Method and apparatus for mitigating static loads in components connecting multiple structures
An apparatus and method are described where one or more pre-stressed spring elements are disposed between two structures to mitigate or cancel the effect of static loads applied to an component connecting the structures. The apparatus and methods may be used, for example, to reduce the adverse impact of static loads on the performance of top-mounts in a suspension system of a vehicle.
1. A top-mount assembly for attaching a suspension component to a vehicle body, the top-mount assembly comprising:
a top-mount bracket;
a strike plate at least partially surrounded by the top mount bracket and configured to be attached to a piston rod of the suspension component; and
a resilient material interposed between the top-mount bracket and the strike plate;
wherein the resilient material has a stiffness that varies as a function of a position of the strike plate relative to the top-mount bracket,
wherein the stiffness has a first value in a first range of positions of the strike plate relative to the top-mount bracket, a second value substantially greater than the first value in a second range of positions of the strike plate relative to the top-mount bracket, and a third value substantially greater than the first value in a third range of positions of the strike plate relative to the top-mount bracket;
wherein application of a predetermined rod force to the strike plate causes the strike plate to be displaced from a first position to a second position relative to the top mount bracket, wherein the second position of the strike plate is more centrally located within the first range of positions than the first position of the strike plate.
2. The top mount assembly of 1 , wherein the suspension component is selected from the group consisting of a passive damper, an active damper, a semi-active dampers, and a magnetorheological damper.
3. The top mount assembly of claim 2 , wherein the predetermined rod force is a force applied by a piston rod of the suspension component under static conditions.
4. The top mount assembly of claim 1 , wherein the resilient material is at least partially made of an elastomer.
5. The top mount assembly of claim 4 , wherein the elastomer includes rubber.
6. The top mount assembly of claim 1 , wherein resilient material is molded onto the strike plate.
7. The top mount assembly of claim 1 , wherein the first value is less than 1000 newtons per millimeter and the second and third values are greater than 1000 newtons per millimeter.
8. The top mount assembly of claim 7 , wherein the second and the third values are greater than 1000 newtons per millimeter.
9. The top mount assembly of claim 1 , wherein the predetermined rod force is between 800 newtons and 900 newtons.
10. The top mount assembly of claim 1 , wherein the first position is a neutral position of the strike plate.
11. The top mount assembly of claim 10 , wherein when the strike plate is located at the neutral position, at least a portion of the resilient material is prestressed.
12. The actuator assembly of claim 1 , wherein the static force is between 800 newtons and 900 newtons.
13. The actuator assembly of claim 1 , wherein at the first position, movement of the strike plate relative to the bracket in one direction always results in a net force applied to the strike plate by the resilient material in a first direction and movement of the strike plate relative to the bracket in an opposite direction always produces a force in a second direction that is opposite the first direction.
14. An actuator assembly for a vehicle, the actuator assembly comprising:
a hydraulic actuator that includes:
a damper body;
a rod protruding from the damper body;
a top mount that includes:
a strike plate that is affixed to the rod;
a top-mount bracket at least partially surrounding the strike plate; and
a resilient material interposed between the top-mount bracket and the strike plate;
wherein the stiffness of the resilient material varies as a function of position of the strike plate relative to the top-mount bracket;
wherein the stiffness of the resilient material has a first value in a first range of positions of the strike plate relative to the top-mount bracket, a second value substantially greater than the first value in a second range of positions of the strike plate relative to the top-mount bracket, and a third value substantially greater than the first value in a third range of positions of the strike plate relative to the top-mount bracket; and
wherein, under static conditions of the hydraulic actuator, the piston rod transmits a static force to the strike plate that causes the strike plate to be displaced from a first position to a second position relative to the top mount bracket, wherein the second position of the strike plate is more centrally located within the first range of positions than the first position of the strike plate.
15. The actuator assembly of claim 14 , wherein the resilient material is at least partially constructed of an elastomer.
16. The actuator assembly of claim 15 , wherein the elastomer includes rubber.
17. The actuator assembly of claim 14 , wherein the resilient material is molded onto the strike plate.
18. The actuator assembly of claim 14 , wherein the first value is less than 1000 newtons per millimeter and the second and third values are greater than 1000 newtons per millimeter.
19. A method of assembling an actuator assembly in a vehicle, the method comprising:
attaching a piston rod of a hydraulic actuator to a strike plate of a top mount, wherein the hydraulic actuator is configured to apply a force to the strike plate;
wherein the top mount includes the strike plate, a top mount bracket, and a resilient material interposed between the top-mount bracket and the strike plate, wherein the stiffness of the resilient material has a first value in a first range of positions of the strike plate relative to the top-mount bracket, a second value substantially greater than the first value in a second range of positions of the strike plate relative to the top-mount bracket, and a third value substantially greater than the first value in a third range of positions of the strike plate relative to the top-mount bracket; and
after attaching the piston rod and with the hydraulic actuator under static conditions, transmitting a static force from the piston rod to the strike plate, thereby displacing the strike plate from neutral first position relative to the top mount bracket to a second position relative to the top mount bracket, wherein the second position is more centrally located within the first range of positions than the first position of the strike plate.