Compact switchable hydraulic lash adjuster with hydraulic lost motion assist
View Patent ↗An improved deactivation hydraulic lash adjuster wherein the prior art lost motion spring or springs formerly located within the body of the DHLA and below the pin housing are either omitted completely or are reduced in length, spring force, and/or number and are augmented hydraulically, allowing a shorter, more compact lifter body and reduced overall lifter length. The prior art lost motion spring chamber becomes a hydraulic chamber connected to a new pressurized oil supply gallery containing an accumulator in the engine. An embodiment having no lost motion spring and solely hydraulic lost motion return can be even shorter than a spring-hydraulic hybrid because the potential hydraulic pressure to be brought against the pin housing is not a function of the length of the lost motion chamber, which length is limited only by the required displacement of the pin housing.
1. A system for providing selective deactivation of a valve in an internal combustion engine, comprising:
a) a deactivation mechanism including a body having an axial bore; a housing slidably disposed in said axial bore wherein said body and said housing conjunctively define a hydraulic chamber adjacent an end of said housing, said hydraulic chamber configured for receiving pressurized oil; a locking mechanism for selectively preventing axial translation of said housing into said body; wherein said body includes a port for admittance of said pressurized oil into said chamber;
b) a pressurized oil supply for supplying said pressurized oil into said chamber via an oil gallery; and
c) an accumulator in communication with said gallery for receiving a volume of oil substantially equal to the volume of oil displaced from said chamber during lost motion of said housing.
2. A system in accordance with claim 1 further comprising a check valve disposed in said gallery between said pressurized oil supply and said accumulator and said body.
3. A system in accordance with claim 1 wherein said accumulator comprises:
a) a cylinder;
b) a piston slidably disposed within said cylinder and in oil communication with said gallery on a first side thereof; and
c) a bias spring disposed within said cylinder and operative again a second side of said piston.
4. A system in accordance with claim 1 comprising a plurality of said deactivation mechanism for variably deactivating a plurality of valves in a multiple-valve engine, wherein said plurality of deactivation mechanisms are connected in parallel to a single pressurized oil supply and accumulator.
5. A system in accordance with claim 1 wherein said locking mechanism includes a lock pin and a plug disposed in axial alignment with said lock pin, and wherein said body includes a longitudinal slot for receiving an end of said plug and wherein a spring is disposed between said at lock pin and said plug.
6. An internal combustion engine comprising a system for providing selective deactivation of a valve in an internal combustion engine, wherein said system includes,
a deactivation mechanism including a body having an axial bore; a housing slidably disposed in said axial bore wherein said body and said housing conjunctively define a hydraulic chamber adjacent an end of said housing, said hydraulic chamber configured for receiving pressurized oil; a locking mechanism for selectively preventing axial translation of said housing into said body; wherein said body includes a port for admittance of said pressurized oil into said chamber,
a pressurized oil supply for supplying said pressurized oil into said chamber via an oil gallery, and
an accumulator in communication with said gallery for receiving a volume of oil substantially equal to the volume of oil displaced from said chamber during lost motion of said housing.