Patent Description:
Existing seat belt retractors can provide functions such as pre-collision protection, man-machine interaction during driving, and comfort. Before a control unit determines that a vehicle may crash, an active seat belt retractor can retract a certain length of a seat belt by means of a motor so as to slightly bind a passenger; when the control unit determines that the risk of crashing disappears, the active seat belt retractor allows the seat belt to be freely pulled.

The motor of the seat belt retractor has small output torque. Therefore, clutches for seat belt retractors are mainly toothed clutches. Such clutches have a long engagement and disengagement delay, a great impact, and loud noise, and inner and outer teeth thereof are not synchronized.

Existing overrunning clutches employing balls are mainly classified into two categories: clutches having no cages and clutches having cages. From the documents <CIT> and <CIT> are known releasable clutches having a cage and comprising all features of the preamble of claim <NUM>. In a clutch having no cage, balls are fixed in an inner ring or an outer ring, and an input end and an output end cannot completely disengage from each other. When the clutch is used in a seat belt, if the motor acts as an input end, motion control can be performed. However, because of incomplete disengagement, the seat belt is jammed if a passenger pulls or retracts the seat belt. In a clutch having a cage, inertia is mainly provided by the cage, engagement is performed when an input end is activated at a high speed, and the input end and an output end can completely disengage from each other. However, because inertia is required when performing engagement and disengagement, the input end needs to be activated at a high speed. When the clutch is used in a seat belt, the functions of comfort and man-machine interaction, which require low-speed activation, cannot be achieved.

Therefore, an improved engagement and disengagement device used in a seat belt retractor is needed.

An objective of the present invention is to provide an engagement and disengagement device capable of engaging and disengaging at a low rotational speed, a seat belt retractor, and a seat belt assembly. An aspect of the present invention provides an engagement and disengagement device in which an input end and an output end are completely separated from each other after disengagement is performed, a seat belt retractor, and a seat belt assembly. Another aspect of the present invention provides an engagement and disengagement device in which a small impact is generated when performing engagement or disengagement, a seat belt retractor, and a seat belt assembly.

According to the suggested solution are suggested an engagement and disengagement device comprising the features of claim <NUM>, a seatbelt retractor comprising the features of claim <NUM> and a seat belt assembly comprising the features of claim <NUM>.

According to an embodiment of the present invention, when the transmission member is at the engagement position, no radial gap exists both between the transmission element and the engagement portion of the first rotating member, and between the transmission element and the radial outer surface of the second rotating member.

According to an embodiment of the present invention, the transmission element is a rolling element.

According to an embodiment of the present invention, the cage has a ring shape, and is rotatably sleeved on the second rotating member.

According to an embodiment of the present invention, the cage defines a retaining portion; the transmission element is disposed in the retaining portion; the retaining portion restricts axial movement of the transmission element relative to the cage.

According to an embodiment of the present invention, the cage comprises a first position-limiting portion located on a radial outer surface thereof; the first rotating member comprises a second position-limiting portion located on the radial inner surface thereof; and the first position-limiting portion and the second position-limiting portion can work with each other to restrict an angle of rotation of the cage relative to the first rotating member.

According to an embodiment of the present invention, the first position-limiting portion is located on an axial side of the cage, and the second position-limiting portion is located on a corresponding axial side of the first rotating member, wherein the second position-limiting portion and the engagement portion are sequentially axially disposed, and the first position-limiting portion is axially located on an outer side of the engagement portion.

According to an embodiment of the present invention, the cage comprises two side rings and a plurality of connecting pieces, the plurality of connecting pieces being spaced apart in a circumferential direction, wherein the side rings and the connecting pieces define the retaining portion, and an end portion of the first elastic component is connected to the connecting pieces.

According to an embodiment of the present invention, the engagement and disengagement device further comprises a housing, wherein the housing defines an accommodation cavity to accommodate the first rotating member and the transmission member.

According to an embodiment of the present invention, the first rotating member is rotatably supported in the housing.

According to an embodiment of the present invention, the first rotating member comprises an annular recess extending axially; the housing comprises an annular protrusion extending axially; and the annular protrusion can be inserted into the annular recess so as to rotatably support the first rotating member.

According to an embodiment of the present invention, the engagement and disengagement device further comprises a cover plate connected to the housing so as to seal the accommodation cavity.

According to an embodiment of the present invention, the engagement and disengagement device further comprises a second elastic component disposed on an axial side of the transmission member away from the cover plate so as to apply a biasing force causing the transmission member to abut the cover plate.

According to an embodiment of the present invention, the second elastic component is a wave spring.

Another aspect of the present invention provides a seat belt retractor, comprising: the engagement and disengagement device according to the embodiment of the present invention; a driving device used to drive the first rotating member of the engagement and disengagement device to rotate around the axis of rotation; and a reel connected to the second rotating member of the engagement and disengagement device in an anti-torsion manner, wherein the reel can wind a seat belt when rotating in the first direction of rotation, and can unwind the seat belt when rotating in the second direction of rotation opposite to the first direction of rotation.

Another aspect of the present invention provides a seat belt assembly, comprising: a seat belt retractor, comprising: the engagement and disengagement device according to the embodiment of the present invention; a driving device used to drive the first rotating member of the engagement and disengagement device to rotate around the axis of rotation; and a reel connected to the second rotating member of the engagement and disengagement device in an anti-torsion manner; and a seat belt having one end portion fixed to the reel, wherein the reel can wind the seat belt when rotating in the first direction of rotation, and can unwind the seat belt when rotating in the second direction of rotation opposite to the first direction of rotation.

According to an embodiment of the present invention, when the engagement and disengagement device is in a disengaged state, the transmission element and the second rotating member are radially spaced apart from each other, such that an input end and an output end of the engagement and disengagement device can be completely separated from each other. In an initial stage of switching a state of the engagement and disengagement device, due to a frictional force between the cage and the cover plate, the transmission element can cause the first rotating member and the second rotating member to engage with each other at a smaller angle of rotation. Therefore, the engagement and disengagement device of the present invention can reduce an engagement and disengagement delay, so as to wind a seat belt more quickly to provide a passenger with protection. In addition, due to the frictional force between the cage and the cover plate, the engagement and disengagement device can also perform engagement and disengagement even at a low rotational speed of a motor, thereby reducing noise and an impact.

These and other aspects and advantages of the present invention will be clearer after the following detailed description of the present invention is read with reference to the accompanying drawings.

It should be understood that the foregoing introduction and the following detailed description are merely exemplary and illustrative, and are not intended to limit the invention to be protected.

The embodiments of the present invention will be described below with reference to the drawings. The detailed description and drawings below are used exemplarily to illustrate the principles of the present invention. The present invention is not limited to the described preferred embodiments. The scope of the present invention is defined by the claims. The present invention is described in detail herein with reference to exemplary embodiments, and some embodiments are illustrated in the accompanying drawings. The following description is provided with reference to the accompanying drawings. Unless otherwise indicated, the same reference numerals in different accompanying drawings represent the same or similar elements. The solutions described in the following exemplary embodiments do not represent all of the solutions of the present invention. Instead, these solutions are merely examples of devices according to aspects of the present invention involved in the appended claims.

<FIG> is an exploded view of an engagement and disengagement device used in a seat belt retractor according to an embodiment of the present invention. As shown in <FIG>, the engagement and disengagement device can include a first rotating member <NUM>, a second rotating member <NUM>, and a transmission member <NUM>.

The first rotating member <NUM> can be driven to rotate around an axis of rotation thereof. The first rotating member <NUM> can have a hollow structure, such that at least part of the second rotating member <NUM> passes therethrough. In some embodiments, the first rotating member <NUM> includes a toothed portion <NUM> located on an outer peripheral surface thereof. The toothed portion <NUM> can engage with a driving device of the seat belt retractor by means of a gear mechanism, such as by means of a worm gear and worm, a rack and pinion, or the like.

According to an embodiment of the present invention, the first rotating member <NUM> includes an engagement portion <NUM> defined on a radial inner surface thereof. In an exemplary embodiment, the first rotating member <NUM> defines a plurality of, for example four, engagement portions <NUM> on the radial inner surface thereof. The engagement portion <NUM> is used to engage with the transmission member <NUM>.

The second rotating member <NUM> and the first rotating member <NUM> are configured to be coaxial. The second rotating member <NUM> can be connected to a reel of the seat belt retractor in an anti-torsion manner, so as to transmit torque to the reel. In an exemplary embodiment, at least part of a radial outer surface of the second rotating member <NUM> can engage with the transmission member <NUM>.

The transmission member <NUM> is disposed between the first rotating member <NUM> and the second rotating member <NUM>. In an exemplary embodiment, the transmission member <NUM> can include a cage <NUM> and a transmission element <NUM>. The cage <NUM> is used to retain one or a plurality of transmission elements <NUM>. In some embodiments, the number of transmission elements <NUM> is equal to the number of engagement portions <NUM>. In some embodiments, the transmission element <NUM> can be a rolling element, such as a cylindrical roller, a needle roller, or the like.

In an exemplary embodiment, the cage <NUM> is annular, and can be rotatably sleeved on the second rotating member <NUM>. In the exemplary embodiment shown in <FIG>, the cage <NUM> can include two side rings <NUM> and <NUM> and a plurality of connecting pieces <NUM>, the plurality of connecting pieces being spaced apart in a circumferential direction. The connecting pieces <NUM> are connected to the side rings <NUM> and <NUM>. In some embodiments, the connecting pieces <NUM> can have identical intervals in the circumferential direction. The connecting pieces <NUM> and the side rings <NUM> and <NUM> define a plurality of retaining portions. The transmission element <NUM> can be disposed and retained in the retaining portion. The retaining portion of the cage <NUM> can restrict axial movement of the transmission element <NUM> relative to the cage <NUM>, for example, by means of the two side rings <NUM> and <NUM>.

According to an embodiment of the present invention, the radial distance from the engagement portion <NUM> of the first rotating member <NUM> to the axis of rotation gradually increases in a first direction of rotation (see description below). The transmission element <NUM> can move radially in a space defined between the engagement portion <NUM> of the first rotating member <NUM> and the radial outer surface of the second rotating member <NUM>.

<FIG> is a side view of the engagement and disengagement device according to an embodiment of the present invention. <FIG> is a cross-sectional view of the engagement and disengagement device according to an embodiment of the present invention. As shown in <FIG>, the distance from the engagement portion <NUM> to the axis of rotation gradually increases in a first direction of rotation A (the counterclockwise direction). Viewed axially, the engagement portion <NUM> can have a shape of any appropriate curve, for example, an evolvent. <FIG> show that the engagement and disengagement device is in an engaged state, where the transmission element <NUM> of the transmission member <NUM> radially maintains in gapless engagement with both the first rotating member <NUM> (the engagement portion <NUM>) and the radial outer surface of the second rotating member <NUM>.

<FIG> is a side view of the engagement and disengagement device according to an embodiment of the present invention. <FIG> is a cross-sectional view of the engagement and disengagement device according to an embodiment of the present invention. As shown in <FIG>, the engagement and disengagement device is in a disengaged state, where the transmission element <NUM> of the transmission member <NUM> does not engage with the second rotating member <NUM>.

The transmission member <NUM> can rotate between an engagement position and a non-engagement position relative to the first rotating member <NUM>.

In the engaged state shown in <FIG>, the transmission element <NUM> radially engages with both the first rotating member <NUM> (the engagement portion <NUM>) and the second rotating member <NUM>. When the first rotating member <NUM> rotates in the first direction of rotation A, the first rotating member <NUM> can transmit torque to the second rotating member <NUM> via the transmission member <NUM> (for example, the transmission element <NUM>), such that the first rotating member <NUM>, the transmission element <NUM>, and the second rotating member <NUM> can rotate together.

In the engaged state of the engagement and disengagement device, when the first rotating member <NUM> rotates in a second direction of rotation B opposite to the first direction of rotation A, the transmission element <NUM> of the transmission member <NUM> can disengage from the second rotating member <NUM> (as shown in <FIG>), such that the first rotating member <NUM> and the second rotating member <NUM> can freely rotate relative to each other.

According to some embodiments of the present invention, the transmission member <NUM> can further include an elastic component <NUM>, so as to elastically retain the transmission element <NUM> in a radial direction. In some embodiments, the elastic component <NUM> can be a torsion spring. In an exemplary embodiment, the elastic component <NUM> can be connected to the cage <NUM>. For example, an end portion of the elastic component <NUM> can be connected to the connecting piece <NUM> of the cage <NUM>. In an exemplary embodiment, the elastic component <NUM> can outwardly apply a biasing force, in the radial direction, to the transmission element <NUM>. The elastic component <NUM> can have any appropriate shape or size, as long as the elastic component <NUM> can radially support and reset the transmission element <NUM>.

As shown in <FIG>, in the engaged state, the transmission element <NUM> is subject to a force from the engagement portion <NUM>, and thus overcomes the biasing force from the elastic component <NUM>. Thus, the transmission element <NUM> moves inwardly, in a radial direction, to engage with the second rotating member <NUM>. As shown in <FIG>, in the disengaged state, the transmission element <NUM> is subject to the biasing force from the elastic component <NUM>, and is spaced apart, in the radial direction, from the second rotating member <NUM>.

According to an embodiment of the present invention, the engagement and disengagement device can further include a housing <NUM> and a cover plate <NUM>, as shown in <FIG>. The housing <NUM> defines an accommodation cavity, so as to accommodate the first rotating member <NUM> and the transmission member <NUM>. The cover plate <NUM> can be connected to the housing <NUM> so as to seal the accommodation cavity. In an exemplary embodiment, the cover plate <NUM> can be fixed to an axial end surface of the housing <NUM> by means of, for example, a screw. The housing <NUM> and the cover plate <NUM> can each have a central through-hole, such that at least part of the second rotating member <NUM> can pass therethrough.

The housing <NUM> can serve as an axial bearing for the first rotating member <NUM>, such that the first rotating member <NUM> can be rotatably supported in the housing <NUM>. In some embodiments, the first rotating member <NUM> includes an annular recess (not shown) extending axially, and the housing <NUM> includes an annular protrusion <NUM> extending axially. The annular protrusion <NUM> of the housing <NUM> can be inserted into the annular recess of the first rotating member <NUM> so as to rotatably support the first rotating member <NUM>.

According to some embodiments of the present invention, the cage <NUM> can further include a position-limiting portion <NUM> located on a radial outer surface thereof, and the first rotating member <NUM> can include a position-limiting portion <NUM> located on the radial inner surface thereof. The position-limiting portion <NUM> of the cage <NUM> and the position-limiting portion <NUM> of the first rotating member <NUM> can work with each other to restrict an angle of rotation of the cage <NUM> relative to the first rotating member <NUM>. In an exemplary embodiment, the position-limiting portion <NUM> is located on an axial side (for example, the side close to the cover plate <NUM>) of the cage <NUM>, and the position-limiting portion <NUM> is located on a corresponding axial side of the first rotating member <NUM>. As shown in <FIG>, during operation of the engagement and disengagement device, when the position-limiting portion <NUM> and the position-limiting portion <NUM> abut each other, the first rotating member <NUM> and the cage <NUM> remain stationary relative to each other.

In an exemplary embodiment, the engagement portion <NUM> and the position-limiting portion <NUM> of the first rotating member <NUM> can be sequentially axially arranged, as shown in <FIG>. In addition, the position-limiting portion <NUM> of the cage <NUM> is axially disposed on an outer side of the engagement portion. In this case, engagement between the first rotating member <NUM> and the transmission member <NUM> is not affected by the position-limiting portions.

According to an embodiment of the present invention, the engagement and disengagement device can further an elastic component <NUM>. In an exemplary embodiment, the elastic component <NUM> is used to apply a biasing force causing the transmission member <NUM> to abut the cover plate <NUM>. In some embodiments, the elastic component <NUM> can be axially disposed between the cage <NUM> of the transmission member <NUM> and the housing <NUM>. In some embodiments, the elastic component <NUM> can be a wave spring. The elastic component <NUM> applies a biasing force to the transmission member <NUM>, such that a frictional force is generated between the transmission member <NUM> and the cover plate <NUM>. At the very beginning of rotation of the first rotating member <NUM>, the elastic component <NUM> is subject to the frictional force and remains stationary, thereby facilitating rapid engagement or disengagement between the transmission member <NUM> and the second rotating member <NUM>.

When the engagement and disengagement device is in the disengaged state, as shown in <FIG>, the transmission element <NUM> is circumferentially located in a position on the engagement portion <NUM> close to the toothed portion <NUM>, and the transmission element <NUM> is, in a radial direction, outwardly subject to the biasing force from the elastic component <NUM>, such that the transmission element <NUM> radially disengages from the second rotating member <NUM>. When the disengaged state is switched to the engaged state, the first rotating member <NUM> is first driven by the driving device to rotate in the first direction of rotation A. Due to the biasing force from the elastic component <NUM>, the transmission member <NUM> is subject to the frictional force between the transmission member <NUM> and the cover plate <NUM> so as to remain stationary during an initial stage. The engagement portion <NUM> of the first rotating member <NUM> is radially in gapless engagement with the transmission element <NUM> of the transmission member <NUM>. As the first rotating member <NUM> rotates, the engagement portion <NUM> applies a force to the transmission element <NUM>, such that the transmission element <NUM> radially and gradually approaches the radial outer surface of the second rotating member <NUM>. When the transmission element <NUM> moves to be in gapless engagement with the radial outer surface of the second rotating member <NUM>, the first rotating member <NUM> can drive, via the transmission element <NUM>, the second rotating member <NUM> to rotate, such that the engagement and disengagement device is in the engaged state, as shown in <FIG>.

When the engagement and disengagement device is in the disengaged state, as shown in <FIG>, the transmission element <NUM> is circumferentially located in a position on the engagement portion <NUM> away from the toothed portion <NUM>. The transmission element <NUM> engages with the engagement portion <NUM>, and is radially inwardly subject to the force from the engagement portion <NUM>, so as to overcome the biasing force from the elastic component <NUM> and radially engage with the second rotating member <NUM>. When the engaged state is switched to the disengaged state, the first rotating member <NUM> is first driven by the driving device to rotate in the second direction of rotation B. Due to the biasing force from the elastic component <NUM>, the transmission member <NUM> is subject to the frictional force between the transmission member <NUM> and the cover plate <NUM> so as to remain stationary during an initial stage. As the first rotating member <NUM> rotates, the elastic component <NUM> outwardly applies a biasing force, in the radial direction, to the transmission element <NUM>, such that the transmission element <NUM> radially and gradually leaves the radial outer surface of the second rotating member <NUM>. When the transmission element <NUM> moves to disengage from the radial outer surface of the second rotating member <NUM>, the first rotating member <NUM> and the second rotating member <NUM> can freely rotate relative to each other, such that the engagement and disengagement device is in the disengaged state, as shown in <FIG>.

The transmission element in the above description is a rolling element. However, the present invention is not limited thereto. According to an embodiment of the present invention, the transmission element can also be in other forms, such as a wedge.

The transmission element in the above description is retained by the cage. However, the present invention is not limited thereto. According to an embodiment of the present invention, the transmission element can also be retained by the first rotating member or the second rotating member. For example, the elastic component <NUM> of the transmission member <NUM> can be connected to the first rotating member <NUM> or the second rotating member <NUM>, such that the transmission element <NUM> is retained via a radial biasing force thereof.

The above describes that when the engagement and disengagement device is in the disengaged state, the transmission element <NUM> of the transmission member <NUM> does not engage with the second rotating member <NUM>. However, the present invention is not limited thereto. According to an embodiment of the present invention, the engagement and disengagement device can also be configured such that when the engagement and disengagement device is in the disengaged state, the transmission element <NUM> does not engage with the first rotating member <NUM> (for example, the engagement portion <NUM>). For example, the elastic component <NUM> can inwardly apply a biasing force, in a radial direction, to the transmission element <NUM>. When the first rotating member <NUM> rotates in the second direction of rotation, the transmission element <NUM> radially and gradually leaves the engagement portion <NUM> of the first rotating member <NUM>, such that the engagement and disengagement device is in the disengaged state.

The engagement and disengagement device according to the embodiment of the present invention can be applied to a seat belt retractor. The seat belt retractor can include the aforementioned engagement and disengagement device, a driving device, and a reel. The driving device is used to drive the first rotating member <NUM> of the engagement and disengagement device to rotate around the axis of rotation. In an exemplary embodiment, the driving device can be a motor. For example, the motor can drive, via a gear mechanism (equivalent to a worm gear and worm, a rack and pinion, or the like), the first rotating member <NUM> to rotate. The reel is connected to the second rotating member <NUM> of the engagement and disengagement device in an anti-torsion manner, and a seat belt can be wound around the reel. The reel can wind the seat belt when rotating in the first direction of rotation, and can unwind the seat belt when rotating in the second direction of rotation opposite to the first direction of rotation. During operation, when the driving device drives the first rotating member <NUM> to rotate in the first direction of rotation, the first rotating member <NUM> drives, via the transmission member <NUM> of the engagement and disengagement device, the second rotating member <NUM> and the reel to rotate, so as wind a certain length of the seat belt around the reel; when the driving device drives the first rotating member <NUM> to rotate in the second direction of rotation, the first rotating member <NUM> and the second rotating member <NUM> disengage from each other so as to be capable of freely rotating relative to each other, such that a passenger can freely pull the seat belt.

The engagement and disengagement device according to the embodiment of the present invention can be applied to a seat belt assembly. The seat belt assembly can include the aforementioned seat belt retractor and a seat belt, and one end portion of the seat belt is fixed to the reel of the seat belt retractor.

The mention of "one embodiment" or "an embodiment" in the description indicates that the specific features, structures, or properties described with reference to embodiments are included in at least one embodiment. Therefore, the terms or variants thereof used in the whole description do not necessarily refer to the same embodiment.

Claim 1:
An engagement and disengagement device used in a seat belt retractor, comprising:
a first rotating member (<NUM>) which can be driven to rotate around an axis of rotation;
a second rotating member (<NUM>), wherein the second rotating member (<NUM>) and the first rotating member (<NUM>) are configured to be coaxial, and the second rotating member (<NUM>) is used to be connected to a reel of the seat belt retractor in an anti-torsion manner; and
a transmission member (<NUM>) disposed between the first rotating member (<NUM>) and the second rotating member (<NUM>), wherein the first rotating member (<NUM>) can transmit, in a first direction of rotation, torque to the second rotating member (<NUM>) via the transmission member (<NUM>),
wherein the first rotating member (<NUM>) defines an engagement portion (<NUM>) on a radial inner surface thereof, the distance from the engagement portion (<NUM>) to the axis of rotation gradually increases in the first direction of rotation, and the engagement portion (<NUM>) is used to engage with the transmission member (<NUM>); and
wherein the transmission member (<NUM>) can rotate between an engagement position and a non-engagement position relative to the first rotating member (<NUM>), wherein when the transmission member (<NUM>) is at the engagement position, the transmission member (<NUM>) engages with both the first rotating member (<NUM>) and the second rotating member (<NUM>), such that the first rotating member (<NUM>), the second rotating member (<NUM>), and the transmission member (<NUM>) can rotate together; when the transmission member (<NUM>) is at the non-engagement position, the transmission member (<NUM>) does not engage with the first rotating member (<NUM>) and the second rotating member (<NUM>), such that the first rotating member (<NUM>) and the second rotating member (<NUM>) can freely rotate relative to each other; characterized in that the transmission member (<NUM>) comprises a cage (<NUM>) and a transmission element (<NUM>), and the transmission element (<NUM>) is disposed in the cage (<NUM>), and can move radially in a space defined between the engagement portion (<NUM>) of the first rotating member (<NUM>) and a radial outer surface of the second rotating member (<NUM>), and in that the device further comprises a first elastic component (<NUM>) connected to the cage (<NUM>) so as to elastically retain the transmission element (<NUM>) in a radial direction.