Patent ID: 12253138

DETAILED DESCRIPTION

With reference to the Figures, wherein like numerals indicate like parts throughout the several views, a damper assembly102for a vehicle100includes a pressure tube104forming a chamber106and defining an axis A, a piston assembly110disposed in the chamber106and dividing the chamber106into two subchambers144,146, and a piston rod114elongated along the axis A and fixed to the piston assembly110. The piston assembly110includes a body116having an inner bore118extending axially through the body116from a first end120to a second end122. The piston assembly110includes a blowoff disc124contacting the body116at the first end120of the inner bore118and having a throughhole126aligned with the inner bore118. The piston rod114extends through and concentrically contacts the inner bore118and extends through and concentrically contacts the throughhole126. The body116has a groove128extending axially along the inner bore118from the first end120to the second end122. The groove128and the piston rod114form a passageway130permitting oil to travel between the first end120and the second end122. The blowoff disc124has a notch132extending from the throughhole126and arranged to permit oil from the passageway130to pass across the blowoff disc124.

A damping force provided by the damper assembly102can depend on the rate of fluid moving between the subchambers144,146as the piston assembly110moves. As the piston assembly110moves, one of the subchambers144,146increases in volume and the other subchamber144,146decreases in volume, leading the fluid to pass from the decreasing subchamber144,146to the increasing subchamber144,146. The passageway130and the notch132provide one way for the fluid to move between the two subchambers144,146as the piston assembly110slides through the chamber106of the cylinder. One benefit of the damper assembly102may be easier assembly because the groove128and the piston rod114can form the passageway130regardless of the orientation of the body116relative to the piston rod114. Another benefit is fine control over the rate of the fluid moving between the subchambers144,146. During design, the rate of fluid transfer can be controlled by adjusting the cross-sectional area of the groove128and/or by changing a number of the grooves128.

With reference toFIG.1, the vehicle100may be any passenger or commercial automobile such as a car, a truck, a sport utility vehicle, a crossover, a van, a minivan, a taxi, a bus, etc.

The vehicle100includes a frame134. The vehicle100may be of a unibody construction, in which the frame134and a body of the vehicle100are a single component. The vehicle100may, alternatively, be of a body-on-frame construction, in which the frame134supports a body that is a separate component from the frame134. The frame134and body may be formed of any suitable material, for example, steel, aluminum, etc.

The vehicle100includes wheels136that control motion of the vehicle100relative to ground supporting the vehicle100, e.g., acceleration, declaration, turning, etc. Vertical movement of the wheels136relative to the frame134affects an amount of traction between the wheels136and the ground and an amount of vertical acceleration experienced by occupants of the vehicle100when the vehicle100travels over bumps and the like, e.g., the ride feel experienced by the occupants.

The vehicle100includes a suspension system138. The suspension system138is coupled to the frame134and to each wheel136. The suspension system138absorbs and dampens shocks and vibrations from the wheels136to the frame134. For each wheel136, the suspension system138may include a coil spring140and the damper assembly102. The damper assembly102may extend through the coil springs140. One end of the damper assembly102and the coil spring140may be connected to and move with the wheel136, and the other end of the damper assembly102and the coil spring140may be connected to and move with the frame134.

The suspension system138is arranged so that an upward motion of the wheel136, such as when the tire hits a bump while the vehicle100is in motion, compresses the coil spring140and the damper assembly102. The coil spring140may exert a force that is a function, e.g., a linear relation, of a difference between the current length of the coil spring140and a relaxed length of the coil spring140. The damper assembly102may exert a force that is a function of a speed of compression or extension of the damper assembly102.

With reference toFIG.2, the damper assembly102is movable from a compressed position to an extended position, and vice versa. A distance between mounting points142of the damper assembly102is less in the compressed position than in the extended position. The coil springs140or the like may urge the damper assemblies102toward the extended position. Force applied to the wheels136of the vehicle100, e.g., from bumps, potholes, etc., may urge to damper assemblies102toward the compressed positions.

Each damper assembly102controls movement of the respective wheels136by limiting fluid flow into, out of, and/or between the subchambers144,146, e.g., between a compression subchamber144and a rebound subchamber146. Fluid movement is caused by a movement of the piston assembly110within the pressure tube104of the damper assembly102, e.g., when the damper assembly102is moved toward the compressed position or the extended position.

The damper assembly102defines the axis A. The axis A extends between the mounting points142of the damper assembly102. The damper assembly102may be elongated along the axis A. The terms “axially,” “radially,” and “circumferentially” used herein are relative to the axis A defined by the damper assembly102.

The pressure tube104defines the chamber106. For example, the pressure tube104may be hollow and tubular, e.g., cylindrical, enclosing the chamber106therein. The axis A may be defined by the cylindrical shape of the pressure tube104. The chamber106is filled with fluid, e.g., an incompressible hydraulic fluid such as oil. Movement of the damper assembly102, e.g., to the extended or compressed position, may increase and/or decrease fluid pressure in the pressure tube104, e.g., in the compression subchamber144and the rebound subchamber146. The pressure tube104may be elongated along the axis A of the damper assembly102. The pressure tube104may be metal, or any suitable material.

The damper assembly102includes the piston rod114extending away from, and movable relative to, the pressure tube104. The piston rod114may be elongated along the axis A of the damper assembly102. The piston rod114is fixed to the piston assembly110. The piston rod114is moved relative to the pressure tube104together with the piston assembly110when the damper assembly102is moved toward the compressed position or the extended position. The piston rod114may extend from within the chamber106of the pressure tube104to outside the chamber106, e.g., from the piston assembly110and through the rebound subchamber146.

The piston assembly110divides the chamber106of the pressure tube104into the compression subchamber144and the rebound subchamber146, i.e., with the compression subchamber144on one side158,160of the piston assembly110and the rebound subchamber146on the opposite side158,160of the piston assembly110along the axis A. An outer circumferential surface148of the piston assembly110, e.g., of the body116, may be sealed to an inner surface of the pressure tube104. The piston assembly110is slidable within the chamber106of the pressure tube104along the axis A. Sliding the piston assembly110along the axis A varies volumes of the compression subchamber144and the rebound subchamber146. For example, a volume of the compression subchamber144may decrease, and a volume of the rebound subchamber146may increase, when the damper assembly102is moved toward the compressed position. As another example, the volume of the rebound subchamber146may decrease, and the volume of the compression subchamber144may increase, when the damper assembly102is moved toward the extended position. The piston assembly110is connected to the piston rod114, i.e., such that the piston assembly110and the piston rod114move generally in unison. The piston assembly110may be fixed to the piston rod114, e.g., via a fastener150and/or other suitable structure such as a weld, friction fit, etc. The piston assembly110may be metal, plastic, or any suitable material.

With reference toFIGS.3A-C, the piston assembly110includes the body116and at least one blowoff disc124. For example, the piston assembly110may include the body116and one blowoff disc124on each side158,160of the body116. The piston assembly110may further include a preload ring152, a plurality of valve discs154, a fulcrum disc156, a preload spacer176, and the fastener150on each side158,160of the body116, e.g., stacked in that order starting from the body116. The piston rod114may extend through and concentrically contacting the inner bore118of the body116and may extend through and concentrically contacting the throughhole126of the blowoff disc124. The piston rod114may further extend through the valve discs154, the fulcrum discs156, the preload spacers176, and the fasteners150. The valve discs154, the fulcrum discs156, and the preload spacers176may be radially symmetric and centered on the axis A.

With reference toFIGS.4-5, the piston assembly110includes the body116. The body116can have the general shape of a squat cylinder, with an axial thickness less than the diameter but significantly greater than the thicknesses of any of the discs124,154,156. The body116may include the inner bore118, the outer circumferential surface148, a first side158, and a second side160. The first side158and the second side160may each extend radially outward from the inner bore118to the outer circumferential surface148. The first side158and the second side160can be opposite each other along the axis A. The first side158and the second side160can face axially toward respective blowoff discs124, as shown inFIGS.3A-C. The first side158may face toward the rebound subchamber146, and the second side160may face toward the compression subchamber144.

The inner bore118extends axially through the body116from the first end120to the second end122. The first end120can be an exit from the inner bore118at the first side158of the body116, and the second end122can be an exit from the inner bore118at the second side160of the body116. The inner bore118can have a constant cross-sectional shape from the first end120to the second end122. For example, the inner bore118can have a cylindrical shape with a constant diameter from the first end120to the second end122. The inner bore118can have a diameter approximately equal to a diameter of the piston rod114such that fluid is blocked from flowing between the inner bore118and the piston rod114.

The body116has at least one groove128, e.g., a plurality of grooves128, extending axially along the inner bore118from the first end120to the second end122. For example, each groove128can be a channel having a depth extending radially outward from the inner bore118. Alternatively, the piston rod114may include the grooves128, in which case each groove128can be a channel having a depth extending radially inward from an outer surface of the piston rod114. In either case, the grooves128may be elongated parallel to the axis A. In the case of multiple grooves128, the grooves128are circumferentially spaced from each other. Each groove128can have a constant cross-sectional shape from the first end120to the second end122and may terminate at the first end120and at the second end122. The body116and the piston rod114form a passageway130through each groove128permitting fluid to travel between the first end120and the second end122, i.e., from the first end120to the second end122or vice versa.

The body116may include lips162at the first end120and at the second end122of the inner bore118, e.g., one lip162at the first end120and one lip162at the second end122. Each lip162can extend completely around the first end120or second end122of the inner bore118, e.g., form a circle centered on the axis A. The lip162can have a width extending radially outward from the inner bore118, i.e., having a greater diameter than the inner bore118. Each lip162can have a constant cross-section projected circumferentially around the first end120or second end122. Each lip162permits fluid to travel between the passageways130formed by the grooves128and the notches132of the blowoff disc124. Each lip162can form a passageway with the piston rod114and the blowoff disc124. Fluid exiting the groove128can then travel circumferentially around the piston rod114until the fluid reaches one of the notches132. Because the lip162extends completely around the first end120or the second end122of the inner bore118, the notches132can be located at any circumferential position relative to the grooves128.

The first side158and the second side160may each include a base surface164and features166,168extending axially from the base surface164toward the blowoff disc124located adjacent to that side158,160of the body116. The base surface164may define a plane perpendicular to the axis A. For example, the first side158and the second side160may each include a center axial projection166extending concentrically around the inner bore118. The center axial projection166can have a height extending axially from the base surface164and a width extending radially outward from the inner bore118. The height and/or the width can be constant around the inner bore118. The lip162can be located in the center axial projection166. The center axial projections166may contact the respective blowoff discs124, e.g., by having the height be at least as great as the height of any other feature166,168extending from the respective base surface164.

The first side158and the second side160may each include a plurality of peripheral axial projections168radially spaced from the respective center axial projection166. The peripheral axial projections168may be circumferentially spaced from each other on each side158,160of the body116. The peripheral axial projections168may border the outer circumferential surface148. The peripheral axial projections168may contact the respective blowoff discs124when the blowoff disc124is in a relaxed position, e.g., by having a height equal to the height of the respective center axial projection166.

The body116includes one or more projection passages170. Each projection passage170may extend from one of the peripheral axial projections168on one side158,160of the body116to the base surface164on the other side158,160of the body116, i.e., from one of the peripheral axial projections168on the first side158to the base surface164on the second side160or vice versa. The projection passages170provide fluid communication between the compression subchamber144and the rebound subchamber146of the pressure tube104, i.e., such that fluid may flow from the compression subchamber144to the rebound subchamber146or vice versa.

With reference toFIG.4, the body116includes one or more throughbores172extending through the body116and permitting fluid to flow between the subchambers144,146. The throughbores172are radially spaced from the inner bore118. The throughbores172may be circumferentially and/or radially spaced from each other and/or from the projection passages170. The throughbores172provide fluid communication between the compression subchamber144and the rebound subchamber146of the pressure tube104, i.e., such that fluid may flow from the compression subchamber144to the rebound subchamber146or vice versa. Each throughbore172may have a greater cross-sectional area than each notch132. During design, modifying the number of throughbores172and cross-sectional area of the throughbores172can provide a large range of potential flowrates across the body116. The combination of the grooves128with the throughbores172can provide fine control of the flowrate over a wide range of flowrates.

With reference toFIG.5, the peripheral axial projections168may include indentations174permitting fluid from the projection passages170to pass outside the peripheral axial projections168under the height of the peripheral axial projections168. Therefore, fluid can flow through the indentations174even if the blowoff disc124is abutting the peripheral axial projections168. The size of the indentations174can be used to tune the flow rate across the piston assembly110.

With reference toFIGS.6-7, the blowoff discs124can be circular plates. The blowoff discs124can have diameters slightly less than the diameter of the outer circumferential surface148of the body116, thereby permitting fluid in the space between the blowoff disc124and the base surface164to flow around the blowoff disc to the respective subchamber144,146. The blowoff discs124can have a constant axial thickness. Each blowoff disc124includes the respective throughhole126. The throughhole126may have a circular shape and may be centered in the blowoff disc124. The throughhole126can have a diameter approximately equal to the diameter of the piston rod114(and the diameter of the inner bore118) such that fluid is blocked from flowing between the throughhole126and the piston rod114. The throughhole126is aligned with the inner bore118, e.g., the throughhole126and the inner bore118are centered on the axis A.

The blowoff discs124decrease a resistance to movement in response to fluid flow past the blowoff disc124and/or a difference in fluid pressure on one side of the blowoff disc124relative to an opposite side. The fluid flow and/or difference in fluid pressure may translate or flex the blowoff disc124to create, and/or increase a size of, an axial gap178through which fluid may flow. Increasing the size of the axial gap178decreases resistance to movement by permitting a greater amount of fluid to flow from one subchamber144,146to the other subchamber144,146. The amount of flex and/or translation of the blowoff discs124and the resulting increase in size of the axial gap178may be proportional to a rate of fluid flow and/or the pressure difference between the compression subchamber144and the rebound subchamber146. For example, the greater the rate of fluid flow and/or difference in fluid pressure, the greater the amount of flex and/or translation of the blowoff discs124away from the body116, providing a greater magnitude of increase of the size the axial gap178therebetween. A threshold rate of fluid flow and/or difference in fluid pressure may be required to flex and/or translate the blowoff disc124. The blowoff discs124may not decrease resistance to movement until the threshold rate of fluid flow and/or difference in fluid pressure is achieved.

Each blowoff disc124includes at least one notch132, e.g., a plurality of notches132, extending from the throughhole126. The notches132extend through the blowoff disc124and thereby permit fluid to pass across the blowoff disc124. The notches132can be circumferentially spaced from each other, allowing shorter paths for fluid to travel from one of the grooves128to one of the notches132. The notches132can extend radially outward from the throughhole126, e.g., radially outward past an outer diameter of the center axial projection166. Fluid from the lip162of the body116can thereby pass into the notch132and travel outside the center axial projection166to the space between the base surface164and the blowoff disc124. The notches132are continuously open, i.e., regardless of the positions of other components of the damper assembly102, and flow is restricted by cross-sectional areas of the notches132. The cross-sectional area of one of the notches132is the area within the notch132and radially outside a diameter of the throughhole126in a plane perpendicular to the axis A. During design, the cross-sectional areas of the notches132can be used to tune the flow rate of fluid across the piston assembly110, even if the grooves128remain the same, so the same body116can be used in damper assemblies102having different flow rates.

Each blowoff disc124includes at least one cutout180. The cutouts180extend through the blowoff disc124. The cutouts180may be spaced from each other. For example, the cutouts180of each blowoff disc124may be circumferentially spaced from each other and radially overlap, as shown inFIG.6, i.e., be located at different circumferential ranges and at overlapping ranges of radiuses. For another example, the cutouts180of each blowoff disc124may circumferentially overlap, i.e., two or more cutouts180may be along a common radius extending from the axis A, as shown inFIG.7. Such cutouts180may be spaced from each other along the common radius. The cutouts180may be positioned radially outside the center axial projection166and radially inside the peripheral axial projections168. The cutouts180may be radially and circumferentially positioned above the base surface164of the respective side158,160of the body116, i.e., aligned along the axis A with the base surface164. The cutouts180may decrease a stiffness of the respective blowoff disc124. The positioning of the cutouts180help control the stiffness of the blowoff disc124to permit the blowoff disc124to deflect away from the peripheral axial projections168, as described below.

The blowoff discs124at each side158,160of the body116may be spaced from the base surface164on that side158,160, e.g., spaced from the base surface164at the throughbores172and/or at the ends of the projection passages170terminating at the base surface164. Spacing the blowoff disc124from the base surface164at the throughbores172permits fluid to freely flow into and out of the throughbores172, e.g., without inhibition of such flow by the blowoff disc124. Spacing the blowoff disc124from one end of the projection passages170permits fluid to freely flow into the projection passage170on that side of the body116, e.g., without inhibition of such flow by the blowoff disc124.

The blowoff discs124at each side158,160of the body116selectively permit fluid flow out of the projection passages170at the ends of the projection passages170terminating at the peripheral axial projections168, i.e., depending on an amount and direction of fluid pressure applied to the blowoff disc124. The blowoff disc124selectively permits fluid flow by controlling the size of the axial gap178between the blowoff disc124and the peripheral axial projections168at which the projection passages170terminate. Thus, the same component performs the distinct tasks of permitting fluid flow through the notches132and selectively permitting fluid to flow through the projection passages170, reducing the number of components in the damper assembly102.

When the damper assembly102is in a neutral state, i.e., not moving toward the extended position or the compressed position, the blowoff discs124on each side158,160of the body116cover one end of the projection passages170and restricts or inhibits fluid flow into, and out of, the projection passages170. Fluid may still flow through the indentations174if present, at a reduced rate compared to the blowoff disc124being flexed away from the respective peripheral axial projection168. The blowoff disc124in the neutral state may abut the peripheral axial projections168, e.g., surrounding an open end of the projection passage170.

When the damper assembly102is moved toward the compressed or extended position, the blowoff disc124facing opposite the direction of movement of the body116may be moved away from the body116, e.g., from the peripheral axial projections168, by the pressure differential and/or fluid flow resulting from such movement. Moving the blowoff disc124away from the body116creates the axial gap178between the peripheral axial projection168of the body116and the blowoff disc124. Fluid may flow out of the projection passages170through the axial gap178to the respective subchamber144,146.

When the damper assembly102is moved toward the compressed or extended position, the blowoff disc124facing in the direction of movement of the body116may be urged toward the body116, not creating or enlarging the axial gap178between the peripheral axial projection168of the body116and the blowoff disc124.

With reference toFIG.8, the damper assembly102may include one or more valve discs154, e.g., one or more valve discs154on each side158,160of the body116. On each side158,160of the body116, the valve discs154may be stacked on the respective blowoff disc124such that the blowoff disc124is axially between the valve discs154and the body116. The valve discs154may be supported by the piston rod114. For example, the piston rod114may extend through center openings of the valve discs154.

The valve discs154are elastically deformable. For example, force applied to an outer edge of the valve discs154may cause the valve discs154to flex such that the outer edge is moved axially relative the respective center opening of the valve discs154. The valve discs154are made from an elastically deformable material, e.g., spring steel, plastic having suitable elastic properties, etc.

The valve discs154on each side158,160of the body116urge the blowoff disc124on that side158,160toward the body116, i.e., the valve discs154increase an amount of force required to flex that blowoff disc124away from the respective peripheral axial projections168.

The valve discs154may progressively decrease in size as a function of the distance from the body116along the axis A (or alternatively, decrease and then increase). For example, the valve disc154closest to the body116may have a larger outer diameter than an outer diameter of the valve disc154adjacent such valve disc154, and so on. The valve disc154farthest from the body116may have a diameter smaller than the diameters of the other valve discs154on that side158,160of the body116. As another example, the valve discs154may be configured similar to a leaf spring.

The valve discs154closest to the body116may abut the respective blowoff discs124proximate the piston rod114. The valve discs154closest the body116may be spaced from the blowoff discs124at radially outer edges of the blowoff discs124. For example, the preload ring152on each side158,160of the body116may be positioned axially between the valve discs154, e.g., the closest valve disc154, and the blowoff disc124on that side158,160of the body116along the axis A. The preload rings152may be circular or any suitable shape. An inner diameter of the preload rings152may be smaller than an outer diameter of the closest valve disc154and smaller than an outer diameter of the respective blowoff disc124. An outer diameter of the preload ring152may be at least as great as an outer diameter of the closest valve disc154. The preload rings152may be radially outward of the cutouts180of the blowoff discs124. The preload rings152may be metal, plastic, or any suitable material. The preload rings152provide internal preload forces to the valve discs154.

Each damper assembly102may include a pair of the fulcrum discs156. The fulcrum discs156provide fulcrum points for the valve discs154. For example, one of the fulcrum discs156may abut the valve discs154such that the valve discs154on that side158,160of the body116are axially between the fulcrum disc156and the body116, e.g., may abut the smallest valve disc154on each side158,160of the body116opposite the adjacent larger valve disc154. An outer diameter of such fulcrum disc156may be smaller than an outer diameter of the abutting smallest valve disc154, i.e., than any of the outer diameters of the valve discs154on that side158,160of the body116.

Each damper assembly102may include a pair of preload spacers176. The preload spacers176protect the valve discs154. The preload spacers176sandwich the body116, the discs, and other components of the damper assembly102supported by the piston rod114. A thickness of the preload spacers176may increase or decrease space available for the discs, the piston, etc. For example, the preload spacer176on each side158,160of the body116may be axially outside of the fulcrum disc156on that side158,160of the body116. The fastener150may be fixed to the piston rod114axially outside of the preload spacer176on that side158,160of the body116. The fastener150may be, for example, a threaded lock nut. The fastener150may confine the preload spacers176, the blowoff discs124, the valve discs154, the body116, etc., to a stack having a predetermined length.

With reference toFIG.9, when the piston assembly110moves toward the compressed or extended position, the passageways130defined by the grooves128and the piston rod114provide a flow path for fluid to move between the compression subchamber144and the rebound subchamber146. For example, fluid located in the space between the blowoff disc124and the base surface164of the body116on one side158,160of the body116travels through the notch132to cross from radially outside the center axial projection166to the lip162radially inside the center axial projection166, then travels circumferentially around the piston rod114through the lip162to one of the grooves128, then travels axially along that groove128to the lip162on the opposite side158,160of the body116, then circumferentially along that lip162to one of the notches132on that side158,160of the body116, and then radially outward through that notch132to the space between the other blowoff disc124and the base surface164on that side158,160of the body116. The space between the blowoff disc124and the base surface164on each side158,160of the body116is in fluid communication with the respective subchamber144,146around the outer diameter of the blowoff disc124.

With reference toFIG.10, when the piston assembly110moves toward the compressed or extended position, the throughbores172provide a flow path for fluid to move between the compression subchamber144and the rebound subchamber146. For example, fluid located in the space between the blowoff disc124and the base surface164of the body116on one side158,160of the body116travels through the throughbores172to the space between the other base surface164and the other blowoff disc124.

When the piston assembly110moves toward the compressed or extended position, the projection passages170provide a flow path for fluid to move between the compression subchamber144and the rebound subchamber146. For example, fluid located in the space between the blowoff disc124and the base surface164of the body116on one side158,160of the body116travels through the projection passages170having ends located at that base surface164. If the difference in fluid pressure between the subchambers144,146is greater than the threshold difference of the blowoff disc124, the opposite blowoff disc124flexes away from the peripheral axial projections168on the opposite side158,160of the body116. The fluid in the projection passages170then travels out of the projection passages170into the opposite subchamber144,146. If the peripheral axial projections168include the indentations174, then fluid can exit the projection passages170through the indentations174even if the difference in pressures is below the threshold.

The disclosure has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. The adjectives “first” and “second” are used throughout this document as identifiers and are not intended to signify importance, order, or quantity. Many modifications and variations of the present disclosure are possible in light of the above teachings, and the disclosure may be practiced otherwise than as specifically described.