Vibration isolator preload mechanism

Abstract

To provide a device.SOLUTION: A vibration insulation device, into which at least two disc spring washers are assembled, is included in a device. Each disc spring washer has at least one ring-shaped outer spacer which is combined with one or two outer edge parts of the disc spring washer, and at least one ring-shaped inner spacer which is combined with one or two inner edge parts of the disc spring washer. A bottom fitting portion supports the disc spring washer, and a top fitting portion compresses the disc spring washer in association with application of downward preload force. A compressing jig applies and holds preload force to the top fitting portion, and a second top fitting portion further compresses at least two disc spring washers in association with application of additional downward force.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The subject matter described in this invention relates to a vibration isolator preload mechanism that is particularly, but not exclusively, useful for reducing seat vibration in cars, trucks, and wagons. [Background technology]

[0002] Seats in vehicles (e.g., cars, trucks, or vans) often include a seat pan or seat cushion pan attached to a seat frame, which is itself attached to a pair of slide rails that are attached to the vehicle floor. To limit the transmission of vibration between the vehicle floor and the seat, a vibration isolator can be installed between the slide rails and the seat frame or between the slide rails and the floor. For example, a linear spring vibration isolator can be used for this purpose. However, vibrations can still be felt within the seat base (e.g., the seat pan and / or seat frame) and may be transmitted from the seat base to the seat back. Instead of a linear spring vibration isolator, a quasi-zero stiffness (QZS) vibration isolator can be used. However, the QZS characteristic of the isolator occurs over a limited force and deflection range. Depending on the weight (e.g., the weight of an occupant or cargo) applied to the seat, the QZS isolator may or may not compress into the QZS region of its force-deflection curve. A need exists for a vibration isolation mechanism that overcomes this issue.

[0003] The information contained in this Background section of the specification, including any references cited herein and any explanation or discussion therein, is included for technical reference purposes only and should not be considered as subject matter that should bind the scope of the disclosure. Summary of the Invention

[0004] To reduce the transmission of vibration along any given axis, stacked disk isolators or quasi-zero stiffness (QZS) isolators can be utilized. Through appropriate selection of spring design parameters, a spring stack can be designed to produce a quasi-zero / negative stiffness response for a range of forces applied to the spring stack. A quasi-zero stiffness response occurs when the spring stack compresses or decompresses very easily in response to small changes in applied force, as if it had a stiffness or spring constant close to zero. For example, when subjected to a force within this design range of forces (e.g., when compressed into its quasi-zero stiffness range), the spring stack can deflect over a relatively wide range of values ​​in response to small or no increases in applied force. Alternatively stated, when the spring stack is in its quasi-zero stiffness range, it may not "push back" against small changes in compressive force, but rather may simply absorb these changes by compressing or "deflecting." It has been discovered that under these conditions, the transmission of vibration from a first element (e.g., a vehicle floor or slide rail) to a second element (e.g., a vehicle seat frame) can be eliminated or substantially attenuated.

[0005] In some instances, it may be desirable to apply an axial preload force on the QZS vibration isolator spring stack sufficient to cause the stack to reach a near-zero / negative stiffness response range when a measured or expected weight is applied to the seat so that maximum benefit of the isolator can be realized. Disclosed is a vibration isolator preload mechanism that addresses the above-mentioned and other concerns.

[0006] The vibration isolator preload mechanism disclosed in this invention is particularly, though not exclusively, useful for reducing seat vibration in passenger cars, trucks, and vans. One general aspect includes an apparatus with a first vibration isolator including: at least two disc spring washers, each including an inner edge, an outer edge, and a central opening; at least one ring-shaped outer spacer, each coupled to the outer edge of one or two of the at least two disc spring washers; at least one ring-shaped inner spacer, each coupled to the inner edge of one or two of the at least two disc spring washers; a bottom mounting portion configured to support the at least two disc spring washers; and a first top mounting portion configured to compress the at least two disc spring washers upon application of a first downward force. The apparatus also includes a compression fixture configured to apply and hold a first downward force against the first top mounting portion and a second top mounting portion configured to further compress the at least two disc spring washers upon application of a second downward force additional to the first downward force. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the method.

[0007] Implementations may include one or more of the following features. In some embodiments, the first top mounting portion comprises a plate or platform. In some embodiments, the second top mounting portion comprises a plate or platform. In some embodiments, the second top mounting portion comprises a plunger. In some embodiments, the first top mounting portion comprises a plate or platform. In some embodiments, the first downward force is a preload force selected to place the at least two disc spring washers within a quasi-zero stiffness (QZS) range. In some embodiments, the first downward force is a preload force selected to place the at least two disc spring washers within a quasi-zero stiffness (QZS) range when the second downward force is applied. In some embodiments, the compression fixture includes a bottom housing; and a top housing configured to move vertically relative to the bottom housing. In some embodiments, the compression fixture further includes a pin or bolt configured to fix the position of the top housing relative to the bottom housing after application of the first downward force. In some embodiments, the compression fixture further includes a motor configured to apply the first downward force. In some embodiments, the compression fixture further includes a sensor configured to measure the second downward force; and a controller configured to adjust the first downward force based on the second downward force. In some embodiments, by adjusting the first downward force, the at least two disc spring washers are placed within a quasi-zero stiffness (QZS) range. In some embodiments, by adjusting the first downward force based on the second downward force, at least one of the first vibration isolator or the second vibration isolator is placed within a quasi-zero stiffness (QZS) range. In some embodiments, the apparatus further includes a second vibration isolator positioned above the first top mounting portion, such that the first downward force compresses the first vibration isolator and decompresses the second vibration isolator, and such that the second downward force compresses both the first vibration isolator and the second vibration isolator.Implementations of the described techniques include hardware, a method or process, or computer software on a computer-accessible medium.

[0008] One general aspect includes a vehicle with a floor; and a seat including: a seat back; a cushion; a frame; slide rails configured to allow the seat to move in a direction parallel to the floor; at least two disc spring washers, each including an inner edge, an outer edge, and a central opening; at least one ring-shaped outer spacer, each coupled to the outer edge of one or two of the at least two disc spring washers; at least one ring-shaped inner spacer, each coupled to the inner edge of one or two of the at least two disc spring washers; a bottom mounting portion configured to support the at least two disc spring washers; and a first top mounting portion configured to compress the at least two disc spring washers upon application of a first downward force. The vehicle also includes a compression fixture configured to apply and hold a first downward force against the first top mounting portion; and a second top mounting portion configured to further compress the at least two disc spring washers upon application of a second downward force additional to the first downward force. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the method.

[0009] Implementations may include one or more of the following features. In some embodiments, the compression fixture includes a bottom housing; a top housing configured to move vertically relative to the bottom housing; and a pin or bolt configured to fix the position of the top housing relative to the bottom housing after application of a first downward force. In some embodiments, the vehicle further includes a second vibration isolator positioned above the first top mounting portion, such that the first downward force compresses the first vibration isolator and decompresses the second vibration isolator, and such that the second downward force compresses both the first and second vibration isolators. In some embodiments, by adjusting the first downward force based on the second downward force, at least one of the first vibration isolator or the second vibration isolator is placed within a quasi-zero stiffness (QZS) range. In some embodiments, the compression fixture further includes a motor configured to apply the first downward force; a sensor configured to measure the second downward force; and a controller configured to adjust the first downward force based on the second downward force. Implementations of the described techniques include hardware, methods or processes, or computer software on a computer-accessible medium.

[0010] This Summary is provided to introduce selected concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter. A more extensive presentation of the features, details, benefits, and advantages of the vibration isolator preload mechanism defined in the claims is provided in the following description of various embodiments of the present disclosure and illustrated in the accompanying drawings.

[0011] Exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. [Brief explanation of the drawings]

[0012] [Figure 1]FIG. 1 is an exemplary representation of a conventional linear spring isolator according to an embodiment of the present disclosure. [Figure 2A] FIG. 2A is a perspective view of a ring-shaped or conical disk, disc spring, or disk spring washer according to an embodiment of the present disclosure. [Figure 2B] FIG. 2B is a cross-sectional side view of an exemplary quasi-zero stiffness (QZS) vibration isolator according to an embodiment of the present disclosure. [Figure 2C] FIG. 2C is a perspective view of an exemplary quasi-zero stiffness (QZS) vibration isolator according to an embodiment of the present disclosure. [Figure 3] FIG. 3 shows performance graphs of an exemplary linear spring isolator and an exemplary QZS isolator, according to an embodiment of the disclosure. [Figure 4] FIG. 4 is a performance graph illustrating force versus displacement for five different exemplary QZS isolators, according to an embodiment of the disclosure. [Figure 5A] FIG. 5A is a perspective view of an exemplary one-dimensional (1D) QZS vibration isolator according to an embodiment of the present disclosure. [Figure 5B] FIG. 5B is a performance graph illustrating the 1D vibration damping performance of two different types of isolators, according to an embodiment of the present disclosure. [Figure 6A] FIG. 6A is a perspective view of an exemplary two-dimensional (2D) QZS (VIS) measurement device according to an embodiment of the present disclosure. [Figure 6B] FIG. 6B is a performance graph illustrating vibration suppression performance of the QZS isolator according to an embodiment of the present disclosure. [Figure 7] FIG. 7 is a perspective view of a vehicle seat with its wiring, cushioning, and upholstery removed, according to an embodiment of the present disclosure. [Figure 8A] FIG. 8A is a perspective view of a vehicle seat according to an embodiment of the present disclosure. [Figure 8B] FIG. 8B is a performance graph illustrating vibration suppression performance of the QZS isolator according to an embodiment of the present disclosure. [Figure 9] FIG. 9 is a perspective view of a vehicle seat incorporating a QZS vibration isolator according to an embodiment of the present disclosure. [Figure 10]FIG. 10 is a perspective view of a vehicle seat incorporating a QZS vibration isolator according to an embodiment of the present disclosure. [Figure 11] FIG. 11 is a cross-sectional side view of a vibration isolator preload mechanism in accordance with at least one embodiment of the present disclosure. [Figure 12] 12 is a cross-sectional side view of the vibration isolator preload mechanism of FIG. 11 in a preloaded state in accordance with at least one embodiment of the present disclosure. [Figure 13] 13 is a cross-sectional side view of the vibration isolator preload mechanism of FIG. 11 in both a loaded and preloaded state in accordance with at least one embodiment of the present disclosure. [Figure 14] FIG. 14 is a cross-sectional side view of a vibration isolator preload mechanism in accordance with at least one embodiment of the present disclosure. [Figure 15] FIG. 15 is a side cross-sectional view of a vibration isolator preload mechanism in accordance with at least one embodiment of the present disclosure. [Figure 16] FIG. 16 illustrates a performance graph of an exemplary QZS isolator at two different preload force levels, in accordance with at least one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] To reduce the transmission of vibration along any given axis, stacked disk isolators or quasi-zero stiffness (QZS) isolators can be utilized, which consist of a stack of flexible Belleville springs or disk spring washers arranged in an alternating conical stack separated by ring-shaped spacers positioned on the inner or outer edges of the washers. By appropriately selecting spring design parameters, such spring stacks can be designed to produce a quasi-zero / negative stiffness response for a range of forces applied to the spring stack (i.e., when subjected to forces within this design force range, the spring stack can deflect over a relatively wide range of values ​​in response to small or zero increases in the applied force). It has been discovered that under these conditions, the transmission of vibration from a first element (e.g., a vehicle floor) to a second element (e.g., a vehicle seat) can be eliminated or substantially attenuated.

[0014] In some instances, it may be desirable to apply an axial preload force to the spring stack of the QZS vibration isolator sufficient to cause the stack to reach a quasi-zero / negative stiffness response range when a measured or expected weight is applied to the QZS isolator (e.g., from an occupant seated in a vehicle seat or from cargo placed on the seat) so that maximum benefit of the isolator can be realized. Disclosed is a vibration isolator preload mechanism that maintains a preload force on the QZS vibration isolator. In some instances, this can be a fixed preload force or a force that is adjustable by manual or mechanical intervention, such as moving a bolt or pin. In other embodiments, the preload force can be automatically adjusted in response to weight applied to the QZS vibration isolator (e.g., by an occupant sitting in a vehicle seat).

[0015] It is possible to estimate the range of forces that will be applied to the spring stack (e.g., the range of weights of people who may be seated in the vehicle seat supported by the spring stack). A fixture is provided to pre-compress the spring stack based on the estimated range of applied forces. The fixture can be adjusted to compress to apply a preload force to the stack to bring the initial applied force to a level that approaches the range required for a quasi-zero / negative stiffness response. The stack can be pre-compressed in such a way that an additional applied force (e.g., due to the weight of a vehicle seat occupant) at the low end of the estimated force range will bring the total applied force to at least the minimum force value required to produce a quasi-zero / negative stiffness response.

[0016] In an automated version of the vibration isolator preload mechanism, a user can be seated in a vehicle seat supported by a spring stack. The user's weight can be determined by a weight sensor. The operation of the vibration isolator preload mechanism can be controlled by a motor and gear system of other motion control mechanisms. A controller can control the operation of the fixture to compress the spring stack in response to the detected user weight, bringing the total force applied to the spring stack within the range required for a near-zero / negative stiffness response.

[0017] The proposed arrangement allows a single spring stack design to be adapted to provide a near-zero / negative stiffness response for a wide range of applied forces, helping to improve vehicle seat comfort, for example, by reducing vibrations transmitted upward through the seat from the vehicle floor. This design offers an improvement over existing vehicle seats because it allows for a near-zero stiffness response from the vibration isolator over a wide range of applied weights. As a result, less vibration is transmitted between the vehicle floor and the vehicle seat, thus providing a smoother ride for the occupant.

[0018] For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation on the scope of the present disclosure is intended. All alterations and further modifications to the described devices, systems, and methods, and any further applications of the principles of the present disclosure, as would normally occur to one skilled in the art to which the present disclosure pertains, are fully contemplated and are included within the present disclosure. In particular, it is fully contemplated that features, components, and / or steps described in connection with one embodiment can be combined with features, components, and / or steps described in connection with other embodiments of the present disclosure. However, for the sake of brevity, many iterations of these combinations will not be separately described.

[0019] These descriptions are provided for illustrative purposes only and should not be considered as limiting the scope of the vibration isolator preload mechanism. Certain features may be added, deleted, or modified without departing from the spirit of the claimed subject matter.

[0020] FIG. 1 is an exemplary representation of a conventional linear spring isolator 100 according to an embodiment of the present disclosure. The linear spring isolator 100 includes a top mounting portion 110 and a bottom mounting portion 120 separated by a spring 130. The spring 130 may be, for example, a metal spring that deflects (e.g., compresses or expands) in a manner that is approximately linearly related to the amount of normal force applied to the isolator 100. In one example, the linear spring isolator 100 may be installed between a vehicle seat and a vehicle floor in an attempt to limit the transmission of vibrations from the floor to the seat. In such a use case, the top mounting portion 110 may be bolted to, for example, a seat frame, while the bottom mounting portion 120 may be bolted to, for example, the vehicle floor or the top of a slide rail to which the seat is mounted. Such an undamped linear spring isolator 100 provides only limited vibration isolation and limited lateral stability and lateral load capacity.

[0021] 2A is a perspective view of a ring-shaped or conical disk 230, also known as a Belleville spring or disk spring washer, according to an embodiment of the present disclosure. Disk 230 may be made of, for example, rubber or another resilient material that has the ability to bend and then return to its original shape. The disk's conical shape is formed because inner and outer edges 204 and 206 of disk 230 are vertically separated by a height H. Inner edge 204 forms a central opening 202 with a diameter D1, while outer edge 206 of disk 230 has a diameter D2. The material forming spring disk or washer 230 has a thickness T.

[0022] 2B is a side cross-sectional view of an exemplary quasi-zero stiffness (QZS) vibration isolator 200 according to an embodiment of the present disclosure. The QZS isolator 200 includes a plurality of ring-shaped or conical rubber discs 230, also known as Belleville springs, disc spring washers, or spring disc washers. The discs 230 are separated by inner spacers 210 coupled to the inner edge of each spring disc washer 230 or each pair of spring disc washers 230. The spring disc washers 230 are also separated by outer spacers 220 coupled to the outer edge of each spring disc washer 230. The discs or Belleville springs 230 are stacked such that when two discs 230 are vertically adjacent to one another, either their two outer edges 206 (see FIG. 1A) are coupled to the same outer spacer 220 or their inner edges 204 (see FIG. 1A) are coupled to the same inner spacer 210. Thus, the stack of disks or washers 230 forms a bellows shape that has the ability to compress vertically and then return to its original shape.

[0023] QZS vibration isolator 200 can include either an even or odd number of spring disc washers 230. Spring disc washers 230 may be coupled to spacers 210 and 220 using a friction fit or an adhesive bond, either or both of which may involve grooves, slots, or indentations, or any combination thereof, in either spacers 210, 220 or spring disc washers 230.

[0024] 2C is a perspective view of an exemplary QZS vibration isolator 200, according to an embodiment of the present disclosure. Visible are inner spacer 210, outer spacer 220, and disc spring washer 230.

[0025] FIG. 3 illustrates a performance graph 300 for an exemplary linear spring isolator 330 and an exemplary QZS isolator 340, according to an embodiment of the present disclosure. The linear spring isolator curve 330 shows a linear or approximately linear relationship between the applied force F and the resulting spring deflection x. The slope of this line is the spring constant k of the spring, such that F = kx. The QZS isolator curve 340 shows a more complex relationship between the applied normal force F and the resulting normal deflection or compression x. This force-deflection relationship includes a first approximately linear region 350 and a second approximately linear region 360 separated by a quasi-zero stiffness (QZS) region 370. Thus, the force-deflection relationship can be approximated as three straight line segments 355, 365, and 375.

[0026] Within the first approximately linear region 350, the slope of curve 340 may be approximated as F = k1x, producing a first line segment 355. For the QZS region, the slope may be approximated as zero, producing a second line segment 375. For the second approximately linear region 360, the slope of curve 340 may be approximated as F = K2x, producing a third line segment 365.

[0027] In the quasi-zero stiffness region 365 of the QZS isolator curve 340, it can be said that a small increase in the downward force F on the QZS isolator results in a disproportionately large increase in deflection x, or alternatively, that a large change in deflection x does not result in a significant change in the upward force F delivered by the isolator. As will be shown below, this force-deflection relationship 340 makes the QZS isolator more effective than a linear spring at damping or isolating vibrations.

[0028] 4 is a performance graph 400 illustrating force 310 versus displacement 320 for five different exemplary QZS isolators, namely, 410A (two disc spring washers), 410B (three disc spring washers), 410C (four disc spring washers), 410D (five disc spring washers), and 410E (six disc spring washers), according to an embodiment of the present disclosure. As shown in FIG. 3, the force-displacement curve for each QZS isolator includes a first approximately linear region 350, a quasi-zero stiffness (QZS) region 370, and a second approximately linear region 360. As can be seen from graph 400, the width or displacement of QZS area 370 (e.g., the number of millimeters of displacement allowed within the QZS area) increases with the number of disc spring washers, so that QZS isolator 410A with two disc spring washers has a QZS area that is approximately 1 mm wide, while QZS isolator 410E with six disc spring washers has a QZS area that is approximately 4 mm wide. Therefore, QZS isolators with more disc spring washers are better able to absorb movement at the bottom of the isolator (e.g., movement of the vehicle floor) without transmitting it to the top of the isolator (e.g., to the bottom of the vehicle seat). However, QZS isolators with more disc spring washers must be correspondingly taller, which may limit where they can be mounted and the applications in which they can be used. Taller QZS isolators also tend to be more costly due to the need for more material, and may have lower lateral stability and lower lateral load capacity than shorter QZS isolators.

[0029] 5A is a perspective view of an exemplary one-dimensional (1D) QZS vibration isolator measurement setup according to an embodiment of the present disclosure. Visible is a proof mass 510 mounted to a vibration table 520 by a vibration isolator 550. For lateral and rotational stability during 1D vibration testing, the proof mass 510 includes three tubular channels 540 through which three shafts 530 pass.

[0030] FIG. 5B is a performance graph 500 illustrating the 1D vibration suppression performance of two different types of isolators in the test fixture of FIG. 5A according to an embodiment of the present disclosure. Graph 500 shows a curve of transmissibility 560 (e.g., measured in decibels, or dB) versus frequency 570 (measured in Hertz, or Hz) for linear spring isolator 580 and QZS isolator 590. This represents, for example, the degree to which vertical vibration of shaker table 520 (see FIG. 5A) is converted into vertical vibration of proof mass 510 (see FIG. 5A). A transmissibility of zero dB may represent complete transmission of vibration through isolator 550 (see FIG. 5A), such that vibration of the shaker table causes equal vibration of the proof mass at that particular frequency. A transmissibility greater than 0 dB may represent amplification by the isolator, such that vibration of the shaker table results in greater or more powerful vibration of the proof mass at that particular frequency. A transmissibility of less than 0 dB may represent vibration attenuation by the isolator such that vibration of the shaker table results in smaller or less powerful vibration of the proof mass at that particular frequency. Generally, values ​​less than 0 dB are desirable at all frequencies, and especially at higher frequencies.

[0031] As can be seen, linear spring isolator curve 580 exhibits a sharp peak 585 at approximately 12 Hz, which is believed to represent the resonant frequency of the spring, possibly causing a transmissibility of more than +30 dB (e.g., vibrations 100 times greater than those observed at 5 Hz and 15 Hz). The linear spring isolator curve does not drop below 0 dB until the vibration frequency exceeds 20 Hz. In contrast, QZS isolator curve 590 does not exhibit any sharp peaks, but rather drops below 0 dB at a vibration frequency of approximately 10 Hz and remains below zero throughout the remainder of the curve. QZS isolator curve 590 is similarly lower at all points than linear spring isolator curve 580, indicating that the QZS isolator is better at suppressing vertical vibrations (or, alternatively, is worse at transmitting such vibrations) than the linear spring isolator.

[0032] 6A is a perspective view of an exemplary two-dimensional (2D) QZS vibration isolator measurement setup according to an embodiment of the present disclosure. Viewed is a vertical proof mass 620 fixedly mounted to a horizontal proof mass 610, which is itself mounted to a vibration table 520 by a pair of QZS vibration isolators 200. The effectiveness of the QZS isolators 200 can be assessed, for example, by measuring vibrations at the top of the vertical proof mass 620 and comparing it to vibrations measured at the surface of the vibration table 520. Vibration of the vibration table 520 results in rocking of the proof masses 610 and 620, which in turn results in torques and lateral forces on the QZS isolators.

[0033] FIG. 6B is a performance graph 600 illustrating the vibration suppression performance of the QZS isolators in the test setup of FIG. 6A , according to an embodiment of the present disclosure. Graph 600 shows a curve of transmissibility 560 (e.g., measured in decibels, or dB) versus frequency 570 (measured in Hertz, or Hz) for a non-insulated mass 680 and a QZS isolated mass 690. This represents the extent to which, for example, vertical vibrations of shaking table 520 (see FIG. 6A ) are translated into vertical and horizontal vibrations of the top of vertical proof mass 620 (see FIG. 6A ) through, for example, lateral oscillations of the lower proof mass due to uneven compression of QZS isolators 200. A transmissibility of zero dB may represent perfect transmission of vibrations through QZS isolators 200 (see FIG. 6A ), such that vibrations of the shaking table cause equal vibrations of the top of the vertical mass at that particular frequency. A transmissibility greater than 0 dB may represent amplification by the isolators and / or proof masses, such that vibration of the shaker table results in a greater or more powerful vibration of the top of the vertical proof mass at that particular frequency. A transmissibility less than 0 dB may represent vibration attenuation by the isolators, such that vibration of the shaker table results in a less or less powerful vibration of the top of the vertical proof mass at that particular frequency. Generally, values ​​less than 0 dB are desirable at all frequencies, and especially at higher frequencies.

[0034] As can be seen, if the test mass were mounted directly to the shaker table without any vibration isolation, the test mass would amplify the vibrations of the shaker table by 10 to 15 dB across all frequencies of interest, as represented by curve 680. QZS isolation curve 690 shows a larger amplification of 15 to 20 dB between 5 Hz and 10 Hz. However, at all frequencies of interest above 10 Hz, the amplification is less than that of curve 680, and is less than zero (indicating a net damping of vibration) at all frequencies of interest above 20 Hz. This demonstrates that the QZS isolators are effective in reducing the vibrations of the 2D shaker.

[0035] It is pointed out that 2D vibrations can induce lateral forces on the sheet.

[0036] 7 is a perspective view of a vehicle seat 700 with its wiring, cushioning, and upholstery removed, according to an embodiment of the present disclosure. The vehicle seat 700 includes a seat pan or seat cushion pan 710, a seat back or seat back frame 720, and a recliner 730 for adjusting the angle between the seat pan 710 and the seat back 720. The seat 700 also includes a seat frame 750 that is attached to the vehicle floor 740 using two slide rails 760 that allow the seat 700 to slide rearward and forward relative to the floor 740.

[0037] 8A is a perspective view of a vehicle seat 700 according to an embodiment of the present disclosure. The vehicle seat 700 includes a seat back 720 coupled to a seat pan 710, which is coupled to a seat frame 750. The seat frame 750 is coupled to a plurality of QZS vibration isolators 200, which are themselves coupled to slide rails 760 coupled to the vehicle floor. The coupling may be, for example, through welding, bolts, screws, rivets, solder, adhesive, or other means known in the art. The QZS isolators 200 are configured to reduce the transmission of vibrations between the vehicle floor 740 and the seat 700.

[0038] FIG. 8B is a performance graph 800 illustrating the vibration suppression performance of QZS isolator 200 of FIG. 8A according to an embodiment of the present disclosure. Graph 800 shows a curve of transmissibility 560 (e.g., measured in decibels, or dB) versus frequency 570 (measured in Hertz, or Hz) for non-insulated mass 810 and QZS isolating mass 820. This represents the extent to which, for example, vibrations of floor 740 (see FIG. 8A) are translated into vibrations of the top of seat back 720 (see FIG. 8A) through lateral rocking of the lower proof mass due to, for example, uneven compression of QZS isolator 200 (see FIG. 8A). A transmissibility of zero dB may represent perfect transmission of vibrations through QZS isolator 200 (see FIG. 6A), such that floor vibrations cause equal vibrations of the top of the seat back at that particular frequency. A transmissibility greater than 0 dB may represent amplification by the seat structure and / or isolators, such that floor vibrations result in larger or more powerful vibrations at the top of the seat at that particular frequency. A transmissibility less than 0 dB may represent vibration attenuation by the isolators, such that floor vibrations result in smaller or less powerful vibrations at the top of the seat back at that particular frequency. Generally, values ​​less than 0 dB are desirable at all frequencies, and especially at higher frequencies.

[0039] As can be seen, both QZS isolation curve 820 and unisolated curve 810 exhibit amplitude spikes at low frequencies. Spike 815 on unisolated curve 810 occurs at 10 Hz and has a maximum value of approximately 30 dB. Spike 825 on QZS isolation curve 820 is actually larger than spike 815 on curve 810, with a peak value of approximately 37 dB, indicating even greater amplification of floor vibrations. However, this spike occurs at a lower frequency (i.e., 7 Hz for spike 825 compared to 10 Hz for spike 815), and therefore may result in less overall discomfort for the seated user. Notably, QZS isolation curve 820 exhibits 10 dB lower amplitude (e.g., 10 times less vibration transmission) than unisolated curve 810 across most frequencies of interest, from 9 Hz to 47 Hz. QZS isolation curve 820 is approximately equal to unisolated curve 810 at 17 Hz and 47-50 Hz. The total area under curve 820 is significantly less than the total area under curve 810, indicating a lower overall vibration transmissibility between the vehicle floor and the top of the seat back. Thus, one skilled in the art will recognize that the QZS isolator can be effective in reducing vibrations in a vehicle seat, generally resulting in a more comfortable ride for the seat occupant.

[0040] It is noted that vibrations of the vehicle floor and / or the vehicle seat can induce lateral forces on the seat.

[0041] FIG. 9 is a perspective view of a vehicle seat incorporating a QZS vibration isolator according to an embodiment of the present disclosure. Visible are a seat pan 710, a seat back 720, and a seat frame 750. In the non-limiting example shown in FIG. 9, a QZS vibration isolator or spring stack 200 is positioned between the seat frame 750 and a slide rail 760. As a result of a normal load (e.g., a seated mass 920, such as an occupant in the vehicle seat 700 or cargo thereon), the seat experiences a downward normal force 910, which is then transmitted to the QZS isolator or spring stack 200. Ideally, this normal force 910 would position the QZS isolators 200 near the center of the quasi-zero stiffness (QZS) range of their force-deflection curves, thereby minimizing overall vibration transmission between the seat rails 760 and the seat frame 750. However, in many cases, normal force 910 will be insufficient to reach the QZS range (e.g., because seating mass 920 is too light), and in other cases, the normal force will be excessive (e.g., because seating mass 920 is too heavy), compressing the QZS isolator beyond its QZS region. It is therefore desirable to provide a mechanism for preloading or not preloading QZS isolator 200 such that expected load 910 or actual measured load 910 places QZS isolator 200 near the center of the QZS region of its force-deflection curve.

[0042] Although a total of four spring stacks or QZS vibration isolators 200 are shown in FIG. 9, one skilled in the art will recognize that the seat 700 can be isolated from vibrations with other numbers of spring stacks or QZS isolators 200 and other arrangements, including one, two, three, five, six or more spring stacks or QZS isolators 200.

[0043] 10 is a perspective view of a vehicle seat 700 incorporating a QZS vibration isolator according to an embodiment of the present disclosure. Visible are a seat pan 710, a seat back 720, and a seat frame 750. As a result of the vibration, the seat 700 also experiences lateral forces 1030 and longitudinal forces 1025, which cause the seat 700 to rock, resulting in torque forces 920.

[0044] 10, the QZS vibration isolators or spring stacks 200 are positioned between the seat frame 750 and the seat pan 710. As a result of normal loading, the seat experiences a normal force 910 in a downward direction, which is then transmitted to the QZS isolators or spring stacks 200. Ideally, this normal force 910 will move the QZS isolators 200 to the quasi-zero point on their force-deflection curves. Tsuyoshi 9. This will place QZS isolators 200 near the center of their QZS region, which may result in the lowest overall vibration transmission between seat rail 760 and seat frame 750. However, in many cases, normal force 910 will be insufficient to reach the QZS region (e.g., because seating mass 920 is too light), and in other cases, the normal force will be excessive (e.g., because seating mass 920 is too heavy), compressing QZS isolators 200 beyond their QZS region. Therefore, it is desirable to provide a mechanism for preloading or not preloading QZS isolators 200 such that expected load 910 or actual measured load 910 places QZS isolators 200 near the center of the QZS region of their force-deflection curves.

[0045] 11 is a side cross-sectional view of a vibration isolator pre-load mechanism 1100 in accordance with at least one embodiment of the present disclosure. Vibration isolator pre-load mechanism 1100 includes a spring stack or QZS vibration isolator 200, as shown, for example, in FIGS. 2B and 2C . The QZS vibration isolator rests on a base plate or base spacer 930, which may serve as a mounting point, and is partially enclosed by a top housing 1110 and a bottom housing 1120. Top housing 1110 includes a top compression surface 1115 in contact with spring stack or QZS vibration isolator 200, which is capable of compressing the spring stack or QZS vibration isolator 200 when moved downward and decompressing it when moved upward. Bottom housing 1120 includes a bottom compression surface 1125 in contact with spring stack or QZS vibration isolator 200, capable of compressing spring stack or QZS vibration isolator 200 when moved upward and decompressing it when moved downward. In the non-limiting example of FIG. 11 , the relative positions of 1110 and 1120 are secured by a bolt or pin 1130 that passes through both locating track 1140 in bottom housing 1120 and locating track 1150 in top housing 1110. Locating tracks 1140 and 1150 may, for example, each be comprised of multiple threaded holes at different vertical positions, or each may be comprised of a vertical slot, or any combination thereof. Bolt or pin 1130 may, in some cases, be secured in place by threads in locating tracks 1140 and 1150, or by a nut (wing nut or lock nut), or by other means known in the art. When the bolt or pin 1130 is in place, the relative positions of the top housing 1110 and bottom housing 1120 are fixed as well.

[0046] 12 is a cross-sectional side view of the vibration isolator preload mechanism 1100 of FIG. 11 in a preloaded state, in accordance with at least one embodiment of the present disclosure. When a downward preload force 1210 is applied to the top compression surface 1115 while the bottom compression surface 1120 is braced or fixedly attached to a surface such as a base plate or base spacer 930, the spring stack or QZS vibration isolator is compressed and the relative positions of the top housing 1110 and bottom housing 1120 change accordingly. Once bolts or pins 1130 are then engaged through locating tracks 1140 and 1150 and secured in place (e.g., using holes or threads in engagement tracks 1140 and 1150, nuts, or other means), top housing 1110 and bottom housing 1120 remain fixed in place, and a compressive force equal to preload force 1210 is exerted on spring stack or QZS isolator 200 by top compression surface 1115 and bottom compression surface 1125, even when external preload force 1210 itself is removed. In some embodiments, this preload force can be selected to place spring stack or QZS isolator 200 within the QZS range of its force-deflection curve when a known or expected weight (e.g., from an occupant or cargo occupying a vehicle seat) presses down on vibration isolator preload mechanism 1100.

[0047] FIG. 13 is a cross-sectional side view of the vibration isolator preload mechanism 1100 of FIG. 11 in both a loaded and preloaded state, according to at least one embodiment of the present disclosure. In this example, the vibration isolator preload mechanism 1100 also includes a base plate or base spacer 930 coupled to the seat rail 760. The base plate or base spacer 930 occupies any excess space between the vehicle floor and the vibration isolator preload mechanism. The pins or bolts 1130 are fixed in place such that the relative positions of the top housing 1110 and the bottom housing 1120 maintain the preload force 1210 on the spring stack or QZS isolator 200, for example, as shown in FIG. 12 . Alternatively, one can say that the spring stack 200 applies an upward force 1210.

[0048] However, in this embodiment, vibration isolator preload mechanism 1100 may also include a top plate or load support platform 1340 (which may serve as an attachment point), and a plunger 940 that is coupled to top plate or load support platform 1340 and penetrates top housing 1110 (e.g., through an opening) to engage a top surface or attachment point 1345 of spring stack or QZS vibration isolator 200. In this arrangement, if a weight, load, or vibration force 1310 greater than preload force 1210 is applied to top plate or load support platform 1340, the plunger will apply this force 1310 to spring stack or QZS vibration isolator 200, further compressing it. If the preload force on spring stack 200 is selected to place spring stack 200 within its QZS range, a force 1310 that exceeds preload force 1210 even by a small amount can result in significant compression of spring stack 200. Alternatively, one could say that spring stack 200 generates a very small additional upward force when compressed beyond its preload compression. This arrangement is beneficial because it may tend to keep the QZS vibration isolators within a range where they are highly effective in limiting the transmission of vibrations (e.g., from seat rails 760 to the top plate or load support platform 1340).

[0049] 14 is a cross-sectional side view of a vibration isolator preload mechanism 1400 in accordance with at least one embodiment of the present disclosure. In this embodiment, the spring stack 200 is at least partially enclosed by a compression fixture 1410, which may include, for example, a top housing 1110 and a bottom housing 1120 coupled by a compression motor 1440 capable of exerting a variable preload force 1210 on the spring stack 200. The vibration isolator preload mechanism 1400 also includes a gravity sensor 1420 capable of sensing gravity or other downward force 1310 exerted on the spring stack 200 by the plunger 940. The vibration isolator preload mechanism 1400 also includes a controller 1430 configured to receive signals from the weight sensor 1420 and send signals to the compression fixture 1410 such that the preload force 1210 can be adjusted based on the applied load 1310 so that the spring stack 200 remains within the QZS region of its force-deflection curve.

[0050] In some cases, this adjustment of the preload force 1210 may occur only when the load force 1310 experiences a significant change (e.g., when a person sits in the vehicle seat). In other cases, the adjustment of the preload force 1210 may occur on a set schedule (e.g., every minute or every five minutes) based on instantaneous values ​​measured at those times or based on smoothed values ​​averaged over a period of time. In still other cases, the adjustment of the preload force may occur continuously. The controller may be, for example, a digital or analog processor configured with a look-up table or other algorithm for relating an input force (e.g., load force 1310) to an output force (e.g., preload force 1210) to achieve the desired result of keeping the spring stack 200 within its QZS range.

[0051] 11-13 also include a compression fixture, whose components may be said to include pin or bolt 1130, top housing 1110, bottom housing 1120, and positioning tracks 1140 and 1150. However, in such embodiments, the compression fixture of FIGS. 11-13 may be unpowered (e.g., compressed only by the weight placed on it) or may be powered by human-provided energy (e.g., with a screw or crank) rather than by motor 1440.

[0052] FIG. 15 is a side cross-sectional view of a vibration isolator preload mechanism 1500 according to at least one embodiment of the present disclosure. In this embodiment, the spring stack 200 of FIG. 14 is replaced with a lower spring stack 1510 and an upper spring stack 1520 separated by a movable control plate 1530. The lower spring stack 1510 and the upper spring stack 1520 are partially surrounded by a top housing 1110 and a bottom housing 1120. In some embodiments, the bottom housing rests on or is coupled to a base plate or base spacer 930, a seat rail 760, a vehicle floor 740, or other surface. The top housing 1110, the bottom housing 1120, and the control plate 1530 may be part of or moveable from a compression fixture 1410 shown in FIG. 14, for example, to apply a preload force to the lower spring stack 1510 and the upper spring stack 1520.

[0053] In the example shown in FIG. 15 , the upper spring stack 1520 exerts an extension force F_up on the movable control plate 1530 (and thus on the lower spring stack 1510 as well). The lower spring stack 1510 exerts an extension force F_lo on the control plate 1530 (and thus on the upper spring stack 1520 as well). Thus, the weight W pushing down on the vibration isolator preload mechanism 1500 is equal to F_lo - F_up, or alternatively, the extension force F_lo of the lower spring stack 1510 is equal to W + F_up. In the example shown in FIG. 15 , the lower spring stack 1510 is larger than the upper spring stack 1520 and therefore has the ability to support a larger force and generate a larger reaction force in response. However, this is not true in all embodiments. The smaller upper spring stack 1520 provides the ability to unload the lower spring stack 1510 outside of its QZS range while still retaining some QZS vibration suppression within the upper spring stack 1520 .

[0054] In one embodiment, either the control plate 1530 or the upper housing 1110 may be floating, while the position of at least one of the control plate 1530 or the upper housing 1110 is determined by a controller 1430 and a motor 1440, for example, as shown in FIG. 14 , to adjust the preload force on the lower spring stack 1510 and the upper spring stack 1520, for example, in response to the value of weight W pressing down on the vibration isolator preload mechanism 1500. In some cases, the position of the control plate 1530 or the upper housing 1110 is selected such that at least one of the lower spring stack 1510 or the upper spring stack 1520 is within the QZS range of its force-deflection curve. Ideally, the position of the control plate 1530 or the upper housing 1110 is selected such that both the lower spring stack 1510 and the upper spring stack 1520 are within the QZS range of their force-deflection curves.

[0055] The top surface 1340 of the top housing 1110 may be considered a top plate, a load-bearing platform and / or a mounting point.

[0056] 16 illustrates a performance graph 1600 of an exemplary QZS isolator at two different preload force levels, in accordance with at least one embodiment of the present disclosure. Graph 1600 illustrates the approximate relationship between force 1610 and displacement 1620 for a no-preload or minimal preload case 1630 and a preload or more significant preload case 1640. As can be seen, no-preload case 1630 requires a larger force to reach its QZS region 1635, while preload case 1640 requires a smaller force to reach its QZS region 1645. Thus, a QZS isolator in preload case 1640 may be within the QZS region if, for example, a child or small adult is seated in the vehicle seat, while a QZS isolator in no-preload case 1630 may be within the QZS region if, for example, a large adult is seated in the vehicle seat. Therefore, it is desirable to adjust the preload force on the QZS isolators based on the weight placed on them, as shown in Figures 14 and 15.

[0057] As one skilled in the art will readily recognize after becoming familiar with the teachings herein, the vibration isolator preload mechanism of the present disclosure advantageously provides the ability to apply an adjustable preload force or deflection to the QZS isolators. In some cases, the preload force or deflection is dynamically adjusted based on the weight applied to the QZS isolators. It should be noted that the above-described examples are provided for illustrative purposes and are not intended to be limiting. Other devices and / or device configurations may be utilized to perform the operations described herein. Many variations on the above-described examples and embodiments are possible. Depending on the implementation, locations or orientations may differ from those shown in the present invention. For example, while the components of the QZS vibration isolators may be illustrated and described herein as circular, conical, or cylindrical, other shapes with non-circular (e.g., elliptical, polygonal, etc.) cross sections may alternatively or additionally be used for one or more components. The techniques described herein may be used in other types of vehicles, including campers, trailer homes, commercial tow vehicles, motorcycles, off-road vehicles, aircraft, and watercraft. The exact configuration of the QZS vibration isolators and / or vibration isolator preload mechanisms can be selected to optimize performance for the vibration frequencies and amplitudes expected in such vehicles. Vibration isolator preload force mechanisms can be used for vibration isolators positioned between fixed vehicle components and other vehicle components, including, but not limited to, seats, engines, engine components, batteries, cargo holds, cargo platforms, wheels, bumpers, and baggage bins.

[0058] Accordingly, the logical operations making up the embodiments of the technology described in this invention are referred to variously as operations, steps, objects, elements, components or modules, and it should be understood that they may be arranged or performed in any order unless expressly claimed otherwise or unless a particular order is inherently required by claim language.

[0059] All directional references, such as upper, lower, medial, lateral, upward, downward, left, right, lateral, center, front, rear, top, bottom, upward, downward, vertical, horizontal, clockwise, counterclockwise, proximal, and distal, are used for identification purposes only to aid the reader in understanding the claimed subject matter and are not intended to create limitations on the location, orientation, or use of the vibration isolator preload mechanism in particular. References to connections, such as attached, coupled, connected, and joined, should be interpreted broadly and, unless otherwise indicated, may include intermediate members between elements and relative movement between elements. As such, connected references do not necessarily imply that two elements are directly connected and in a fixed relationship to each other. The term "or" should be interpreted to mean "and / or" rather than "exclusive or." The term "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. Unless otherwise indicated in the claims, the values ​​listed are to be construed as merely exemplary and not as limiting.

[0060] The above specification, examples, and data provide a complete description of the structure and use of exemplary embodiments of the vibration isolator preload mechanism as defined in the claims. While various embodiments of the claimed subject matter have been described above with a certain degree of specificity, or with reference to one or more individual embodiments, it is believed that those skilled in the art could make many modifications to the disclosed embodiments without departing from the spirit or scope of the claimed subject matter.

[0061] Further embodiments are contemplated. All matter contained in the above description and shown in the accompanying drawings is to be interpreted as merely illustrative of particular embodiments, and not as limiting. Changes in detail or structure may be made without departing from the essential elements of the subject matter defined in the following claims.

Claims

1. at least two disc spring washers, each including an inner edge, an outer edge and a central opening; at least one ring-shaped outer spacer, each outer spacer being coupled to an outer edge of one or two of the at least two disc spring washers; at least one ring-shaped inner spacer, each spacer being coupled to an inner edge of one or two of the at least two disc spring washers; a bottom mounting portion configured to support the at least two disc spring washers; a first top mounting portion configured to compress the at least two disc spring washers upon application of a first downward force; a first vibration isolator including: a compression fixture configured to apply and maintain the first downward force against the first top mounting portion; a second top mounting portion configured to further compress the at least two disc spring washers upon application of a second downward force additional to the first downward force; Including, The apparatus, wherein the compression fixture further includes a motor configured to apply the first downward force.

2. The apparatus of claim 1 , wherein the first top mounting portion comprises a plate or platform.

3. The apparatus of claim 1 , wherein the second top mounting portion comprises a plate or platform.

4. The device of claim 1 , wherein the second top mounting portion comprises a plunger.

5. The apparatus of claim 1 , wherein the first downward force is a preload force selected to place the at least two disc spring washers in a near-zero stiffness (QZS) range.

6. 2. The apparatus of claim 1, wherein the first downward force is a preload force selected to place the at least two disc spring washers within a near-zero stiffness (QZS) range when the second downward force is applied.

7. The compression tool comprises: a bottom housing; a top housing configured to move vertically relative to the bottom housing; The apparatus of claim 1 , comprising:

8. 8. The apparatus of claim 7, wherein the compression fixture further comprises a pin or bolt configured to fix the position of the top housing relative to the bottom housing after application of the first downward force.

9. The compression tool further comprises: a sensor configured to measure the second downward force; a controller configured to adjust the first downward force based on the second downward force; The apparatus of claim 1 , comprising:

10. 10. The apparatus of claim 9, wherein the first downward force is adjusted to place the at least two disc spring washers within a near-zero stiffness (QZS) range.

11. a second vibration isolator positioned above the first top mounting portion; the first downward force compresses the first vibration isolator and decompresses the second vibration isolator; and the second downward force compresses both the first vibration isolator and the second vibration isolator; adjusting the first downward force based on the second downward force to place at least one of the first vibration isolator or the second vibration isolator within a quasi-zero stiffness (QZS) range; 10. The apparatus of claim 9.

12. a second vibration isolator positioned above the first top mounting portion; the first downward force compresses the first vibration isolator and decompresses the second vibration isolator; and the second downward force compresses both the first vibration isolator and the second vibration isolator; 10. The apparatus of claim 1.

13. Floor and; backrest; cushion; Frame; a slide rail configured to allow the seat to move in a direction parallel to said floor; at least two disc spring washers, each including an inner edge, an outer edge and a central opening; at least one ring-shaped outer spacer, each outer spacer being coupled to an outer edge of one or two of the at least two disc spring washers; at least one ring-shaped inner spacer, each spacer being coupled to an inner edge of one or two of the at least two disc spring washers; a bottom mounting portion configured to support the at least two disc spring washers; a first top mounting portion configured to compress the at least two disc spring washers upon application of a first downward force; a first vibration isolator including: a compression fixture configured to apply and maintain the first downward force against the first top mounting portion; a second top mounting portion configured to further compress the at least two disc spring washers upon application of a second downward force additional to the first downward force; a sheet comprising: Including, The compression tool further comprises: a motor configured to apply the first downward force; a sensor configured to measure the second downward force; a controller configured to adjust the first downward force based on the second downward force; Vehicles including.

14. The compression tool comprises: a bottom housing; a top housing configured to move vertically relative to the bottom housing; a pin or bolt configured to fix the position of the top housing relative to the bottom housing after application of the first downward force; 14. The vehicle of claim 13, comprising:

15. a second vibration isolator positioned above the first top mounting portion; the first downward force compresses the first vibration isolator and decompresses the second vibration isolator; and the second downward force compresses both the first vibration isolator and the second vibration isolator; 14. The vehicle of claim 13.

16. a second vibration isolator positioned above the first top mounting portion; the first downward force compresses the first vibration isolator and decompresses the second vibration isolator; and the second downward force compresses both the first vibration isolator and the second vibration isolator; adjusting the first downward force based on the second downward force to place at least one of the first vibration isolator or the second vibration isolator within a quasi-zero stiffness (QZS) range; 16. The vehicle of claim 15.

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