Seat belt retractor and seat belt apparatus

Abstract

To provide a seat belt retractor capable of suppressing power consumption in an electromagnetic lock type configuration.SOLUTION: The seat belt retractor 3 includes the electromagnetic vehicle sensor 40 having the electromagnet 50 and the actuator 60 and configured to switch between the locked state in which the locking mechanism 30 is operated and the unlocked state in which the locking mechanism 30 is not operated by operating the actuator 60 in response to energization of the electromagnet 50, the microswitch 90 as an example of the detection unit configured to detect the operation transition of the actuator 60, and the control unit 100 configured to control the current flowing through the electromagnet 50. A control part 100 switches a current flowing to the electromagnet 50 to a holding current C1 smaller than an operation current C1 when the operation transition of the actuators 60 is detected by the microswitch 90 after the operation current C2 for operating the actuators 60 is made to flow to the electromagnet 50.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present disclosure relates to a seat belt retractor and a seat belt device. [Background technology]

[0002] 2. Description of the Related Art A so-called electromagnetic locking seat belt retractor is known, which is a seat belt retractor configured to control the operation of the seat belt retractor using an electromagnetic actuator.

[0003] As an example of such an electromagnetic locking seat belt retractor, for example, Patent Document 1 discloses a configuration in which a solenoid that operates when energized is used to switch between a state in which the operation of the seat belt retractor is restricted and a state in which it is released. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 02-256545 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional electromagnetic locking seat belt retractors are generally classified into two types: a current ON lock type and a current OFF lock type.

[0006] With the current-off lock type, when there is no electrical signal and the electromagnetic actuator is not operating, the seat belt retractor locks (i.e., the operation of the seat belt retractor is restricted). With this type, the seat belt retractor locks even when there is no electrical signal due to a malfunction of the ECU of the vehicle in which the seat belt retractor is installed, so a fail-safe is established. However, to maintain the unlocked state with this type, it is necessary to keep current flowing at all times, which consumes a lot of power.

[0007] On the other hand, with the current-on lock type, in contrast to the current-off lock type, the operation of the seat belt retractor is restricted and current only needs to be passed when it is locked. However, in situations where the seat belt retractor must remain locked, such as when the vehicle is parked on a slope, it becomes necessary to continue passing current at all times, which increases power consumption.

[0008] In short, there is room for improvement in terms of power consumption in both the current ON lock type and the current OFF lock type.

[0009] An object of the present disclosure is to provide a seat belt retractor and a seat belt device that can reduce power consumption in an electromagnetic locking configuration. [Means for solving the problem]

[0010] A seat belt retractor according to one aspect of an embodiment of the present invention comprises a spool around which a seat belt is wound, a locking mechanism that, when activated, prevents rotation of the spool in the direction of withdrawing the seat belt, an electromagnetic vehicle sensor having an electromagnet and an actuator, which switches between a locked state in which the locking mechanism is activated and an unlocked state in which the locking mechanism is deactivated by operating the actuator in response to current being passed through the electromagnet, a detection unit that detects the operational transition of the actuator, and a control unit that controls the current flowing to the electromagnet, and after the control unit passes an operating current to the electromagnet to operate the actuator, when the operational transition is detected by the detection unit, switches the current flowing to the electromagnet to a holding current that is smaller than the operating current. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide a seat belt retractor and a seat belt device that can reduce power consumption in an electromagnetic locking configuration. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a seat belt device according to an embodiment; [Figure 2] 1 is a perspective view of a seat belt retractor according to an embodiment; [Figure 3] 1 is an exploded perspective view of a current-ON lock type electromagnetic vehicle sensor according to an embodiment; [Figure 4] Diagram showing the non-lock state of a current-ON lock type electromagnetic vehicle sensor [Figure 5] A diagram showing the locked state of a current-on lock type electromagnetic vehicle sensor [Figure 6] FIG. 10 is a diagram showing an example of lock determination based on the output of a microswitch; [Figure 7] Functional block diagram of the control unit of the electromagnetic vehicle sensor [Figure 8] A diagram showing an example of electromagnet attraction characteristics [Figure 9] FIG. 10 is a diagram showing an example of current input in this embodiment. [Figure 10] 1 is a flowchart showing current value control of a current ON lock type electromagnetic vehicle sensor according to the present embodiment. [Figure 11] 1 is a flowchart illustrating error detection control for an electromagnetic vehicle sensor according to an embodiment of the present invention. [Figure 12] 1 is an exploded perspective view of a current OFF lock type electromagnetic vehicle sensor according to an embodiment; [Figure 13] Diagram showing the non-lock state of a current-off lock type electromagnetic vehicle sensor [Figure 14] A diagram showing the locked state of a current-off lock type electromagnetic vehicle sensor [Figure 15] 1 is a flowchart showing current value control of a current OFF lock type electromagnetic vehicle sensor according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0014] In the following description, the X direction, Y direction, and Z direction shown in each of the drawings relating to the seat belt retractor 3 from Fig. 2 onwards are perpendicular to one another. The X direction is the extension direction of the axis center CA of the rotation shaft of the spool 12. The Y direction and Z direction are each centrifugal directions from the rotation shaft of the spool 12, and typically the Z direction is the up-down direction, which is the direction in which the seat belt 4 is withdrawn and wound relative to the seat belt retractor 3. In addition, in the direction of the rotation shaft of the seat belt retractor 3, the retainer 14 side is the X positive direction side, and the opposite side is the X negative direction side.

[0015] First, with reference to FIG. 1, an example of the configuration of a seat belt device 1 to which a seat belt retractor 3 according to an embodiment is applied will be described.

[0016] The seatbelt device 1 is an example of an in-vehicle system installed in a vehicle. The seatbelt device 1 includes, for example, a seatbelt 4, a seatbelt retractor 3, a shoulder anchor 6, a tongue 7, and a buckle 8.

[0017] The seat belt 4 is an example of a webbing that restrains an occupant 9 seated in a vehicle seat 2, and is a belt-shaped member that is retractable and wound around a seat belt retractor 3. A belt anchor 5 at the tip of the seat belt 4 is fixed to the seat 2 or to a vehicle body in the vicinity of the seat 2.

[0018] The seat belt retractor 3 is an example of a retracting device that enables retracting or unretracting of the seat belt 4, and when deceleration equal to or greater than a predetermined value is applied to the vehicle, such as during a vehicle collision, the seat belt retractor 3 restricts the seat belt 4 from being unretracted from the seat belt retractor 3. The seat belt retractor 3 is fixed to the seat 2 or to a vehicle body in the vicinity of the seat 2.

[0019] The shoulder anchor 6 is an example of a belt insertion tool through which the seat belt 4 is inserted, and is a member that guides the seat belt 4 pulled out from the seat belt retractor 3 toward the shoulder of the occupant 9.

[0020] The tongue 7 is an example of a belt insertion tool through which the seat belt 4 is inserted, and is a component slidably attached to the seat belt 4 guided by the shoulder anchor 6.

[0021] The buckle 8 is a component to which the tongue 7 is releasably fastened, and is fixed to the seat 2 or a part of the vehicle body in the vicinity of the seat 2, for example.

[0022] Next, the configuration of the seat belt retractor 3 according to the embodiment will be described with reference to Fig. 2. Fig. 2 is a perspective view of the seat belt retractor 3 according to the embodiment. Fig. 2 shows only a part of the seat belt retractor 3 as an exploded perspective view, illustrating the lock gear 32 of the lock mechanism 30, the electromagnetic vehicle sensor 40, and the retainer 14 in an exploded state.

[0023] As shown in FIG. 2, the seat belt retractor 3 includes a pretensioner (PT) subassembly 10, a shaft subassembly 20, and a locking mechanism 30.

[0024] The PT subassembly 10 has a pretensioner 13 mounted on a frame 11. The pretensioner 13 is connected to a paddle wheel of the shaft subassembly 20. When the pretensioner 13 is activated, the paddle wheel receives a rotational force from the pretensioner 13, which causes the spool 12 to rotate in a direction that retracts the seatbelt 4.

[0025] The frame 11 includes a back plate 11a facing the Y direction and left and right side walls 11b and 11c projecting perpendicularly from both ends of the back plate 11a in the X direction. The side wall 11b faces the positive X direction, and the side wall 11c faces the negative X direction, facing each other. Circular openings 11d and 11e are formed in the side walls 11b and 11c, respectively.

[0026] The shaft subassembly 20 includes a spool 12 to which one end of the seat belt 4 is fastened and around which the seat belt 4 is wound. The shaft subassembly 20 is inserted into openings 11d and 11e in the side walls 11b and 11c and attached to the frame 11 so as to be rotatable about a rotation axis 21 in the X direction.

[0027] The seat belt 4 is wound counterclockwise around the outer periphery of the spool 12 when viewed from the X-positive side, as shown by the dotted line in FIG. 2, for example, and is installed so that it is pulled out from a position on the Y-negative side of the outer periphery of the wound portion toward the Z-positive side.

[0028] The locking mechanism 30 is connected to the rotary shaft 21 of the spool 12, and allows the spool 12 to rotate when not in operation, and prevents the spool 12 from rotating in the seat belt withdrawing direction when in operation. The locking mechanism 30 has a lock subassembly 31, a locking base 34, a pawl 35, and engagement teeth 36. The seat belt retractor 3 also has an electromagnetic vehicle sensor 40 as an element for controlling the operation of the locking mechanism 30.

[0029] The lock subassembly 31 has a lock gear 32. The lock gear 32 is formed in a bottomed cylindrical shape with a bottom surface 32A on the X negative direction side, and components such as a flywheel 33 are assembled and housed inside the cylindrical shape. The flywheel 33 is one of the components that make up the webbing sensor that detects when the seat belt 4 is suddenly withdrawn from the spool 12, but since it is not closely related to the features of this embodiment, a description of it will be omitted here. The bottom surface 32A can also be expressed as the main surface of the lock gear 32 on the side where the flywheel 33 and the like are installed.

[0030] Furthermore, a through-hole 32B that passes through the rotary shaft 21 is provided at the center of the circular bottom surface 32A of the lock gear 32. The through-hole 32B is formed in a substantially cylindrical shape that protrudes from the bottom surface 32A in the positive X direction. The lock gear 32 is a rotating member that rotates together with the rotary shaft 21 and is concentric with the rotary shaft 21 of the spool 12, and is fitted and supported by the rotary shaft 21. The lock gear 32 has an outer periphery on which a predetermined number of ratchet teeth 32C are formed.

[0031] 2, shaft subassembly 20 is installed so as to pass through openings 11d and 11e in side walls 11b and 11c of frame 11 in the X direction, and the portion protruding from opening 11d on the X positive side is connected to lock subassembly 31. Retainer 14 is attached to side wall 11b on the X positive side of frame 11, and lock subassembly 31 is built in. In this state, spool 12 is rotatably supported by frame 11 and can retract seat belt 4.

[0032] Furthermore, a plurality of engagement teeth 36 are formed on the inner circumferential surface of opening 11d on the X-positive side of frame 11 so as to protrude toward the center of the circular shape of opening 11d. As described above, engagement teeth 36 are one element of locking mechanism 30.

[0033] 2, shaft subassembly 20 has, in addition to spool 12, a locking base 34 and a pawl 35. As described above, locking base 34 and pawl 35 are elements of locking mechanism 30. Locking base 34 is, for example, a cylindrical member having approximately the same diameter as the spool, and is connected to the end of spool 12 on the X positive side so as to be rotatable together with spool 12. Rotation shaft 21 of spool 12 passes through locking base 34 and protrudes further in the X positive direction than locking base 34.

[0034] A pawl 35 is connected to the end face on the X-positive side of the locking base 34. The pawl 35 is installed in a recess formed by carving from the end face of the locking base 34 toward the X-negative side so that the position of the end face on the X-positive side of the pawl 35 is aligned with the end face of the locking base 34. This recess reaches the outer edge on the radially outer side, and the pawl 35 is rotatably supported in the recess, so that the pawl 35 can rotate to protrude radially outward from the outer edge of the locking base 34.

[0035] The electromagnetic vehicle sensor 40 is attached to the side wall 11b on the X positive side of the frame 11, for example, as shown in FIG.

[0036] The surface of the retainer 14 facing the side wall 11b in the negative X direction is provided with a first recess 14A capable of accommodating the lock subassembly 31 and a second recess 14B capable of accommodating the electromagnetic vehicle sensor 40. As a result, the lock mechanism 30 is built into the retainer 14 when the retainer 14 is attached to the side wall 11b.

[0037] The outer shape of first recess 14A is circular with a diameter larger than that of lock subassembly 31 so that it can accommodate circular lock subassembly 31. A cylindrical bearing portion 14C capable of fitting rotating shaft 21 of shaft subassembly 20 is provided at the center of the circle of first recess 14A. Bearing portion 14C is formed to stand on the X negative side from bottom surface 14D on the X positive side of the first recess. Rotating shaft 21 of spool 12 is rotatably supported by retainer 14 fixed to frame 11.

[0038] FIG. 3 is an exploded perspective view of a current-on lock type electromagnetic vehicle sensor 40 according to an embodiment.

[0039] The term "electromagnetic vehicle sensor" used in this embodiment refers to a device that has an electromagnet 50 and an actuator 60, and switches between a locked state in which the locking mechanism 30 is activated and an unlocked state in which the locking mechanism 30 is not activated by operating the actuator 60 in response to the energization of the electromagnet 50. In the following description, the unlocked state may also be referred to as a "non-locked state."

[0040] Furthermore, the "current-ON lock type electromagnetic vehicle sensor 40" is a type of vehicle sensor in which the lock of the seat belt retractor 3 is turned ON (i.e., the operation of the seat belt retractor 3 is restricted by the lock mechanism 30) when current flows through the electromagnet 50 and the electromagnetic actuator 60 is activated. In the following description, the "current-ON lock type electromagnetic vehicle sensor 40" may also be simply referred to as the "electromagnetic vehicle sensor 40."

[0041] The current ON lock type electromagnetic vehicle sensor 40 has a configuration such as that shown in FIG.

[0042] The electromagnet 50 includes a coil 51 , a bobbin 52 , and a yoke 53 .

[0043] The bobbin 52 has a generally cylindrical winding shaft 54 ​​and a pair of side plates 55, 56 arranged opposite each other in the axial direction of the winding shaft 54. One side plate 55 is connected to the end of the winding shaft 54 ​​on the Y negative side, and the other side plate 56 is connected to the end of the winding shaft 54 ​​on the Y positive side. The normal directions of the main surfaces of the pair of side plates 55, 56 are the same as the axial direction of the winding shaft 54. The bobbin 52 also has a through hole 57 that penetrates the Y negative side plate 55, the winding shaft 54, and the Y positive side plate 56. The central axis of the through hole 57 is preferably the same as the axis of the winding shaft 54.

[0044] Coil 51 is an electronic component formed by winding a conductor wire in a spiral shape around the outer periphery of winding axis 54 of bobbin 52. When a current flows through the conductor wire of coil 51, electromagnet 50 can be energized.

[0045] The yoke 53 is a rod-shaped metal member formed into a shape that allows it to be inserted into the through-hole 57 of the bobbin 52. In the example of FIG. 3 , a flange is provided at the end of the yoke 53 on the Y negative side. As a result, the yoke 53 is inserted into the through-hole 57 from the side of the side plate 55, and its tip passes through the winding shaft 54 ​​and the side plate 56, protruding from the through-hole 57 in the Y positive direction. The flange is then engaged with the end of the through-hole 57 on the Y negative side, thereby connecting the yoke 53 to the bobbin 52. In this installed state, most of the axial portion of the yoke 53 is located toward the center of the coil 51. Therefore, when a current flows through the coil 51, a magnetic field passing through the central axis of the coil 51 is generated. At this time, a magnetic flux along the magnetic field also flows through the yoke 53, amplifying the attractive force of the electromagnet 50.

[0046] The actuator 60 includes a suction portion 61 , a lever portion 62 , support grooves 63 a and 63 b , an engagement portion 64 , a switching portion 65 , and a connecting portion 66 .

[0047] Attraction portion 61 is a portion that is disposed opposite the axial direction of coil 51 of electromagnet 50 and is attracted toward electromagnet 50 when electromagnet 50 is energized. In the example of Fig. 3, attraction portion 61 is a flat plate-shaped member that is disposed on the Y negative side of side plate 55 on the Y negative side of bobbin 52 of electromagnet 50, and is opposed to the main surface of side plate 55. With this configuration, attraction portion 61 is configured to be attracted in a direction approaching side plate 55 of electromagnet 50, i.e., toward the Y positive direction, when electromagnet 50 is energized.

[0048] Lever portion 62 is a portion that moves toward lock gear 32 of lock mechanism 30 when attraction portion 61 is attracted by electromagnet 50. In the example of FIG. 3 , lever portion 62 is a rectangular flat plate member whose base end is connected to the upper end portion of attraction portion 61 on the Z positive side and extends from this connection in one direction toward the Y positive direction and the Z positive direction. Note that in the example of FIG. 3 , lever portion 62 is disposed at the end portion of the upper end portion of attraction portion 61 on the X positive direction side. The reason for this is that when actuator 60 is accommodated in housing 41 (described later), the portion of the upper end portion of attraction portion 61 on the X positive direction side protrudes in the X positive direction with respect to the outer frame of housing 41, making it easy to pull out the tip portion of lever portion 62 to the outside of housing 41 and move it toward lock gear 32.

[0049] The support grooves 63a and 63b are supported by a bracket 70 (described later) and serve as the rotation center of the actuator 60. In the example of Fig. 3, the support grooves 63a and 63b are disposed at the same position in the X direction of the suction unit 61, and are recessed from both ends of the suction unit 61 in the X direction toward the center. This allows the actuator 60 to be installed so as to be rotatable around a rotation axis that is a straight line extending in the X direction and connecting the pair of support grooves 63a and 63b.

[0050] The engaging portion 64 is provided at the tip of the lever portion 62, and when the lever portion 62 moves toward the lock gear 32, it engages with ratchet teeth 32C provided on the outer periphery of the lock gear 32 to restrict the rotation of the lock gear 32, thereby activating the lock mechanism 30. In the example of Fig. 3, the engaging portion 64 is formed by bending the tip portion of the strip-shaped lever portion 62 toward the positive Z direction, i.e., toward the lock gear 32.

[0051] The electromagnetic vehicle sensor 40 has a bracket 70. The bracket 70 is a member that connects to the electromagnet 50 and the actuator 60 and maintains a constant positional relationship between the electromagnet 50 and the actuator 60. The bracket 70 is a plate-shaped member that is bent at a substantially right angle when viewed in the X direction. The bracket 70 has a first flat plate portion 71 that extends in the Y direction and a second flat plate portion 72 that extends in the Z direction. The first flat plate portion 71 and the second flat plate portion 72 are integrally formed, and an end portion of the first flat plate portion 71 on the Y positive side and an end portion of the second flat plate portion 72 on the Z positive side are connected and bent at a substantially right angle.

[0052] The first flat plate portion 71 is formed so that its width direction is along the X direction and its dimension in the width direction is approximately the same as that of the suction portion 61 of the actuator 60. A pair of protrusions 73a, 73b is provided at the tip of the first flat plate portion 71 on the negative Y direction side, with both ends in the width direction protruding in the negative Y direction from the center portion. The pair of protrusions 73a, 73b are inserted into a pair of support grooves 63a, 63b of the actuator 60, respectively, and support the actuator 60 via the contact portions with the support grooves 63a, 63b.

[0053] Furthermore, first flat plate portion 71 is preferably formed so that the top surfaces corresponding to the respective sides of the rectangular shape of a pair of side plates 55, 56 of bobbin 52 come into contact with each other when connected to electromagnet 50. This makes it possible to prevent displacement of electromagnet 50 around the Y axis when connected to electromagnet 50, thereby enabling more reliable holding.

[0054] A support hole 74 is provided in the second flat plate portion 72, penetrating along the Y direction. The support hole 74 is formed so that, when connected to the electromagnet 50, the central axis of the hole is aligned with the axis of the electromagnet 50. Meanwhile, a mating portion 58 is formed at the tip of the yoke 53 of the electromagnet 50 on the Y positive side. The mating portion 58 has a cylindrical shape similar to the yoke 53, but is formed with a smaller diameter than the yoke 53. The diameter of the mating portion 58 is formed to be approximately the same as the diameter of the support hole 74, and is formed so that it can be mated with the support hole 74. With the components of the electromagnet 50 assembled, the electromagnet 50 can be connected to the bracket 70 by mating the mating portion 58 of the yoke 53 with the support hole 74 of the bracket 70.

[0055] The electromagnetic vehicle sensor 40 also has a spring 80. The spring 80 is an example of an elastic member that is biased to apply an external force to the actuator 60 in a direction in which the attraction portion 61 of the actuator 60 moves away from the electromagnet 50. In the example of FIG. 3, the spring 80 is a coil spring that is biased in the axial direction by expanding in the axial direction. In the example of FIG. 3, the spring 80 is disposed so that the axial direction substantially coincides with the Y direction, and an annular portion 81 is provided at the end on the Y negative side, and a similar annular portion 82 is provided at the end on the Y positive side.

[0056] As shown in FIG. 3, the actuator 60 further includes a connecting portion 66. The connecting portion 66 can be connected to the end of the spring 80 on the negative Y direction side by connecting to the annular portion 81 of the spring 80. In the example of FIG. 3, the connecting portion 66 is formed in a claw shape that protrudes from approximately the center in the X direction of the upper end of the attraction portion 61 toward the positive Z direction and then bends toward the negative Y direction. This claw-shaped portion engages with the annular portion 81 of the spring 80. In addition, in the example of FIG. 3, the connecting portion 66 is disposed adjacent to the base end of the lever portion 62 at the upper end of the attraction portion 61.

[0057] Meanwhile, bracket 70 also has a connecting portion 75. By connecting to annular portion 82 of spring 80, connecting portion 75 can connect to the end of spring 80 on the Y-positive side. In the example of FIG. 3 , connecting portion 75 is formed so as to protrude toward the Z-positive side from approximately the center in the X-direction of the boundary between first flat plate portion 71 and second flat plate portion 72, and has a groove formed in the middle portion in the Z direction that is recessed from the end face on the Y-positive side toward the Y-negative side. This groove engages with annular portion 82 of spring 80.

[0058] As shown in Fig. 3, the connecting portion 66 of the actuator 60 is disposed further away in the positive Z direction than the support grooves 63a, 63b. Therefore, when the actuator 60 rotates about the support grooves 63a, 63b, the distance between the connecting portion 66 of the actuator 60 and the connecting portion 75 of the bracket 70 varies. This variation causes the spring 80 to expand and contract via the annular portions 81, 82 to which the connecting portions 66, 75 are connected, thereby generating an urging force in the spring 80. Note that in the case of the current-on lock type electromagnetic vehicle sensor 40, when the electromagnet 50 is in a non-energized state where no current is flowing through it, the spring 80 is connected to the connecting portions 66, 75 in an expanded state so as to apply an urging force (arrow B shown in Fig. 4) that moves the connecting portion 66 of the actuator 60 toward the connecting portion 75 of the bracket 70.

[0059] The seat belt retractor 3 also has a microswitch 90. The microswitch 90 is an example of a detection unit that detects the operational transition of the actuator 60 of the electromagnetic vehicle sensor 40. In the example of FIG. 3, the microswitch 90 is housed in the housing 41 together with the elements of the electromagnetic vehicle sensor 40, namely, the electromagnet 50, the actuator 60, the bracket 70, and the spring 80. In other words, the microswitch 90 is built into the electromagnetic vehicle sensor 40.

[0060] As shown in FIG. 3 , the microswitch 90 includes a main body 91 and a lever 92. The main body 91 is a housing that houses the main components related to the switch function. A switch that can be contacted by the lever 92 is provided on the main body 91 and is exposed to the outside. The lever 92 is a rectangular plate-like member. One longitudinal end of the lever 92 is connected to one surface of the main body 91, extends along this surface, and extends obliquely relative to this surface so that the other end is spaced apart from this surface. In the example shown in FIG. 3 , the lever 92 is provided on the surface of the main body 91 facing the negative Y direction. The negative Z end of the lever 92 is connected to the main body 91, and the longitudinal direction of the lever 92 extends in both the positive Z direction and the negative Y direction. As a result, the positive Z end of the lever 92 is spaced apart from the negative Y direction relative to the main body 91.

[0061] Although not shown in Figure 3, a switch is provided on the surface of the main body 91 facing the negative Y direction, and the switch is pressed when the lever 92 is pressed toward the main body 91, thereby switching the output of the microswitch 90 from the OFF state to the ON state.

[0062] The actuator 60 further includes a switching unit 65. The switching unit 65 is a part that presses a lever 92 of the microswitch 90 to switch it to the ON state when the attraction unit 61 is attracted toward the electromagnet 50. In the example of FIG. 3, the switching unit 65 is provided to protrude downward from approximately the center of the lower end of the attraction unit 61 on the negative Z direction side. The amount of protrusion of the switching unit 65 is formed to a length that allows it to come into contact with at least the tip portion of the lever 92 of the microswitch 90 on the positive Z direction side when both the actuator 60 and the microswitch 90 are accommodated in the housing 41.

[0063] The housing 41 is an annular member formed by a peripheral wall having a constant width in the X direction. In the example of Fig. 3, the housing 41 has a bottom end wall 44 extending along the Y direction at the end on the Z negative side. The housing 41 also has an intermediate wall 43 extending along the Y direction at an intermediate portion in the Z direction, i.e., at a position above the bottom end wall 44. The intermediate wall 43 is disposed on the Y positive side of the bottom end wall 44. In other words, the internal space of the housing 41 is formed so that the portion above the intermediate wall 43 protrudes further in the Y positive direction than the portion below.

[0064] The housing 41 has a sidewall 45 extending along the Z direction at its end on the Y negative side. A groove 42 extending along the X direction and opening toward the Y positive side is provided on the surface of the sidewall 45 facing the internal space, above the intermediate wall 43. The groove 42 receives the tips of the protrusions 73a and 73b of the bracket 70. The lower end surface of the side plate 56 of the bobbin 52 of the electromagnet 50 is placed on the upper surface of the intermediate wall 43 facing the internal space. The depth of the groove 42 in the Y direction is determined so that, when the bracket 70 is positioned within the internal space of the housing 41 by the groove 42 and the intermediate wall 43, a gap is formed between the side plate 55 of the bobbin 52 of the electromagnet 50 connected to the bracket 70 and the side wall 45 of the housing 41. When the actuator 60 is accommodated in the housing 41, the attraction portion 61 of the actuator 60 is disposed between the side plate 55 and the side wall 45. By providing a gap between the side plate 55 and the side wall 45, the attraction part 61 can move within this gap, making it possible to change the position of the electromagnet 50 when it is energized and when it is not, thereby allowing the actuator 60 to rotate.

[0065] Furthermore, the lower end surface of the main body 91 of the microswitch 90 is placed on the upper surface of the lower end wall 44 that faces the internal space. In this manner, each element of the electromagnetic vehicle sensor 40 is accommodated within the housing 41 in a positioned state, and is thereby integrated.

[0066] Next, the mechanical operation of the electromagnetic vehicle sensor 40 will be described with reference to Figures 4 and 5. Figure 4 is a diagram showing the non-lock state of the electromagnetic vehicle sensor 40 of the current-on lock type.

[0067] In the case of a current-on lock type electromagnetic vehicle sensor 40, the electromagnet 50 is not energized in the non-locked state. At this time, as described above, the spring 80 is installed in a state in which it is stretched from its natural length. Furthermore, the annular portion 82 provided at the end of the spring 80 on the Y positive side is connected to the connecting portion 75 of the bracket 70 fixed to the housing 41. Meanwhile, the annular portion 81 provided at the end of the spring 80 on the Y negative side is not fixed to the housing 41, but is connected to the connecting portion 66 of the actuator 60 that is rotatably supported by the bracket 70. Due to these actions, as shown by arrow B, the spring 80 applies a biasing force to the connecting portion 66 of the actuator 60 in a direction toward the connecting portion 75 of the bracket 70 (the Y positive direction).

[0068] The action of such biasing force B causes actuator 60 to rotate counterclockwise about the X axis, viewed from the X positive side, around support grooves 63a and 63b. As a result, lever portion 62 of actuator 60 moves in a direction away from lock gear 32 of lock mechanism 30 (toward the Z negative direction), as shown in Figure 4, and engaging portion 64 is separated from ratchet teeth 32C of lock gear 32 and is held in a position where it cannot engage.

[0069] Furthermore, due to the rotation of actuator 60 described above, attraction portion 61 of actuator 60 moves in a direction (Y negative direction) away from electromagnet 50. As a result, as shown by dotted circle C in Fig. 4, switching portion 65 provided at the lower end of attraction portion 61 of actuator 60 moves further in the Y negative direction than lever 92 of microswitch 90, and is maintained in a non-contact state with lever 92. As a result, lever 92 is not pressed, and microswitch 90 is maintained in the OFF state.

[0070] As a result of the action of these electromagnetic vehicle sensors 40, as shown by arrow A in Figure 4, the lock gear 32 of the lock mechanism 30 is able to rotate in the seat belt withdrawing direction without being restricted in rotation, and the lock mechanism 30 is in a non-locked state where it is not activated.

[0071] FIG. 5 is a diagram showing the locked state of the current-ON lock type electromagnetic vehicle sensor 40. In FIG.

[0072] In the case of a current-on lock type electromagnetic vehicle sensor 40, in the locked state, current is applied to the electromagnet 50. This generates a magnetic field along the axial direction (Y direction in FIG. 5) at the center of the electromagnet 50, and the yoke 53 of the electromagnet 50 attracts the attraction part 61 of the actuator 60. As a result, as shown by arrow D in FIG. 5, the attraction part 61 moves in a direction approaching the side plate 55 of the electromagnet 50 (positive Y direction in FIG. 5).

[0073] Such movement of attraction portion 61 causes actuator 60 to rotate clockwise around the X axis (as viewed from the X positive side) about support grooves 63a, 63b against the biasing force of spring 80. As a result, lever portion 62 of actuator 60 moves in a direction approaching lock gear 32 of lock mechanism 30 (in the Z positive direction), as shown by arrow E in FIG. 5 , and engagement portion 64 engages with ratchet teeth 32C of lock gear 32.

[0074] As a result of the action of these electromagnetic vehicle sensors 40, the rotation of the lock gear 32 of the lock mechanism 30 is restricted, the lock mechanism 30 is activated, and the lock mechanism 30 transitions to a locked state in which withdrawal of the seat belt is restricted.

[0075] Furthermore, as a result of attraction portion 61 of actuator 60 moving toward electromagnet 50, switching portion 65 provided at the lower end of attraction portion 61 of actuator 60 moves to a position where it comes into contact with lever 92 of microswitch 90, as shown by dotted circle F in Fig. 5. As a result, lever 92 is pressed toward main body 91 by switching portion 65, as shown by arrow G in Fig. 5, and lever 92 presses the switch, switching microswitch 90 to the ON state.

[0076] Fig. 6 is a diagram showing an example of a lock determination based on the output of the microswitch 90. In the example of Fig. 6, the vertical axis represents the output of the microswitch 90, and the horizontal axis represents the displacement of the actuator 60. In the examples of Figs. 4 and 5, the displacement of the actuator 60 is, for example, the amount of movement of the switching unit 65 of the actuator 60 in the positive Y direction, and the state of Fig. 4 is equivalent to 0 on the horizontal axis of Fig. 6.

[0077] As shown in Fig. 6, when the displacement of the actuator 60 is equal to or smaller than a predetermined value d1, the output of the microswitch 90 is in the OFF state. This is a state in which the switching unit 65 of the actuator 60 is not in contact with the lever 92 of the microswitch 90, or the switching unit 65 is in contact with the lever 92 but the lever 92 has not been pressed to a position where it can press the switch of the main body 91, as shown by the dotted circle C in Fig. 4.

[0078] On the other hand, when the displacement of the actuator 60 becomes larger than a predetermined value d1, the output of the microswitch 90 switches to the ON state. This is the state in which the switching unit 65 of the actuator 60 presses the lever 92 of the microswitch 90, and the lever 92 presses the switch of the main body 91, as shown by the dotted circle F in Figure 5.

[0079] That is, in the case of the electromagnetic vehicle sensor 40 of the current-on lock type, the output of the microswitch 90 is OFF in the non-lock state and switches to ON in the locked state. Therefore, when the output of the microswitch 90 is ON, it can be determined that the locking mechanism 30 has been activated and transitioned to the locked state. In other words, the operational transition in which the actuator 60 switches from the non-lock state to the locked state can be detected based on the output of the microswitch 90.

[0080] 7 is a functional block diagram of the control unit 100 of the electromagnetic vehicle sensor 40. The seat belt retractor 3 includes the control unit 100. The control unit 100 controls the current flowing to the electromagnet 50 of the electromagnetic vehicle sensor 40.

[0081] In particular, in this embodiment, the control unit 100 performs current value control to switch the current flowing to the electromagnet 50 to a holding current C2 that is smaller than the operating current C1 when the microswitch 90 detects an operation transition of the actuator 60 after passing an operating current C1 to the electromagnet 50 for operating the actuator 60 (see FIG. 9). The control unit 100 has a lock control unit 101 and a current control unit 102 as functions related to such current value control.

[0082] The lock control unit 101 controls the operation of the lock mechanism 30. In the case of a current-on lock type electromagnetic vehicle sensor 40, the lock control unit 101 controls the lock mechanism 30 to operate when a predetermined operating condition of the lock mechanism 30 is met (for example, when the acceleration of the vehicle exceeds a predetermined value or when an impact is detected). In this example, the lock control unit 101 outputs an operation command to the current control unit 102 to activate the electromagnetic vehicle sensor 40 and transition the lock mechanism 30 to the locked state.

[0083] In response to an operation command input from the lock control unit 101, the current control unit 102 supplies an operating current C1 to the electromagnet 50 of the electromagnetic vehicle sensor 40 to activate the electromagnetic vehicle sensor 40. Furthermore, after the supply of the operating current C1, the current control unit 102 determines that the electromagnetic vehicle sensor 40 has been activated and has completed the transition from the non-locked state to the locked state when the output of the microswitch 90 switches from the OFF state to the ON state. After this determination, the current control unit 102 switches the current supplied to the electromagnet 50 of the electromagnetic vehicle sensor 40 to a holding current C2 that is smaller than the operating current C1. The magnitude of the holding current C2 may be such that the actuator 60 can maintain the locked state against the biasing force of the spring 80.

[0084] The control unit 100 can be physically configured as a computer system including a CPU (Central Processing Unit), a RAM (Random Access Memory) and a ROM (Read Only Memory) as main storage devices, an input device, an output device, a communication module, an auxiliary storage device, and the like. The functions of the control unit 100 described with reference to FIG. 7 are realized by loading predetermined computer software onto hardware such as the CPU and RAM, thereby operating the communication module, the input device, and the output device under the control of the CPU, and reading and writing data from and to the RAM and the auxiliary storage device. The control unit 100 may be implemented as part of an ECU of a vehicle in which the seat belt retractor 3 according to this embodiment is mounted.

[0085] Here, the operating current C1 and the holding current C2 will be further described with reference to FIGS. 8 and 9. FIG. 8 is a diagram showing an example of the electromagnet attraction characteristics. The vertical axis of FIG. 8 represents the attractive force of the electromagnet, and the horizontal axis represents the stroke. The stroke is the amount of movement of an object to be attracted by the electromagnet (in this embodiment, the attraction part 61 of the actuator 60) due to the attractive force. FIG. 8 illustrates three types of characteristics: the electromagnet attraction characteristics when the current value is 150 mA are shown by a fine dotted line, the electromagnet attraction characteristics when the current value is 300 mA are shown by a large dotted line, and the electromagnet attraction characteristics when the current value is 600 mA are shown by a solid line.

[0086] As shown in FIG. 8, one characteristic of an electromagnet is that the relationship between attractive force and stroke is such that the attractive force increases as the stroke decreases. This characteristic is common regardless of the current value. Regarding this characteristic, considering the attractive force of the electromagnet 50 that can move the actuator 60 of the electromagnetic vehicle sensor 40 against the biasing force of the spring 80 in this embodiment, as shown in FIG. 8, for example, a stroke of less than a predetermined stroke amount S1 can be considered to be a range (lockable range) in which the actuator 60 can be operated and the locking mechanism 30 can be transitioned to the locked state. On the other hand, a stroke greater than the predetermined stroke amount S1 is considered to be a range (non-lock range) in which the actuator 60 cannot be operated due to insufficient attractive force, and the locking mechanism 30 can only be transitioned to the non-locked state. Furthermore, as shown in FIG. 8, within the lockable range, the attractive force decreases as the current value decreases.

[0087] 9 is a diagram showing an example of current input in this embodiment, in which the vertical axis represents the value of the current flowing to the electromagnet 50, and the horizontal axis represents time.

[0088] In this embodiment, attention is focused on the electromagnet attraction characteristics described with reference to Figure 8, and when the electromagnet 50 operates the actuator 60 (seat belt non-locking state), it is operated with an operating current C1, and after reaching a specified stroke amount (seat belt lockable state), the movement of the actuator is maintained with a smaller current (holding current C2).

[0089] In the example of FIG. 9 , at time t1, the trigger that activates the electromagnetic vehicle sensor 40 is turned on, and an operating current C1 begins to be supplied to the electromagnet 50. The supply of the operating current C1 continues until time t2, during which time the actuator 60 of the electromagnetic vehicle sensor 40 continues to move toward the lock gear 32 of the lock mechanism 30. At time t2, the actuator 60 of the electromagnetic vehicle sensor 40 engages with the lock gear 32, and when the output of the microswitch 90 detects that the lock mechanism 30 has transitioned to a locked state (locked state detection), the attractive force to move the actuator 60 further is no longer necessary. Therefore, at time t2, the current supplied to the electromagnet 50 is changed to a holding current C2 that is smaller than the operating current C1. The holding current C2 may be a current value that enables the electromagnet 50 to output an attractive force sufficient to enable the actuator 60 of the electromagnetic vehicle sensor 40 to maintain the engaged state of the lock gear 32 against the biasing force of the spring 80.

[0090] Furthermore, if the locked state changes to the non-locked state for some reason (for example, due to webbing getting caught), the locked state can be maintained by inputting the operating current C1 again.

[0091] 9, at time t3, a transition from the locked state to the non-locked state is detected based on the output of the microswitch 90, for example, and the current supplied to the electromagnet 50 is switched from the holding current C2 to the operating current C1. This state continues until time t4, and when it is detected at time t4 that the locking mechanism 30 has transitioned to the locked state, the current supplied to the electromagnet 50 is switched back from the operating current C1 to the holding current C2.

[0092] 10 is a flowchart showing the current value control of the current ON lock type electromagnetic vehicle sensor 40 according to this embodiment. The processing of the flowchart shown in FIG.

[0093] In step S101, the lock control unit 101 determines whether or not information that satisfies a predetermined operating condition of the lock mechanism 30 has been detected, such as when the vehicle has detected acceleration or tilt equal to or greater than a predetermined threshold. If the operating condition has not been detected (No in step S101), the lock control unit 101 waits until the operating condition is detected.

[0094] On the other hand, if the operating condition is detected (Yes in step S101), the process proceeds to step S102. The lock control unit 101 outputs a control command to the current control unit 102 to activate the electromagnetic vehicle sensor 40.

[0095] In step S102, in response to a control command input from the lock control unit 101, the current control unit 102 passes an operating current C1 through the electromagnet 50 of the electromagnetic vehicle sensor 40 to activate the actuator 60, thereby transitioning the lock mechanism 30 to a locked state.

[0096] In step S103, the current control unit 102 determines whether the output of the microswitch 90 is in the ON state. If the output of the microswitch 90 is OFF (No in step S103), the process waits until the output is switched ON. On the other hand, if the output of the microswitch 90 is ON (Yes in step S103), the process proceeds to step S104.

[0097] In step S104, the current control unit 102 determines that the locking mechanism 30 has entered the locked state because the output of the microswitch 90 has been switched to the ON state in step S103, and therefore changes the current flowing through the electromagnet 50 of the electromagnetic vehicle sensor 40 from the operating current C1 to the holding current C2. When the processing of step S104 is completed, this control flow ends.

[0098] As described above, the seat belt retractor 3 according to this embodiment includes a spool 12 around which the seat belt 4 is wound, a locking mechanism 30 that, when activated, prevents rotation of the spool 12 in the unwinding direction of the seat belt 4, an electromagnetic vehicle sensor 40 having an electromagnet 50 and an actuator 60, which switches between a locked state in which the locking mechanism 30 is activated and an unlocked state (non-locked state) in which the locking mechanism 30 is deactivated by operating the actuator 60 in response to energization of the electromagnet 50, a microswitch 90 as an example of a detector that detects an operation transition of the actuator 60, and a control unit 100 that controls the current flowing to the electromagnet 50. After the control unit 100 passes an operating current C1 to the electromagnet 50 to operate the actuator 60, when the microswitch 90 detects an operation transition of the actuator 60, the control unit 100 switches the current flowing to the electromagnet 50 to a holding current C2 that is smaller than the operating current C1.

[0099] With this configuration, in the seat belt retractor 3 according to this embodiment, after an operating current C1 of a magnitude required to operate the actuator 60 of the electromagnetic vehicle sensor 40 flows through the electromagnet 50, the microswitch 90 can detect the transition of operation of the actuator 60. After the transition of operation of the actuator 60, it is not necessary to operate the actuator 60, and it is sufficient to maintain the state after the transition of operation. Therefore, even if the current flowing through the electromagnet 50 is switched to a holding current C2 which is smaller than the operating current C1, there is no effect on the operation of the electromagnetic vehicle sensor 40 or the locking mechanism 30. Therefore, since the current flowing through the electromagnet 50 can be reduced after the transition of operation of the actuator 60, power consumption can be reduced in the electromagnetic locking seat belt retractor 3.

[0100] In the seat belt retractor 3 according to this embodiment, the electromagnetic vehicle sensor 40 is of a current-on lock type that is in an unlocked state (non-locked state) when no current is passed through the electromagnet 50 and in a locked state when current is passed through the electromagnet 50. The microswitch 90 as a detection unit detects the operation transition in which the actuator 60 switches from the unlocked state to the locked state.

[0101] In the case of the current-on lock type electromagnetic vehicle sensor 40, it is sufficient to pass current through the electromagnet 50 only when the seat belt retractor 3 is in a locked state where its operation is restricted and locked. However, in situations where the seat belt retractor 3 must be kept locked, such as when the vehicle is parked on a slope, it is necessary to keep the current flowing at all times, resulting in increased power consumption. In contrast, in this embodiment, when the seat belt retractor 3 is kept locked, that is, when the seat belt retractor 3 is kept locked, i.e., to maintain the state after the actuator 60 has transitioned in operation, the current that continues to flow is switched to a holding current C2 that is smaller than the operating current C1. This makes it possible to suitably reduce power consumption in a seat belt retractor 3 to which the current-on lock type electromagnetic vehicle sensor 40 is applied.

[0102] Furthermore, the seat belt device 1 including the seat belt retractor 3 of this embodiment may be configured to include an error detection unit that detects the occurrence of an error in the operation of the seat belt retractor 3. The error detection unit is provided in an ECU 200 of the vehicle, for example, as shown in Fig. 7. In the following description, the error detection unit may be denoted by the reference numeral 200.

[0103] 7, the error detection unit 200 is electrically connected to the electromagnet 50 of the electromagnetic vehicle sensor 40 of the seat belt retractor 3. The error detection unit 200 can acquire information on whether or not the electromagnet 50 is energized. Note that the configuration for detecting the energization of the electromagnet 50 by the error detection unit 200 may be a simple one that detects whether or not a current is flowing through the electromagnet 50 based on a potential difference when a current flows through a drive circuit of the electromagnet 50, or may be a configuration that applies other elements, such as a sensor that measures a current value.

[0104] The error detection unit 200 detects that an error has occurred in the operation of the seat belt retractor 3, for example, when a change in whether or not electricity is supplied to the electromagnet 50 is not detected when the operating conditions of the locking mechanism 30 of the seat belt retractor 3 are met, or when a change in whether or not electricity is supplied to the electromagnet 50 is detected and the microswitch 90 does not detect a transition in operation of the actuator 60 of the electromagnetic vehicle sensor 40.

[0105] The error detection control by the error detection unit 200 will be described with reference to Fig. 11. Fig. 11 is a flowchart of the error detection control of the electromagnetic vehicle sensor 40 in this embodiment.

[0106] In step S201, a control command to activate the electromagnetic vehicle sensor 40 is output.

[0107] In step S202, it is determined whether the error detection unit 200 of the ECU detects that a current is flowing through the electromagnet 50 or not.

[0108] If no current is detected (No in step S202), the process proceeds to step S203, where it is determined that an electrical abnormality has occurred, in which no current is flowing through the electromagnet 50 in response to the control command.

[0109] On the other hand, if a current is detected (Yes in step S202), the process proceeds to step S204, where it is determined whether or not operation of the actuator 60 of the electromagnetic vehicle sensor 40 is detected. The output of the microswitch 90, for example, can be used to determine whether operation is detected.

[0110] If the operation of the actuator 60 is detected (Yes in step S204), the process proceeds to step S205, where the electromagnet 50 is energized, which causes the actuator 60 to undergo an operational transition, and it is therefore determined that the electromagnetic vehicle sensor 40 is operating normally.

[0111] On the other hand, if the operation of the actuator 60 is not detected (No in step S204), the process proceeds to step S206, where it is determined that an abnormality in the operation of the actuator 60 has occurred, since the electromagnet 50 is energized but the actuator 60 is not undergoing an operational transition due to energization.

[0112] If it is determined in step S205 that the electromagnetic vehicle sensor 40 is operating normally, the process proceeds to step S207, where the seat belt retractor 3 is locked as usual, locking the withdrawal of the seat belt 4. When the process of step S207 is completed, this control flow ends.

[0113] If it is determined in step S203 that there is an abnormality in the energization of the electromagnet 50, or if it is determined in step S206 that there is an abnormality in the operation of the actuator 60, the process proceeds to step S208, where an error message is displayed on the vehicle. When the process of step S208 is completed, this control flow ends.

[0114] In this embodiment, by providing the vehicle's ECU 200 with a current detection mechanism (error detection unit) for the electromagnet 50 and combining it with the operation detection mechanism (microswitch 90) for the actuator 60 of the electromagnetic vehicle sensor 40, if the actuator 60 is not operating for some reason, it is possible to send a signal to the vehicle to inform it that the seat belt cannot be locked by the electromagnetic vehicle sensor 40.

[0115] Although the above description has been given by way of example of a configuration in which a current ON lock type electromagnetic vehicle sensor 40 is used as the electromagnetic vehicle sensor of the seat belt retractor 3, it is also possible to use a current OFF lock type electromagnetic vehicle sensor 40A.

[0116] An application example of the current OFF lock type electromagnetic vehicle sensor 40A will be described below with reference to Figures 12 to 15. Figure 12 is an exploded perspective view of the current OFF lock type electromagnetic vehicle sensor 40A according to the embodiment.

[0117] The "electromagnetic vehicle sensor 40A of current OFF lock type" used in this embodiment is a vehicle sensor of a type in which the lock of the seat belt retractor 3 is ON (i.e., the operation of the seat belt retractor 3 is restricted by the lock mechanism 30) when the electromagnet 50 is not energized and the electromagnetic actuator 60 is not operating. In the following description, the "electromagnetic vehicle sensor 40A of current OFF lock type" may also be simply referred to as the "electromagnetic vehicle sensor 40A."

[0118] The current OFF lock type electromagnetic vehicle sensor 40A has a configuration as shown in FIG. 12, for example.

[0119] As shown in FIG. 12, the electromagnet 50 and the bracket 70 are composed of the same components as those of the current-on lock type electromagnetic vehicle sensor 40, but their orientation when housed in the housing 41A is different. Compared to the current-on lock type electromagnetic vehicle sensor 40, the electromagnet 50 and the bracket 70 are rotated 90 degrees around the X axis and then 180 degrees around the Z axis. As a result, the electromagnet 50 is positioned so that its axis faces the Z direction. Furthermore, the second flat plate portion 72 of the bracket 70 is positioned below the electromagnet 50 (on the negative Z side), and the first flat plate portion 71 is positioned on the negative Y side of the electromagnet 50. Furthermore, the pair of protrusions 73a, 73b of the bracket 70 are provided at the tip of the first flat plate portion 71 on the positive Z side, with both widthwise ends protruding upward (toward the positive Z side) relative to the center portion.

[0120] Attraction portion 61A of actuator 60A is a flat plate-shaped member, and is arranged on the Z positive side of side plate 55 on the Z positive side of bobbin 52 of electromagnet 50, and is arranged opposite the main surface of side plate 55. With this configuration, attraction portion 61A is configured to be attracted in a direction approaching side plate 55 of electromagnet 50, i.e., in the Z negative direction, when electromagnet 50 is energized.

[0121] Lever portion 62A of actuator 60A is a rectangular flat plate member whose base end is connected to the end of suction portion 61A on the Y positive side, and which extends from this connection toward the Y positive side so as to be flush with the main surface of suction portion 61A. Engagement portion 64 is provided at the tip of lever portion 62A on the Y positive side.

[0122] The connecting portion 66A of the actuator 60A is formed in a claw shape that protrudes from the approximate center in the X direction of the end of the suction portion 61A on the negative Y side toward the negative Y side and then bends toward the positive Z side. This claw-shaped portion engages with the annular portion 81 of the spring 80.

[0123] The microswitch 90 is composed of the same components as the current-on lock type electromagnetic vehicle sensor 40, but its posture when housed in the housing 41A is different. The microswitch 90 is rotated 180 degrees around the Z axis compared to the current-on lock type electromagnetic vehicle sensor 40. As a result, the microswitch 90 is positioned so that the lever 92 is provided on the surface of the main body 91 facing the positive Y direction.

[0124] Switching portion 65A of actuator 60A is a rectangular flat plate member whose base end is connected to approximately the center of the Y positive end of suction portion 61A and extends from this connection toward the Z negative side. Switching portion 65A is bent at approximately a right angle to suction portion 61A. The length of switching portion 65A toward the Z negative side is long enough to allow it to come into contact with at least the Z positive side tip portion of lever 92 of microswitch 90 when both actuator 60 and microswitch 90 are accommodated in housing 41A.

[0125] 12, the middle wall 43A of the housing 41A is disposed on the Y negative side relative to the bottom end wall 44A. In other words, the internal space of the housing 41A is formed so that the portion above the middle wall 43A protrudes further in the Y negative direction than the portion below.

[0126] Groove 42A of housing 41A is provided on the lower surface of the upper end wall of the peripheral wall at a position facing intermediate wall 43A, extending along the X direction and opening in the Z negative direction. As a result, when the tip portions of protrusions 73a, 73b of bracket 70 are inserted into groove 42A, first flat plate portion 71 of bracket 70 is accommodated in a portion of the internal space of housing 41A that protrudes in the Y negative direction, with the first flat plate portion 71 extending in the Z direction. In addition, second flat plate portion 72 of bracket 70 extends in the Y positive direction from the lower end of first flat plate portion 71 and is disposed opposite intermediate wall 43A.

[0127] Furthermore, the lower end surface of main body 91 of microswitch 90 is placed on the upper surface of lower end wall 44A facing the internal space. The tip surface of engagement portion 58 of yoke 53 of electromagnet 50 is placed on the upper end surface of main body 91 of microswitch 90. In other words, bracket 70 is positioned within the internal space of housing 41A by groove 42A and the upper end surface of main body 91 of microswitch 90.

[0128] The side wall 45A of the housing 41 is provided at the end of the housing 41 on the Y positive side, extending along the Z direction. The position of groove 42A in the Y direction is formed so that, when bracket 70 is positioned within the internal space of housing 41A, a gap is formed between the Y positive side end of electromagnet 50, which is connected to bracket 70, and sidewall 45A of housing 41A. When actuator 60A is accommodated within housing 41A, switching unit 65A of actuator 60 is disposed between electromagnet 50 and sidewall 45A. Providing a gap between electromagnet 50 and sidewall 45A allows switching unit 65A to move within this gap, and therefore, its position can be changed within this gap in accordance with the change in the position of attraction unit 61A when electromagnet 50 is energized and de-energized, thereby allowing actuator 60A to rotate.

[0129] In this way, the elements of the electromagnetic vehicle sensor 40A are housed in a positioned state within the housing 41A, and are integrated into one unit.

[0130] Next, the mechanical operation of the electromagnetic vehicle sensor 40A will be described with reference to Figures 13 and 14. Figure 13 is a diagram showing the non-locked state of the current-off lock type electromagnetic vehicle sensor 40A.

[0131] In the case of the current-off lock type electromagnetic vehicle sensor 40A, the electromagnet 50 is energized in the non-locked state. This generates a magnetic field along the axial direction (Z direction in FIG. 13) at the center of the electromagnet 50, and the yoke 53 of the electromagnet 50 attracts the attraction portion 61A of the actuator 60A. As a result, as shown by arrow H in FIG. 13, the attraction portion 61A moves in a direction approaching the side plate 55 of the electromagnet 50 (negative Z direction in FIG. 13).

[0132] Such movement of attraction portion 61A causes actuator 60A to rotate counterclockwise about the X axis when viewed from the X positive side, around support grooves 63a, 63b, against the biasing force of spring 80. As a result, as shown by arrow I in Figure 13, lever portion 62A of actuator 60A moves in a direction away from lock gear 32 of lock mechanism 30 (toward the Z negative side), and engagement portion 64 is separated from ratchet teeth 32C of lock gear 32 and is held at a position where it cannot engage.

[0133] As a result of the action of these electromagnetic vehicle sensors 40A, as shown by arrow A in Figure 13, the lock gear 32 of the lock mechanism 30 is able to rotate in the seat belt withdrawing direction without being restricted in rotation, and the lock mechanism 30 is in a non-locked state where it is not activated.

[0134] Furthermore, as the attraction portion 61A of the actuator 60A moves toward the electromagnet 50, the switching portion 65A of the actuator 60A moves to a position where it contacts the lever 92 of the microswitch 90, as shown by the dotted circle J in Fig. 13. As a result, the lever 92 is pressed toward the main body 91 by the switching portion 65A, as shown by the arrow K in Fig. 13, and the lever 92 presses the switch, maintaining the microswitch 90 in the ON state. In other words, in the case of the electromagnetic vehicle sensor 40A of the current OFF lock type, the output of the microswitch 90 is maintained in the ON state while the sensor is in the non-lock state.

[0135] FIG. 14 is a diagram showing the locked state of the current-off lock type electromagnetic vehicle sensor 40A.

[0136] In the case of electromagnetic vehicle sensor 40A of the current-off lock type, electromagnet 50 is not energized in the locked state. At this time, spring 80 is installed in a state in which it is extended from its natural length. An annular portion 82 provided at the end of spring 80 on the negative Z side is connected to connecting portion 75 of bracket 70 fixed to housing 41A. Meanwhile, an annular portion 81 provided at the end of spring 80 on the positive Z side is not fixed to housing 41A but is connected to connecting portion 66A of actuator 60A that is rotatably supported on bracket 70. Due to these actions, as indicated by arrow L, spring 80 applies a biasing force to connecting portion 66A of actuator 60A in a direction toward connecting portion 75 of bracket 70 (negative Z direction).

[0137] The action of such biasing force L causes actuator 60A to rotate clockwise around the X axis when viewed from the X positive side, centering on support grooves 63a, 63b. As a result, lever portion 62A of actuator 60A moves in a direction approaching lock gear 32 of lock mechanism 30 (in the Z positive direction), as shown by arrow M in Figure 14, and engagement portion 64 engages with ratchet teeth 32C of lock gear 32.

[0138] Furthermore, due to the rotation of actuator 60A described above, attraction portion 61A of actuator 60A moves in a direction away from electromagnet 50 (toward the positive Z direction). As a result, as shown by arrow N in FIG. 14, switching portion 65A of actuator 60A moves further toward the positive Y direction than lever 92 of microswitch 90. This movement causes switching portion 65A to transition to a state where it is not in contact with lever 92, as shown by dotted circle O. As a result, lever 92 is no longer pressed, so lever 92 also moves toward the positive Y direction relative to main body 91, as shown by arrow P, and microswitch 90 switches to the OFF state. In other words, in the case of electromagnetic vehicle sensor 40A of a current OFF lock type, the output of microswitch 90 is maintained in the OFF state while in the locked state.

[0139] As a result of the action of these electromagnetic vehicle sensors 40A, the rotation of the lock gear 32 of the lock mechanism 30 is restricted, the lock mechanism 30 is activated, and the lock mechanism 30 transitions to a locked state in which withdrawal of the seat belt is restricted.

[0140] 15 is a flowchart showing the current value control of the electromagnetic vehicle sensor 40A of the current OFF lock type according to this embodiment. The processing of the flowchart shown in FIG.

[0141] In step S301, in response to a control command input from the lock control unit 101, the current control unit 102 causes an operating current C1 to flow through the electromagnet 50 of the electromagnetic vehicle sensor 40A to activate the actuator 60A, thereby transitioning the lock mechanism 30 to a non-lock state.

[0142] In step S302, the current control unit 102 determines whether the output of the microswitch 90 is in the ON state. If the output of the microswitch 90 is OFF (No in step S302), the process waits until the output is switched ON. On the other hand, if the output of the microswitch 90 is ON (Yes in step S302), the process proceeds to step S303.

[0143] In step S303, the current control unit 102 determines that the locking mechanism 30 has entered the non-lock state because the output of the microswitch 90 has been switched to the ON state in step S302, and therefore changes the current flowing through the electromagnet 50 of the electromagnetic vehicle sensor 40A from the operating current C1 to the holding current C2.

[0144] In step S304, the lock control unit 101 determines whether or not information that satisfies a predetermined operating condition of the lock mechanism 30 has been detected, such as when the vehicle has detected an acceleration or tilt equal to or greater than a predetermined threshold. If the operating condition has not been detected (No in step S304), the lock control unit 101 waits until the operating condition is detected.

[0145] On the other hand, if the operating condition is detected (Yes in step S304), the process proceeds to step S305. The lock control unit 101 outputs a control command to the current control unit 102 to switch the electromagnetic vehicle sensor 40A to the inactive state.

[0146] In step S305, the current control unit 102 stops the power supply to the electromagnet 50 of the electromagnetic vehicle sensor 40 in response to the control command input from the lock control unit 101, thereby transitioning the lock mechanism 30 to the locked state. When the processing of step S305 is completed, this control flow ends.

[0147] In the seat belt retractor 3 according to this embodiment, the electromagnetic vehicle sensor 40A is of a current-off lock type that is in a locked state when no current flows through the electromagnet 50 and is in an unlocked state (non-locked state) when current flows through the electromagnet 50. The microswitch 90 as a detection unit detects the operation transition in which the actuator 60A switches from the locked state to the unlocked state.

[0148] In the case of the current-off lock type electromagnetic vehicle sensor 40A, when there is no electrical signal (the electromagnet 50 is not energized) and the electromagnetic actuator 60A is not operating, the seat belt retractor is locked (i.e., the operation of the seat belt retractor 3 is restricted). With this type, the seat belt retractor 3 is locked even when there is no electrical signal due to a malfunction of the ECU 200 of the vehicle in which the seat belt retractor 3 is installed, thereby establishing a fail-safe. However, to maintain the unlocked state with this type, it is necessary to continuously flow current, which increases power consumption. In contrast, in this embodiment, when maintaining the non-locked state of the seat belt retractor 3, i.e., to maintain the state after the operation transition of the actuator 60, the current that continues to flow is switched to a holding current C2 that is smaller than the operating current C1. This allows for optimal suppression of power consumption even in a seat belt retractor 3 to which the current-off lock type electromagnetic vehicle sensor 40A is applied.

[0149] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise.

[0150] In the above embodiment, a configuration in which the microswitch 90 is used as an example of a detector that detects an operation transition of the actuator 60 of the electromagnetic vehicle sensor 40 has been exemplified. However, an element other than the microswitch 90 may be used as long as it can detect an operation transition of the actuator 60. For example, an optical sensor, a piezoelectric sensor, a magnetic sensor, or the like may be used as the detector. In this case, if the sensor does not require physical contact and can detect an operation transition of the actuator 60 by approaching or passing through a detection range, the switching unit 65 of the actuator 60 is not limited to a configuration in which the sensor output is switched to the ON state by contact with the sensor, but may be a configuration in which the sensor output is switched to the ON state by approaching or passing through the detection range of the sensor. [Explanation of symbols]

[0151] 1 Seat belt device 3 Seat belt retractor 4 Seatbelts 7 Tongue 8 Buckle 12 spools 30 Locking mechanism 40, 40A Electromagnetic Vehicle Sensor 50 Electromagnet 60, 60A actuator 61, 61A Suction part 62, 62A Lever part 64 Engagement part 65, 65A switching unit 80 Spring (elastic member) 90 Microswitch (detection part) 100 control section 200 Error detection unit, ECU C1 operating current C2 holding current

Claims

1. A spool onto which the seat belt is wound, a locking mechanism that, when activated, prevents the spool from rotating in the seat belt withdrawing direction; an electromagnetic vehicle sensor having an electromagnet and an actuator, and switching between a locked state in which the locking mechanism is activated and an unlocked state in which the locking mechanism is deactivated by operating the actuator in response to energization of the electromagnet; a detection unit that detects an operation transition of the actuator; a control unit that controls a current flowing to the electromagnet; Equipped with the control unit, after causing an operating current for operating the actuator to flow to the electromagnet, switches the current to be flowed to the electromagnet to a holding current smaller than the operating current when the detection unit detects the operation transition. Seat belt retractor.

2. the electromagnetic vehicle sensor is a current-on lock type that is in the unlocked state when the current is not passed through the electromagnet and in the locked state when the current is passed through the electromagnet, The detection unit detects an operation transition in which the actuator switches from the unlocked state to the locked state.

2. The seat belt retractor according to claim 1.

3. the electromagnetic vehicle sensor is a current-off lock type that is in the locked state when the current is not passed through the electromagnet and is in the unlocked state only when the current is passed through the electromagnet, The detection unit detects an operation transition in which the actuator switches from the locked state to the unlocked state.

2. The seat belt retractor according to claim 1.

4. The actuator is an attracting portion disposed opposite to the axial direction of the coil of the electromagnet and attracted to the electromagnet when the electromagnet is energized; a lever portion that moves toward a lock gear side of the lock mechanism when the suction portion is attracted; an engaging portion provided at a tip of the lever portion, which engages with ratchet teeth provided on an outer periphery of the lock gear when the lever portion moves toward the lock gear, thereby restricting rotation of the lock gear and thereby activating the lock mechanism; and the electromagnetic vehicle sensor has an elastic member that is biased to apply an external force to the actuator in a direction in which the attraction portion moves away from the electromagnet; 2. The seat belt retractor according to claim 1.

5. the detection unit is a microswitch, The actuator is a switching part that presses the microswitch to switch it to an on state when the attraction part is attracted to the electromagnet side; 5. The seat belt retractor according to claim 4.

6. the detection unit includes an optical sensor, a piezoelectric sensor, or a magnetic sensor, The actuator is a switching unit that approaches or comes into contact with the detection unit to switch the detection unit to an on state when the attraction unit is attracted to the electromagnet; 5. The seat belt retractor according to claim 4.

7. Seat belts to restrain the occupants, The seat belt retractor according to any one of claims 1 to 6, which retracts the seat belt so that it can be withdrawn, and is activated in an emergency to prevent the seat belt from being withdrawn; a tongue slidably supported by the seat belt pulled out from the seat belt retractor; a buckle provided on the vehicle body or the seat, to which the tongue is releasably fastened; A seat belt device comprising:

8. When the switching of energization and de-energization of the electromagnet is not detected when the activation condition of the locking mechanism of the seat belt retractor is satisfied, or When the switching between energization and de-energization of the electromagnet is detected and the detection unit does not detect an operation transition of the actuator, an error detection unit that detects an error occurring in the operation of the seat belt retractor; 8. The seat belt device according to claim 7.

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