Vehicle-sensing seat belt retractor control with suppressed Z-axis sensitivity

Abstract

A vehicle-sensing retractor control system is provided that has reduced sensitivity to Z-axis acceleration experienced during normal driving. The retractor control system incorporates a rotating mass and locking lever that are positioned such that, in a rest position, the locking lever does not engage a ratchet wheel of a seat belt retractor spool. In response to acceleration in the horizontal plane, the rotating ball mass is displaced from its rest position, allowing the locking lever to rotate due to the location of its center of gravity relative to a pivot point, allowing the locking lever to pivot and lock the retractor. In response to Z-axis acceleration, the rotating mass is prevented from contacting the locking lever by a mass restrictor.

Description

【Technical Field】 【0001】 (Cross - Reference to Related Applications) This PCT application claims the benefit of priority of U.S. Patent Application No. 17 / 474,165, filed on September 14, 2021, under 35 U.S.C. § 119, the contents of which are hereby incorporated by reference in their entirety. 【0002】 (Field of the Invention) The present invention relates to an automotive occupant restraint seat belt retractor, and more particularly to a vehicle - sensing control system for such a retractor with reduced sensitivity to Z - axis acceleration. 【Background Art】 【0003】 Automobiles are often equipped with active occupant restraint systems such as seat belt assemblies. A seat belt assembly typically has a lap and shoulder belt portion for restraining an occupant during a collision or rollover accident. To improve the comfort and convenience provided by the seat belt system, a retractor is provided that allows the belt webbing to be freely payed out or retracted when the vehicle is not subject to abnormal acceleration forces or inclines. When exposed to such forces, a retractor control system activates to lock the retractor in order to prevent further pay - out of the webbing. Thus, the retractor locks so that the seat belt webbing can restrain the occupant. Such retractor control systems take various forms. One category of such control systems is known as vehicle - sensing control systems. These systems are sensitive to the acceleration forces acting on the vehicle, for example, in the case of a frontal collision where the vehicle is subject to a high - level deceleration load. Such devices also lock the retractor in the case of a side - impact, rollover, and when certain other forces act on the vehicle. 【0004】 Another category of such retractor control systems is known as webbing-sensing control systems. These devices operate much like centrifugal clutches, sensing the rotational speed of the retractor spool, so that when extremely high angular acceleration occurs in the retractor spool in connection with the rapid extension of the webbing, the control system engages and locks the retractor. This invention relates to an improved vehicle-sensing retractor control system. 【0005】 As mentioned earlier, vehicle-sensing retractor control systems must be sensitive to acceleration loads acting in various axes and planes. Of particular importance are impacts to the vehicle that create acceleration loads acting in the horizontal plane, such as forward, rearward, or lateral impacts. However, in the event of a rollover, it is crucial that the retractors lock to restrain the occupants. A typical vehicle-sensing retractor control system utilizes the inertial mass of a pendulum or rotating ball to activate a locking lever that engages with the ratchet wheel of the retractor webbing spool. When an acceleration load acts on the vehicle, the rotating ball mass or pendulum moves, biasing the locking lever to engage with the ratchet wheel of the retractor spool, thereby locking the spool from further webbing extension. These devices have been in use for decades and have proven to be reliable and effective retractor control systems. 【0006】 Designers of vehicle-sensing control systems attempt to design the system to lock the retractor when necessary to restrain the occupants while minimizing locking during normal driving conditions (i.e., "unwanted locking"). Normal vehicle operation, driving uphill and downhill, and driving on uneven roads can generate forces that periodically lock the retractor. Such periodic locking during normal driving conditions is undesirable from the standpoint of occupant comfort. The problem of unwanted retractor locking tends to be particularly serious in heavy-duty truck-type vehicles. These vehicles, due to their operating conditions, heavy loads, and suspension systems, tend to experience significant swaying and vertical displacement, especially when driving on uneven surfaces. This motion creates acceleration in the Z-axis direction, defined as the vehicle's vertical axis. Currently available vehicle-sensing retractor control systems generally generate unwanted locking due to the Z-axis acceleration commonly encountered, particularly in heavy-duty truck applications. 【0007】 Considering the above, it is clear that the retractor control system is not sensitive to the Z-axis acceleration commonly encountered and requires an improved system, especially one suited for heavy-duty truck applications. [Overview of the Initiative] 【0008】 To satisfy the above needs and overcome the enumerated shortcomings and other limitations of related technologies, the present invention provides a vehicle-sensing retractor control system that is intentionally less sensitive to the Z-axis acceleration commonly encountered by automobiles. This control system utilizes a rotating mass, which, when moving, allows a locking lever to lock the seatbelt retractor. A mass restrictor is positioned to limit the distance the mass can move upward (i.e., vertically) along the Z-axis when subjected to Z-axis acceleration, preventing the mass from displacing from the locking lever under such conditions. Locking between the locking lever and the ratchet wheel of the retractor locking system occurs when the inertial mass is displaced, allowing the lever to rotate and engage due to its weight balance. The combination of the mass restrictor and the engagement system makes the control system relatively insensitive to Z-axis acceleration. However, when the vehicle is subjected to sufficient acceleration along other axes, the mass is freed from the locking lever, allowing the retractor to lock when needed. 【0009】 Further benefits and advantages of the present invention will become apparent to those skilled in the art, in conjunction with the accompanying drawings, the following description of preferred embodiments, and the accompanying claims. [Brief explanation of the drawing] 【0010】 [Figure 1] This is a perspective view of an inertial sensor assembly for a heavy truck sensor (HTS) with reduced Z-axis sensitivity. [Figure 2] Figure 1 shows another perspective view of the inertial sensor assembly for HTS. [Figure 3] This is an exploded view of an inertial sensor assembly. [Figure 4] This is a side view of the inertial sensor assembly in its normal stationary state. [Figure 5] Figure 1 shows the control system that receives upward Z-axis acceleration. [Figure 6]Figure 1 shows the control system that receives forward X-axis acceleration. [Modes for carrying out the invention] 【0011】 A heavy-duty truck sensor (HTS) according to a first embodiment of the present invention is shown in Figure 1 and identified by reference numeral 10. The HTS 10 is used in conjunction with a ratchet wheel 12 (as shown in Figure 4), which is part of a belt retractor having a rotating webbing spool (not shown), the rotating webbing spool rotates when the seat belt webbing is pulled out of and retracted into the retractor 14 during the normal operation of the retractor 14. A torsion spring (not shown) acts on the webbing spool, causing it to rotate and retract the webbing into the retractor. The ratchet wheel 12 includes an array of teeth 20 around it. These teeth 20 engage with a locking lever (described below) to allow a control system to lock the webbing retractor spool under certain operating conditions. This is a common locking system that has been used for decades for inertia-responsive retractor assemblies. 【0012】 The main component of the HTS10 is the inertial sensor assembly 24, which responds to the inertial forces acting on the belt retractor and the vehicle to which the belt retractor is mounted. The inertial sensor assembly 24 is provided to lock the retractor when the vehicle is subjected to an acceleration force or due to the tilt of the vehicle. As mentioned earlier, the HTS10 is intentionally designed to be relatively insensitive to acceleration acting in the Z-axis direction (i.e., perpendicular to the associated vehicle). 【0013】 The locking lever 22 of the inertial sensor assembly 24 includes an upwardly projecting engaging finger 24 and is rotatable over a limited range of angular motion around a pivot 28. When a predetermined acceleration force acts on the inertial sensor assembly 24, the locking lever 22 is lifted, allowing the engaging finger 26 to engage with the ratchet wheel teeth 20. This action causes the locking bar to engage with the outer teeth formed by the webbing spool in a well-known manner. 【0014】 Additional components of the inertial sensor assembly 24 will be described with particular reference to Figures 2 and 3. The sensor housing 30 is adapted to be fixedly mounted to the frame of the associated belt retractor and forms a nested surface 32 for the sensor ball 34. A retaining mechanism 54 allows the housing 30 to be attached to the frame of the associated retractor. The sensor ball 34 is of a conventional configuration and is preferably made of metal, in which case it has a spherical shape. As will be described in detail below, the sensor ball 34 can move from its normal central position within the nested surface 32 to positions displaced in both the X-axis (forward and backward of the vehicle) and Y-axis (lateral of the vehicle), and within a limited range in the Z-axis (upward and downward of the vehicle). The housing 30 further forms a hinge mount 36 that receives the shaft 38. The lever 22 forms a pair of arms, including a lower arm 42 and an upper arm 44, the upper arm 44 forming an engaging finger 26 at its unsupported end. Arms 42 and 44 form a caliper-like structure that can engage with the upper and lower surfaces of the sensor ball 34. The restrictor 56 is formed by the housing 30 and has an arch shape to engage with the upper portion of the sensor ball 34 in certain situations. 【0015】 The lever 22 forms a cavity 46 for receiving a counterweight 48. The lower arm 42 is shaped to wrap around the sensor ball 34 and forms a central post 50 projecting upward. The upper arm 44 forms an engagement ring 52, which has a distal end with upwardly oriented engagement fingers 26, as previously mentioned. The counterweight 48 may be provided as a separate component shown here as a dumbbell-shaped component that can be installed in the cavity 46, or the counterweight may be insert-molded into a fixed position within the cavity 46. The upper arm 42 forms a slot 58, which allows the upper arm 42 to be positioned so that a restrictor 56 fits into the slot, and allows the lever 22 to rotate over a limited angular range without interfering with the restrictor 56. 【0016】 Next, the operation of the HTS10 will be described with reference to Figures 4, 5, and 6. Figure 4 illustrates the normal operating conditions of the HTS10, where no external inertial forces exceeding a predetermined level act on the sensor and the vehicle is in a normal horizontal orientation. In this state, the sensor ball 34 is seated at the center of the nested surface 32 and rests around the circular aperture 60. In this position, the center post 50 protrudes through the aperture 60 and takes the position shown in Figure 4. The lever 22 is balanced such that its center of gravity (CG) is to the right of its axis of rotation around the axis 38 (the system is shown in Figures 4, 5, and 6). In other words, the lever 22 is biased to rotate clockwise, as illustrated by the drawings in which these components are referred, but rotation is prevented by the interaction between the sensor ball 34 and the center post 50. Figure 4 also illustrates that the restrictor 56 is positioned to form a gap with respect to the upper vertically opposing surface of the sensor ball 34. The restrictor 56 is configured to interact with the sensor ball 34 in response to the Z-axis acceleration. Thus, the sensor ball 34 is capable of moving vertically within a limited range, thereby determining the level of sensitivity to such acceleration. 【0017】 Figure 5 illustrates the state of the inertial sensor element when the unit is subjected to Z-axis acceleration (upward or downward relative to the associated vehicle). This state is illustrated as exceeding a predetermined threshold of Z-axis acceleration at which the sensor ball 34 contacts the restrictor 56. In this state, the interaction between the sensor ball and the central post 50 of the lower arm is released, and gravity acting on the lever 22 causes the lever to rotate clockwise, creating engagement between the engaging finger 26 and the ratchet wheel teeth 20, thereby locking the retractor. 【0018】 Figure 6 illustrates a state in which the inertial sensor assembly 24 is subjected to forward deceleration (X-axis), for example, a head-on collision of the associated vehicle or a braking operation that causes acceleration above a predetermined level. In this state, the sensor ball 34 shifts to the left, as shown in the figure, and therefore lifts from the central portion of the nesting surface 32. This allows the locking lever 22 to rotate clockwise and connect. 【0019】 As mentioned earlier, the HTS10 is intentionally designed to be relatively insensitive to acceleration in the vertical Z-axis. However, the end of the ball restrictor 56 that contacts the sensor ball 34 can be shaped to bias the ball mass 42 to contact the upper arm 44 of the locking lever when the vehicle is in an overturned orientation. For example, an angled, pointed, or rounded shape can be provided. Thus, when the vehicle overturns, the sensor ball 34 tends to roll out of the ball restrictor 56 and contact the locking lever 22, engaging the locking lever 22 with the ratchet wheel 12. 【0020】 Therefore, in the operation of the inertial sensor assembly 24, when an inertial force is applied to the belt retractor 14 in a manner desirable to cause engagement, the sensor ball 34 disengages from the locking lever 22, and the locking lever 22 can rotate due to its weight bias and engagement state. Thus, the position of the sensor ball 34 functions to forcibly hold the locking lever 22 in a disengaged state, or to disengage from contact with the sensor lever, allowing the sensor lever to engage, rotate, and engage due to its normal bias. 【0021】 While the above description constitutes a preferred embodiment of the present invention, it will be understood that the present invention can be modified, altered, and changed without departing from the appropriate scope and fair meaning of the appended claims.

Claims

[Claim 1] A vehicle-sensing seat belt retractor (14) control system (10) for locking the retractor (14) when an acceleration load acts on the vehicle seat belt retractor (14) in the horizontal plane, while having reduced sensitivity to acceleration load acting in the Z-axis direction perpendicular to the horizontal plane, wherein the control system (10) engages with a toothed ratchet wheel (12) rotatable together with the spool of the retractor (14), and the control system (10) Sensor ball (34) and A housing (30) forms a nesting surface (32) for the sensor ball (34), allowing the sensor ball (34) to move from a normal stationary position to a displaced position. A locking lever (22) pivotable around a pivot (28), comprising an upper arm (44) and a lower arm (42), wherein the upper arm (44) forms an engaging finger (26) that engages with the ratchet wheel (12) to prevent the rotation of the spool when the locking lever (22) is displaced from the disengaged position to the engaged position, The nested surface (32) of the housing (30) forms a lower aperture and has an upper restrictor (56) that can engage with the sensor ball (34) when the sensor ball (34) is vertically displaced. The locking lever (22) has a center of gravity positioned relative to the pivot (28) such that the locking lever (22) is biased toward the engagement position with the ratchet wheel (12), and the lower arm (42) forms a central post (50) that can engage with the lower surface (32) of the sensor ball (34) and engages with the sensor ball (34) through the lower aperture of the housing (30), As a result, the sensor ball (34) is displaceable from the normal stationary position to the displaced position in response to acceleration loads acting in the horizontal plane and the Z-axis direction, and while in the normal stationary position, the sensor ball (34) engages with the central post 50 of the lower arm (42) of the locking lever, biasing the locking lever (22) to remain in the disengaged position, and when an acceleration load of a defined direction and magnitude acts on the sensor ball (34), the sensor ball (34) moves to the displaced position and disengages from the locking lever (22), allowing the locking lever (22) to rotate to the engaged position in response to the acceleration load, and restricting the sensor ball (34) from moving to the displaced position and contacting the locking lever (22) in response to an acceleration load acting in the Z-axis direction. A control system (10) for a vehicle-sensing seat belt retractor (14), characterized in that the upper restrictor (56) includes an end that protrudes downward opposite to the upper surface of the sensor ball (34) so ​​as to guide the sensor ball (34) toward the locking lever (22) and bring it into contact with the locking lever (22) when the vehicle is in an overturned state, thereby moving the locking lever (22) to the engagement position. [Claim 2] The vehicle-sensing retractor control system (10) according to Claim 1, further characterized in that the end portion and the central post (50) cooperate to hold the sensor ball (34) and bring the sensor ball (34) into contact with the locking lever (22). [Claim 3] The vehicle-sensing retractor control system (10) according to claim 2, further characterized in that the end portion has an angled shape. [Claim 4] A vehicle-sensing retractor control system (10) according to any one of claims 1 to 3, further characterized in that the position of the center of gravity of the locking lever (22) is displaced horizontally from the pivot (28). [Claim 5] A vehicle-sensing retractor control system (10) according to any one of claims 1 to 3, further characterized in that the center of gravity of the locking lever (22) is positioned on the side of the locking lever (22) opposite to the side on which the locking lever (22) forms the engaging finger (26) with respect to the pivot (28).

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