Engine valve actuation systems with lost motion valve train components, including collapsing valve bridges with locking pins
Systems for valve actuation in internal combustion engines provide configurations for collapsing valve train components, particularly collapsing valve bridges. Various configurations for locking a bridge piston to a bridge housing include substantially cylindrical locking pins that may be housed within a substantially cylindrical receptacles defined by a transverse bore in the bridge piston and actuated hydraulically and may include an actuating pin that interacts with the locking pins to synchronize motion and provide positive positioning within an annular recess in the bridge housing to lock or unlock the bridge piston for movement relative to the bridge housing. Various geometries for locking pins and actuating pins provide benefits of manufacturing, ease of assembly, alignment and reduced wear.
1. In an internal combustion engine comprising a valve train for actuating one or more engine valves, a device for controlling motion applied to the one or more engine valves, comprising:
a housing disposed within the valve train, the housing including a housing bore and at least one housing locking surface;
a piston disposed within the housing bore, the piston having a piston bore and at least one locking pin receptacle defined therein, the at least one locking pin receptacle having a cylindrical shape;
a locking assembly for selectively locking the piston to the housing, the locking assembly comprising an actuator pin supported for movement within the piston bore and at least one respective locking pin disposed in the at least one locking pin receptacle, the at least one locking pin having a cylindrical surface for supporting the at least one locking pin in a respective one of the at least one locking pin receptacle, the actuator pin including an outer locking pin engagement surface adapted to support the at least one locking pin in an extended position, and an inner locking pin support surface adapted to support the at least one locking pin in a retracted position, whereby movement of the actuator pin causes the at least one locking pin to selectively engage or disengage the housing locking surface thereby selectively locking or unlocking the piston relative to the housing, wherein the at least one locking pin includes a locking pin alignment surface adapted to maintain the locking pin in an aligned orientation relative to the actuator pin as the locking pin moves to the retracted position.
2. The device of claim 1 , wherein the actuator pin includes a transition surface extending from the outer locking pin engagement surface to the inner locking pin engagement surface and wherein the locking pin alignment surface comprises a chamfer on the locking pin adapted to engage the transition surface and maintain alignment of the locking pin with the actuator pin.
3. The device of claim 2 , wherein the transition surface is conical and wherein the locking pin alignment surface comprises a conical chamfer.
4. The device of claim 1 , wherein the at least one locking pin includes at least two locking pin alignment surfaces adapted to maintain the locking pin in an aligned orientation relative to the actuator pin as the locking pin moves to the retracted position.
5. The device of claim 4 , wherein the actuator pin includes first and second transition surfaces extending from the outer locking pin engagement surface to the inner locking pin engagement surface and wherein the at least two locking pin alignment surfaces comprise a first and second chamfer on the locking pin adapted to engage the first and second transition surfaces and maintain alignment of the locking pin with the actuator pin.
6. The device of claim 1 , wherein the housing locking surface is defined in an annular recess in the housing bore.
7. The device of claim 1 , wherein the housing locking surface is an inclined surface relative to an axis of the housing bore and wherein the at least one locking pin includes a housing engagement surface that is shaped complementarily to the housing locking surface.
8. The device of claim 1 , wherein the housing locking surface has the shape of a conical frustum and wherein the at least one locking pin includes a housing engagement surface that is shaped complementarily to the housing locking surface.
9. The device of claim 1 , wherein the housing is a valve bridge.
10. The device of claim 1 , wherein the at least one locking pin includes at least two asymmetrical actuator pin engagement surfaces for engaging the actuator pin such that only a single orientation of the locking pin in the locking pin receptacle allows the locking pin to be fully retracted into the piston.
11. The device of claim 10 , wherein the at least one locking pin includes asymmetrical conical actuator pin engagement surfaces.
12. The device of claim 1 wherein the locking pin includes a conical surface for engaging the housing surface and a guiding surface extending above the conical surface for guiding the at least one locking pin within the locking pin receptacle.
13. The device of claim 1 , wherein the at least one locking pin includes a pair of conical surfaces for engaging the actuator pin.
14. The device of claim 1 , wherein the at least one locking pin receptacle is dimensioned to accommodate tilting of the locking pin within the locking pin receptacle.
15. The device of claim 1 , wherein the at least one locking pin receptacle comprises two axially aligned locking pin receptacles.