A multistage jounce bumper, including a jounce bumper cushion integrated with a hydraulic jounce bumper, wherein provided are the damping characteristic of the hydraulic jounce bumper and the damping/spring characteristics of a jounce bumper cushion. The hydraulic jounce bumper hydraulic response is tunable via adjustment of hydraulic flow with respect to a communicating hydraulic fluid reservoir. When maximum jounce is approached, jounce force and energy are exchanged, at a first stage, with the jounce bumper cushion, then at a predetermined compression, jounce force and energy are exchanged, at a second stage, with the hydraulic jounce bumper. Thereafter, a mechanical abutment is provided as a third stage of jounce management.

TECHNICAL FIELD

The present invention relates to automotive suspension systems, particularly the bumper mount, the jounce bumper, and conventional dampers. More particularly, the present invention relates to a multistage jounce bumper which is a synthesis of a jounce bumper cushion and a hydraulic jounce bumper, the combination providing enhanced suspension system energy absorption and improved ride characteristics.

BACKGROUND OF THE INVENTION

Motor vehicle suspension systems are configured so that the wheels are able to follow elevational changes in the road surface as the vehicle travels therealong. When a rise in the road surface is encountered, the suspension responds in “jounce” in which the wheel is able to move upwardly relative to the frame of the vehicle. On the other hand, when a dip in the road surface is encountered, the suspension responds in “rebound” in which the wheel is able to move downwardly relative to the frame of the vehicle. In either jounce or rebound, a spring (i.e., hydraulic fluid, leaf, torsion, etc.) is incorporated at the wheel in order to provide a resilient response to the respective vertical movements with regard to the vehicle frame. However, in order to prevent wheel bouncing and excessive vehicle body motion, a shock absorber is placed at the wheel to dampen wheel bounce. Additionally, when the limit of jounce is encountered, it is customary to provide a maximum jounce impact absorber in the form of a bumper cushion.

Referring now toFIGS. 1 through 1B, components of a conventional suspension system10are depicted which allow for jounce and rebound at a wheel of the subject motor vehicle12.

Firstly with regard toFIG. 1, a control arm14is pivotally mounted with respect to the frame16, wherein, in the depicted example, a torsion spring18is utilized to provide resilient response for the jounce and rebound of the control arm relative to the frame. To provide control over the rate of jounce and rebound, a damper in the form of a shock absorber20is connected pivotally at one end to the frame16and connected pivotally at the other end to the control arm14. Alternatively, a damper in the form of a strut may be used in the suspension system, as for example disclosed in U.S. Pat. No. 5,467,971. To provide cushioning in the event a maximum jounce occurs, a jounce bumper cushion22is mounted to the frame16which is resiliently compressed by movement of the control arm as jounce approaches its maximum.

Referring next toFIG. 1A, the internal components and operational aspects of a conventional shock absorber20′ (a remote reservoir high pressure gas type shock absorber being shown merely by way of example) can be understood. A valved piston30is reciprocably movable within a shock cylinder32. A shock rod34is attached to the valved piston30and is guided by a shock rod guide36at one end of the shock cylinder32. Below the valved piston30and above the shock rod guide36is a mutually interacting rebound limiter38. The instantaneous position of the valved piston30within the shock cylinder32defines a first interior portion32F and a second interior portion32S of the interior of the shock cylinder. In the example depicted atFIG. 1A, the pressurization in the first and second interior portions32F,32S is provided by an hydraulic fluid O which is pressurized by pressurized gas, preferably nitrogen, G acting on a divider piston40of an hydraulic fluid reservoir cylinder42, wherein a tube44, including a base valve44V, connects the hydraulic fluid between the hydraulic fluid reservoir cylinder and the first interior portion. In operation, as the control arm undergoes jounce, the hydraulic fluid is displaced from the first interior portion into the hydraulic fluid reservoir cylinder, causing the pressure of the nitrogen gas to increase as its volume decreases and thereby causing an increased hydraulic pressure on the valved piston30in a direction toward the shock rod guide. Hydraulic fluid is able to directionally meter through valving46of the valved piston30in a manner which provides damping.

Referring next toFIG. 1B, the internal structure of a conventional jounce bumper cushion22can be understood. An optional skin50of a compliant material (i.e., having energy absorbing or damping properties) may, or may not, overlay an interior of resilient elastomeric material52, which may be for example a rubber, rubber-like material, or micro-cellular urethane. In operation as the control arm approaches maximum jounce, the jounce bumper cushion22compresses, delivering a reaction force on the control arm which increases with increasing compression so as to minimize the severity of impact of the control arm with respect to the frame at the limit of jounce. Immediately following the jounce, the rebound involves the energy absorbed by the compression of the conventional bumper cushion being delivered resiliently back to the suspension.

In the art of motor vehicle suspension systems, it is known that a conventional jounce bumper cushion and related dampers can show wear. It is also known that when the energy absorbed from a particular bump or dip exceeds the capacity of a conventional jounce bumper cushion, a hard mechanical stop is engaged. This abrupt transfer of jounce force and energy to the frame manifests itself in the passenger compartment as a sharp jolt, which can create load management issues in addition to the discomfort of a rough ride.

What remains needed in the art is a multistage jounce bumper, which can absorb an enhanced level of suspension system jounce force and energy as compared to a conventional jounce bumper cushion, while improving the feel and control of the ride.

SUMMARY OF THE INVENTION

The present invention is a multistage jounce bumper, which absorbs additional jounce force and energy as compared with a conventional jounce bumper cushion of motor vehicles, while improving the feel and control of the ride.

The multistage jounce bumper according to the present invention includes a jounce bumper cushion integrated with a hydraulic jounce bumper. The present invention allows for an enhancement of energy absorption as a vehicle wheel goes into a full jounce position. The present invention provides the damping characteristic of a hydraulic jounce bumper as well as the damping/spring characteristics of a jounce bumper cushion. The hydraulic jounce bumper hydraulic response to a jounce is tunable via adjustment of hydraulic fluid flow with respect to a communicating hydraulic fluid reservoir.

In operation, as maximum jounce is approached, jounce force and energy are exchanged between the knuckle or control arm of the suspension system and the multistage jounce bumper. The jounce bumper cushion provides a first stage of response to the jounce force by providing a resilient reaction force against the jounce force and may absorb jounce energy until it is fully compressed (i.e., saturated). A second stage of response to the jounce force is provided by the hydraulic jounce bumper, which is engaged at a predetermined amount of compression of the jounce bumper cushion (which may be before saturation). Tuning of the initial response of the hydraulic jounce bumper provides a seamless transition of jounce force management to the hydraulic jounce bumper from the jounce bumper cushion. As the hydraulic jounce bumper increases reaction force against the jounce force and absorbs more jounce energy, the feel of the ride stiffens in an increasing manner to minimize the ride disruption and enhancement of load control. Once the hydraulic jounce bumper has absorbed a predetermined maximum amount of jounce energy and/or provides a predetermined maximum reaction force to the jounce force, a third stage of response to the jounce force is provided by a hard stop abutment engagement, either in the form of a mechanical abutment or a hydraulic lock (i.e., force transfer through the incompressible hydraulic fluid) of the hydraulic jounce bumper, whereby the remaining jounce force is transferred directly to the vehicle frame.

Accordingly, it is an object of the present invention to provide a multi-stage jounce bumper, including a j ounce bumper cushion integrated with a hydraulic jounce bumper, which absorbs jounce energy beyond that possible of a conventional jounce bumper cushion alone, while improving the feel and control of the ride.

This and additional objects, features and advantages of the present invention will become clearer from the following specification of a preferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the Drawing,FIG. 2throughFIG. 6depict various aspects of structure and function of a multistage jounce bumper according to the present invention. The multistage jounce bumper is a novel synthesis of a jounce bumper cushion, a tunable hydraulic jounce bumper, and related damper components. The resulting expanded jounce management provides improved feel of the ride and enhances the capacity for load control in high-energy, uneven terrain inputs. While any type of damper may be used with the present invention (see discussion of dampers hereinabove), the most preferred form of damper is a strut.

Referring firstly toFIG. 2, the multistage jounce bumper100according to the present invention is depicted. A lower aspect AL of the multistage jounce bumper100consists of a damper110(i.e., a strut or shock absorber) which is connected to a knuckle or control arm of the suspension system as generally depicted with respect to the shock absorber20ofFIG. 1, wherein the damper has connected to an end thereof a damper bump plate112, and wherein a damper rod114passes through the damper bump plate and is internally hydraulically operable in a shock absorber to provide jounce/rebound damping as generally described hereinabove with respect toFIG. 1Aor operable in a strut type damper as for example disclosed in U.S. Pat. No. 5,467,971, the disclosure of which is hereby herein incorporated by reference. An upper aspect AU of the multi-stage jounce bumper100consists of a jounce bumper cushion120connected to a floating puck124of a hydraulic jounce bumper126, wherein the damper rod114passes therethrough to a connection at a top mount140, which is, itself, affixed with respect to the vehicle frame (such as is generally depicted atFIG. 1).

The jounce bumper cushion120, by way of preferred example, is composed of a resilient material, preferably a urethane material, as generally discussed with respect toFIG. 1B. The jounce bumper cushion120has a predetermined maximum compression limit (i.e., saturation) when compressed or squeezed between the damper bump plate112and the floating puck124(seeFIG. 2B), the details of which will be discussed further hereinbelow.

The hydraulic jounce bumper126consists of a hydraulic cylinder128having a cylinder head128h. The floating puck124serves as a piston movably mounted with respect to the hydraulic cylinder128, which in combination with the hydraulic cylinder and the cylinder head, collectively define a hydraulic fluid filled cavity130, the hydraulic fluid O being preferably oil. A stop ring134is attached to the hydraulic cylinder exterior to the hydraulic fluid filled cavity which serves as a travel limiter of the floating puck. The cylinder head128his also affixed to the top mount140.

The response of the hydraulic jounce bumper126of the multistage jounce bumper100is preferably hydraulically tunable. For example, hydraulic fluid flow may be adjusted through the use of a communicating reservoir150via a control valve (which may be in the form of multistage valving)154and line152, whereby the control valve is selectively set so that it meters, in a predetermined manner, hydraulic fluid flow between the hydraulic fluid filled cavity and the communicating reservoir.

At the communicating reservoir150, a movable piston156separates the hydraulic fluid O from a pressurized gas chamber160. A gas valve158is located at the gas chamber160which provides for selective connection thereto to a source of pressurized gas G, and may serve as a pressure regulator. The hydraulic jounce bumper126may be further tuned by means of adjusting the pressure of the pressurized gas G in the gas chamber160. The piston156prevents the gas G mixing in the hydraulic fluid O and thus compromising the pressure response characteristics of the hydraulic jounce bumper126.

Turning attention now toFIGS. 2A through 2C, operation of the multistage jounce bumper100will be detailed.

Referring first toFIG. 2A, as a vehicle wheel approaches maximum jounce, the damper bump plate112makes contact with the jounce bumper cushion120. As the damper110moves further toward the top mount140(see arrow A inFIG. 2), the jounce bumper cushion120is compressed or squeezed between the damper bump plate112and the floating puck124(which at present remains stationary); whereupon the jounce bumper cushion compresses providing a reaction force to the jounce force and absorption of energy from the jounce motion, which compression constitutes a first stage response of the multistage jounce bumper to the jounce force.

Referring next toFIG. 2B, once a predetermined amount of compression of the jounce bumper cushion120has been reached (ie., it is at a predetermined amount of saturation), the floating puck124force against the hydraulic fluid O in the hydraulic fluid filled cavity130is such that, based upon the hydraulic tuning at the control valve154, the hydraulic fluid begins a metered flow to the communicating reservoir150, whereupon the gas G becomes increasingly pressurized. The jounce bumper cushion may continue to compress further, if at the predetermined amount of compression, saturation of the jounce bumper cushion had not yet been reached. This now constitutes a second stage of response by the multistage jounce bumper to the jounce force. The transition between the first and second stages of response to the jounce force is characterized by the floating puck providing a reaction force to the jounce force which is seamlessly continuous with respect to that provided by the jounce bumper cushion at the point of its predetermined amount of compression.

Referring finally toFIG. 2C, the hydraulic fluid O in the hydraulic fluid filled cavity130will have absorbed a predetermined maximum of jounce energy, whereat a predetermined minimum volume and/or the hydraulic fluid a predetermined maximum pressure hydraulic fluid is attained. Now a third stage response of the multistage jounce bumper to the jounce force will occur, wherein the remainder of the jounce force and energy will be transferred to the frame of the vehicle through the top mount140. In one scenario, the control valve154closes so as to stop hydraulic fluid flow at a preselected pressure indicative of the minimum volume, whereupon the hydraulic fluid O instantly provides a direct conduit of the jounce force to the top mount as it is incompressibly pressurized. In another scenario, the damper110ceases to slide with respect to the damper rod by114, for example by being mutually abuttingly interconnected, whereupon the jounce force is transferred from the damper rod to the top mount. In yet another scenario, a remotely located bump member connected with the moving wheel component abuttingly strikes a frame component.

Turning attention now toFIG. 3A, a first alternative embodiment of a multistage jounce bumper100″ according to the present invention is depicted, which embodiment may be considered the most preferred embodiment. In this first alternative embodiment, the communicating reservoir150′ is integrated with the hydraulic cylinder128′.

The communicating reservoir150′ is integrated with the cylinder head128h′ of a hydraulic cylinder128′ of the hydraulic jounce bumper126′, wherein a piston156′ separates the hydraulic fluid O′ from the pressurized gas G′ of a gas chamber160′. The pressurized gas G′ is introduced by a gas valve158′. A floating puck124′ serves as a movable piston with respect to the hydraulic cylinder128′ and they collectively define a hydraulic fluid filled cavity130′. A ring134′ limits travel of the floating puck with respect to the hydraulic cylinder128′. A control valve (which may be in the form of a multistage valve)154′ tunably meters the flow of hydraulic fluid O′ between the hydraulic fluid filled cavity130′ and the communicating reservoir150′. A jounce bumper cushion120′ is affixed to the floating puck124′. A damper (not shown, but like110inFIG. 2) has a damper bump plate (not shown, but like112inFIG. 2), wherein a damper rod114′ of the damper is connected with a top mount140′. The top mount140′ is connected to the head160h′ of the gas chamber160′.

In operation, much like the operation described with respect toFIGS. 2Athough2C, the damper moves toward the top mount140′ during jounce, whereupon the damper plate abuts the jounce bumper cushion120′ and compresses the jounce bumper cushion during the first stage response. Upon the jounce bumper cushion reaching a predetermined amount of compression, the hydraulic fluid O′ begins to meter through the control valve154′ into the communicating reservoir150′ in the manner described hereinabove with respect to the second stage response ofFIGS. 2Athough2C. Once the hydraulic fluid filled cavity130′ has reached a minimum volume, whereat the hydraulic fluid O′ is pressurized to a predetermined maximum and/or the hydraulic fluid has reached a predetermined maximum pressure, the third stage response is implemented, wherein the jounce force and energy are transmitted to the frame, as for example by any of the second and third aforementioned scenarios.

Turning attention now toFIG. 3B, a second alternative embodiment of a multistage jounce bumper100″ according to the present invention is depicted. In this second alternative embodiment, the order of the jounce bumper cushion120″ and the hydraulic jounce bumper126″ are reversed as compared toFIGS. 2 and 3A, and, by way of example, the communicating reservoir150″ is integrated with the hydraulic cylinder128″. Although not specifically shown, it is clear that the hydraulic jounce bumper126″ may alternatively be integrated within the damper110″.

The communicating reservoir150″ is integrated with the cylinder head128h″ of a hydraulic cylinder128″ of the hydraulic jounce bumper126″, wherein a piston156″ separates the hydraulic fluid O″ from the pressurized gas G″ of a gas chamber160″. The pressurized gas G″ is introduced by a gas valve158″. A floating puck124″ serves as a movable piston with respect to the hydraulic cylinder128″ and they collectively define a hydraulic fluid filled cavity130″. A ring134″ limits travel of the floating puck with respect to the hydraulic cylinder128″. A control valve (which may be in the form of a multistage valve)154″ tunably meters the flow of hydraulic fluid O″ between the hydraulic fluid filled cavity130″ and the communicating reservoir150″. A jounce bumper cushion120″ is affixed to a top mount140″. A damper110″ is connected, via a damper plate112″, to the head160h′ of the gas chamber160″ and has a damper rod114″ connected to the top mount140″.

In operation, much like the operation described with respect toFIGS. 2Athough2C, the damper110″ moves toward the top mount140″ during jounce, whereupon the floating puck124″ abuts the jounce bumper cushion120″ and compresses the jounce bumper cushion during the first stage response. Upon the jounce bumper cushion reaching a predetermined compression, the hydraulic fluid O″ begins to meter through the control valve154″ into the communicating reservoir150″ in the manner described hereinabove with respect to the second stage of response ofFIGS. 2Athough2C. Once the hydraulic fluid filled cavity130″ has reached a minimum volume and/or the hydraulic fluid has attained a predetermined maximum pressure, the third stage is implemented, wherein the jounce force and energy are transmitted to the frame, as for example by any of the second and third aforementioned scenarios.

FIG. 4shows a graph200of the performance of the multistage jounce bumper100as compared to a conventional jounce bumper cushion, each being subjected to two static loads. A first plot202shows the deflection in millimeters produced by a static force of 5,500 Newtons applied to the multistage jounce bumper. A second plot204shows the deflection of multistage jounce bumper when subjected to a static force of 3,500 Newtons. A third plot206shows the displacement produced by a static force of 5,500 Newtons applied to a conventional jounce bumper cushion. A fourth plot shows the deflection of a conventional jounce bumper cushion when subjected to a static force of 3,500 Newtons. These plots show that the multistage jounce bumper allows for an additional 18 millimeters of travel compared to the conventional jounce bumper cushion, thus allowing for an improved over-all management of the jounce force and energy.

FIG. 5shows a graph220of the performance of the multistage jounce bumper100as compared to a conventional jounce bumper cushion, each being subjected to low frequency ramp waves. A first plot222shows the deflection of a conventional jounce bumper cushion subjected to a 4 Hz frequency ramp wave with maximum amplitude of 25 millimeters. A second plot224shows the deflection of a conventional jounce bumper cushion subjected to a 2 Hz frequency ramp wave with maximum amplitude of 25 millimeters. A third plot226shows the deflection of a multistage jounce bumper subjected to a 2 Hz frequency ramp wave with maximum amplitude of 25 millimeters. A fourth plot228shows the deflection of a multistage jounce bumper subjected to a 4 Hz frequency ramp wave with maximum amplitude of 25 millimeters. These plots show that the multistage jounce bumper can absorb a load approximately 1,300 Newtons greater than the conventional jounce bumper cushion.

FIG. 6shows a graph240of the performance of the multistage jounce bumper100as compared to a conventional jounce bumper cushion, each being subjected to low frequency square waves. A first plot242shows the deflection of a conventional jounce bumper cushion subjected to a 2 Hz frequency square wave with maximum amplitude of 25 millimeters. A second plot244shows the deflection of a conventional jounce bumper cushion subjected to a 4 Hz frequency square wave with maximum amplitude of 25 millimeters. A third plot246shows the deflection of a multistage jounce bumper subjected to a 4 Hz frequency square wave with maximum amplitude of 25 millimeters. A fourth plot248shows the deflection of a multistage jounce bumper subjected to a 2 Hz frequency square wave with maximum amplitude of 25 millimeters. These plots show that the multistage jounce bumper can absorb a load approximately 1,500 Newtons greater than the conventional jounce bumper cushion.

To those skilled in the art to which this invention appertains, the above described preferred embodiment may be subject to change or modification. Such change or modification can be carried out without departing from the scope of the invention, which is intended to be limited only by the scope of the appended claims.