Development of a switching roller finger follower for cylinder deactivation in internal combustion engines
A system includes a rocker arm assembly for operative engagement with a first and second cam. The assembly includes a first arm for operatively engaging the first cam for a first desired lift profile, a second arm for operatively engaging the second cam for a second desired lift profile, where the second arm includes a latch to engage the second arm with the first arm. The latch is responsive to supplied oil pressure and release oil pressure to switch between lift profiles. The system includes the latch coupled to the supplied or released oil pressure to engage the arms before the first and second arms are engaged with the base circle portion of each of the respective first and second cams.
1. A system for preloading a latch used in controlling variable valve actuation in an internal combustion engine, the system comprising:
a rocker arm assembly for operative engagement with a first and second cam, wherein each of the first and second cam comprise a base circle portion and a lift portion;
the rocker arm assembly comprising: a first arm for operatively engaging the first cam for a first desired lift profile, a second arm for operatively engaging the second cam for a second desired lift profile, the second arm comprising a selectively-activatable latch to operatively engage the second arm with the first arm;
an oil control valve structured to receive electronic communications from an electronic control unit (ECU), operatively coupled to the rocker arm assembly and at least one of supplying and releasing oil pressure to operate the latch; and
wherein the oil control valve responds to an electronic communication to at least one of supply oil pressure or release oil pressure prior to the first and second arms being engaged with the base circle portion of each of the respective first and second cams.
2. The system of claim 1 , wherein the rocker arm is fluidly coupled to a hydraulic lash adjuster, and wherein the oil control valve provides the supplied oil pressure via the hydraulic lash adjuster, and wherein the hydraulic lash adjuster is a dual feed hydraulic lash adjuster.
3. The system of claim 2 , wherein the selectively-activatable latch is disposed adjacent a first end of the rocker arm, and where the hydraulic lash adjuster is fluidly coupled to the rocker arm at a position adjacent the first end of the rocker arm.
4. The system of claim 1 , wherein the selectively-activatable latch comprises a circular cross-section.
5. The system of claim 4 , wherein the first arm comprises an arcuate latch seat, wherein the selectively-activatable latch in an extended position engages the arcuate latch seat to operatively engage the second arm with the first arm.
6. The system of claim 1 , wherein the first arm comprises a cam-contacting member to engage the first cam, and wherein the cam-contacting member comprises a slider pad.
7. The system of claim 6 , further comprising at least one biasing spring disposed between the first arm and the second arm, the at least one biasing spring biasingly coupled to the cam-contacting member.
8. A system for preloading a latch used in controlling variable valve actuation in an internal combustion engine having a first and second cam each comprising a base circle portion and a lift portion, the system comprising:
a rocker arm assembly for operative engagement with the cams;
the rocker arm assembly comprising: a first arm for operatively engaging the first cam for a first desired lift profile, a second arm for operatively engaging the second cam for a second desired lift profile, the second arm comprising a selectively-activatable latch to operatively engage the second arm with the first arm;
the selectively-activatable latch responsive to at least one of supplied oil pressure and released oil pressure; and
wherein the selectively-activatable latch is structured to switch between one of the first desired lift profile and the second desired lift profile to the other of the first desired lift profile and the second desired lift profile, wherein the switching comprises the selectively-activatable latch being coupled to at least one of supplied oil pressure and released oil pressure prior to the first and second arms being engaged with the base circle portion of each of the respective first and second cams.
9. The system of claim 8 , wherein the rocker arm is fluidly coupled to a hydraulic lash adjuster, and wherein the oil control valve provides the supplied oil pressure via the hydraulic lash adjuster, and wherein the hydraulic lash adjuster is a dual feed hydraulic lash adjuster.
10. The system of claim 9 , wherein the selectively-activatable latch comprises a circular cross-section.
11. The system of claim 10 , wherein the first arm comprises an arcuate latch seat, wherein the selectively-activatable latch in an extended position engages the arcuate latch seat to operatively engage the second arm with the first arm.
12. The system of claim 11 , wherein the first arm comprises a cam-contacting member to engage the first cam, and wherein the cam-contacting member comprises a slider pad.
13. The system of claim 12 , further comprising at least one biasing spring disposed between the first arm and the second arm, the at least one biasing spring biasingly coupled to the cam-contacting member.
14. The system of claim 13 , wherein the selectively-activatable latch is disposed adjacent a first end of the rocker arm, and where the hydraulic lash adjuster is fluidly coupled to the rocker arm at a position adjacent the first end of the rocker arm.
15. A system for preloading a latch used in controlling variable valve actuation in an internal combustion engine, the system comprising:
at least a first and second cam each comprising a base circle portion and a lift portion;
a rocker arm assembly for operative engagement with the cams,
the rocker arm assembly comprising: a first arm for operatively engaging the first cam for a first desired lift profile, a second arm for operatively engaging the second cam for a second desired lift profile, the second arm comprising a selectively-activatable latch to operatively engage the second arm with the first arm; and
an oil control valve structured to receive a switching communication that commands switching between one of the first desired lift profile and the second desired lift profile to the other of the first desired lift profile and the second desired lift profile, the oil control valve operatively coupled to the rocker arm assembly and responsive to the switching command to at least one of supply and release oil pressure to operate the latch prior to the first and second arms being engaged with the base circle portion of each respective first and second cams.
16. The system of claim 15 , wherein the rocker arm is fluidly coupled to a hydraulic lash adjuster, and wherein the oil control valve provides the supplied oil pressure via the hydraulic lash adjuster, and wherein the hydraulic lash adjuster is a dual feed hydraulic lash adjuster.
17. The system of claim 15 , wherein the selectively-activatable latch comprises a circular cross-section.
18. The system of claim 17 , wherein the first arm comprises an arcuate latch seat, wherein the selectively-activatable latch in an extended position engages the arcuate latch seat to operatively engage the second arm with the first arm.
19. The system of claim 18 , wherein the first desired lift profile comprises a high lift profile, and wherein the second desired lift profile comprises a low lift profile.
20. The system of claim 15 , wherein the first arm comprises a cam-contacting member to engage the first cam, and wherein the cam-contacting member comprises a slider pad.
21. The system of claim 19 , further comprising at least one biasing spring disposed between the first arm and the second arm, the at least one biasing spring biasingly coupled to the cam-contacting member.