and backward around a central axis 10x (see FIG. 2, etc.). For convenience, in this specification, the forward rotation direction of the spindle 10, etc. so as to wind up the seat belt 2 (counterclockwise, indicated as CCW in FIG. 5) will be referred to as the "winding direction," and the reverse rotation direction so as to let out the seat belt 2 (clockwise, indicated as CW in FIG. 5) will be referred to as the "clutch release direction" (see FIG. 5, etc.).

[0036] The motor 20 is a power source that generates power to rotate the spindle 10 (see FIG. 14). The motor 20 in this embodiment is provided, for example, in the lower part of the housing 3 (see FIG. 1, etc.). When the motor 20 is rotated in one direction (referred to as the "first direction" in this specification), power is transmitted by the clutch mechanism 34, and the spindle 10 rotates in the winding direction. When the motor 20 is rotated in a second direction opposite to the first direction, the final gear 33 rotates in the clutch release direction (see Figures 1, 5, etc.).

[0037] The power transmission mechanism 30 is a mechanism for transmitting the power from the motor 20 to the spindle 10. For example, in this embodiment, the power transmission mechanism 30 includes a motor gear 31, a transmission shaft (intermediate gear) 32, a final gear 33, and a clutch mechanism 34 (see Figs. 2, 14, etc.). The motor gear 31 is composed of a worm attached to the output shaft 21 of the motor 20 (see Fig. 14). The transmission shaft 32 is a member for transmitting the power of the motor 20 to the final gear 33. The transmission shaft 32 is provided with a first helical gear 32a meshing with the motor gear 31 and a second helical gear 32b meshing with the final gear 33 (see Figs. 2, 14, etc.).

[0038] The final gear 33 is one of the gears constituting the power transmission mechanism 30, and is composed of a large-diameter helical gear rotatably arranged on the central axis 10x of the spindle 10 (see FIG. 2, etc.). The final gear 33 of this embodiment is a gear arranged at the end of a gear train constituting the power transmission mechanism 30. A helical tooth (helical tooth) 33a that meshes with the second helical gear 32b of the transmission shaft 32 is formed on the outer periphery of the final gear 33. In addition, the final gear 33 is provided with a protrusion 33m, a pin 33p, and a protrusion 33t that protrude on the side opposite to the side where the housing 3 is located (see FIG. 2).

[0039] The clutch mechanism 34 is a mechanism for transmitting or blocking the rotation of the final gear 33 to the spindle 10, and is disposed between the final gear 33 and the spindle 10 (see Figs. 1, 2, etc.). In this embodiment, a so-called one-way clutch is used for the clutch mechanism 34, which is in an engaged state when the motor 20 is rotated in a first direction and transmits the rotation of the final gear 33 to the spindle 10, and is not engaged when the motor 20 is rotated in a second direction. The configuration of the one-way clutch itself is similar to that of a conventional seat belt retractor, and therefore detailed description thereof will be omitted in this specification, but for example, a one-way clutch equipped with a one-way clutch pawl (latch) 34b that engages with a ratchet gear 35a only when the final gear 33 rotates in one direction corresponds to the clutch mechanism (see Fig. 14).

[0040] The clutch mechanism 34 of this embodiment is composed of a friction type one-way clutch 34a including a one-way clutch pawl 34b, a one-way clutch friction ring 34f, a clutch housing 35, etc. (see Figs. 15 to 17). The operation of this friction type one-way clutch 34a from the initial state to the engaged state will be briefly described. In the initial state, the one-way clutch pawl 34b is not engaged with the ratchet gear 35a of the clutch housing 35 (see Fig. 15). When the motor 20 is rotated in the first direction from this initial state, the final gear 33 rotates clockwise in the figures (note that Figs. 15 to 17 show a state as viewed along the central axis 10x of the spindle 10 from the opposite side to the side where the return spring 40, etc. are located, and therefore, in Figs. 15 to 17, this clockwise rotation corresponds to the "winding direction"). When the final gear 33 rotates clockwise in the figure (i.e., in this case, the winding direction), the friction ring 34f for the one-way clutch tries to stay in place without co-rotating due to the action of friction (see FIG. 16). When the final gear 33 further rotates clockwise (winding direction) from there, the claw 34g of the friction ring 34f for the one-way clutch comes into contact with the pawl 34b for the one-way clutch, preventing the pawl 34b for the one-way clutch from co-rotating with the final gear 33 (see FIG. 17). Then, the pawl 34b for the one-way clutch moves while being guided toward the outer periphery along the guide 34h, and then the tooth tip 34c of the pawl 34b is engaged with the ratchet gear (internal teeth) 35a of the clutch housing 35 (see FIG. 17). Then, the friction type one-way clutch 34a is in an engaged state, and transmits the rotation of the final gear 33 to the spindle 10.

[0041] The return spring 40 is provided as a member that applies a winding force to the spindle 10 in a direction in which the seat belt 2 is wound (winding direction) (see Figs. 1, 2, etc.). In this embodiment, the return spring 40 is configured by a spiral spring that is wound in a spiral shape around the spindle 10 and housed in a spring cassette 41 (see Figs. 2 and 4). The return spring 40, which is configured by a spiral spring, has an inner end 40i fixed to the spindle 10 via a boss member 40b and an outer end 40o fixed to the spring cassette 41, and stores a biasing force according to the amount of rotation of the spindle 10 and applies a rotational torque to the spindle 10 (see Fig. 2, etc.). In this embodiment, when the seat belt 2 is pulled out by the user and the spindle 10 rotates in the clutch release direction, the return spring 40 is wound, stores a spring force corresponding to the amount of rotation of the spindle 10, and applies a force (winding force) to rotate the spindle 10 in the winding direction (see Figure 1, etc.).

[0042] The FA spring (winding force adjustment spring) 50 is connected to the spindle 10 and is provided as a member capable of storing a force (counter-winding force) that reduces the magnitude of the winding force acting on the spindle 10 from the return spring 40 (see FIG. 1, etc.). In this embodiment, the FA spring 50 is configured as a spiral spring wound around the spindle 10 in the opposite direction to the return spring 40 (see FIG. 2, etc.). The FA spring 50 is housed in the FA housing 51 with its inner end 50i fixed to the spindle 10 via a boss member 50b and its outer end 50o fixed to the rotatable FA housing 51 (see FIGS. 2, 4, etc.). When the FA housing 51 rotates, the FA spring 50 is wound and its spring force (torque) changes.

[0043] The FA housing 51 is a cylindrical housing rotatably arranged on the central axis 10x of the spindle 10. By rotating this FA housing 51 in one direction around the central axis 10x, it is possible to store a counter-winding force in the FA spring 50 (see FIG. 1, etc.). In the seat belt retractor 1 of this embodiment, when the FA housing 51 is rotated in the clutch release direction, the FA spring 50 is wound, storing a counter-winding force according to the amount of rotation, and canceling out and reducing the winding force in the winding direction stored in the return spring 40.

[0044] The latch mechanism (connecting mechanism) 60 is a mechanism for connecting the final gear 33 and the FA housing 51 to rotate together when the final gear 33 rotates in a predetermined direction (in this embodiment, the direction opposite to the direction in which the seat belt 2 is retracted, i.e., the clutch release direction described above). In this embodiment, a mechanism consisting of a ratchet gear 59, a pawl 61, a friction ring (co-rotating ring) 63, etc. is used as the latch mechanism 60, and when the final gear 33 rotates in the clutch release direction, the pawl 61 engages with the ratchet gear 59, thereby connecting the final gear 33 and the FA housing 51, and when the final gear 33 rotates in the retraction direction, the pawl 61 is released by the force of a pawl return spring 62, thereby separating the final gear 33 and the FA housing 51.

[0045] The ratchet gear 59 is a gear consisting of asymmetric teeth formed, for example, on the outer circumferential surface of the FA housing 51. The ratchet gear 59 in this embodiment is formed in a shape that allows the pawl 61 to be engaged only when the final gear 33 rotates in the clutch release direction (see FIGS. 5, 8, etc.).

[0046] The pawl 61 is a member provided so that its pawl tip 61t can be engaged with the ratchet gear 59 only when the final gear 33 rotates in the clutch release direction. The pawl 6 in this embodiment is rotatably attached to the pin 33p of the final gear 33, and is biased by the pawl return spring 62 in a direction in which the pawl tip 61t moves away from the ratchet gear 59 (in FIG. 5 and the like, a direction in which the pawl 61 rotates counterclockwise) (see FIG. 5, FIG. 6, and the like). The pawl return spring 62 is attached to the projection 33m of the final gear 33 (see FIG. 2 and the like). In this specification, the tip of the pawl 61 that engages with the ratchet gear 59 is referred to as the "pawl tip", but this is merely a name for convenience, and it goes without saying that the name and specific shape are not particularly limited as long as it is formed to engage with the ratchet gear 59.

[0047] The friction ring (co-rotating ring) 63 is a disk-shaped or annular member disposed between the final gear 33 and the FA housing 51 (see FIG. 2, etc.). The friction ring 63 has an elongated hole 63h formed along the circumferential direction, with which the protrusion 33t of the final gear 33 engages (see FIG. 2, FIG. 5, FIG. 11A, etc.). The friction ring 63 is rotatable relative to the final gear 33 at a stroke width corresponding to the elongated hole 63h, and when the final gear 33 rotates beyond the stroke width, the friction ring 63 co-rotates with the final gear 33. A coil spring 36 is provided between the friction ring 63 and the clutch housing 35 (see FIG. 2, FIG. 11A, FIG. 11B). The coil spring 36 generates friction between the friction ring 63 and the clutch housing 35. Due to this friction force, when the final gear 33 rotates, the friction ring 63 tries to stay in place without co-rotating. Furthermore, a guide 63g is formed in the friction ring 63 (see FIG. 2, etc.).

[0048] The guide 63g is formed on the friction ring 63 so as to bring the tip 61t of the pawl 61 close to the ratchet gear 59 when the final gear 33 rotates in the clutch release direction (see FIG. 5, etc.). In this embodiment, an inclined edge formed in a cutout portion on the outer periphery of the friction ring 63 functions as the guide 63g (see FIG. 11A, etc.). The guide 63g guides the tip 61t of the pawl 61 so as to bring it close to the ratchet gear 59 (see FIG. 8, etc.).

[0049] <Seatbelt retractor operation> The operation of the seat belt retractor 1 of this embodiment configured as described above will be described below (see Figs. 6 to 10, etc.). In the seat belt retractor 1 of this embodiment, other members perform predetermined operations in conjunction with the final gear 33, so the description will be centered on how the other members move in conjunction with the rotational operation of the final gear 33.

[0050] [Initial position (Fig. 6)] The seat belt retractor 1 in the initial position is in the state shown in FIG.

[0051] [When the final gear 33 rotates in the winding direction from the initial position (Fig. 7)] When the motor 20 is rotated in the first direction, the final gear 33 rotates from the initial position in the winding direction. The pawl 61 attached to the final gear 33 moves in the winding direction together with the final gear 33. When the protrusion 33t on the final gear 33 abuts against the left end of the long hole 63h of the friction ring 63 in the figure, the friction ring 63 also rotates in the winding direction together with the final gear 33. If power is transmitted by the clutch mechanism 34, the spindle 10 also rotates in the winding direction. At this time, the FA spring 50, the inner end 50i of which is fixed to the spindle 10 via the boss member 50b, also rotates in the winding direction. The FA housing 51 also rotates in the winding direction together with the FA spring 50, which is not energized and remains in a neutral state.

[0052] [When the final gear 33 rotates from the initial position in the clutch release direction (Figure 8)] When the motor 20 is rotated in the second direction, the final gear 33 rotates from the initial position in the clutch release direction. When the final gear 33 rotates in the clutch release direction, the friction ring 63 tries to stay in place without rotating with the final gear 33 by the stroke width corresponding to the long hole 63h. While the friction ring 63 stays in place in this manner, the tip 61t of the pawl 61 abuts against the guide 63g of the friction ring 63 and is guided down in the axial direction of the spindle 10, and is engaged with the ratchet gear 59 of the FA housing 51.

[0053] [When the final gear 33 further rotates in the clutch release direction (Figure 9)] When the final gear 33 further rotates in the clutch release direction, the projection 33t on the final gear 33 abuts against the right end of the long hole 63h of the friction ring 63 as viewed in the figure, and thereafter the friction ring 63 rotates together with the final gear 33 in the clutch release direction. At this time, the pawl 61 engaged with the ratchet gear 59 rotates the FA housing 51 in the clutch release direction. When the FA housing 51 rotates in the clutch release direction, the FA spring 50 is wound, a counter-winding force is stored, and the torque of the FA spring 50 increases. Then, the belt winding force (the force that tries to wind up the seat belt 2 in the entire seat belt retractor 1) is the difference obtained by subtracting the torque (counter-winding force) stored in the FA spring 50 from the torque (winding force) stored in the return spring 40, that is, Belt winding force = torque of return spring 40 - torque of FA spring 50 As a result, the belt winding force decreases as the counter winding force increases, resulting in a low winding force state.

[0054] [When the final gear 33 rotates in the winding direction (Figure 10)] When the final gear 33 is rotated in the winding direction from the state shown in FIG. 9, the friction ring 63 does not rotate with the final gear 33 and tends to remain in place. At this time, the claw tip 61t of the pawl 61 biased by the return spring 40 disengages from the ratchet gear 59 of the FA housing 51 along the guide 63g of the friction ring 63, and the claw tip 61t of the pawl 61 disengaged from the ratchet gear 59 separates from the ratchet gear 59 and is released from the locked state until the final gear 33 rotates at least an amount exceeding the stroke width of the length of the long hole 63h. The FA housing 51 from which the pawl 61 has been disengaged rotates in the winding direction due to the torque (counter-winding force) stored in the FA spring 50, and stops rotating when the torque of the FA spring 50 disappears and the neutral state is reached. When the torque of the FA spring 50 disappears in this way, Belt winding force = torque of return spring 40 - torque of FA spring 50 (disappears at this point) In this way, the torque of the FA spring 50 disappears and does not act on the spindle 10, so the belt winding force = the torque of the return spring 40, and the winding force becomes maximum.

[0055] <Seatbelt retractor control> The control of the seat belt retractor 1 when the user unfastens the seat belt 2 will be described (see Figs. 12 and 13). Although not particularly shown, unfastening the seat belt 2 specifically refers to the user releasing the tongue (not shown) of the seat belt 2 from the buckle (not shown) to release the seat belt from its fastened state. The fact that the seat belt 2 has been unfastened can be detected, for example, by a buckle switch (not shown) built into the buckle. The following describes how the seat belt retractor 1 controls the seat belt 2 to retract the seat belt 2 when it has been unfastened.

[0056] First, for reference, an example of control in an existing motorized seat belt retractor will be described (see FIG. 12). When a buckle switch detects that a user has unfastened the seat belt (step SP21), a control device (not shown) rotates the motor in a first direction and rotates the spindle in a winding direction to wind up the seat belt 2 (step SP22). When the operation of winding up and storing a predetermined amount of the seat belt is completed (Yes in step SP23), the motor is stopped once (step SP24), rotated in a second direction (step SP25), and stopped again (step SP26). Here, the seat belt is wound up only by the force of the motor.

[0057] Next, an example of control in the seatbelt retractor 1 with the FA spring 50 according to this embodiment will be described (see FIG. 13). When the buckle switch detects that the user has released the seatbelt 2 (step SP11), the control device (not shown) rotates the motor 20 in the first direction (step SP12). While the motor 20 is rotating in the first direction (in FIG. 13, After this period (which may be a short time), the latch mechanism 60 is released, the pawl 61 is disengaged, the FA housing 51 rotates, and the torque (counter winding force) of the FA spring (winding force adjustment spring) 50 weakens (see FIG. 13B). When the torque (counter winding force) of the FA spring 50 disappears and becomes 0 (zero), the motor 20 is then stopped once (step SP13). Note that in this SP13, the determination may be based on, for example, a condition that "belt winding amount>storage determination threshold value." When the torque (counter winding force) of the FA spring 50 disappears and the belt winding force becomes maximum, and the operation of winding up and storing the seat belt 2 by a predetermined amount using the winding force of the return spring 40 is completed (Yes in step SP14), the motor 20 is rotated in the second direction (step SP15), and while the motor 20 is rotating (in FIG. 13, the torque (counter winding force) of the FA spring 50 disappears and becomes 0 (zero), the motor 20 is stopped once (step SP16). <c>The FA spring 50 is wound up to store torque (counter-winding force) (see FIG. 13(C)). A predetermined torque (counter-winding force) is stored in the FA spring 50, and the belt winding force is set to a low state.

[0058] In the case of an existing motorized seat belt retractor, the torque (winding force) of the return spring is set to a low value in advance to reduce the uncomfortable feeling felt by the user, while the motor assists the winding to ensure that the seat belt is wound and stored (see FIG. 12). In contrast, in the case of a seat belt retractor 1 of the present embodiment, which has an FA spring 50, the torque (winding force) of the return spring 40 can be set to a normal strength because the uncomfortable feeling can be reduced by the action of the FA spring 50. Therefore, if the latch mechanism 60 is released to put the FA spring 50 in an inoperative state, the seat belt 2 can be wound up to the stored position by the torque (winding force) stored in the return spring 40. The above-described control (see FIG. 13) is suitable for reliably winding the seat belt 2 while reducing the uncomfortable feeling based on such a configuration. Moreover, in the case of a configuration in which the seat belt 2 is wound up mainly by using the torque (winding force) stored in the return spring 40, as in the present embodiment, Spring winding feels more natural The motor only needs to be driven for a shorter time than when the belt is wound up by the motor alone (the latch mechanism 60 can be released by rotating the motor 20 in the first direction for a short time, and the torque (counter-winding force) of the FA spring 50 can be eliminated). As a result, the motor drive time is shorter, and noise and electrical noise during motor drive are reduced, resulting in energy savings and low noise. Such advantages can be obtained.

[0059] Further advantages of the seat belt retractor 1 of this embodiment include the following.

[0060] First, in the seat belt retractor 1 of this embodiment, by adjusting (specifically, increasing) the magnitude of the counter-winding force produced by the FA spring (winding force adjustment spring) 50, which is capable of storing a counter-winding force, it is possible to reduce the magnitude of the winding force acting on the spindle 10 from the return spring 40, thereby weakening the pulling force required by the user when pulling out the belt.

[0061] In addition, in the seat belt retractor 1 of this embodiment, the magnitude of the counter winding force by the FA spring (winding force adjustment spring) 50 capable of storing the counter winding force is adjusted, so that the seat belt 2 can be wound with an appropriate force by the return spring 40 alone. Therefore, according to this seat belt retractor 1, while having a mechanism of PP (a seat belt with a motor 20 that winds the seat belt 2 by the force of the motor 20), when PP driving is requested while the belt is fastened (for example, when a sudden deceleration state of the vehicle such as when a collision is possible is detected by a sensor), the motor 20 is driven in the first direction to drive the seat belt 2 in the winding direction, and at this time, the latch mechanism 60 is released to eliminate the counter winding force of the FA spring 50, so that the belt winding force can be instantaneously increased. In this case, even if the belt winding force increases, the force of the motor 20 is stronger, so that the user is unlikely to feel uncomfortable. When the above-mentioned PP driving is completed, the motor 20 is driven in the first direction to store the counter winding force of the FA spring 50, so that the belt winding force can be set to a weak state again. In this way, according to the seatbelt retractor 1 of the present embodiment, the belt winding force can be adjusted without impairing the function of the conventional PP.

[0062] In the case of a conventional device using an inertia clutch, although the restriction on the amount of rotation when rotating the FA housing is eliminated, the mechanism becomes complicated, and the inertia clutch cannot accommodate a mode in which the seat belt is wound slowly with the force of the motor. This mode is necessary, for example, when performing a belt extension suppression operation to hold the body of the occupant when driving on a sharp curve where lateral G is applied. However, the inertia clutch cannot accommodate a situation in which the torque of the motor is required to support the occupant, while the seat belt must be wound slowly to avoid giving a strange feeling. In this regard, the seat belt retractor 1 of this embodiment, which is equipped with a clutch mechanism 34 including a friction type one-way clutch 34a and an FA spring (winding force adjustment spring) 50 for adjusting the winding force of the return spring 40 for winding the seat belt using the same motor 20 as a power source, is capable of handling a mode in which the belt is wound slowly with a high load, unlike the conventional device. Therefore, for example, when the belt extension suppression operation is performed to hold the occupant's body when driving a curve where lateral G is applied, the belt can be slowly wound up to fit the body without giving the user a sense of discomfort. Moreover, in this embodiment, the torque of the return spring 40 is adjusted by using a mechanism in which the counter-winding force is stored when the motor 20 is driven in the second direction (clutch release direction) and released when driven in the first direction (winding direction), thereby achieving both the mechanism of the clutch mechanism 34 including the friction type one-way clutch 34a described above and the mechanism for adjusting the spring force.

[0063] The above-described embodiment is one example of a preferred embodiment of the present invention, but the present invention is not limited to this embodiment and various modifications can be made without departing from the scope of the present invention. For example, although not shown in the drawings, the above-described seat belt retractor 1 can be controlled as follows. That is, - When a specified time has elapsed after the vehicle engine is turned off and it can be determined that the occupants have exited the vehicle and it is stationary. - When it is possible to determine that a passenger has exited the vehicle by detecting that the vehicle door has been opened and then closed When either or both of the above conditions are met, the motor 20 rotates in the second direction to wind up the FA spring 50 and store torque (counter winding force). As a result, the belt winding force is maintained in the same state from the time the belt is withdrawn to the time the belt is fastened, unless the motor is operated. Furthermore, by controlling as described above, the motor can be driven to weaken the belt winding force again after the belt is stored in a situation in which it is assumed that the occupant has dismounted, so that discomfort to the occupant can be prevented. [Industrial Applicability]

[0064] The present invention is suitable for application to a seat belt retractor configured to retract a seat belt for a vehicle. [Explanation of symbols]

[0065] 1...Seat belt retractor 2. Seat belt 3. Housing 10…Spindle 10x…center axis 20…Motor 21...Output shaft 30...Power transmission mechanism 31…Motor gear 32...Transmission shaft 32a…1st helical gear 32b…Second helical gear 33…Final gear (first rotating gear) 33a...Hasuba 33m…protrusion 33p…pin 33t…protrusion 34…Clutch mechanism 34a…Friction type one-way clutch 34b...One-way clutch pawl 34c…One-way clutch pawl teeth 34f...Friction ring for one-way clutch 34g…Nail 34h…Guide 35…Clutch housing 35a…Ratchet gear 36…Coil spring 37…Gear case 38…Gear cover 40…Return spring 40b...Boss member 40i…Inner end 40o…Outer end 41…Spring cassette 50...FA spring (winding force adjustment spring) 50b…Boss member 50i…Inner end 50o…Outer end 51...FA housing (housing) 59…Ratchet gear 60...Latch mechanism (connection mechanism) 61…Paul 61t…Paul's toe 62…Pawl return spring 63...Friction ring (rotating ring) 63g…Guide 63h…long hole CCW...Retraction direction (first direction, the direction in which the seat belt is retracted) CW: Clutch release direction (opposite the direction in which the seat belt is retracted)< / c> < / c>

Claims

1. A seat belt retractor configured to retract a seat belt for a vehicle, A spindle for winding the seat belt; A motor that generates power to rotate the spindle; a power transmission mechanism capable of transmitting power from the motor to the spindle; a first rotary gear that constitutes the power transmission mechanism and is rotatably disposed on a central axis of the spindle; a clutch mechanism provided in the power transmission mechanism that enables the transmission of power from the motor to the spindle when the motor rotates in a first direction; a return spring that applies a winding force to the spindle in a direction in which the seat belt is wound; a winding force adjusting spring connected to the spindle and capable of storing a counter winding force that reduces a magnitude of the winding force acting on the spindle from the return spring; a housing that is rotatably disposed on a central axis of the spindle and that is capable of storing the counter-winding force in the winding force adjustment spring by rotating; a coupling mechanism that couples the first rotary gear to the housing when the first rotary gear rotates in a predetermined direction as the motor rotates in a second direction opposite to the first direction; A seat belt retractor comprising:

2. 2. The seat belt retractor according to claim 1, wherein the first rotary gear rotates in a predetermined direction, the predetermined direction being a direction opposite to a direction in which the seat belt is wound.

3. 3. The seat belt retractor according to claim 2, wherein the connecting mechanism is configured as a latch mechanism that is engaged when the first rotating gear rotates in a direction opposite to a direction in which the seat belt is wound, and connects the first rotating gear to the housing.

4. 4. The seat belt retractor according to claim 3, wherein the latch mechanism includes a ratchet gear formed in the housing, and a pawl rotatably attached to the first rotating gear and engaging a toe of the ratchet gear only when the first rotating gear rotates in a direction opposite to a direction in which the seat belt is wound up.

5. 5. The seat belt retractor according to claim 4, wherein the latch mechanism further includes a pawl return spring that biases the tip of the pawl in a direction away from the ratchet gear, and a guide that brings the tip of the pawl closer to the ratchet gear when the first rotating gear rotates in a direction opposite to a direction in which the seat belt is retracted.

6. 6. The seat belt retractor according to claim 5, wherein the guide is formed on a co-rotating ring which rotates together with the first rotary gear.

7. 7. The seat belt retractor according to claim 6, wherein the co-rotating ring has a long hole with which a protrusion of the first rotating gear engages, and the co-rotating ring is capable of rotating relative to the first rotating gear at a stroke width corresponding to the long hole.

8. 8. The seat belt retractor according to claim 7, wherein when the first rotating gear rotates in the direction of winding up the seat belt by at least an amount that exceeds the stroke width, a pawl return spring moves the tip of the pawl that has disengaged from the ratchet gear away from the ratchet gear.

9. 2. The seat belt retractor according to claim 1, wherein the return spring is formed of a spiral spring wound around the spindle.

10. 10. The seat belt retractor according to claim 9, wherein the winding force adjusting spring is formed of a spiral spring wound around the spindle in a direction opposite to that of the return spring.

11. 11. The seat belt retractor according to claim 10, wherein the winding force adjusting spring has an inner end fixed to the spindle and an outer end fixed to the housing.

12. 12. The seat belt retractor according to claim 11, wherein the winding force adjusting spring is accommodated in the housing.

13. 2. The seat belt retractor according to claim 1, wherein the first rotary gear is a final gear arranged at an end of a gear train that constitutes the power transmission mechanism.

14. 14. The seat belt retractor according to claim 13, wherein the clutch mechanism is provided between the first rotary gear and the spindle.

15. 15. The seat belt retractor of claim 14, wherein the clutch mechanism includes a one-way clutch.

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