Hub-integrated inflation system
A hub-integrated inflation system which functions to convert relative motion at the wheel end (e.g., between the axle and the hub or wheel) into a pumping motion. The relative motion is then converted into mechanical or electrical energy, which can be used to actuate a pump of an inflator.
1. A hub-integrated inflation system for an axle on a vehicle with an axle spindle defining an axis of rotation, the hub-integrated inflation system comprising:
a hub body defining a lubricant cavity;
a bearing spacer, arranged within the hub body, that is circumferentially mounted to the axle spindle;
a floating cam arranged within the lubricant cavity, the floating cam defining:
a follower surface;
a concave reference surface arranged radially inward of the follower surface, wherein the concave reference surface contacts an outer surface of the bearing spacer over a contact area and cooperatively defines a gap with the outer surface of the bearing spacer, wherein the gap is diametrically opposed to the contact area across the bearing spacer;
a pump mounted to the hub body; and
a cam follower mechanically coupled to the pump;
wherein the hub-integrated inflation system is operable between:
a pumping mode, wherein the pump is mechanically coupled to the bearing spacer via the cam follower and the floating cam; and
a non-pumping mode, wherein the pump is decoupled from the bearing spacer.
2. The hub-integrated inflation system of claim 1 , further comprising a selective engagement mechanism, wherein a normal force exerted by the floating cam on the bearing spacer is larger in the pumping mode than in the non-pumping mode, wherein the selective engagement mechanism changes the normal force exerted by the floating cam on the bearing spacer.
3. The hub-integrated inflation system of claim 2 , wherein the follower surface defines a concave dimple, wherein the selective engagement mechanism further comprises a stopper precluding radial extension of the cam follower beyond a bottom of the dimple.
4. The hub-integrated inflation system of claim 1 , wherein a pump interior is fluidly connected to a hub exterior in a non-pumping state, wherein the pump interior is fluidly connected to a tire interior in the pumping mode.
5. The hub-integrated inflation system of claim 1 , wherein the hub body defines a pump cavity extending through a radial hub thickness, wherein the pump is arranged inside the pump cavity.
6. The hub-integrated inflation system of claim 5 , wherein the hub body further defines a lubricant fill hole extending through the radial hub thickness, wherein the pump cavity is separate and distinct from the lubricant fill hole.
7. The hub-integrated inflation system of claim 1 , wherein the floating cam defines a set of lobes.
8. The hub-integrated inflation system of claim 1 , wherein the floating cam is disengaged from the bearing spacer in the non-pumping mode.
9. A hub-integrated inflation system for a vehicle, the hub-integrated inflation system comprising:
a hub body defining an axis of rotation, the hub body configured to rotatably mount to a static axle component;
a cam encircling the static axle component, the cam defining:
an inner reference surface defining a central axis parallel to and offset from the axis of rotation; and
an asymmetric follower surface arranged radially outward of the inner reference surface;
an output component mounted to the hub body; and
a cam follower selectively connecting the output component to the follower surface.
10. The hub-integrated inflation system of claim 9 , wherein the output component comprises a piston pump.
11. The hub-integrated inflation system of claim 9 , further comprising a selective engagement mechanism configured to selectively statically retain the cam relative to the hub body.
12. The hub-integrated inflation system of claim 11 , the selective engagement mechanism comprising at least one dimple, the dimple arranged proximate the follower surface, the dimple located at a local minimum of a radial thickness of the cam.
13. The hub-integrated inflation system of claim 9 , wherein the inner radius of the cam is larger than an outer radius of the static axle component.
14. The hub integrated inflation system of claim 13 , wherein the inner reference surface and the static axle component each define circular cross sections.
15. The hub-integrated inflation system of claim 13 , wherein the static axle component comprises a bearing spacer coaxially aligned with the axis of rotation.
16. The hub-integrated inflation system of claim 9 , wherein the cam follower is arranged radially outward of the follower surface.
17. The hub-integrated inflation system of claim 9 , wherein the system outputs a torque of less than 50 inch-ounces on the output component.
18. The hub integrated inflation system of claim 9 , wherein the static axle component comprises a static axle spindle.
19. The hub integrated inflation system of claim 9 , wherein the cam is freely rotatable about the static axle component.
20. A system, comprising:
a vehicle comprising an axle spindle, the axle spindle defining an axis of rotation;
a hub body, the hub body configured to rotatably mount a wheel and a tire to the axle spindle about the axis of rotation, the wheel configured to rotate with a first angular frequency;
a piston pump radially mounted to the hub body;
a cam defining:
a circular inner arcuate surface encircling the axle spindle, the inner arcuate surface defining a central axis offset from the axis of rotation; and
a noncircular outer arcuate surface defining a set of lobes, the outer arcuate surface configured to rotate with a second angular frequency different from the first angular frequency; and
a cam follower selectively connecting to the outer arcuate surface to the piston pump.