Locking device for seat belt retractor

Abstract

An embodiment of the present disclosure provides a locking device for a seatbelt retractor, comprising a housing, an armature, a spring, a coil, an ECU module, and a lock signal module. The housing includes a base plate, an arm, and a mounting cavity between the base plate and the arm. The armature is pivotally supported above the arm and includes a first leg extending above the mounting cavity. One end of the spring is fixed to the armature and the other end is fixed to the housing. The coil is mounted within the mounting cavity. When energized, it generates a magnetic field that attracts the first leg, overcoming the pull of the spring and causing it to move from a locked position to a released position. The ECU module controls the connection to the lock signal module and controls the initial action time and / or magnitude of the current flowing through the coil to control the rebound force of the first leg. Controlling the coil current through the ECU module can reduce the impact force between the armature and the metal housing without affecting the rapid resetting of the armature.

Description

Technical Field

[0001] The present invention relates to the technical field of seat belt retractor locking, and in particular to a locking device for a seat belt retractor. Background Art

[0002] Currently, when the seat belt retractor is locked, the armature will hit the metal shell during the reset process. Because the armature reset action needs to be quick, the collision between the armature and the metal shell will produce a certain amount of noise, affecting the user experience. At the same time, as the number of armature resets increases, the wear of the armature and the metal shell will be accelerated, resulting in a reduced service life of the retractor. Summary of the Invention

[0003] In view of this, an embodiment of the present specification provides a locking device for a seat belt retractor, which controls the current of the coil through an ECU module, thereby reducing the impact force between the armature and the metal shell without affecting the rapid resetting of the armature.

[0004] The embodiments of this specification provide the following technical solutions: a locking device for a seat belt retractor, comprising a housing, an armature, a spring, a coil, an ECU module, and a lock signal module, wherein the housing comprises a base plate, a vertical arm, and a mounting cavity between the base plate and the vertical arm, the armature being pivotally supported above the vertical arm, and comprising a first leg extending above the mounting cavity, one end of the spring being fixed to the armature and the other end being fixed to the housing, the spring pulling the armature to always move the first leg from a release position close to the mounting cavity to a locking position away from the mounting cavity, and when the first leg is in the locking position, the retractor reel is locked to prevent the webbing from being further pulled out, the coil being mounted in the mounting cavity, and generating a magnetic field when energized to attract the first leg to overcome the pulling action of the spring and move it from the locking position to the release position;

[0005] The ECU module controls the connection to the lock signal module, and the ECU module controls the starting action time and / or magnitude of the current flowing through the coil to control the rebound force of the first leg.

[0006] Preferably, the ECU module includes a PWM signal generating circuit, a lock signal detecting circuit and a timing circuit;

[0007] The lock signal detection circuit detects the lock signal output by the lock signal module, and the PWM signal generation circuit generates a pulse width modulation control signal with a varying duty cycle according to the lock signal to control the suction force of the coil on the first leg;

[0008] The timing circuit controls the on and off of the current flowing through the coil after the pulse width modulation control signal changes.

[0009] Preferably, when the lock signal module sends a lock signal to move the first leg from the locked position to the released position, the ECU module controls the lock signal detection circuit not to work, so that the PWM signal generating circuit works within a fourth time, and the coil is energized to generate suction to the armature. From the fourth time to the fifth time, the ECU module controls the lock signal detection circuit to work, and the PWM signal generating circuit does not work from the fourth time to the fifth time. From the fifth time to the sixth time, the ECU module controls the lock signal detection circuit not to work, and the duty cycle of the PWM signal generating circuit gradually increases. After the sixth time, the constant current generated by the PWM signal generating circuit flows through the coil, adsorbing the first leg at the release position.

[0010] Preferably, when the lock signal module sends a lock signal to move the first leg from the release position to the lock position, the ECU module controls the lock signal detection circuit to work, so that the PWM signal generating circuit does not work within the first time, and the armature moves from the release position to the lock position. From the first time to the second time, the duty cycle of the PWM signal generating circuit gradually increases, and the suction force generated by the coil being energized on the armature is less than the elastic force of the spring. From the second time to the third time, the suction force generated by the coil being energized on the armature is greater than the elastic force of the spring. After the third time, the first leg is in the lock position, the timing circuit works, and the voltage of the PWM signal generating circuit passes through the timing circuit to cut off the power to the coil.

[0011] Preferably, the PWM signal generating circuit includes a sawtooth wave signal generating circuit, a comparator, a resistor R1, a resistor R4, a capacitor C1 and a power supply U1;

[0012] The positive electrode of the power supply U1 is connected to the positive electrode of the capacitor C1 and one end of the comparator through the resistor R1, the comparator is connected to the sawtooth wave signal generating circuit, the positive electrode of the capacitor C1 is connected to the lock signal detection circuit, the negative electrode of the power supply U1 and the negative electrode of the capacitor C1 are grounded, and the sawtooth wave signal generating circuit is connected to the coil through the resistor R4.

[0013] Preferably, the sawtooth wave signal generating circuit includes an operational amplifier A1, an operational amplifier A2, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a capacitor C4, a diode D1 and a diode D2;

[0014] The inverting input terminal of the operational amplifier A1 is grounded, the non-inverting input terminal is connected to the first end of the resistor R5, the output terminal is connected to the second end of the resistor R5, the anode of the diode D1 and the cathode of the diode D2 through the resistor R6, the cathode of the diode D1 is connected to the first end of the resistor R7, the second end of the resistor R7 is connected to the anode of the diode D2, the capacitor C4 and the inverting input terminal of the operational amplifier A2, the non-inverting input terminal of the operational amplifier A2 is grounded through the resistor R8, and the output terminal is connected to the other end of the comparator.

[0015] Preferably, the lock signal detection circuit includes a switch PS, a resistor R2, a capacitor C2 and a transistor Q1;

[0016] One end of the switch PS is connected to the positive electrode of the power supply U1, the other end of the switch PS is connected to the positive electrode of the capacitor C2, the negative electrode of the capacitor C2 is connected to one end of the resistor R2 and the gate of the transistor Q1, the drain of the transistor is connected to the positive electrode of the capacitor C1, and the source of the transistor Q1 and the other end of the resistor R2 are both grounded.

[0017] Preferably, when the lock signal module sends a lock signal, the ECU module controls the switch PS to close, so that the lock signal detection circuit works, and the capacitor C1 discharges through the transistor Q1, so that the duty cycle of the PWM signal generating circuit becomes zero.

[0018] Preferably, the timing circuit includes a resistor R3, a capacitor C3 and a transistor Q2, one end of the resistor R3 is connected to the other end of the switch PS, the other end of the resistor R3 is connected to the positive electrode of the capacitor C3 and the gate of the transistor Q2, the drain of the transistor Q2 is connected to the output end of the resistor R4, and the negative electrode of the capacitor C3 and the source of the transistor Q2 are both grounded.

[0019] Preferably, when the lock signal module sends a lock signal, the ECU module controls the switch PS to close. At the third time, the voltage on the capacitor C3 reaches the gate threshold voltage of the transistor Q2, and the transistor Q2 is turned on, so that the timing circuit works after the third time.

[0020] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0021] The ECU module and the lock signal module are controlled by the ECU module, and the current of the coil is controlled by the ECU module. On the basis of not affecting the rapid reset of the armature, the impact force between the armature and the metal shell can be reduced, the noise can be reduced, and the service life of the retractor can be avoided from being reduced due to the impact of the armature reset. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] Figure 1 A schematic diagram of the locking device provided by the present invention when unlocked;

[0024] Figure 2 is a schematic diagram of the locking device provided by the present invention when locked;

[0025] Figure 3 This is a schematic diagram of the ECU module circuit of the locking device provided by the present invention;

[0026] Figure 4 This is a schematic diagram of a PWM signal generating circuit for a locking device provided by the present invention;

[0027] Figure 5 This is a schematic diagram of a lock signal detection circuit for a locking device provided by the present invention;

[0028] Figure 6 is a schematic diagram of a timing circuit of a locking device provided by the present invention;

[0029] Figure 7 This is a schematic diagram of the force variation of the armature of the locking device provided by the present invention;

[0030] Figure 8 It is a schematic diagram of the change of the spring elastic force of the locking device provided by the present invention. DETAILED DESCRIPTION

[0031] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0032] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents 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 embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the features in the following embodiments and embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of this application.

[0033] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this application, it should be understood by those skilled in the art that an 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 aspect described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0034] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The illustrations only show components related to the present application and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0035] Additionally, in the following description, specific details are provided to provide a thorough understanding of the examples. However, one skilled in the art will appreciate that the aspects described can be practiced without these specific details.

[0036] In the prior art, when the seat belt retractor is locked, the armature needs to lock the reel of the retractor to prevent the webbing from being pulled out further. Therefore, the armature needs to be quickly reset. However, when the armature resets too quickly, when the armature contacts the metal shell in the final stage of the reset process, a strong impact will be generated between the armature and the metal shell, resulting in noise.

[0037] After extensive and in-depth experiments, the inventors designed a locking device for a seat belt retractor that can reduce the impact force between the armature and the metal shell without affecting the rapid resetting of the armature.

[0038] The technical problem solved by the present invention is to avoid generating large noise when the retractor is locked.

[0039] More specifically, the solution adopted by the present invention includes: controlling the operation of the lock signal module through the ECU module, and controlling the current of the coil through the ECU module, which can reduce the impact force between the armature and the metal shell and reduce noise without affecting the rapid resetting of the armature.

[0040] The following describes the technical solutions provided by various embodiments of the present application in conjunction with the accompanying drawings.

[0041] like Figure 1-Figure 2As shown, a locking device for a seat belt retractor includes a housing 1, an armature 3, a spring 4, a coil 2, an ECU module, and a lock signal module. The housing 1 includes a base plate, a vertical arm 101, and a mounting cavity between the base plate and the vertical arm 101. The armature 3 is pivotally supported above the vertical arm 101 and includes a first leg 301 extending above the mounting cavity. One end of the spring 4 is fixed to the armature 3 and the other end is fixed to the housing 1. The spring 4 pulls the armature 3 to always move the first leg 301 from a release position close to the mounting cavity to a locking position away from the mounting cavity. When the first leg 301 is in the locked position, it locks the retractor reel to prevent the webbing from being further pulled out. The coil 2 is installed in the mounting cavity. When energized, it generates a magnetic field that can attract the first leg 301 to overcome the pulling action of the spring 4 and move it from the locked position to the released position.

[0042] The ECU module controls the connection to the lock signal module, and the ECU module controls the starting action time and / or magnitude of the current flowing through the coil 2 to control the rebound force of the first leg 301.

[0043] Under normal conditions, the coil 2 is energized to generate a magnetic field, which attracts the first leg 301 of the armature 3 to the top of the housing 1 in the released position. As the armature 3 moves to the released position, the spring 4 is stretched, causing the spring 4 to be in a stretched state. The spring 4 stores elastic potential energy, and the armature 3 is in a closed state, without locking the retractor. The current in the coil 2 can be controlled by the ECU module to reduce the noise generated when the armature 3 collides with the top of the housing 1.

[0044] When the retractor is locked, the lock signal module sends a lock signal and the ECU module works. Within the first time, the ECU module does not supply power to the coil 2. Under the elastic force of the spring 4, the first leg 301 of the armature 3 moves rapidly from the release position to the locking position. From the first time to the second time, the ECU module controls the current in the coil 2 to gradually increase. At this time, the suction force generated by the coil 2 on the armature 3 is less than the elastic force of the spring 4, and the armature 3 continues to reset. From the second time to the third time, the suction force generated by the coil 2 on the armature 3 is greater than the elastic force of the spring 4, and the reset speed of the armature 3 slows down, thereby avoiding the armature 3 from colliding with the metal parts in the retractor to generate noise. After the third time, the ECU module controls the coil 2 to cut off power, maintains low power consumption, and the armature 3 is reset.

[0045] like Figure 1-Figure 3 As shown, in some embodiments, the ECU module includes a PWM signal generating circuit, a lock signal detecting circuit, and a timing circuit;

[0046] The lock signal detection circuit detects the lock signal output by the lock signal module, and the PWM signal generation circuit generates a pulse width modulation control signal with a varying duty cycle based on the lock signal to control the suction force of the coil 2 on the first leg 301; the timing circuit controls the on and off of the current flowing through the coil 2 after the pulse width modulation control signal changes.

[0047] When the retractor is locked, the lock signal module sends a lock signal, and the ECU module controls the lock signal detection circuit to operate, so that the PWM signal generation circuit generates a variable duty cycle, thereby adjusting the current passing through the coil 2, so that the adsorption force between the coil 2 and the first leg 301 changes, ensuring that the armature 3 does not generate large noise on the basis of rapid recovery. After the armature 3 is reset, the timing circuit operates to disconnect the current on the coil 2, and the coil 2 no longer generates a magnetic field, maintaining low power consumption.

[0048] Specifically, when the lock signal module sends a lock signal to move the first leg 301 from the release position to the lock position, the ECU module controls the lock signal detection circuit to work, so that the PWM signal generating circuit does not work within the first time, and no current flows through the coil 2 within the first time. The coil 2 no longer has an adsorption force on the armature 3. Under the elastic force of the spring 4, the armature 3 moves from the release position to the lock position, and the movement speed of the armature 3 gradually accelerates, which can ensure the rapid reset of the armature 3. From the first time to the second time, the duty cycle of the PWM signal generating circuit gradually increases, and the suction force generated by the coil 2 on the armature 3 when it is energized is less than the elastic force of the spring 4. Since the suction force of the coil 2 on the armature 3 is less than the elastic force of the spring 4, this During this time, the armature 3 is still in an accelerated state to ensure rapid resetting of the armature 3. From the second time to the third time, the suction force generated by the coil 2 on the armature 3 when it is energized is greater than the elastic force of the spring 4. When the suction force of the coil 2 on the armature 3 is greater than the elastic force of the spring 4, the spring 4 begins to decelerate under the action of the coil 2. This suction force offsets a portion of the elastic potential energy stored in the spring 4, thereby reducing the noise generated by the impact of the armature 3 with the metal parts in the retractor during the resetting process. After the third time, the first leg 301 is in the locked position, the timing circuit operates, and the voltage of the PWM signal generating circuit passes through the timing circuit to de-energize the coil 2. When the armature 3 is completely reset, the timing circuit starts to operate, and no current flows through the coil 2, thereby maintaining low power consumption.

[0049] When the lock signal module sends a lock signal to move the first leg 301 from the locked position to the released position (that is, when the retractor needs to be unlocked), the ECU module controls the lock signal detection circuit to not work, so that the PWM signal generating circuit works within the fourth time, and the PWM signal generating circuit outputs a duty cycle of 100%, so that the coil 2 is always in an energized state, and the coil 2 generates suction force on the armature 3 when it is energized. The coil 2 attracts the first leg 301 of the armature 3 and moves it from the locked position to the released position. The first leg 301 of the armature 3 is in a state of accelerating to the released position. From the fourth time to the fifth time, the ECU module controls the lock signal detection circuit to work, and the PWM signal generating circuit does not work from the fourth time to the fifth time. The coil 2 is powered off, and the first leg 301 of the armature 3 is in a state of decelerating to the released position. Within the sixth time, the ECU module controls the lock signal detection circuit to not work, the duty cycle of the PWM signal generating circuit gradually increases, and the current passing through the coil 2 also gradually increases. The suction force generated by the coil 2 on the armature 3 when it is energized is less than or equal to the elastic force of the spring 4. The first leg 301 of the armature 3 is in a state of decelerating movement toward the release position. The suction force of the coil 2 on the armature 3 will offset part of the elastic force of the spring 4, so that the first leg 301 of the armature 3 moves to the release position at a relatively slow speed, thereby avoiding a large impact between the first leg 301 and the housing 1, and avoiding noise. After the sixth time, the first leg 301 is in the release position, the constant current generated by the PWM signal generating circuit flows through the coil 2, the PWM signal generating circuit outputs a duty cycle of 100%, the coil 2 is always energized, and the first leg 301 is adsorbed at the release position.

[0050] It should be noted that the duty cycle generated by the PWM signal generating circuit can be from 0% to 100%, thereby controlling the current flowing through the coil 2 to achieve different suction forces of the coil 2 on the armature 3.

[0051] It should also be noted that the values ​​of the first time, second time, third time, fourth time, fifth time and sixth time can be set according to actual needs to meet the locking requirements of different models of retractors.

[0052] like Figure 4 As shown, in some embodiments, the PWM signal generating circuit includes a sawtooth wave signal generating circuit, a comparator, a resistor R1, a resistor R4, a capacitor C1 and a power supply U1;

[0053] The positive electrode of the power supply U1 is connected to the positive electrode of the capacitor C1 and one end of the comparator through the resistor R1, the comparator is connected to the sawtooth wave signal generating circuit, the positive electrode of the capacitor C1 is connected to the lock signal detection circuit, the negative electrode of the power supply U1 and the negative electrode of the capacitor C1 are grounded, and the sawtooth wave signal generating circuit is connected to the coil 2 through the resistor R4;

[0054] Power supply U1 charges capacitor C1 through resistor R1, compares the voltage on capacitor C1 with the voltage of the sawtooth wave signal generating circuit, and generates a pulse width modulation control signal that varies from 0 to 100%. When the voltage on capacitor C1 is greater than the maximum voltage of the sawtooth wave signal generating circuit, the voltage is maintained at a 100% duty cycle. At this time, coil 2 is always energized, and the coil 2 generates a magnetic field, which attracts the first leg 301 of the armature 3 to the top of the housing 1 in a released position. As the armature 3 moves to the released position, the spring 4 is stretched, causing the spring 4 to be in a stretched state. The spring 4 stores elastic potential energy in preparation for resetting the armature 3.

[0055] In some embodiments, the sawtooth wave signal generating circuit includes an operational amplifier A1, an operational amplifier A2, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a capacitor C4, a diode D1, and a diode D2;

[0056] The inverting input terminal of the operational amplifier A1 is grounded, the non-inverting input terminal is connected to the first end of the resistor R5, the output terminal is connected to the second end of the resistor R5, the anode of the diode D1 and the cathode of the diode D2 through the resistor R6, the cathode of the diode D1 is connected to the first end of the resistor R7, the second end of the resistor R7 is connected to the anode of the diode D2, the capacitor C4 and the inverting input terminal of the operational amplifier A2, the non-inverting input terminal of the operational amplifier A2 is grounded through the resistor R8, and the output terminal is connected to the other end of the comparator;

[0057] By connecting diodes D1 and D2 to the non-inverting input of operational amplifier A2, with diodes D1 and D2 set in opposite directions, and providing resistor R7 between diode D2 and operational amplifier A2, the charging speed of capacitor C4 is different in the positive half-cycle and the negative half-cycle, thereby generating a sawtooth wave. The voltage on capacitor C1 is compared with the sawtooth wave voltage to generate a PWM signal.

[0058] like Figure 3-Figure 5 As shown, in some embodiments, the lock signal detection circuit includes a switch PS, a resistor R2, a capacitor C2 and a transistor Q1;

[0059] One end of the switch PS is connected to the positive electrode of the power supply U1, the other end of the switch PS is connected to the positive electrode of the capacitor C2, the negative electrode of the capacitor C2 is connected to one end of the resistor R2 and the gate of the transistor Q1, the drain of the transistor is connected to the positive electrode of the capacitor C1, and the source of the transistor Q1 and the other end of the resistor R2 are both grounded;

[0060] In normal state (i.e. when the retractor is not locked), the switch PS is in the off state. At this time, there is no connection between the power supply U1 and the capacitor C2. The lock signal detection circuit is in the off state, the PWM signal generation circuit is in the working state, and the coil 2 is energized to attract the armature 3 to the release position.

[0061] When locking, the lock signal module sends a lock signal, and the ECU module controls the closing of switch PS. At the moment switch PS closes, power supply U1 and capacitor C2 are connected, supplying power to capacitor C2. Since the voltage across the capacitor cannot change suddenly, the moment switch PS opens, capacitor C2 is effectively short-circuited, and voltage is applied to resistor R2. This voltage across resistor R2 turns on transistor Q1, which rapidly discharges capacitor C1 through transistor Q1. At this point, the voltage across capacitor C1 returns to zero, and the duty cycle of the pulse-width modulation control signal becomes zero. Coil 2 loses power, and the armature 3 loses its attraction. Under the elastic force of spring 4, armature 3 is quickly lifted and reset. However, as power supply U1 charges capacitor C1, the duty cycle of the PWM signal generation circuit gradually increases, and the voltage across coil 2 also increases, generating a suction force on armature 3 during the reset process. This suction force offsets some of the elastic potential energy stored in spring 4, thereby reducing the noise caused by armature 3 hitting the bottom during the reset process.

[0062] like Figure 3-Figure 6 As shown, in some embodiments, the timing circuit includes a resistor R3, a capacitor C3, and a transistor Q2, one end of the resistor R3 is connected to the other end of the switch PS, the other end of the resistor R3 is connected to the positive electrode of the capacitor C3 and the gate of the transistor Q2, the drain of the transistor Q2 is connected to the output end of the resistor R4, and the negative electrode of the capacitor C3 and the source of the transistor Q2 are both grounded;

[0063] In normal state (i.e. when the retractor is not locked), the switch PS is in the off state, the power supply U1 and the resistor R3 are not connected, and the timing circuit is in the non-working state;

[0064] When locking, the lock signal module sends a lock signal, the ECU module controls the switch PS to close, and the power supply U1 charges the capacitor C3 through the resistor R3. When the voltage on the capacitor C3 reaches the gate threshold voltage of the transistor Q2, the transistor Q2 is in the on state, and the resistor R4 is grounded through the drain of the transistor Q2 and the source of the transistor Q2. After passing through the resistor R4, the current flows out through the transistor Q2 and no longer passes through the coil 2. The coil 2 is powered off and no longer generates a magnetic field, maintaining low power consumption.

[0065] In some embodiments, when the lock signal module sends a lock signal, the ECU module controls the switch PS to close. At a third time, the voltage on the capacitor C3 reaches the gate threshold voltage of the transistor Q2, and the transistor Q2 is turned on, causing the timing circuit to operate after the third time. Since the power supply U1 needs to charge the capacitor C3 through the resistor R3, the voltage on the capacitor C3 does not change instantaneously. Before the third time, the voltage on the capacitor C3 is less than the gate threshold voltage of the transistor Q2. At this time, the transistor Q2 is in the off state, and there is no conduction between the drain of the transistor Q2 and the source of the transistor Q2. When the third time comes, the voltage on the capacitor C3 reaches the gate threshold voltage of the transistor Q2, and the drain of the transistor Q2 and the source of the transistor Q2 are turned on. At this time, the current flows out through the resistor R4 and the transistor Q2, and no longer flows through the coil 2. The coil 2 is powered off to maintain low power consumption.

[0066] A specific implementation of this application will be described below:

[0067] In this embodiment, the coil parameters are: number of turns 680, coil wire diameter 0.18 mm, coil resistance 13.59 ohms, and the voltage of power supply U1 is 5V;

[0068] See also Figures 1-8 When the retractor is unlocked, switch PS is disconnected, the lock signal detection circuit and the timing circuit are inactive, and power supply U1 charges capacitor C1 through resistor R1. The voltage on capacitor C1 is compared with the voltage of the sawtooth wave signal generating circuit to generate a varying pulse width modulation control signal. After 0.7s, the voltage on capacitor C1 reaches 10V. At this time, the duty cycle is large, the voltage on coil 2 is large, and a current of 1A is generated in coil 2. A magnetic field is generated around coil 2, which can generate a large suction force. The magnetic field generated by coil 2 generates a force of 0.7N on armature 3, causing armature 3 to be attracted to the top of housing 1 in the released position. As armature 3 moves to the released position, spring 4 is stretched, causing spring 4 to be in a stretched state and storing 0.5J of elastic potential energy in spring 4, preparing for the reset of armature 3.

[0069] When the retractor is locked, the ECU module receives the lock signal from the lock signal module, and the ECU module controls the switch PS to close. In the first 0.5s, the switch PS is in an unclosed state. At the moment the switch PS is closed, the power supply U1 is connected to the capacitor C2, and the power supply U1 supplies power to the capacitor C2. Since the voltage across the capacitor cannot change suddenly, when the switch PS is opened, the capacitor C2 is equivalent to a short circuit, and the voltage is applied to the resistor R2. The voltage on the resistor R2 turns on the transistor Q1. When the transistor Q1 is turned on, the capacitor C1 is quickly discharged through the transistor Q1. At this time, the voltage on the capacitor C1 returns to 0, and the duty cycle of the pulse width modulation control signal becomes 0. Between 0.5s and 0.52s, the coil 2 loses power and loses the suction force on the armature 3. Under the elastic force of the spring 4, the armature 3 will be quickly lifted up for reset, but as the power supply U1 1 is charged, and the duty cycle generated by the PWM signal generating circuit will gradually increase. Between 0.52s and 0.56s, the force on the spring 4 is greater than the suction force of the coil 2. Since the suction force of the coil 2 on the armature 3 is less than the elastic force of the spring 4, the armature 3 is still in an accelerated state to ensure the rapid reset of the armature 3. Between 0.56s and 0.65s, the elastic force of the spring 4 is gradually less than the suction force of the coil 2, which slows down the speed of the armature 3 and slowly resets the armature 3. After the switch PS is turned on, the power supply U1 charges the capacitor C3 through the resistor R3. When 0.65s, the voltage on the capacitor C3 reaches the gate threshold voltage of the transistor Q2, and the drain of the transistor Q2 and the source of the transistor Q2 are connected. At this time, the current flows out through the transistor Q2 after passing through the resistor R4, and the current on the coil 2 gradually decreases to 0. After 0.75s, the coil 2 is completely de-energized and the armature 3 is reset.

[0070] In this specification, references to the same or similar parts between the various embodiments can be made to each other, and 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 the relevant parts can be referred to the partial description of the system embodiment.

[0071] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A locking device for a seat belt retractor, characterized in that: The invention comprises a housing, an armature, a spring, a coil, an ECU module and a lock signal module. The housing comprises a base plate, a vertical arm and a mounting cavity between the base plate and the vertical arm. The armature is pivotally supported above the vertical arm and comprises a first leg extending above the mounting cavity. One end of the spring is fixed to the armature and the other end is fixed to the housing. The spring pulls the armature to always move the first leg from a release position close to the mounting cavity to a locked position away from the mounting cavity. When the first leg is in the locked position, the retractor reel is locked to prevent the webbing from being further pulled out. The coil is mounted in the mounting cavity and, when energized, generates a magnetic field that can attract the first leg to overcome the pulling action of the spring and move it from the locked position to the released position. The ECU module controls the connection to the lock signal module, and the ECU module controls the starting action time and / or magnitude of the current flowing through the coil to control the rebound force of the first leg.

2. The locking device for a seat belt retractor according to claim 1, wherein: The ECU module includes a PWM signal generating circuit, a lock signal detecting circuit and a timing circuit; The lock signal detection circuit detects the lock signal output by the lock signal module, and the PWM signal generation circuit generates a pulse width modulation control signal with a varying duty cycle according to the lock signal to control the suction force of the coil on the first leg; The timing circuit controls the on and off of the current flowing through the coil after the pulse width modulation control signal changes.

3. The locking device for a seat belt retractor according to claim 2, wherein: When the lock signal module sends a lock signal to move the first leg from the release position to the lock position, the ECU module controls the lock signal detection circuit to operate, so that the PWM signal generating circuit does not operate within a first time. From the first time to the second time, the duty cycle of the PWM signal generating circuit gradually increases, and the suction force generated by the coil being energized on the armature is less than the elastic force of the spring. From the second time to the third time, the suction force generated by the coil being energized on the armature is greater than the elastic force of the spring. After the third time, the first leg is in the lock position, the timing circuit operates, and the voltage of the PWM signal generating circuit passes through the timing circuit to de-energize the coil.

4. The locking device for a seat belt retractor according to claim 2, wherein: When the lock signal module sends a lock signal to move the first leg from the locked position to the released position, the ECU module controls the lock signal detection circuit not to work, so that the PWM signal generating circuit works within a fourth time, and the coil is energized to generate suction to the armature. From the fourth time to the fifth time, the ECU module controls the lock signal detection circuit to work, and the PWM signal generating circuit does not work from the fourth time to the fifth time. From the fifth time to the sixth time, the ECU module controls the lock signal detection circuit not to work, and the duty cycle of the PWM signal generating circuit gradually increases. After the sixth time, the constant current generated by the PWM signal generating circuit flows through the coil, so that the first leg is adsorbed in the release position.

5. The locking device for a seat belt retractor according to any one of claims 2 to 4, characterized in that: The PWM signal generating circuit includes a sawtooth wave signal generating circuit, a comparator, a resistor R1, a resistor R4, a capacitor C1 and a power supply U1; the positive electrode of the power supply U1 is connected to the positive electrode of the capacitor C1 and one end of the comparator through the resistor R1, the comparator is connected to the sawtooth wave signal generating circuit, the positive electrode of the capacitor C1 is connected to the lock signal detection circuit, the negative electrode of the power supply U1 and the negative electrode of the capacitor C1 are grounded, and the sawtooth wave signal generating circuit is connected to the coil through the resistor R4.

6. The locking device for a seat belt retractor according to claim 5, wherein: The sawtooth wave signal generating circuit includes an operational amplifier A1, an operational amplifier A2, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a capacitor C4, a diode D1 and a diode D2; The inverting input terminal of the operational amplifier A1 is grounded, the non-inverting input terminal is connected to the first end of the resistor R5, the output terminal is connected to the second end of the resistor R5, the anode of the diode D1 and the cathode of the diode D2 through the resistor R6, the cathode of the diode D1 is connected to the first end of the resistor R7, the second end of the resistor R7 is connected to the anode of the diode D2, the capacitor C4 and the inverting input terminal of the operational amplifier A2, the non-inverting input terminal of the operational amplifier A2 is grounded through the resistor R8, and the output terminal is connected to the other end of the comparator.

7. The locking device for a seat belt retractor according to claim 6, wherein: The lock signal detection circuit includes a switch PS, a resistor R2, a capacitor C2 and a transistor Q1; One end of the switch PS is connected to the positive electrode of the power supply U1, the other end of the switch PS is connected to the positive electrode of the capacitor C2, the negative electrode of the capacitor C2 is connected to one end of the resistor R2 and the gate of the transistor Q1, the drain of the transistor is connected to the positive electrode of the capacitor C1, and the source of the transistor Q1 and the other end of the resistor R2 are both grounded.

8. The locking device for a seat belt retractor according to claim 7, wherein: When the lock signal module sends a lock signal, the ECU module controls the switch PS to close, so that the lock signal detection circuit operates, and the capacitor C1 discharges through the transistor Q1, so that the duty cycle of the PWM signal generating circuit becomes zero.

9. The locking device for a seat belt retractor according to claim 8, wherein: The timing circuit includes a resistor R3, a capacitor C3 and a transistor Q2. One end of the resistor R3 is connected to the other end of the switch PS, the other end of the resistor R3 is connected to the positive electrode of the capacitor C3 and the gate of the transistor Q2, the drain of the transistor Q2 is connected to the output end of the resistor R4, and the negative electrode of the capacitor C3 and the source of the transistor Q2 are both grounded.

10. The locking device for a seat belt retractor according to claim 9, wherein: When the lock signal module sends a lock signal, the ECU module controls the switch PS to close. At the third time, the voltage on the capacitor C3 reaches the gate threshold voltage of the transistor Q2, and the transistor Q2 is turned on, so that the timing circuit operates after the third time.

Images