Seat belt retractor

Abstract

To provide a retractor for a seat belt which prevents end lock without fail when a belt is stored and inhibits inadvertent end lock when the belt is worn.SOLUTION: In a case that a belt is drawn when a user wears the belt, a switch lever 90 is rotated in a first direction through a friction lever 120 in conjunction with rotation of a spindle 10 to be moved to a position where the switch lever 90 may engage with a latch ring 50 and thereby enable webbing acceleration sensing means to be operated. Meanwhile, in a case that the belt is wound up when the user wears the belt, the switch lever 90 is rotated in a second direction through the friction lever 120 in conjunction with rotation of the spindle 10 to be moved to a position where the switch lever 90 is not engaged with the latch ring 50. When the belt is stored, the switch lever 90 is rotated in the second direction through a cam of a control plate 110 in conjunction with rotation of the spindle 10 to be moved to the position where the switch lever 90 is not engaged with the latch ring 50.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD

[0001] The present invention relates to a seatbelt retractor. BACKGROUND ART

[0002] Conventionally, as a seatbelt retractor for safely holding a vehicle occupant or the like on a seat, an emergency lock type retractor has been used which is provided with an emergency lock mechanism that physically locks the withdrawal of the webbing (seatbelt) by vehicle body acceleration sensing means that reacts to sudden acceleration, collision or deceleration, so as to effectively and safely restrain the occupant.

[0003] By the way, in a seatbelt retractor provided with an emergency lock mechanism, the rotation of the spindle (winding shaft) in the webbing withdrawal direction may be locked even at unnecessary times other than a vehicle emergency. That is, in the vehicle mounted state, when the entire amount of the webbing is rapidly wound up from the webbing withdrawn state according to the spring force of the winding spring, the impact may actuate the emergency lock mechanism and lock the rotation of the spindle in the webbing withdrawal direction, in which case the webbing cannot be withdrawn. Moreover, at this time, since the webbing is in the fully wound state, the spindle cannot rotate in the webbing winding direction either, and there is a problem that the retractor falls into a so-called end lock state.

[0004] For example, the following are examples of emergency lock mechanisms. One is a mechanism that senses sudden withdrawal of the webbing and blocks rotation of the spindle in the webbing withdrawal direction (webbing acceleration sensing means: WS), and the other is a mechanism that senses a sudden deceleration state of the vehicle and blocks rotation of the spindle in the webbing withdrawal direction (vehicle body acceleration sensing means: CS). In either case, the pawl of the lock member is engaged with the internal teeth of the frame that supports the spindle by the swing of the lock member that rotates integrally with the spindle, so as to lock the spindle (for example, see Patent Documents 1 and 2).

[0005] In such retractable mechanisms, there are three possible cases in which end lock can occur: (1) Caused by unintentional operation of the webbing acceleration sensing means (WS). Generally, webbing acceleration sensing mechanisms work on the principle that when the belt is pulled out rapidly, the rotation of the mass lags behind that of the spindle due to the inertia of the mass, causing the locking member to spring out and engage with the internal teeth of the frame. However, if the webbing becomes taut after rapid winding, the force can cause the mass to move relative to the spindle, resulting in the locking member engaging with the internal teeth of the frame. (2) Due to unintentional operation of the vehicle acceleration sensing means (CS). This occurs when vibrations in the retractor, such as those caused by the rapid winding of the webbing, input acceleration to the vehicle acceleration sensing means, causing the ball, which is an inertial member, to move, the lever to swing, and engage with the latch member to lock. (3) Caused by unintentional operation of the locking mechanism itself. This occurs when the force of winding up the webbing causes the locking mechanism itself to engage with the internal teeth of the frame.

[0006] Patent Document 3 describes a seat belt retractor that can prevent end locking of both the webbing acceleration sensing means and the vehicle body acceleration sensing means with a simple configuration. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 9-58410 [Patent Document 2] Japanese Patent Application Publication No. 10-129417 [Patent Document 3] Patent No. 5748712 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In the lock canceller mechanism described in Patent Document 3, an end lock prevention mechanism is activated when the belt is retracted by controlling a single switch lever to prevent end locking. On the other hand, when the belt is installed (when the webbing is pulled out by a predetermined amount), the end lock prevention mechanism is switched to a non-operational state. If it is possible to suppress the possibility of unintentional end locking (especially end locking due to unintentional operation of the WS) when the belt is installed, it would be even more technologically advantageous.

[0009] Furthermore, when the belt is attached, the CS lever is in a free position, which may cause it to inadvertently come into contact with other components while the vehicle is in motion, depending on the road surface conditions, potentially generating noise.

[0010] The present invention aims to provide a seat belt retractor that can reliably prevent end locking when the belt is retracted and suppress unintentional end locking when the belt is fastened, and that can contribute to suppressing noise generation due to its structure. [Means for solving the problem]

[0011] A seat belt retractor according to one aspect of the present invention includes: a spindle rotatably supported on a frame and around which a seat belt is wound; a locking member that engages with the frame to lock the rotation of the spindle in the seat belt extension direction; a steering wheel rotatably supported on the spindle and which acts as the locking member by creating a rotational lag relative to the spindle; a latch ring rotatably disposed on a bearing plate fixed to the frame, with internal and external teeth formed on its inner and outer surfaces, respectively; and a pivotally supported member on the steering wheel in a position where it can engage and disengage with the internal teeth of the latch ring, which prevents the steering wheel from rotating in the seat belt extension direction. A seat belt retractor comprising a webbing sensor lever that displaces between an operating position in which it stops and a non-operating position in which the rotation of the steering wheel in the seat belt pull-out direction is not prevented, and a control plate that rotates at a different rotational speed from the spindle in accordance with the rotation of the spindle, further comprising a friction lever having an engaging gear portion and capable of rotating together with the spindle as the spindle rotates, a switch lever having an engaging portion that is rotatably supported on a bearing plate and capable of engaging and disengaging with the external teeth of a latch ring, a cam follower guided by a cam portion formed on the control plate, and an engaging gear receiving portion that engages with the engaging gear portion of the friction lever. (1) When the belt is attached, (a) when the belt is wound from a stationary state to a first winding amount, the friction lever rotates in the first rotational direction in conjunction with the winding rotation of the spindle, thereby rotating the switch lever in the second rotational direction via the engagement between the engagement gear portion of the friction lever and the engagement gear receiving portion of the switch lever, moving the engagement portion of the switch lever to a position where it does not engage with the external teeth of the latch ring, while (b) when the belt is pulled out from a stationary state to a first pull-out amount, the friction lever rotates in the second rotational direction in conjunction with the unwinding rotation of the spindle, thereby rotating the switch lever in the first rotational direction via the engagement between the engagement gear portion of the friction lever and the engagement gear receiving portion of the switch lever, moving the engagement portion of the switch lever to a position where it can engage with the external teeth of the latch ring.Furthermore, (2) when the seat belt is retracted into its storage location, the control plate rotates in conjunction with the retraction rotation of the spindle, thereby rotating the switch lever in the second rotational direction via a cam mechanism consisting of the cam portion of the control plate and the cam follower of the switch lever, moving the engaging portion of the switch lever to a position where it does not engage with the external teeth of the latch ring.

[0012] In this embodiment, when the seat belt is pulled out while the belt is fastened, the switch lever is rotated in a first direction via the friction lever, moving it to a position where it can engage with the latch ring. This makes the webbing acceleration sensing means (WS) operable. In other words, the displacement of the webbing sensor lever to the operating position due to inertia when the seat belt is pulled out rapidly can prevent the steering wheel from rotating in the seat belt pulling direction.

[0013] On the other hand, when the belt is being retracted during belt installation, the switch lever is rotated in a second direction via the friction lever, moving the switch lever to a position where it is not engaged with the latch ring. This suppresses end locking caused by unintentional operation of the webbing acceleration sensing means (WS). In other words, when the belt is being retracted, the rotation prevention of the latch ring that engages with the webbing sensor lever is released, thus suppressing unintentional end locking.

[0014] Furthermore, when the belt is retracted, the switch lever is rotated in a second direction via the control plate, moving the switch lever to a position where it is not engaged with the latch ring. This prevents end locking due to unintentional operation of the webbing acceleration sensing means (WS), as described above. [Brief explanation of the drawing]

[0015] [Figure 1] This is an exploded perspective view of a seat belt retractor according to an embodiment. [Figure 2A] This is a front view of the bearing plate showing how the hub and control plate are gear-coupled. [Figure 2B] It is a front view of the control plate, the first idle gear, and the second idle gear. [Figure 3A] It is a perspective view of the acceleration sensor. [Figure 3B] It is a perspective view of the acceleration sensor lever of the acceleration sensor. [Figure 4A] It is an exploded perspective view of the switch lever and the return spring. [Figure 4B] It is a front view of the switch lever. [Figure 5A] It is a perspective view of the control plate. [Figure 5B] It is a front view of the control plate. [Figure 5C] It is a diagram showing the relationship between the control plate and the switch lever, wherein (A) is a front view showing a state where the protrusion of the switch lever is positioned inside the first cam portion of the control plate when the belt is worn, (B) is a front view showing a state where the protrusion of the switch lever is positioned inside the first cam portion of the control plate when the belt is worn at a timing different from that of (A), and (C) is a front view showing a state where the protrusion of the switch lever is positioned inside the second cam portion of the control plate when the belt is retracted. [Figure 6A] It is an exploded perspective view of the hub, the friction lever, and the friction spring. [Figure 6B] It is a front view showing a state where the hub, the friction lever, and the friction spring are assembled. [Figure 6C] It is a diagram showing the relationship between the friction lever and the switch lever, wherein (A) is a front view showing that the friction lever rotates the switch lever in the clockwise direction when the belt is pulled out while the belt is worn, and (B) is a front view showing that the friction lever rotates the switch lever in the counterclockwise direction when the belt is wound up while the belt is worn. [Figure 7]The diagram shows the relationship between the switch lever, the latching ring, and the acceleration sensor lever. (A) is a front view showing the state when the belt is pulled out while the belt is installed, where the switch lever is rotated clockwise by the friction lever, moving the engaging portion of the switch lever to a position where it can engage with the outer teeth of the latching ring, and the claw portion of the switch lever is moved to a position where it is separated from the locking piece of the acceleration sensor lever. (B) is a front view showing the state when the belt is unwound while the belt is installed, where the switch lever is rotated counterclockwise by the friction lever, moving the engaging portion of the switch lever to a position where it does not engage with the outer teeth of the latching ring, and the claw portion of the switch lever is moved to a position where it contacts the locking piece of the acceleration sensor lever. [Figure 8] This diagram illustrates the operation when the belt is installed. (A) shows the state when transitioning from a stationary belt state to a belt winding state, (B) shows the initial state when the belt is extended, and (C) shows the later state when the belt is extended. [Figure 9] This diagram illustrates the operation of the belt when it is retracted over time. (A) shows the initial stage of belt winding, where the engaging portion of the switch lever has moved to a position where it does not engage with the external teeth of the latch ring. (B) shows the completed state of belt winding (belt retracted state). [Figure 10] This diagram illustrates the operation of the WS lock over time. (A) shows the state when transitioning from a stationary belt state to belt extension, (B) shows the initial state of belt extension where the engaging portion of the switch lever moves to a position where it can engage with the external teeth of the latch ring, and the claw of the webbing sensor lever engages with the internal teeth of the latch ring, and (C) shows the state when belt extension is locked (WS is activated). [Figure 11] This diagram illustrates the operation when the CS is locked, showing the state where the belt pull-out is locked (the state where the CS is activated). [Modes for carrying out the invention]

[0016] A preferred embodiment of the present invention will be described with reference to the attached drawings. In this document, up and down, left and right, and front and back are defined as follows: When an occupant is seated in a vehicle seat in a normal posture, the direction in which the occupant faces forward is called the front, and the opposite direction is called the rear. Similarly, left and right and up and down are also based on the occupant being seated in a vehicle seat in a normal posture. Clockwise and counterclockwise directions refer to the direction of rotation in each figure. For example, in Figure 6C, (A) means that the switch lever rotates clockwise, and (B) means that the switch lever rotates counterclockwise.

[0017] First, with reference to Figure 1, the main components of the seat belt retractor 1 will be described.

[0018] The seat belt retractor 1 includes a metal spindle 10 on which a seat belt (not shown) is wound, a spring-type winding device 11 housed in a cover 12 that biases the spindle 10 to rotate in the winding direction, a metal U-shaped frame 13 that rotatably supports the spindle 10, a metal lock dog 20 as a locking member, a resin steering wheel 30, a resin webbing sensor lever 40 that also functions as an inertial body, a bearing plate 60 fixed to the frame 13, a latch ring 50 rotatably disposed on the bearing plate 60, an acceleration sensor 70 as a vehicle acceleration sensing means (CS) that senses the acceleration of the vehicle body, and a cover member 15 fixed to the frame 13 so as to cover the bearing plate 60. The seat belt retractor 1 also includes a switch lever 90, a return spring 100, a control plate 110, a friction lever 120, a friction spring 130, and a hub 140.

[0019] The frame 13 has left and right side plates 13A and 13B that face each other, sandwiching the axial central portion of the spindle 10. An emergency locking mechanism (composed of a lock dog 20, steering wheel 30, webbing sensor lever 40, latch ring 50, acceleration sensor 70, etc.) that physically locks the seat belt extension is located on the outside of one side plate 13A, and a winding device 11 is located on the outside of the other side plate 13B. The shaft 14 at one end of the spindle 10 passes through the steering wheel 30 and bearing plate 60, and a hub 140 is fixed to its tip so as to rotate together with it. The hub 140 and the control plate 110 are gear-coupled via one or more gears (idler gears 82, 83) (see Figure 2).

[0020] Numerous internal teeth 17 are formed on the inner circumference of the circular opening in the side plate 13A of the frame 13, into which the claws 22 of the lock dog 20 can engage. The lock dog 20 is displaceably housed in a space secured between one end face of the spindle 10 and a metal safety plate 25 fixed to that end face, and the claws 22 are held in the unlocking direction away from the internal teeth 17 of the frame 13 by an omega spring 26. The lock dog 20 also includes a cam pin 21 that is inserted into a cam hole 31 formed in the steering wheel 30.

[0021] The steering wheel 30 is supported so as to be rotatable relative to the spindle 10 and has a cam hole 31 into which the cam pin 21 of the lock dog 20 engages, a convex shaft 32 that fits into the shaft hole of the webbing sensor lever 40 and pivotably supports the webbing sensor lever 40, and teeth 34 formed on its outer circumferential surface.

[0022] The cam hole 31 pushes the claw 22 of the lock dog 20 outward via the cam pin 21 when the steering wheel 30 rotates relative to the spindle 10. For example, when the seat belt is extended, if the steering wheel 30 lags behind the spindle 10 in rotation, the relative rotation of the spindle 10 and the steering wheel 30 causes the lock dog 20 to move to the lock position. The outwardly protruding claw 22 then engages with the internal teeth 17 of the frame 13, locking the spindle 10 to the internal teeth 17 of the frame 13 and mechanically locking rotation in the seat belt extension direction.

[0023] The webbing sensor lever 40 is equipped with a claw 42 that can engage with the internal teeth 52 of the latch ring 50 and is pivotably fitted onto the convex shaft 32 of the steering wheel 30. A webbing sensor spring 48 (not shown) is attached to the webbing sensor lever 40 and rotationally biases the webbing sensor lever 40 in a direction that retracts the claw 42 inward (away from the internal teeth 52 of the latch ring 50). Therefore, under normal conditions, the claw 42 is held in a non-operating position where it does not engage with the internal teeth 52 of the latch ring 50. In other words, the steering wheel 30, the webbing sensor lever 40, and the webbing sensor spring 48 constitute a webbing acceleration sensing means (WS).

[0024] As a result, the seat belt is pulled out by the sudden movement of the occupant, the webbing sensor lever 40 rotates due to inertia, and the claw 42 of the webbing sensor lever 40 protrudes outward and engages with the internal teeth 52 of the latch ring 50. In other words, the webbing sensor lever 40 is displaced to an operating position that prevents the steering wheel 30 from rotating in the direction of webbing extension.

[0025] The latch ring 50 is formed in a ring shape with multiple external teeth 51 and internal teeth 52 provided on its outer and inner circumferential surfaces, respectively, and is rotatably mounted on a bearing plate 60 fixed to the frame 13.

[0026] Next, the bearing plate 60 will be described with reference to Figures 2A and 2B.

[0027] The bearing plate 60 has shaft portions 61, 62, 63, and 64 protruding from it. The first idler gear 82 is rotatably supported on shaft portion 61, the second idler gear 83 is rotatably supported on shaft portion 62, and the control plate 110 is rotatably supported on shaft portion 63. The switch lever 90 is rotatably supported on shaft portion 64 (see Figure 7). The bearing plate 60 is also provided with a spring receiving portion 65 that receives one end 101 of the return spring 100 (see Figure 7).

[0028] Then, the gear 141 of the hub 140 meshes with the large gear of the first idler gear 82, the small gear of the first idler gear 82 meshes with the large gear of the second idler gear 83, and furthermore, the small gear of the second idler gear 83 meshes with the gear 112 of the control plate 110. Therefore, the rotation of the shaft 14 of the spindle 10 is transmitted from the hub 140 to the control plate 110 via the first and second idler gears 82 and 83, causing the control plate 110 to rotate at a reduced speed in conjunction with the spindle 10.

[0029] Here, the reduction ratio of the gear train consisting of the hub 140, idler gears 82 and 83, and control plate 110 is set so that the rotation of the spindle 10 when moving the seat belt from the fully extended state to the fully retracted state is converted into one rotation of the control plate 110.

[0030] Next, the acceleration sensor 70 (vehicle acceleration sensing means: CS) will be described with reference to Figures 3A and 3B.

[0031] The acceleration sensor 70 includes a sensor holder 71 positioned between the bearing plate 60 and the cover member 15, an inertial body (ball) 72 housed within the sensor holder 71 that displaces according to the horizontal (vehicle longitudinal direction) acceleration, and an acceleration sensor lever 73 that can be locked onto the teeth 34 of the steering wheel 30.

[0032] The acceleration sensor lever 73 has a shaft portion 75 at one end that is rotatably supported, and a toothed tip 74 at the other end opposite to the one end. The toothed tip 74 is configured to engage with and disengage from the teeth portion 34 of the steering wheel 30. A locking piece 77 extends from the toothed tip 74 toward the shaft portion 75, and the claw portion 96 of the switch lever 90 is positioned opposite the locking piece 77 (see Figure 7).

[0033] Then, as the ball 72 moves in response to the vehicle's acceleration, the acceleration sensor lever 73 rotates, causing the tooth tip 74 to engage with the teeth 34 of the steering wheel 30, locking the steering wheel 30 (see Figure 11). This activates the lock dog 20, which engages its claw 22 with the internal teeth 17 of the frame 13, thereby locking the spindle 10 and mechanically locking its rotation in the seat belt pull-out direction.

[0034] Next, the switch lever 90 and the return spring 100 will be described with reference to Figures 4A and 4B. The switch lever 90 switches the emergency locking mechanism between the activated and deactivated states.

[0035] The switch lever 90 has a hole 91 formed at the lower part of one end in the longitudinal direction, an engaging portion 93 which is a projection with a substantially triangular cross-section protruding from the first surface 92a, a cylindrical projection 94 which protrudes from the second surface 92b opposite to the first surface 92a, an engaging gear receiving portion 95 formed at the upper center in the longitudinal direction, a claw portion 96 formed on the other end in the longitudinal direction, and a spring mounting portion 97 formed around the hole 91.

[0036] The switch lever 90 is pivotally supported on the bearing plate 60 by the hole 91 fitting onto the shaft portion 64 of the bearing plate 60 (see Figure 7). The engaging portion 93 is configured to engage with and disengage from the external teeth 51 of the latch ring 50 (see Figure 10). The claw portion 96 protrudes from the first surface 92a, similar to the engaging portion 93, and is configured to be able to move toward and away from the locking piece 77 of the acceleration sensor lever 73 (see Figure 7).

[0037] The projection 94 is a cam follower guided by a cam groove 113 (see Figure 2) formed in the control plate 110, and moves within the cam groove 113 as the control plate 110 rotates. The engagement gear receiving portion 95 is formed on the side surface portion 92c connecting the first surface 92a and the second surface 92b, and engages with the engagement gear portion 124 of the friction lever 120, which will be described later (see Figure 6C).

[0038] The switch lever 90 rotates around the hole 91 by receiving rotational force from the control plate 110 and the friction lever 120, respectively. Specifically, the switch lever 90 rotates when rotational force is received from the control plate 110 via a cam mechanism formed by the projection 94 of the switch lever 90 and the cam groove 113 of the control plate 110 (see Figure 5(C)). In addition, the switch lever 90 rotates when rotational force is received from the friction lever 120 via the engagement between the engaging gear receiving portion 95 of the switch lever 90 and the engaging gear portion 124 of the friction lever 120 (see Figure 6(C)). Further details will be described later.

[0039] The return spring 100 is composed of a torsion coil spring having, for example, a coil portion 103 between one end 101 and the other end 102. The coil portion 103 is attached to the spring mounting portion 97 of the switch lever 90, the other end 102 is locked to a part of the switch lever 90 around the spring mounting portion 97, and the one end 101 is locked to the spring receiving portion 65 of the bearing plate 60 (see Figure 7).

[0040] As a result, the return spring 100 biases the switch lever 90 in a counterclockwise direction. In other words, the switch lever 90 is biased by the return spring 100 in a direction that separates the engaging portion 93 from the external teeth 51 of the latch ring 50, and in a direction that brings the claw portion 96 into contact with the locking piece 77 of the acceleration sensor lever 73 (see Figure 7).

[0041] Next, the control plate 110 will be described with reference to Figures 5A, 5B, and 5C.

[0042] The control plate 110 is configured to rotate at a different speed than the spindle 10 in response to the rotation of the spindle 10. Here, as described above, the rotation of the spindle 10 when moving the seat belt from the fully extended state to the fully retracted state is converted into one rotation of the control plate 110.

[0043] The control plate 110 is formed in the shape of a disc with a central shaft hole 111, and has a gear 112 that meshes with the small gear of the second idler gear 83, and a cam groove 113 formed on one side. The control plate 110 is rotatably supported on the bearing plate 60 by the shaft hole 111 fitting into the shaft portion 63 of the bearing plate 60.

[0044] The projection 94 of the switch lever 90 is housed in the cam groove 113. The cam groove 113 has a first cam portion 113a formed in an arc shape centered on the shaft hole 111, a second cam portion 113b formed in an arc shape centered on the shaft hole 111 with a larger radius than the first cam portion 113a, and a switching portion 113c that smoothly connects the first cam portion 113a and the second cam portion 113b. The switching portion 113c is set to a phase such that it switches between a belt storage state in which the seat belt is wound onto the spindle 10 and a belt state in which the buckle is latched when the seat is not occupied.

[0045] Here, when the control plate 110 rotates 1 turn counterclockwise to move the seat belt from the fully extended position to the fully retracted position, the projection 94 is guided in the order of the first cam portion 113a, the switching portion 113c, and the second cam portion 113b. When guided to the second cam portion 113b, the projection 94 is pushed by the second cam portion 113b, thereby causing the switch lever 90 to rotate counterclockwise.

[0046] Specifically, as shown in Figure 5C(A), when the belt is fastened (the seat belt is fully extended or extended by a predetermined amount), the projection 94 is located within the first cam portion 113a. At this time, the projection 94 is free from the first cam portion 113a, and even if the control plate 110 rotates in the forward or reverse direction within the cam region of the first cam portion 113a, no rotational force is input from the control plate 110 (see Figure 5C(B)).

[0047] On the other hand, as shown in Figure 5C(C), when the belt is retracted, the projection 94 passes through the switching section 113c and moves from the first cam section 113a to the second cam section 113b, where it is pushed by the second cam section 113b and receives rotational force from the control plate 110. As a result, the switch lever 90 rotates counterclockwise. When the belt is retracted (the seat belt is fully wound into its storage position), the projection 94 is held by the second cam section 113b, and the switch lever 90 is restricted from freely rotating clockwise.

[0048] Needless to say, the same applies to the reverse operation (when moving from a fully retracted seat belt to a fully unretracted seat belt).

[0049] Next, the friction lever 120, friction spring 130, and hub 140 will be described with reference to Figures 6A, 6B, and 6C.

[0050] The hub 140 is fixed to the shaft 14 at one end of the spindle 10 and rotates integrally with the spindle 10. The hub 140 has a gear 141 and a cylindrical portion 142 formed coaxially with the gear 141. The gear 141 forms a gear train together with the first and second idler gears 82 and 83 and the gear 112 of the control plate 110.

[0051] The friction spring 130 connects the friction lever 120 and the hub 140 by frictional force. In other words, the friction spring 130 provides the friction lever 120 with the frictional force necessary to transmit the rotation of the spindle 10 to the friction lever 120.

[0052] The friction lever 120 is configured to rotate together with the spindle 10 as the spindle 10 rotates. The friction lever 120 has a substantially C-shaped base portion 121, a mounting portion 122 formed on the outer circumference of the base portion 121 on which the friction spring 130 is attached, a sliding portion 123 formed on the inner circumference of the base portion 121 on which it is slidably coupled (fitted) to the cylindrical portion 142 of the hub 140, and an engaging gear portion 124 formed to protrude radially outward from the outer circumference of the base portion 121 on which it engages with the engaging gear receiving portion 95 of the switch lever 90.

[0053] The base portion 121 has a radially extending notched groove 121a formed on the opposite side of the roughly C-shaped notch. This allows the base portion 121 to be elastically deformed (reduced in diameter) in the radial direction. The base portion 121 is reduced in diameter by the elastic force of the friction spring 130 attached to the mounting portion 122, thereby connecting the sliding portion 123 and the cylindrical portion 142 of the hub 140 by frictional force. The magnitude of this frictional force is approximately proportional to the elastic force of the friction spring 130.

[0054] In this case, when the belt is attached, the friction lever 120 rotates together with the hub 140 due to the frictional force of the friction spring 130, and rotates in conjunction with the spindle 10.

[0055] Specifically, as shown in Figure 6C(A), when the spindle 10 rotates in the direction of pulling out the seat belt, the friction lever 120 rotates counterclockwise together with the hub 140 due to the friction action of the friction spring 130. As a result, the friction lever 120 inputs rotational force from the engagement gear portion 124 to the engagement gear receiving portion 95, causing the switch lever 90 to rotate clockwise.

[0056] Conversely, as shown in Figure 6C(B), when the spindle 10 rotates in the direction of winding the seat belt, the friction lever 120 rotates clockwise together with the hub 140 due to the friction action of the friction spring 130. This causes the friction lever 120 to input rotational force from the engagement gear portion 124 to the engagement gear receiving portion 95, causing the switch lever 90 to rotate counterclockwise.

[0057] On the other hand, when the belt is stored, the torque transmitted by the winding rotation of the spindle 10 exceeds the frictional force of the friction spring 130, and as a result, the spindle 10 rotates relative to the friction lever 120. That is, the friction lever 120 does not rotate together with the spindle 10, and the spindle 10 rotates in the winding direction, sliding the hub 140 against the sliding part 123, against the frictional force of the friction spring 130. Therefore, the switch lever 90 does not receive rotational force from the friction lever 120. In this case, as described above, the switch lever 90 receives rotational force from the control plate 110 via the cam mechanism and rotates in a counterclockwise direction (see Figure 9).

[0058] Next, the specific operation of the seat belt retractor 1 will be explained with reference to Figures 8-11.

[0059] 1. Operation when the belt is attached (Figure 8) "Belt fastened" means when the seat belt is fully extended or by a predetermined amount from the seat belt retractor 1, and the occupant is fastened with the seat belt.

[0060] In the following explanation, "stationary belt state" refers to the state in which the seat belt is not moving when fastened (i.e., neither retracted nor extended).

[0061] Furthermore, "belt winding" in the context of belt fastening refers to the time when the seat belt is wound onto the spindle 10 from a stationary state to a first winding amount. "First winding amount" refers to the amount of winding (winding amount near the stationary state) when the seat belt in a fastened state moves slightly due to the movement of the occupant, etc. Therefore, "first winding amount" does not mean the total length of the seat belt when the tongue is released from the buckle and the seat belt is wound into its storage location.

[0062] Furthermore, "belt extension" in the context of belt fastening refers to the time when the seat belt is extended from the spindle 10 from its stationary position to a first extension amount. "First extension amount" refers to the amount of extension (extension amount near the stationary position) when the seat belt in its fastened state moves slightly due to the movement of the occupant, etc.

[0063] (a) Belt stationary state As shown in Figure 8(A), when the belt is stationary, the switch lever 90 is biased in a counterclockwise direction by the return spring 100. Therefore, the engaging portion 93 of the switch lever 90 is spaced apart from the external teeth 51 of the latch ring 50.

[0064] Furthermore, the return spring 100 causes the claw portion 96 of the switch lever 90 to contact the locking piece 77 of the acceleration sensor lever 73, biasing the acceleration sensor lever 73 in a direction that prevents it from engaging with the teeth portion 34 of the steering wheel 30. This prevents noise from the acceleration sensor lever 73.

[0065] (i) When the belt is retracted During belt winding, the friction lever 120 rotates clockwise (reference: reference numeral 200 in Figure 8(A)) in conjunction with the winding rotation of the spindle 10. This is because, as described above, the frictional force of the friction spring 130 causes the friction lever 120 to rotate clockwise together with the spindle 10 and the hub 140. When the friction lever 120 rotates clockwise, the switch lever 90 rotates counterclockwise via the engagement between the engagement gear portion 124 and the engagement gear receiving portion 95. As a result, the engagement portion 93 of the switch lever 90 moves to a position where it is less engaged with the external teeth 51 of the latch ring 50.

[0066] Therefore, when the belt is being wound, the latch ring 50 is free to rotate, thus preventing unintentional end locking. More specifically, since the latch ring 50, which can engage with the webbing sensor lever 40, is released from its fixed position (rotation prevention) when the belt is being wound, end locking due to unintentional operation of the webbing acceleration sensing means (WS) is prevented when the belt is being wound.

[0067] Furthermore, when the belt is being retracted, the counterclockwise rotation of the switch lever 90 causes the claw portion 96 of the switch lever 90 to contact the locking piece 77 of the acceleration sensor lever 73 more strongly than when the belt is stationary, biasing the acceleration sensor lever 73 in a direction that prevents it from engaging with the teeth portion 34 of the steering wheel 30. This ensures that noise prevention of the acceleration sensor lever 73 continues.

[0068] (c) When the belt is pulled out As shown in Figure 8(B), when the belt is pulled out, the friction lever 120 rotates counterclockwise (reference: reference numeral 210 in Figure 8(B)) in conjunction with the rotation of the spindle 10. This is because, as described above, the friction force of the friction spring 130 causes the friction lever 120 to rotate counterclockwise together with the spindle 10 and the hub 140. When the friction lever 120 rotates counterclockwise, the switch lever 90 rotates clockwise against the biasing force of the return spring 100 via the engagement between the engagement gear portion 124 and the engagement gear receiving portion 95. As a result, as shown in Figure 8(C), the engagement portion 93 of the switch lever 90 moves to a position where it can engage with the external teeth 51 of the latch ring 50.

[0069] Therefore, when the belt is pulled out, the latch ring 50 can be fixed (rotation prevented), which enables the webbing acceleration sensing means (WS) to operate. In other words, if the seat belt is pulled out due to a sudden movement of the occupant, the operation of the webbing acceleration sensing means (WS) can prevent further pulling out of the seat belt. This point will be discussed in more detail in section 3 below.

[0070] Furthermore, when the seatbelt is extended, the clockwise rotation of the switch lever 90 causes the claw portion 96 of the switch lever 90 to separate from the locking piece 77 of the acceleration sensor lever 73. This allows the acceleration sensor lever 73 to move in the direction that engages with the teeth 34 of the steering wheel 30. In other words, the lock of the acceleration sensor 70 (vehicle acceleration sensing means: CS) is canceled. Therefore, if the vehicle acceleration exceeds a predetermined level, the operation of the acceleration sensor lever 73 can prevent the seatbelt from being extended. This point will be discussed in more detail in section 4 below.

[0071] Furthermore, when the belt is being retracted or extended while the belt is installed, the projection 94 of the switch lever 90 moves within the first cam portion 113a of the control plate 110. Therefore, the counterclockwise and clockwise rotation of the switch lever 90 is not obstructed by the control plate 110.

[0072] 2. Operation when the belt is retracted (Figure 9) "Belt stowed" refers to the time when the seat belt is retracted to the storage location beyond the first retraction amount described above. For example, this refers to the time when the tongue is detached from the buckle and the seat belt is retracted onto the spindle 10.

[0073] As shown in Figure 9, when the belt is retracted, the seat belt is rapidly retracted as the spindle 10 rotates, and is wound up to the vicinity of the retraction location. Then, the rotation of the control plate 110 accompanying the rotation of the spindle 10 generates a rotational force in the switch lever 90 via a cam mechanism consisting of the cam portion (second cam portion 113b) of the control plate 110 and the cam follower (projection portion 94) of the switch lever 90, causing the switch lever 90 to rotate in a counterclockwise direction.

[0074] As described above, this is because the torque transmitted by the winding rotation of the spindle 10 exceeds the frictional force of the friction spring 130, causing the spindle 10 to rotate relative to the friction lever 120, and this rotation causes the control plate 110 to rotate 1 full turn counterclockwise via the gear train. At this time, the cam mechanism causes the control plate 110 to rotate the switch lever 90 counterclockwise. As a result, the engaging portion 93 of the switch lever 90 moves to a position where it does not engage with the external teeth 51 of the latch ring 50. Also, at this time, the projection 94 is held by the second cam portion 113b, so the switch lever 90 is restricted from freely rotating clockwise.

[0075] Therefore, even when the belt is retracted, the latch ring 50 is not engaged with the switch lever 90, thus preventing end locking.

[0076] More specifically, when the belt is retracted, the webbing sensor lever 40 rotates due to acceleration to a position where it can engage with the internal teeth 52 of the latch ring 50. Furthermore, when the seat belt is retracted and the rotation axis comes to a sudden stop, the reaction (inertia) causes the claw 42 of the webbing sensor lever 40 to engage with the internal teeth 52 of the latch ring 50, and it rotates counterclockwise together with the steering wheel 30. At this time, the external teeth 51 of the latch ring 50 and the engaging portion 93 of the switch lever 90 are not engaged. Therefore, even if the claw 42 of the webbing sensor lever 40 engages with the internal teeth 52 of the latch ring 50, the lock dog 20 does not spring outward and is not locked to the internal teeth 17 of the frame 13 (the webbing acceleration sensing means (WS) does not operate). Thus, end lock caused by the webbing acceleration sensing means (WS) is prevented.

[0077] Furthermore, when the belt is retracted, the counterclockwise rotation of the switch lever 90 via the cam mechanism and the return spring 100 cause the claw portion 96 of the switch lever 90 to contact the locking piece 77 of the acceleration sensor lever 73, biasing the acceleration sensor lever 73 in a direction that prevents it from engaging with the teeth portion 34 of the steering wheel 30. Therefore, even if the vehicle decelerates suddenly, the acceleration sensor lever 73 does not move, preventing end lock caused by the acceleration sensor 70 (vehicle acceleration sensing means: CS).

[0078] 3. Operation when WS is locked (Figure 10) WS locking refers to the activation of the webbing acceleration sensing means (WS), which is one of the emergency locking mechanisms. For example, when the seat belt is pulled out rapidly due to a sudden movement of the occupant, the rotation of the webbing sensor lever 40 is used to prevent the seat belt from rotating in the pulling direction.

[0079] As shown in Figure 10, when the seat belt is pulled out rapidly, the friction lever 120 rotates counterclockwise as the spindle 10 extends, and the switch lever 90 rotates clockwise against the biasing force of the return spring 100 via the engagement of the engagement gear portion 124 and the engagement gear receiving portion 95, and the engagement portion 93 of the switch lever 90 moves to a position where it can engage with the external teeth 51 of the latch ring 50 (see Figure 10(B). This is the same as 1(c) above).

[0080] Then, as shown in Figure 10(C), when the seat belt is pulled out further, the webbing sensor lever 40 rotates due to inertia, and the claw 42 of the webbing sensor lever 40 engages with the internal teeth 52 of the latch ring 50, causing it to rotate counterclockwise together with the steering wheel 30. As the latch ring 50 rotates counterclockwise together with the webbing sensor lever 40 and the steering wheel 30, the external teeth 51 of the latch ring 50 engage with the engagement portion 93 of the switch lever 90. This causes a rotational lag between the steering wheel 30 and the spindle 10, causing the lock dog 20 to spring outward and lock into the internal teeth 17 of the frame 13. In other words, the webbing acceleration sensing means (WS) is activated.

[0081] 4. Operation when CS is locked (Figure 11) CS locking refers to the activation of the acceleration sensor 70 (vehicle acceleration sensing means: CS), which is one of the emergency locking mechanisms. For example, it refers to the time when, in the event of a sudden deceleration of the vehicle, the movement of the inertial body (ball) 72 is used to prevent rotation in the direction of seat belt extension.

[0082] As shown in Figure 11, as described in 1(c) above, when the belt is extended, the switch lever 90 rotates clockwise by the friction lever 120, so that it moves away from the acceleration sensor lever 73. This allows the acceleration sensor lever 73 to move in the direction that locks it to the steering wheel 30.

[0083] Then, when the ball 72 moves due to the vehicle's sudden deceleration, the acceleration sensor lever 73 rotates counterclockwise, and the teeth 74 of the acceleration sensor lever 73 engage with the teeth 34 of the steering wheel 30, locking the steering wheel 30. This causes a rotational lag between the steering wheel 30 and the spindle 10, causing the lock dog 20 to spring outward and lock into the internal teeth 17 of the frame 13. In other words, the acceleration sensor 70 (vehicle acceleration sensing means: CS) is activated.

[0084] As described above, the seat belt retractor 1 according to this embodiment can reliably prevent end locking when the belt is stored and suppress unintentional end locking when the belt is fastened.

[0085] In particular, when the seat belt is extended (for example, when the belt is extended while the belt is fastened), the switch lever 90 is moved via the friction lever 120 to a position where it can engage with the latch ring 50, thereby activating the webbing acceleration sensing means (WS). On the other hand, when the seat belt is retracted (for example, when the belt is stored or when the belt is retracted while the belt is fastened), the switch lever 90 is moved via the friction lever 120 or the control plate 110 to a position where it is not engaged with the latch ring 50, thereby preventing end locking due to unintentional operation of the webbing acceleration sensing means (WS).

[0086] Furthermore, according to this embodiment, when the belt is fastened, the acceleration sensor lever 73 is biased by the switch lever 90 when the belt is stationary and when the belt is retracted, thus suppressing the generation of noise from the acceleration sensor lever 73. Also, when the belt is retracted, the acceleration sensor lever 73 is biased to the unlocked side by the switch lever 90, so for example, the seat belt retractor 1 can be built into the vehicle seat and the vehicle seat can be tilted forward (even when the vehicle seat is tilted forward, the vehicle acceleration sensing means (CS) does not operate).

[0087] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. The elements of the embodiments, as well as their arrangement, materials, conditions, shapes, and sizes, are not limited to those exemplified and can be modified as appropriate.

[0088] For example, with respect to the cam mechanism, the cam follower of the switch lever 90 is designated as a projection 94, and the cam portion of the control plate 110 is designated as a cam groove 113, but the relationship between the projection and the groove may be reversed.

[0089] Furthermore, while the direction in which the switch lever 90 rotates when the belt is pulled out is defined as clockwise (first direction), and the direction in which the switch lever 90 rotates when the belt is retracted is defined as counterclockwise (second direction, opposite to the first direction), the relationship between the directions of rotation may be reversed.

[0090] <Additional considerations regarding various embodiments> [Embodiment 1] A spindle 10 is rotatably supported on the frame 13 and around which a seat belt is wound, A locking member (lock dog 20) engages with the frame 13 to lock the rotation of the spindle 10 in the seat belt pull-out direction, A steering wheel 30 is supported so as to be rotatable relative to the spindle 10, and acts on the locking member (lock dog 20) by creating a rotational lag relative to the spindle 10, A latch ring 50 is rotatably mounted on a bearing plate 60 fixed to the frame 13, with internal teeth 52 and external teeth 51 formed on its inner and outer surfaces, respectively. A webbing sensor lever 40 is pivotably supported on the steering wheel 30 in a position where it can engage with and disengage from the internal teeth 52 of the latch ring 50, and is displaceable between an operating position that prevents the steering wheel 30 from rotating in the seat belt pull-out direction and a non-operating position where the steering wheel 30 is not prevented from rotating in the seat belt pull-out direction. A seat belt retractor 1 is provided with a control plate 110 that rotates at a different rotational speed than the spindle 10 in accordance with the rotation of the spindle 10, A friction lever 120 having an engaging gear portion 124 and capable of rotating together with the spindle 10 as the spindle 10 rotates, A switch lever 90 having an engagement portion 93 that is rotatably supported on the bearing plate 60 and can engage with and disengage from the external teeth 51 of the latch ring 50, a cam follower (projection portion 94) that is guided by a cam portion (cam groove 113) formed on the control plate 110, and an engagement gear receiving portion 95 that engages with the engagement gear portion 124 of the friction lever 120, Furthermore, (1) When wearing the belt, During belt winding from a stationary state to a first winding amount, the friction lever 120 rotates in a first rotational direction (clockwise) in conjunction with the winding rotation of the spindle 10, thereby causing the switch lever 90 to rotate in a second rotational direction (counterclockwise) opposite to the first rotational direction via the engagement of the engagement gear portion 124 of the friction lever 120 and the engagement gear receiving portion 95 of the switch lever 90, moving the engagement portion 93 of the switch lever 90 to a position where it does not engage with the external teeth 51 of the latch ring 50, When the belt is pulled out from a stationary state to a first pull-out amount, the friction lever 120 rotates in a second rotational direction as the spindle 10 is pulled out, thereby causing the switch lever 90 to rotate in the first rotational direction via the engagement between the engagement gear portion 124 of the friction lever 120 and the engagement gear receiving portion 95 of the switch lever 90, and moving the engagement portion 93 of the switch lever 90 to a position where it can engage with the external teeth 51 of the latch ring 50. Also, (2) When the seat belt is retracted into its storage location, A seat belt retractor 1, wherein the control plate 110 rotates in conjunction with the winding rotation of the spindle 10, thereby rotating the switch lever 90 in the second rotational direction via a cam mechanism formed by the cam portion of the control plate 110 and the cam follower of the switch lever 90, and moving the engaging portion 93 of the switch lever 90 to a position where it does not engage with the external teeth 51 of the latch ring 50.

[0091] [Embodiment 2] The seat belt retractor 1 according to Embodiment 1, further comprising a return spring 100 that biases the switch lever 90 in the second rotational direction.

[0092] [Embodiment 3] The steering wheel 30 further comprises an acceleration sensor 70 having an acceleration sensor lever 73 that can be engaged with teeth 34 formed on the outer circumference of the steering wheel 30, The switch lever 90 further has a claw portion 96 that can move toward and away from the acceleration sensor lever 73, When the belt is attached, in the state where the belt is stationary, The seat belt retractor 1 according to Embodiment 2, wherein the return spring 100 causes the claw portion 96 of the switch lever 90 to contact the acceleration sensor lever 73, thereby biasing the acceleration sensor lever 73 in a direction that does not engage with the teeth portion 34.

[0093] [Embodiment 4] When the belt is attached and when the belt is being rewound, The seat belt retractor 1 according to Embodiment 3, wherein the rotation of the switch lever 90 in the second rotational direction causes the claw portion 96 of the switch lever 90 to contact the acceleration sensor lever 73 more strongly than when the belt is stationary, thereby biasing the acceleration sensor lever 73 in a direction that does not engage with the teeth portion 34.

[0094] [Embodiment 5] When the belt is attached and when the belt is pulled out, A seat belt retractor 1 according to embodiment 3 or 4, wherein the friction lever 120 rotates in the second rotational direction as the spindle 10 is extended, thereby causing the switch lever 90 to rotate in the first rotational direction against the biasing force of the return spring 100 via the engagement between the engagement gear portion 124 of the friction lever 120 and the engagement gear receiving portion 95 of the switch lever 90, thereby separating the claw portion 96 of the switch lever 90 from the acceleration sensor lever 73 and allowing the acceleration sensor lever 73 to move in a direction that engages with the teeth portion 34.

[0095] [Embodiment 6] When the belt is retracted, A seat belt retractor 1 according to any one of embodiments 3 to 5, wherein the rotation of the switch lever 90 in the second rotational direction via the cam mechanism (projection 94, cam groove 113) and the return spring 100 cause the claw portion 96 of the switch lever 90 to contact the acceleration sensor lever 73, thereby biasing the acceleration sensor lever 73 in a direction that does not engage with the tooth portion 34.

[0096] [Embodiment 7] The system further includes a friction spring 130 that provides frictional force to the friction lever 120 so that the rotation of the spindle 10 is transmitted to the friction lever 120. When the belt is attached, the friction lever 120 rotates together with the spindle 10 due to the frictional force of the friction spring 130 as the spindle 10 rotates. In the seat belt retractor 1 according to any one of embodiments 1 to 6, when the belt is stored, the torque transmitted by the winding rotation of the spindle 10 exceeds the frictional force of the friction spring 130, and the spindle 10 rotates relative to the friction lever 120.

[0097] [Embodiment 8] The system further comprises a hub 140 fixed to the shaft of the spindle 10 and rotating integrally with the spindle 10, The friction spring 130 connects the hub 140 and the friction lever 120 by frictional force. When the belt is installed, the friction lever 120 rotates together with the hub 140 as the spindle 10 rotates due to the frictional force of the friction spring 130. In the seat belt retractor 1 according to Embodiment 7, when the belt is stored, the torque transmitted by the winding rotation of the spindle 10 exceeds the frictional force of the friction spring 130, and the spindle 10 rotates relative to the friction lever 120 while sliding the hub 140 against the friction lever 120 against the frictional force of the friction spring 130.

[0098] [Embodiment 9] The friction lever 120 is A roughly C-shaped base 121, A mounting portion 122 is formed on the outer circumference of the base portion 121 and the friction spring 130 is attached thereto, It has a sliding portion 123 formed on the inner circumference of the base portion 121 and slidably coupled to the hub 140, The seat belt retractor 1 according to Embodiment 8, wherein the base portion 121 is reduced in diameter by the friction spring 130 attached to the mounting portion 122, thereby connecting the hub 140 and the sliding portion 123 by frictional force.

[0099] [Embodiment 10] The seat belt retractor 1 according to Embodiment 9, wherein the engaging gear portion 124 of the friction lever 120 is formed to protrude from the outer circumference of the base portion 121.

[0100] [Embodiment 11] The seat belt retractor 1 according to any one of embodiments 8 to 10, wherein the hub 140 and the control plate 110 are gear-coupled via one or more gears (first idler gear 82, second idler gear 83).

[0101] [Embodiment 12] The switch lever 90 has a first surface 92a, a second surface 92b opposite to the first surface 92a, and a side portion 92c connecting the first surface 92a and the second surface 92b. The engagement portion 93 is formed on the first surface 92a, The cam follower (projection 94) is formed on the second surface 92b, The seat belt retractor 1 according to any one of embodiments 1 to 11, wherein the engagement gear receiving portion 95 is formed on the side portion 92c.

[0102] [Embodiment 13] The seat belt retractor 1 according to embodiment 12, wherein the engaging portion 93 and / or the cam follower (projection portion 94) is a projection. [Explanation of symbols]

[0103] 1...Seat belt retractor, 10...Spindle, 11...Winding device, 12...Cover, 13...Frame, 13A, 13B...Side plate, 14...Shaft, 15...Cover member, 17...Internal tooth, 20...Lock dog, 21...Cam pin, 22...Claw, 25...Safety plate, 26...Omega spring, 30...Steering wheel, 31...Cam hole, 32...Convex shaft, 34...Tooth section, 40...Webbing sensor lever, 42...Claw, 48...Webbing sensor spring, 50...Latch ring, 51...External tooth, 52...Internal tooth, 60...Bearing plate, 61, 62, 63, 64...Shaft section, 65...Receiving section, 70...Accelerometer (CS), 71...Sensor holder, 72...Inertial body (ball), 73...Accelerometer lever, 74...Tooth tip, 75...Shaft section, 7 7... Locking piece, 82... First idler gear, 83... Second idler gear, 90... Switch lever, 91... Hole, 92a... First surface, 92b... Second surface, 92c... Side surface, 93... Engaging part, 94... Projection, 95... Engaging gear receiving part, 96... Claw part, 97... Spring mounting part, 100... Return spring, 101... One end, 102... Other end, 103... Coil part, 110... Co Control plate, 111... shaft hole, 112... gear, 113... cam groove, 113a... first cam part, 113b... second cam part, 113c... switching part, 120... friction lever, 121... base part, 121a... notch groove, 122... mounting part, 123... sliding part, 124... engaging gear part, 130... friction spring, 140... hub, 141... gear, 142... cylindrical part,

Claims

1. A spindle that is rotatably supported by the frame and around which the seat belt is wound, A locking member that engages with the frame to lock the rotation of the spindle in the seat belt pull-out direction, A steering wheel is supported so as to be rotatable relative to the spindle, and acts on the locking member by creating a rotational lag relative to the spindle, A latch ring is rotatably mounted on a bearing plate fixed to the frame, with internal teeth and external teeth formed on its inner and outer surfaces, respectively. A webbing sensor lever is pivotably supported on the steering wheel in a position where it can engage with and disengage from the internal teeth of the latch ring, and is displaceable between an operating position that prevents the steering wheel from rotating in the seat belt pull-out direction and a non-operating position where the steering wheel does not prevent rotation in the seat belt pull-out direction. A seat belt retractor comprising a control plate that rotates at a different rotational speed than the spindle in accordance with the rotation of the spindle, A friction lever having an engaging gear portion and capable of rotating together with the spindle as the spindle rotates, A switch lever rotatably supported on the bearing plate, the switch lever having an engaging portion that can engage with and disengage from the external teeth of the latch ring, a cam follower guided by a cam portion formed on the control plate, and an engaging gear receiving portion that engages with the engaging gear portion of the friction lever, Furthermore, (1) When wearing the belt, During belt winding from a stationary state to a first winding amount, the friction lever rotates in a first rotational direction as the spindle winds, thereby rotating the switch lever in a second rotational direction opposite to the first rotational direction via the engagement between the engagement gear portion of the friction lever and the engagement gear receiving portion of the switch lever, moving the engagement portion of the switch lever to a position where it does not engage with the external teeth of the latch ring, When the belt is extended from a stationary state to a first extension amount, the friction lever rotates in the second rotational direction in conjunction with the spindle's payout rotation, thereby rotating the switch lever in the first rotational direction via the engagement between the engagement gear portion of the friction lever and the engagement gear receiving portion of the switch lever, and moving the engagement portion of the switch lever to a position where it can engage with the external teeth of the latch ring. Also, (2) When the seat belt is retracted into its storage location, A seat belt retractor, wherein the control plate rotates in conjunction with the winding rotation of the spindle, thereby rotating the switch lever in the second rotational direction via a cam mechanism formed by the cam portion of the control plate and the cam follower of the switch lever, and moving the engaging portion of the switch lever to a position where it does not engage with the external teeth of the latch ring.

2. The seat belt retractor according to claim 1, further comprising a return spring that biases the switch lever in the second rotational direction.

3. The steering wheel further comprises an acceleration sensor having an acceleration sensor lever that can be locked to teeth formed on the outer circumference of the steering wheel, The switch lever further has a claw portion that can move toward and away from the acceleration sensor lever, When the belt is attached, in the state where the belt is stationary, The seat belt retractor according to claim 2, wherein the return spring causes the claw portion of the switch lever to contact the acceleration sensor lever, thereby biasing the acceleration sensor lever in a direction that does not engage with the teeth portion.

4. When the belt is attached and when the belt is being rewound, The seat belt retractor according to claim 3, wherein the rotation of the switch lever in the second rotational direction causes the claw portion of the switch lever to contact the acceleration sensor lever more strongly than when the belt is stationary, thereby biasing the acceleration sensor lever in a direction that does not engage with the teeth portion.

5. When the belt is attached and when the belt is pulled out, The seat belt retractor according to claim 3, wherein the friction lever rotates in the second rotational direction as the spindle is extended, thereby causing the switch lever to rotate in the first rotational direction against the biasing force of the return spring via the engagement between the engagement gear portion of the friction lever and the engagement gear receiving portion of the switch lever, separating the claw portion of the switch lever from the acceleration sensor lever, and allowing the acceleration sensor lever to move in a direction that engages with the teeth portion.

6. When the belt is retracted, The seat belt retractor according to claim 3, wherein the rotation of the switch lever in the second rotational direction via the cam mechanism and the return spring cause the claw portion of the switch lever to contact the acceleration sensor lever, thereby biasing the acceleration sensor lever in a direction that does not engage with the teeth portion.

7. The system further includes a friction spring that provides frictional force to the friction lever so that the rotation of the spindle is transmitted to the friction lever. When the belt is attached, the friction lever rotates together with the spindle due to the frictional force of the friction spring, A seat belt retractor according to any one of claims 1 to 6, wherein when the belt is retracted, the torque transmitted by the winding rotation of the spindle exceeds the frictional force of the friction spring, and the spindle rotates relative to the friction lever.

8. The system further comprises a hub fixed to the shaft of the spindle and rotating integrally with the spindle, The friction spring connects the hub and the friction lever by frictional force. When the belt is installed, the friction lever rotates together with the hub as the spindle rotates due to the frictional force of the friction spring. The seat belt retractor according to claim 7, wherein when the belt is retracted, the torque transmitted by the winding rotation of the spindle exceeds the frictional force of the friction spring, and the spindle rotates relative to the friction lever while sliding the hub against the friction lever against the frictional force of the friction spring.

9. The aforementioned friction lever is A roughly C-shaped base, A mounting portion formed on the outer circumference of the base, on which the friction spring is attached, It has a sliding portion formed on the inner circumference of the base and slidably coupled to the hub, The seat belt retractor according to claim 8, wherein the base is reduced in diameter by the friction spring attached to the mounting portion, thereby coupling the hub and the sliding portion by frictional force.

10. The seat belt retractor according to claim 9, wherein the engaging gear portion of the friction lever is formed to protrude from the outer circumference of the base.

11. The seat belt retractor according to claim 8, wherein the hub and the control plate are gear-coupled via one or more gears.

12. The switch lever has a first surface, a second surface opposite to the first surface, and a side portion connecting the first surface and the second surface. The engagement portion is formed on the first surface, The cam follower is formed on the second surface, The seat belt retractor according to any one of claims 1 to 6, wherein the engagement gear receiving portion is formed on the side portion.

13. The seat belt retractor according to claim 12, wherein the engaging portion and / or the cam follower is a projection.

Images