The subject matter disclosed herein relates to devices, systems, and methods for reducing and controlling gross vehicle cab vibrations. More particularly, the subject matter disclosed herein relates to devices, systems and methods for reducing and controlling movement in off-highway cabs, particularly for reducing vibration and increasing high-frequency isolation in off-highway cabs.
Gross off-highway cab movement and vibration are particularly troublesome in that they can cause fatigue and wear on equipment. In cabs of industrial vehicles or construction equipment, vibrations are particularly problematic in that they create multiple fatigue and wear points. In addition to the fatigue and wear on the equipment, the same movement and vibration causes fatigue to the operator and interferes with the operator's ability to operate the equipment.
In contrast to narrowband damping, which provides for a narrow vibrational band and/or only provides damping at either low or high vibrational frequencies, broadband damping provides damping across a large spectrum of vibrational frequencies. Broadband damping is usually achieved by using annular damping and a relatively high viscosity fluid, which results in damping across a wide range of frequencies.
There is a need for an improved device that reduces gross vibration and movement in off-highway vehicle cabs, yet is durable and/or can be manufactured in a cost-effective manner.
In accordance with this disclosure, improved damping fluid mount devices, systems and methods are provided, for example with a damping fluid mount and a method or process for assembling a fluid mount easily adaptable to different static load and damping fluid mount configurations.
In one aspect, the present subject matter provides a damping fluid mount, which includes an inner member, an elastomer section that is affixed to an outer surface of the inner member, an annular damping plate attached to a bottom portion of the inner member, a cup containing viscous fluid positioned about the elastomer section and the damper plate, and a collar positioned about a portion of the elastomer section, the collar having an inner diameter that is less than an outer diameter of the damper plate.
In another aspect, a damping fluid mount includes an inner member, an elastomer section that is affixed to an outer surface of the inner member, an annular damping plate attached to a bottom portion of the inner member, a cup containing viscous fluid positioned about the elastomer section and the damper plate, and a collar positioned about the portion of the cup that is crimped. In this configuration, however, a portion of the cup is radially crimped into a precompressed portion of the elastomer section, an inner diameter of the portion of the cup that is crimped being less than an outer diameter of the annular damping plate, and the collar having an inner diameter that is less than the outer diameter of the damper plate.
In yet another aspect, a method for assembling a damping fluid mount is provided. The method includes coupling an elastomer section to an outer surface of an inner member, coupling a damping plate to a bottom portion of the inner member, inserting the elastomer section coupled to the inner member and to the damping plate into a cup, wherein the cup contains a quantity of viscous fluid, and positioning a collar about a portion of the elastomer section, the collar having an inner diameter that is less than an outer diameter of the damper plate.
Although some of the aspects of the subject matter disclosed herein have been stated hereinabove, and which are achieved in whole or in part by the presently disclosed subject matter, other aspects will become evident as the description proceeds when taken in connection with the accompanying drawings as best described hereinbelow.
The present subject matter provides improvement to vibration damping fluid mounts for use in off-highway vehicle cabs, particularly those incorporating a roll-over protection structure (ROPS). The disclosed devices and methods manufacture a damping fluid mount that creates an overlap between the damping plate held within the fluid mount and a ROPS support collar that is provided to carry the required ROPS loading. In some embodiments, this interleaved ROPS support collar is provided in combination with a crimped cup design that pre-compresses the elastomer section of the fluid mount, which provides a fluid mount with superior sealing, improved fatigue life, increased durability and improved high-frequency isolation.
In one exemplary configuration shown in
As further illustrated in
As indicated above, the assembled combination of the inner member 110, the elastomer section 130, and the damping plate 140 are contained within an outer cup 200, an example of which is illustrated in
In any configuration, the outer cup 200 additionally contains a quantity of viscous fluid F, which provides damping in the fluid mounts 100 and 102. For example, when the bonded core is placed within outer cup 200, the quantity of fluid F is disposed beneath damping plate 140. Thus, the quantity of viscous fluid F and the damping plate 140 act as a dashpot damper by allowing fluid flow around an outer diameter of the damping plate 140 (i.e. annular damping). Where holes (not shown) are included in the damping plate 140, the damping plate 140 further exhibits orifice damping as the quantity of viscous fluid F flows through the holes in the damping plate 140. In this case, the dashpot damper dissipates the overall energy of the system and creates softer mount stiffness for equivalent motion control. In some embodiments, air is present on both sides of the damping plate 140 (i.e., above the damping plate 140, but below a bottom of the elastomer section 130, and below the damping plate 140 in the portion of the outer cup 200 in which the viscous fluid F is provided).
However, increasing the overall damping of a system can result in increased dynamic stiffness. Therefore, in order to increase overall system damping and maintain isolation, a low-amplitude decoupler can be used to reduce the damping at low-amplitude, high frequency input. One means of achieving decoupling is to have the bottom 220 of the outer cup 200 be a substantially flat surface. The flat surface provides decreased volume stiffness for the quantity of viscous fluid F disposed below the damping plate 140, thereby providing improved high-frequency isolation. Alternatively or in addition, the volume of the viscous fluid F is selected so that a certain percentage of air is present in the fluid cavity to allow deflection even at frequencies at which the damping fluid F may get very stiff (such as at the annular and/or orifice damping interfaces).
The outer cup 200 is further coupled to a supporting frame structure 300, such as a vehicle frame of an off-highway vehicle. In the embodiment shown in
In addition, in the embodiments shown in
Regardless of the particular method used, the radially crimping of the outer cup 200 securely contains the bonded core within. In addition, the fluid mounts 100 and 102 exhibit increased durability from radially crimping the outer cup 200, since radially crimping the outer cup 200 both reinforces the radially precompression of the elastomer section 130 and radially crimps an inner surface of the outer cup 200 such that the elastomer contour 134 and the inner surface of the outer cup 200 have a substantially similar contour. In one aspect, as shown in
It is noted, however, that the substantial similarity of contours between the elastomer contour 134 and the inner surface of the outer cup 200 are not absolutely necessary due to the incompressible nature of elastomer section 130. For example, the crimp axial length may actually be longer than the axial length of the molded undercut, thereby axially stretching the elastomer at the interface. In any configuration, the relative motion at the interface between the elastomer contour 134 and the outer cup 200 are substantially minimized. A precompressed friction interface has been previously used for elastomeric mounts, but precompressed friction interface are not known to be used for elastomeric mounts used in fluid mounts, as disclosed herein.
Radial precompression of the elastomer section 130 further reduces relative motion, improves fatigue life, and provides superior sealing of the fluid mount 100 or 102 (e.g., by creating a beadles seal between the elastomer section 130 and the outer cup 200 to seal the viscous fluid F within the outer cup 200). The particular degree of precompression can be designed to provide the desired response in the elastomer section 130. In some configurations, for example, radial precompression of the elastomer section 130 ranges from approximately 5% of the original (i.e., uncompressed) elastomer section wall thickness to approximately 30% of original elastomer section wall thickness. In some particular examples, the percentage of radial precompression is between approximately 12% and 20% of the original elastomer wall thickness. That being said, those having skill in the art will recognize that the amount of precompression is adjustable to adapt fluid mount 100 or 102 to different desired static and/or snubbing load responses. In addition, by selecting the properties of the elastomer section 130 prior to manufacture, the 1G static load rating of the fluid mount 100 or 102 can be adjusted from its largest load rating to its smallest load rating (e.g., by adjusting the modulus of the elastomer section 130).
Furthermore, in some embodiments, a ring 120 is encapsulated or bonded within the elastomer section 130 and, in conjunction with the radially precompressed elastomer section 130, increases durability and damping of the fluid mounts 100 and 102. In particular, where the ring 120 is integrated within the elastomer contour 134, between approximately 12% and 20% radial precompression of the elastomer section 130 results in a significant reduction in relative motion at the interface, such that the axial position at the interface will not substantially change over time, which will result in an improved durability resulting from reduced wear at the interface. In other aspects, the fluid mounts 100 and 102 do not include the ring 120. Instead, these embodiments rely substantially on the radial crimp of the outer cup 200 and the elastomer section 130 and on the collar 310 to reduce relative motion at the crimped interface. In addition, in some configurations, the outer cup 200 stretches the elastomer contour 134 in the axial direction to minimize the relative motion at the interface. By integrating the ring 120 into the elastomer contour 134, however, the relative motion at the interface is diminished, thus providing even more increased durability of the fluid mounts 100 and 102. Similarly, a second ring (not shown) can be added above the elastomer contour 134 and provide a higher reduction in relative motion.
Further, radial precompression of the elastomer section 130 provides improved sealing of the viscous fluid F inside the fluid mounts 100 and 102. Traditionally, sealing a specified volume of viscous fluid within an interior of a fluid mount has been accomplished by using sealing beads incorporated into the outer contours of the elastomer. Maintaining the specified volume of viscous fluid within the fluid mount is desirable because of the damping accomplished by the viscous fluid and the damping plate acting in combination as a dashpot damper. Even small quantities of leakage of the viscous fluid impacts the efficiency and ability of the fluid mount to control and reduce gross vehicle cab movement and vibration. Therefore, radially precompressing the elastomer section 130 provides superior sealing of the broadband damping fluid mounts 100 and 102, as disclosed herein, because the elastomer section 130 is compressed to a higher percentage and over a larger area than traditional sealing beads typically allow. Radial precompression of between about 12% and 20% of the elastomer section 130 provides effective sealing, although radial precompression substantially between 5% and 30% can also be sufficient. The use of traditional sealing beads incorporated into the outer elastomer contour 134, in addition to radial precompression of the elastomer 130, provides for similar results. The radial precompression of the elastomer section 130 provides sealing even during use in low-temperature environments affecting the different materials' coefficient of thermal expansion. This approach creates a tight seal over a large area. In addition, in some embodiments, a vacuum is used during the assembly process to control the amount of negative or positive pressure in the assembled mount.
Furthermore, in combination with or in addition to the pull-out prevention provided by the collar 310, radially crimping the outer cup 200 provides an additional pull-out limiting effect that has safety benefits. When the outer cup 200 is radially crimped, the outer cup 200 has a smaller diameter at the crimped portion than the outer diameter of the damping plate 140 (e.g.
In each configuration of the fluid mounts 100 and 102, an upper portion of the inner member 110 is configured to be coupled to a top plate assembly 150, which provides a point of connection to a supporting structure, such as a cab of an off-highway vehicle. In particular, the inner member 110 is configured to receive a top plate fastener 152 (e.g. a bolt as illustrated in
In addition to providing a load path between the top plate assembly 150 and the supporting frame structure 300, the fluid mounts 100 and 102 acts as a “dashpot” damper to remove energy of motion of the cab with respect to the frame. Specifically, the particular configurations of the fluid mounts 100 and 102 disclosed herein provide a “soft ride” operating zone designed to the natural frequency of the components of the mounts. Specifically, for example, in some embodiments, the materials and configurations of the inner member 110, the elastomer section 130, the ring 120 (if provided), the damper plate 140, and the viscous fluid F are selected based on a natural frequency range from about 8 Hz to about 10 Hz (e.g., having a nominal natural frequency of about 9 Hz).
Furthermore, the configurations of the fluid mounts 100 and 102 disclosed herein additionally provide a motion-controlling “snubbing” region in both the axial and radial directions to allow for limited cab movement with respect to the frame of the vehicle. As used herein, the term “snubbing” means reducing or stopping movement between fixed and movable portions of a vehicle (e.g., the frame and the cab) by absorbing kinetic energy therebetween by engaging stiffer elements after a certain deflection. In the configurations disclosed herein, for example, this engagement of stiffer elements is achieved via the elastomeric profile member of the vehicle mount devices described herein. Specifically, the elastomeric profile part can include snubbing surfaces for absorbing and/or dissipating kinetic energy. Thus, in some aspects, “snubbing” is a form of shock absorbing.
In the particular embodiments disclosed herein and illustrated in
In this configuration, where fluid mount 100 or 102 is secured to a top plate assembly 150 as shown in
Further, in configurations in which at portion of the outer cup 200 is crimped about an elastomer contour 134 of the elastomer section 130, the decreased cup diameter D1 resulting from radially crimping the outer cup 200 is also operable to react the downward and upward snubbing loads. Specifically, the wall of the crimped cup between the original cup diameter D0 and the decreased cup diameter D1 react with the snubbing load transmitted into the precompressed elastomer section 130 from the inner member 110 and snubbing elements.
The present subject matter can be embodied in other forms without departing from the spirit and essential characteristics thereof. The embodiments described therefore are to be considered in all respects as illustrative and not restrictive. Although the present subject matter has been described in terms of certain preferred embodiments, other embodiments that are apparent to those of ordinary skill in the art are also within the scope of the present subject matter.
Filing Document | Filing Date | Country | Kind |
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PCT/US2014/062093 | 10/24/2014 | WO | 00 |