Internal-combustion engines – Charge forming device – Exhaust gas used with the combustible mixture
Reexamination Certificate
2000-07-31
2001-06-12
Yuen, Henry C. (Department: 3748)
Internal-combustion engines
Charge forming device
Exhaust gas used with the combustible mixture
C123S090120, C123S090390, C123S090460
Reexamination Certificate
active
06244257
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to internal combustion engines, and more particularly to internal combustion engines with valves that are opened by cams cooperating with hydraulic circuits to produce at least one of a main exhaust event, an engine regarding event and an exhaust gas recirculation event. The valves are partly controlled by electrically operated hydraulic fluid valves to modify the timing and duration of the events.
BACKGROUND OF THE INVENTION
In most internal combustion engines the engine cylinder intake and exhaust valves are opened and closed (at least for the most part) by cams in the engine. This makes it relatively difficult and perhaps impossible to adjust the timings and/or amounts of engine valve openings to optimize those openings for various engine operating conditions such as changes in engine speed.
It is known to include hydraulic lash adjusting mechanisms in the linkage between an engine cam and the engine cylinder valve controlled by that cam to make it possible to make relatively small adjustments in the valve strokes relative to the profile of the cam (see, for example, Rembold, et al., U.S. Pat. No. 5,113,812 and Schmidt et al., U.S. Pat. No. 5,325,825). These lash adjustments may be used to provide additional valve openings when it is desired to convert the engine from positive power mode to compression release engine braking mode (see, for example, Cartledge, U.S. Pat. No. 3,809,033 and Gobert et al., U.S. Pat. No. 5,145,890). Hydraulic circuitry may also be used to cause apart of the engine other than the cam which normally controls an engine valve to provide additional openings of the valve when it is desired to convert the engine from positive power mode to compression release engine braking mode (see, for example, Cummins, U.S. Pat. No. 3,220,392, and Hu, U.S. Pat. No. 5,379,737).
Schechter, U.S. Pat. No. 5,255,641, shows in
FIG. 16
that an engine cam can be linked to an engine cylinder valve by a hydraulic circuit which includes a solenoid valve for selectively releasing hydraulic fluid from the hydraulic circuit. Schechter points out that various phases of the engine cylinder valve lift versus the cam curve can be obtained by varying the solenoid voltage pulse timing and duration. However, Schechter does not suggest that any lobe on the cam can be completely overridden in this way. It may not be possible to convert an engine from positive power mode to compression release engine braking mode and vice versa without the ability to selectively completely override any lobe on an engine cam.
Sickler, U.S. Pat. No. 4,572,114, shows internal combustion engine cylinder valve control which essentially uses two substantially separate hydraulic circuits for controlling the motion of each engine cylinder valve. One of these two hydraulic circuits controls selective decoupling of each engine cylinder valve from its normal cam-driven mechanical input. The other hydraulic circuit provides alternative hydraulic inputs to the engine cylinder valve when the normal mechanical input is decoupled. The control for these two hydraulic systems may be essentially mechanical and/or hydraulic as shown in
FIG. 5
of the Sickler patent, or it may be essentially electronic as shown in FIG.
7
. The two hydraulic circuits may have a common source of hydraulic fluid and they may have other cross-connections, but they are largely separate in operation and they each require a separate hydraulic connection (e.g.,
136
and
212
in
FIG. 5
, or
258
and
212
in
FIG. 7
) to each cylinder valve operating mechanism.
From the foregoing it will be seen that the known hydraulic modifications of cam control for engine cylinder valves tend to be either relatively limited in extent and purpose (e.g., as in
FIG. 16
of the Schechter patent), or tend to require relatively complex hydraulic circuitry (e.g., as in the Sickler patent).
OBJECTS OF THE INVENTION
It is therefore an object of this invention to provide improved and simplified hydraulic circuitry which can be used to more extensively modify the operation of engine cylinder valves in response to engine cams.
It is another object of this invention to provide relatively simple hydraulic circuitry which can be used selectively to partly or completely suppress any engine valve operation associated with the engine cam that otherwise controls that engine valve, for example, switch the engine between positive power mode operation, compression release engine braking mode operation and exhaust gas recirculation mode operation and/or to adjust the timing of engine valve openings for various engine operating conditions.
SUMMARY OF THE INVENTION
These and other objects of the invention are accomplished in accordance with the principles of the invention by providing a hydraulic circuit linkage in the connection between an engine cam and an engine valve associated with that cam. The hydraulic circuit is partly controlled by an electrically operated hydraulic valve (e.g., for selectively relieving hydraulic fluid pressure in the hydraulic circuit). The hydraulic circuit is preferably constructed so that when the electrically operated hydraulic valve relieves hydraulic fluid pressure in that circuit, there is sufficient lost motion between the mechanical input to the circuit and the mechanical output from the circuit to prevent any selected cam function or functions including but not limited to engine braking, compression release retarding, and exhaust gas recirculation from being transmitted to the engine valve associated with that cam. This allows the electrically controlled hydraulic circuit to fully control which cam function(s) the associated engine valve will respond to and which cam function(s) the engine valve will not respond to. In addition, the electrically operated hydraulic circuit can modify the response of the engine valve to various cam functions (e.g., to modify the timing of engine valve responses to those cam functions). In the preferred embodiments only a single hydraulic fluid connection to the mechanism of each valve is needed. Also in the preferred embodiments the ultimate input for all openings of each engine valve comes from a single cam that is associated with that valve.
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patent: 4793307 (1988-12-01), Quenneville et al.
patent: 5000145 (1991-03-01), Quenneville
patent: 5036810 (1991-08-01), Meneely
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Collier Shannon Scott PLLC
Diesel Engine Retarders, Inc.
Vo Hieu T.
Yohannan David R.
Yuen Henry C.
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