A locking device for a seat belt retractor

Abstract

An embodiment of the present specification provides a locking device for a seat belt retractor, which includes a housing, an armature, a spring, coil A and coil B. The housing includes a bottom plate, a vertical arm and an installation cavity. The armature is pivotally supported above the vertical arm and includes a first leg extending above the installation cavity and a second leg extending below the bottom plate. One end of the spring is fixed to the armature and the other end is fixed to the housing. After coil A is energized, a magnetic field is generated to adsorb the first leg and overcome the traction of the spring to move from the locking position to the release position; coil B is installed on the housing, and after being energized, a magnetic field is generated to attract or repel the second leg, thereby controlling the resilience force of the first leg between the release position and the locking position. By adding coil B to the housing, when the retractor locks, coil B is energized to generate a magnetic field to repel the second leg of the armature, so that the noise generated by the spring hitting the iron sheet during spring resilience can be reduced without affecting the rapid resilience of the armature.

Description

Technical Field

[0001] This specification relates to the technical field of seat belt retractor locking, and particularly relates to a locking device for a seat belt retractor. Background Art

[0002] In the prior art, the locking device of a seat belt retractor is as Figure 1 shown. Figure 1 In it, 1. Outer shell, 2. Armature, 3. Spring, 4. Coil. When the retractor is not locked, the coil is energized to generate suction force to adsorb the armature on the coil, so that the spring connected to the armature is stretched and stores elastic potential energy; when the retractor is locked, the coil is de-energized, resulting in the coil no longer having adsorption force. Because the spring stored elastic potential energy before, it will be released at this time. The spring pulls the armature to reset. Since the reset action of the armature needs to be rapid, the elastic potential energy stored by the spring required is also relatively large. As a result, when the spring rebounds, it will hit the iron sheet and generate noise. This will not only affect the user experience but also cause harm to the wear of the armature. Summary of the Invention

[0003] In view of this, an embodiment of this specification provides a locking device for a seat belt retractor. By adding coil B on the outer shell, when the retractor is locked, coil B is energized to generate a magnetic field to repel the second leg of the armature, thereby controlling the rebounding force of the first leg between the release position and the locking position, so as to reduce the noise generated when the spring rebounds and hits the iron sheet without affecting the rapid rebound of the armature.

[0004] The embodiment of this specification provides the following technical solution: A locking device for a seat belt retractor, including an outer shell, an armature, a spring, coil A and coil B. The outer shell includes a bottom plate, a vertical arm and an installation cavity between the bottom plate and the vertical arm. The armature is pivotally supported above the vertical arm and includes a first leg extending above the installation cavity and a second leg extending towards the bottom plate. One end of the spring is fixed on the armature and the other end is fixed on the outer shell. The spring pulls the armature, always making the first leg move from the release position close to the installation cavity to the locking position away from the installation cavity. When the first leg is in the locking position, it locks the retractor reel to prevent the webbing from being further pulled out.

[0005] Coil A is installed in the installation cavity. After being energized, it generates a magnetic field that can adsorb the first leg to overcome the pulling action of the spring and move from the locking position to the release position; Coil B is installed on the outer shell. After being energized, it generates a magnetic field that can attract or repel the second leg, thereby controlling the rebounding force of the first leg between the release position and the locking position.

[0006] Preferably, the locking device further includes an ECU module, a latch signal module, and a PWM signal generation module. The ECU module is controllably connected to the PWM signal generation module and the latch signal module. The PWM signal generation module outputs to control the on / off of the current flowing through coil A and / or the starting action time, magnitude, and direction of the current flowing through coil B.

[0007] Preferably, the PWM signal generation module includes a PWM signal generation circuit, a latch signal detection circuit, and a switching circuit. The switching circuit controls the on / off of the current flowing through coil A. The PWM signal generation circuit and the switching circuit control one or more of the starting action time, magnitude, and direction of the current flowing through coil B.

[0008] Preferably, the switching circuit includes a first switching circuit that controls the energization and de-energization of coil A. The first switching circuit includes: triode Q2, relay C, resistor R1, power supply B1, power supply B2, and power supply B4;

[0009] One end of resistor R1 is connected to the latch signal detection circuit, and the other end is connected to the base of triode Q2. The emitter of triode Q2 is grounded, and the collector of triode Q2 is connected to the negative pole of power supply B2. The positive pole of power supply B2 is connected to one end of the coil of relay C, and the other end of the coil is grounded. The normally open contact of relay C is connected to the positive pole of power supply B4, the normally closed contact of relay C is grounded, the negative pole of power supply B4 is connected to one end of coil A, and the other end of coil A is grounded.

[0010] Preferably, the switching circuit further includes a second switching circuit that controls the energization and de-energization of coil B. The second switching circuit includes MOS transistor Q1, resistor R2, resistor R3, capacitor C1, and power supply B3;

[0011] One end of resistor R2 is connected to the PWM signal generation circuit, and the other end is connected to one end of resistor R3 and the gate of MOS transistor Q1. The other end of resistor R3 is grounded. The drain of MOS transistor Q1 is connected to the positive pole of capacitor C1 and the negative pole of power supply B3. The source of MOS transistor Q1 is connected to the negative pole of capacitor C1 and grounded. The positive pole of power supply B3 is connected to one end of coil B, and the other end of coil B is grounded.

[0012] Preferably, the latch signal detection circuit includes switch PS. One end of switch PS is connected to the positive pole of power supply B1, the other end of switch PS is connected to the other end of resistor R1, and the negative pole of power supply B1 is grounded;

[0013] When the switch PS is closed, the first switch circuit works and the second switch circuit does not work, enabling the coil A to be energized. When the switch PS is opened, the first switch circuit does not work and the second switch circuit works, enabling the coil B to be energized.

[0014] Preferably, the PWM signal generation circuit includes a sawtooth wave generation circuit, a sine signal circuit, and a comparator. One input terminal of the comparator is connected to the sawtooth wave generation circuit, the other input terminal of the comparator is connected to the sine signal circuit, and the output terminal of the comparator is connected to the resistor R2.

[0015] Preferably, after the first leg moves from the release position to the locking position for a first period of time, the duty cycle of the PWM signal generation circuit increases as the distance between the second leg and the coil B decreases. After the first leg moves to the locking position, the duty cycle of the PWM signal generation module gradually decreases to zero.

[0016] Preferably, the device further includes a magnet disposed on the second leg. When the first leg moves from the release position near the installation cavity to the locking position away from the installation cavity, before the second leg contacts the housing, a repulsive force is generated between the magnet and the coil B.

[0017] Preferably, the magnet is disposed on the end face of the second leg close to the coil B.

[0018] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in the embodiments of the present specification at least include:

[0019] By adding the coil B on the housing, when the retractor locks, the coil B is energized to generate a magnetic field to repel the second leg of the armature, thereby controlling the resilience force of the first leg between the release position and the locking position, so as to reduce the noise generated when the spring rebounds and hits the iron sheet without affecting the rapid rebound of the armature. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 is a schematic structural diagram of a locking device of a retractor in the prior art;

[0022] Figure 2It is a schematic diagram when the locking device provided by the present invention is not locked;

[0023] Figure 3 It is a schematic diagram when the locking device provided by the present invention is locked;

[0024] Figure 4 It is a circuit diagram of the PWM signal generation module of the locking device provided by the present invention;

[0025] Figure 5 It is the first switch circuit diagram of the locking device provided by the present invention;

[0026] Figure 6 It is the second switch circuit diagram of the locking device provided by the present invention;

[0027] Figure 7 It is a schematic diagram of the suction force change of coil A and coil B of the locking device provided by the present invention. Detailed implementation manners

[0028] The following will describe the embodiments of the present application in detail with reference to the accompanying drawings.

[0029] The following uses specific specific examples to illustrate the implementation manners of the present application. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application.

[0030] It should be noted that the following describes various aspects of the embodiments within the scope of the appended claims. It should be obvious that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is illustrative only. Based on the present application, those skilled in the art should understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects described herein can be used to implement the device and / or practice the method. In addition, this device can be implemented and this method can be practiced using other structures and / or functions in addition to one or more of the aspects described herein.

[0031] It should also be noted that the illustrations provided in the following embodiments only schematically illustrate the basic concept of the present application. The diagrams only show the components related to the present application, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0032] In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0033] In the prior art, the locking device of a seat belt retractor is as Figure 1 shown. Figure 1 In [the figure], 1. Outer shell, 2. Armature, 3. Spring, 4. Coil. The armature is pivotally connected to the outer shell, and the coil is arranged inside the outer shell. When the retractor is not locked, the coil is energized and generates a relatively large adsorption force, which adsorbs the armature on the coil. When the retractor is locked, the coil is de-energized, resulting in the coil no longer having an adsorption force. At the same time, under the action of the spring, the previously adsorbed armature is reset, enabling the retractor to be locked; because the spring stores elastic potential energy before, when the coil no longer has an adsorption force, it will be released, and the spring pulls the armature to reset. Since the reset action of the armature needs to be rapid, the elastic potential energy stored by the spring also needs to be relatively large. As a result, when the spring rebounds, the armature will hit the outer shell and generate noise, which will not only affect the user experience but also cause harm to the wear of the armature.

[0034] Through extensive and in-depth experiments, the inventor has designed a locking device for a seat belt retractor. By adding coil B to the outer shell, when the retractor is locked, coil B is energized to generate a magnetic field to repel the second leg of the armature, reducing the noise generated when the armature hits the outer shell.

[0035] The technical problem solved by the present invention is to avoid generating relatively large noise when the retractor is locked.

[0036] More specifically, the solution adopted by the present invention includes: by adding coil B to the outer shell, when the retractor is locked, coil B is energized to generate a magnetic field to repel the second leg of the armature, thereby controlling the rebound force of the first leg between the release position and the lock position, so as to reduce the noise generated when the spring rebounds and hits the iron sheet without affecting the rapid rebound of the armature.

[0037] The following describes the technical solutions provided by the embodiments of the present application with reference to the accompanying drawings.

[0038] As Figures 2 - 3As shown in the figure, a locking device for a seat belt retractor includes a housing 5, an armature 6, a spring 7, a coil A 8, and a coil B 9. The housing 5 includes a bottom plate, a vertical arm 501, and an installation cavity between the bottom plate and the vertical arm 501. The armature 6 is pivotally supported above the vertical arm 501 and includes a first leg 601 extending above the installation cavity and a second leg 602 extending toward the bottom plate. One end of the spring 7 is fixed to the armature 6, and the other end is fixed to the housing 5. The spring 7 pulls the armature 6, always moving the first leg 601 from a release position close to the installation cavity to a locking position away from the installation cavity. When the first leg 601 is in the locking position, it locks the retractor reel to prevent the webbing from being further pulled out.

[0039] The coil A 8 is installed in the installation cavity. After being energized, it generates a magnetic field that can adsorb the first leg 601 to overcome the pulling force of the spring 7 and move from the locking position to the release position. The coil B 9 is installed on the housing 5. After being energized, it generates a magnetic field that can attract or repel the second leg 602, thereby controlling the resilience of the first leg 601 between the release position and the locking position.

[0040] As Figure 2 shown, under normal conditions, the coil A 8 is energized and the coil B 9 is not energized. The energized coil A 8 generates a magnetic field that adsorbs the first leg 601 of the armature 6 at the release position on the top of the housing 5. During the movement of the armature 6 to the release position, the spring 7 is stretched, causing the spring 7 to be in a stretched state and store elastic potential energy. As Figure 3 shown, when locking, the coil A 8 is de-energized. Under the action of the elastic potential energy of the spring 7, the spring 7 drives the armature 6 to move. The first leg 601 moves from the release position to the locking position, and the second leg 602 moves toward the position close to the coil B 9. At this time, the energized coil B 9 generates a changing magnetic field force that generates a changing resistance to the armature 6, thereby controlling the resilience of the first leg 601 between the release position and the locking position and reducing the noise generated when the armature 6 resets.

[0041] Further, in this embodiment, the coil B 9 is installed below the bottom plate, which can ensure the compactness of the installation. In other embodiments, the coil B 9 can also be installed at other positions on the housing 5. The installation position of the coil B 9 can be selected according to the actual situation and will not be elaborated in detail here.

[0042] As Figures 2 - 3As shown, in some embodiments, the locking device further includes an ECU module, a latch signal module, and a PWM signal generation module. The ECU module is controllably connected to the PWM signal generation module and the latch signal module. The PWM signal generation module outputs to control the on / off of the current flowing through coil A8 and controls one or more of the starting action time, magnitude, and direction of the current flowing through coil B9. When the ECU module receives the latch signal from the latch signal module, the ECU module controls the PWM signal generation module to operate. By setting the PWM signal generation module to control one or more of the starting action time, magnitude, and direction of the current flowing through coil B9, it is possible to control the time, magnitude, and direction of the magnetic force generated by coil B9. The generated magnetic force acts on the second leg 602 of the armature 6, thereby controlling the resilience of the first leg 601 of the armature 6 between the release position and the locking position, and reducing the noise generated when the armature 6 resets.

[0043] As Figures 2 - 3 shown, in some embodiments, the PWM signal generation module includes a PWM signal generation circuit, a latch signal detection circuit, and a switch circuit. The switch circuit controls the on / off of the current flowing through coil A8, and the PWM signal generation circuit and the switch circuit control one or more of the starting action time, magnitude, and direction of the current flowing through coil B9.

[0044] Under normal conditions (i.e., when not locked), the latch signal circuit is in a closed state, and the switch circuit controls coil A8 to be energized. Coil A8 attracts the first leg 601 of the armature 6 to the release position. When locking, the latch signal circuit is disconnected, and the switch circuit controls coil A8 to be de-energized. Under the action of spring 7, the armature 6 resets. The ECU module controls the PWM signal generation circuit to generate a PWM signal. When coil A8 is just de-energized, the PWM signal generation circuit outputs a low duty cycle. At this time, only a small current passes through coil B9, and the repulsive force between coil B9 and the second leg 602 of the armature 6 is small. As the distance between the second leg 602 and coil B9 decreases, the duty cycle output by the PWM signal generation circuit gradually increases. Under the action of the PWM signal generation circuit and the switch circuit, the current flowing through coil B9 increases, and a larger repulsive force is generated between coil B9 and the second leg 602. Moreover, when the second leg 602 is closer to coil B9, the greater the repulsive force it receives, thereby reducing the rebound noise generated when the armature 6 resets. When the armature 6 has completed resetting, the ECU module controls the duty cycle output by the PWM signal generation circuit to gradually decrease to zero, the current flowing through coil B9 gradually decreases to zero, and there is no longer a repulsive force between coil B9 and the second leg 602.

[0045] As Figures 4 - 5As shown, in some embodiments, the switching circuit includes a first switching circuit that controls the energization and de-energization of the coil A8. The first switching circuit includes: a triode Q2, a relay C, a resistor R1, a power supply B1, a power supply B2, and a power supply B4;

[0046] One end of the resistor R1 is connected to the latch signal detection circuit, and the other end is connected to the base of the triode Q2. The emitter of the triode Q2 is grounded, and the collector of the triode Q2 is connected to the negative pole of the power supply B2. The positive pole of the power supply B2 is connected to one end of the coil of the relay C, and the other end of the coil is grounded. The normally open contact of the relay C is connected to the positive pole of the power supply B4, the normally closed contact of the relay C is grounded, the negative pole of the power supply B4 is connected to one end of the coil A8, and the other end of the coil A8 is grounded;

[0047] The on / off of the current in the coil A8 is controlled by the latch signal detection circuit and the first switching circuit. When the latch signal circuit is in the closed state, the power supply B1 is connected to the base of the triode Q2 via the latch signal detection circuit and R1. The triode Q2 is in the conducting state, and the power supply B2 supplies power to the relay C, making the relay C in the normally open closed state. The power supply B4 supplies power to the coil A8, causing the coil A8 to generate a magnetic field to attract the first leg 601 of the armature 6 at the release position;

[0048] When the latch signal circuit is in the open state, the triode Q2 is cut off, the power supply B2 cannot supply power to the relay C, the relay C is in the normally closed state, the power supply B4 cannot supply power to the coil A8, and the coil A8 no longer generates a magnetic field.

[0049] As Figures 4 - 6 As shown, in some embodiments, the switching circuit further includes a second switching circuit that controls the energization and de-energization of the coil B9. The second switching circuit includes an MOS transistor Q1, a resistor R2, a resistor R3, a capacitor C1, and a power supply B3;

[0050] One end of the resistor R2 is connected to the PWM signal generation circuit, and the other end is connected to one end of the resistor R3 and the gate of the MOS transistor Q1. The other end of the resistor R3 is grounded. The drain of the MOS transistor Q1 is connected to the positive pole of the capacitor C1 and the negative pole of the power supply B3. The source of the MOS transistor Q1 is connected to the negative pole of the capacitor C1 and grounded. The positive pole of the power supply B3 is connected to one end of the coil B9, and the other end of the coil B9 is grounded;

[0051] The current on coil B9 is controlled by a latch signal detection circuit, a second switch circuit, and a PWM signal generation circuit. When the latch signal circuit is in the closed state, the PWM signal generation circuit does not output a PWM signal, MOS transistor Q1 is in the cut-off state, power supply B3 cannot supply power to coil B9, and coil B9 is in a power-off state and cannot generate a magnetic field;

[0052] When the latch signal circuit is open, the PWM signal generation circuit generates a PWM signal. After this voltage is divided by resistor R2 and resistor R3, the voltage on R3 is applied to the gate of MOS transistor Q1 to charge MOS transistor Q1. When the gate voltage reaches the turn-on voltage of MOS transistor Q1, MOS transistor Q1 conducts. The negative pole of power supply B3 is grounded via the drain and source of MOS transistor Q1, and power supply B3 supplies power to coil B9, causing a magnetic field to be generated around coil B9, thereby generating a repulsive force between coil B9 and the second leg 602;

[0053] The magnitude of the current flowing through coil B9 is controlled by the PWM signal generation circuit. When the latch signal circuit just opens, the PWM signal generation circuit outputs a lower duty cycle. At this time, only a small current passes through coil B9, and the repulsive force between coil B9 and the second leg 602 of armature 6 is small, which can ensure the rapid reset of armature 6. After armature 6 moves for a certain time, the PWM signal generation circuit provides a higher duty cycle, and the current flowing through coil B9 increases. When the second leg 602 gets closer to coil B9, the repulsive force it receives is greater, thereby reducing the rebound noise generated when armature 6 resets. After armature 6 completes the reset, the duty cycle output by the PWM signal generation circuit gradually decreases to zero, causing the current flowing through coil B9 to gradually decrease to zero, and there is no longer a repulsive force between coil B9 and armature 6.

[0054] As Figures 4 - 6 shown, in some embodiments, the latch signal detection circuit includes switch PS. One end of switch PS is connected to the positive pole of power supply B1, the other end of switch PS is connected to the other end of resistor R1, and the negative pole of power supply B1 is grounded;

[0055] When switch PS is closed, the first switch circuit works and the second switch circuit does not work, causing coil A8 to be energized. When switch PS is open, the first switch circuit does not work and the second switch circuit works, causing coil B9 to be energized;

[0056] When the switch PS is in the closed state: The first switch circuit is in the working state. The power supply B1 supplies power to the triode Q2. The triode Q2 is in the conducting state. The power supply B4 supplies power to the coil A8. The coil A8 generates a magnetic field. The coil A8 adsorbs the first leg 601 of the armature 6 at the release position. The PWM signal generation circuit does not generate a PWM signal. The second switch circuit is in the non-working state. The MOS tube Q2 is in the cut-off state. The power supply B3 cannot supply power to the coil B9.

[0057] When the switch PS is in the open state: The second switch circuit cannot work properly. The power supply B1 cannot supply power to the triode Q2. The triode Q2 is in the cut-off state. The power supply B4 cannot supply power to the coil A8. The coil A8 no longer generates a magnetic field. The ECU module controls the PWM signal generation circuit to generate a PWM signal. The second switch circuit works. When the duty cycle of the PWM signal generation circuit reaches a certain value, the MOS tube Q1 conducts. The power supply B3 supplies power to the coil B9, causing the coil B9 to generate a magnetic field.

[0058] As Figures 4 - 6 shown, in some embodiments, the PWM signal generation circuit includes a sawtooth wave generation circuit, a sine signal circuit, and a comparator. One input end of the sawtooth wave generation circuit is connected to the comparator. The sine signal circuit is connected to the other input end of the comparator. The output end of the comparator is connected to the resistor R2. A PWM signal is generated through the sawtooth wave generation circuit, the sine signal circuit, and the comparator, and then is divided by the resistors R2 and R3. The voltage at the resistor R3 is applied to the MOS tube Q1. By controlling the duty cycle, the current in the coil B9 is controlled.

[0059] In some embodiments, when the first leg 601 moves from the release position to the locking position for the first time, the duty cycle of the PWM signal generation circuit increases as the distance between the second leg 602 and the coil B9 decreases. After the first leg 601 moves to the locking position, the duty cycle of the PWM signal generation module gradually decreases to zero. Before the first time, the duty cycle of the PWM signal generation circuit is relatively small, so that the armature 6 can be quickly reset. After the first time, the armature 6 continues to move. The duty cycle of the PWM signal generation circuit increases, causing the current in the coil B9 to increase. The closer the armature 6 is to the coil B9, the greater the repulsive force it receives, thereby reducing the noise generated when the armature 6 is reset.

[0060] As Figures 2 - 3As shown, in some embodiments, the device further includes a magnet disposed on the second leg 602. When the first leg 601 moves from the release position near the installation cavity to the locking position away from the installation cavity, before the second leg 602 contacts the housing 5, a repulsive force is generated between the magnet and the coil B9. By installing a magnet on the second leg 602, when the armature 6 resets, the coil B9 is energized to generate a magnetic field, and a repulsive force is generated between the magnetic field and the magnet. The closer the second leg 602 is to the coil B9, the greater the repulsive force, which slows down the movement speed of the second leg 602, thereby reducing the noise generated when the armature 6 resets.

[0061] Further, the magnet is disposed on the end face of the second leg 602 close to the coil B9. By disposing the magnet on the end face of the second leg 602 close to the coil B9, when the coil B9 is energized to generate a magnetic field, when the second leg 602 moves in the direction close to the coil B9, it is ensured that a repulsive force is generated between the magnet and the coil B9, thereby slowing down the movement speed of the second leg 602.

[0062] A specific embodiment of the present application will be described below:

[0063] In this embodiment, the parameters of the coil A8 and the coil B9 are: the number of turns is 680, the wire diameter of the coil is 0.18 mm, the coil resistance is 13.59 ohms, and the voltages of the power supplies B3 and B4 are both 5V.

[0064] Please refer to Figures 2 - 6 , when the retractor is not locked, the switch PS is in the closed state. The power supply B1 is connected to the base of the triode Q2 via the switch PS and R1. The triode Q2 is in the conducting state. The power supply B2 supplies power to the relay C, making the relay C in the normally open closed state. The power supply B4 supplies power to the coil A8, making the coil A8 generate a magnetic field to adsorb the first leg 601 of the armature 6 at the release position. During the process of the armature 6 moving to the release position, the spring 7 is stretched, making the spring 7 in a stretched state, and the spring 7 stores 0.5 J of elastic potential energy;

[0065] When the retractor is locked, the ECU module receives the locking signal from the latch signal module. The ECU module controls the switch PS to disconnect, the triode Q2 is cut off, the power supply B2 cannot supply power to the relay C, the relay C is in the normally closed state, the power supply B4 cannot supply power to the coil A8, the coil A8 is powered off, and after 0.07 s, the magnetic field around the coil A8 disappears, and the elastic potential energy stored in the spring 7 is released, pulling the armature 6 to quickly reset. At the same time when the switch PS is disconnected, the ECU module controls the PWM signal generation circuit to generate a PWM signal. This voltage is divided by the resistor R2 and the resistor R3, and the voltage is applied to the gate of the MOS transistor Q1 on the R3 to charge the MOS transistor Q1. When the turn-on voltage of the MOS transistor Q1 is reached, the MOS transistor Q1 conducts, and the negative pole of the power supply B3 is grounded through the drain and source of the MOS transistor Q1, and the power supply B3 supplies power to the coil B9, causing a magnetic field to be generated around the coil B9. A repulsive force is generated between the magnetic field and the magnet, and the change trend of the repulsive force is controlled by the PWM signal generation circuit. In order to ensure that the armature 6 can quickly reset when the retractor is locked, when the switch PS is just disconnected, the PWM signal generation circuit outputs a lower duty cycle. Before 0.07 s, only a small current passes through the coil B9, and the repulsive force between the coil B9 and the second leg 602 of the armature 6 is small, which can ensure the quick reset of the armature 6. When the armature 6 approaches the bottom, that is, after 0.07 s, the PWM signal generation circuit provides a higher duty cycle, and the current flowing through the coil B9 increases. At this time, a larger repulsive force is generated between the magnetic field generated by the coil B9 and the magnet on the second leg 602 to resist the pulling force of the spring 7. When the second leg 602 is closer to the coil B9, the greater the repulsive force received, so that the rebound noise generated when the armature 6 resets can be reduced. When the armature 6 completes the reset, the duty cycle output by the PWM signal generation circuit gradually decreases to zero, so that the current flowing through the coil B9 gradually decreases to zero, and there is no longer a repulsive force between the coil B9 and the armature 6.

[0066] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the method embodiments described later, since they correspond to the system, the description is relatively simple, and reference can be made to the relevant parts of the system embodiments for the relevant parts.

[0067] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A locking device for a seat belt retractor, characterized in that, It includes a housing, an armature, a spring, coil A and coil B. The housing includes a bottom plate, a vertical arm, and an installation cavity between the bottom plate and the vertical arm. The armature is pivotally supported above the vertical arm, and includes a first leg extending above the installation cavity and a second leg extending towards the bottom plate. One end of the spring is fixed to the armature, and the other end is fixed to the housing. The spring pulls the armature, always moving the first leg from a release position close to the installation cavity to a locking position away from the installation cavity. When the first leg is in the locking position, it locks the retractor reel to prevent the webbing from being further pulled out; Coil A is installed in the installation cavity. After being energized, it generates a magnetic field that can adsorb the first leg to overcome the pulling force of the spring and move from the locking position to the release position. Coil B is installed on the housing. After being energized, it generates a magnetic field that can attract or repel the second leg, thereby controlling the resilience of the first leg between the release position and the locking position.

2. The locking device for a seat belt retractor according to claim 1, characterized in that, The locking device further includes an ECU module, a latch signal module, and a PWM signal generation module. The ECU module is controllably connected to the PWM signal generation module and the latch signal module. The PWM signal generation module outputs to control the on / off of the current flowing through coil A and one or more of the start time, magnitude, and direction of the current flowing through coil B.

3. The locking device for a seat belt retractor according to claim 2, characterized in that, The PWM signal generation module includes a PWM signal generation circuit, a latch signal detection circuit, and a switch circuit. The switch circuit controls the on / off of the current flowing through coil A. The PWM signal generation circuit and the switch circuit control one or more of the start time, magnitude, and direction of the current flowing through coil B.

4. The locking device for a seat belt retractor according to claim 3, characterized in that, The switch circuit includes a first switch circuit. The first switch circuit controls the energization and de-energization of coil A. The first switch circuit includes: triode Q2, relay C, resistor R1, power supply B1, power supply B2, and power supply B4; One end of resistor R1 is connected to the latch signal detection circuit, and the other end is connected to the base of triode Q2. The emitter of triode Q2 is grounded. The collector of triode Q2 is connected to the negative pole of power supply B2. The positive pole of power supply B2 is connected to one end of the coil of relay C. The other end of the coil is grounded. The normally open contact of relay C is connected to the positive pole of power supply B4. The normally closed contact of relay C is grounded. The negative pole of power supply B4 is connected to one end of coil A. The other end of coil A is grounded.

5. The locking device for a seat belt retractor according to claim 4, characterized in that, The switch circuit further includes a second switch circuit. The second switch circuit controls the energization and de-energization of coil B. The second switch circuit includes MOS tube Q1, resistor R2, resistor R3, capacitor C1, and power supply B3; One end of the resistor R2 is connected to the PWM signal generation circuit, and the other end is connected to one end of the resistor R3 and the gate of the MOS transistor Q1. The other end of the resistor R3 is grounded. The drain of the MOS transistor Q1 is connected to the positive electrode of the capacitor C1 and the negative electrode of the power supply B3. The source of the MOS transistor Q1 is connected to the negative electrode of the capacitor C1 and grounded. The positive electrode of the power supply B3 is connected to one end of the coil B, and the other end of the coil B is grounded.

6. The locking device for a seat belt retractor according to claim 5, characterized in that, The latch signal detection circuit includes a switch PS. One end of the switch PS is connected to the positive electrode of the power supply B1, and the other end is connected to the other end of the resistor R1. The negative electrode of the power supply B1 is grounded. When the switch PS is closed, the first switch circuit works and the second switch circuit does not work, so that the coil A is energized. When the switch PS is opened, the first switch circuit does not work and the second switch circuit works, so that the coil B is energized.

7. The locking device for a seat belt retractor according to claim 5 or 6, characterized in that, The PWM signal generation circuit includes a sawtooth wave generation circuit, a sine signal circuit and a comparator. The sawtooth wave generation circuit is connected to one input end of the comparator, the sine signal circuit is connected to the other input end of the comparator, and the output end of the comparator is connected to the resistor R2.

8. The locking device for a seat belt retractor according to claim 7, characterized in that, When the first leg moves from the release position to the locking position for the first time, the duty cycle of the PWM signal generation circuit increases as the distance between the second leg and the coil B decreases. After the first leg moves to the locking position, the duty cycle of the PWM signal generation module gradually decreases to zero.

9. The locking device for a seat belt retractor according to claim 1, characterized in that, The device further includes a magnet disposed on the second leg. When the first leg moves from the release position near the installation cavity to the locking position away from the installation cavity, before the second leg contacts the housing, a repulsive force is generated between the magnet and the coil B.

10. The locking device for a seat belt retractor according to claim 9, characterized in that, The magnet is disposed on the end face of the second leg close to the coil B.

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