System and method for controlling the amount of lost motion between an engine valve and a valve actuation means

Claim 2

An internal combustion engine lost motion valve actuation system, comprising: a variable length connection means for transmitting a valve actuation force from a force source to a valve, said connection means having an internal hydraulic fluid chamber of variable volume and being adapted to assume a predetermined minimum length for providing at least one minimum valve opening event which is greater than zero; and a control means for controlling the length of the variable length connection means, said control means being adapted to vary the length of the connection means one or more times per cycle of said engine by selectively blocking and unblocking a hydraulic fluid drain in communication with said chamber independent of the position of the force source.

Claim 3

The system of claim 1 wherein the connection means comprises a variable length tappet that includes the internal hydraulic fluid chamber of variable volume.

Claim 4

The system of claim 2 wherein the control means comprises a trigger valve in hydraulic communication with said hydraulic fluid chamber in the tappet.

Claim 5

The system of claim 2 wherein said tappet comprises a master piston slidably disposed within a bore of a slave piston such that said chamber is formed between the pistons.

Claim 6

The system of claim 4 further comprising a means for biasing said master piston into the slave piston bore to thereby cause the connection means to assume a minimum length.

Claim 7

The system of claim 2 wherein said tappet comprises a master piston and a slave piston of unequal diameters.

Claim 8

The system of claim 5 wherein the means for biasing comprises a spring.

Claim 9

The system of claim 1 wherein said control means causes said connection means to assume a first length when the engine is in a positive power mode and to assume a second length when the engine is in an engine braking mode.

Claim 10

The system of claim 3 wherein the control means further comprises an electronic controller operatively connected to said trigger valve.

Claim 11

The system of claim 1 further comprising a second variable length connection means for transmitting a valve actuation force to a second valve, the length of which may be controlled by said control means.

Claim 12

The system of claim 2 wherein said tappet is disposed between a valve rocker arm and a valve push tube.

Claim 13

The system of claim 2 wherein said tappet is disposed between a valve stem and a valve rocker arm.

Claim 14

The system of claim 2 wherein said tappet is disposed between a valve push tube and a valve cam.

Claim 15

The system of claim 2 wherein said tappet is disposed between a valve rocker arm and a valve cam.

Claim 16

The system of claim 2 wherein said tappet is disposed between a valve stem and a valve cam.

Claim 17

The system of claim 2 wherein said tappet comprises an outer piston which also serves as a cross head for applying a valve actuation force to two or more valves.

Claim 18

The system of claim 1 wherein said control means comprises an electronically controlled solenoid switch.

Claim 19

The system of claim 2 wherein said hydraulic fluid comprises oil.

Claim 20

The system of claim 1 wherein said control means selectively controls the length of the connection means such that the valve actuation for a compression release valve event is absorbed by the connection means.

Claim 21

The system of claim 1 wherein said control means selectively controls the length of the connection means such that the valve actuation for an exhaust gas recirculation valve event is absorbed by the connection means.

Claim 22

The system of claim 1 wherein said connection means minimum length enables the valve to be opened for positive power events and reduces the valve lift for a compression release valve event or an exhaust gas recirculation valve event.

Claim 23

The system of claim 1 wherein said connection means may be selectively varied in length to individually vary the dwell and lift of one or more events of the group consisting of a positive power valve event, a compression release valve event, and an exhaust gas recirculation valve event.

Claim 24

The system of claim 1 further comprising a manually adjustable valve lash adjuster in a valve train intermediate the force source and the valve.

Claim 25

The system of claim 4 wherein a bottom surface of said master piston is stepped.

Claim 26

The system of claim 4 wherein a bottom surface of said master piston is chamfered.

Claim 27

The system of claim 4 further comprising a guide housing in which said slave piston is disposed.

Claim 28

The system of claim 26 wherein said guide housing comprises a rocker arm pedestal.

Claim 29

The system of claim 27 wherein said control means is disposed in a bore in said rocker arm pedestal.

Claim 30

In an internal combustion engine valve actuation system, a hydraulic system for controlling the amount of lost motion between a means for opening an engine cylinder valve and a valve, comprising: a source of pressurized hydraulic fluid having an outgoing fluid feeding conduit; a variable length tappet having an internal expansible chamber in communication with the fluid feeding conduit and with a fluid bleeding conduit, and being adapted to assume a minimum operable length; and means for selectively blocking and unblocking said fluid bleeding conduit at a sufficient rate to vary the length of the tappet at least once per cycle of the engine independent of the position of the means for opening the engine cylinder valve, wherein the blocking of the fluid bleeding conduit causes said chamber to retain fluid and expand thereby increasing the length of the tappet and decreasing the amount of lost motion between the means for opening and the valve, and wherein the unblocking of the fluid bleeding conduit causes said chamber to drain off fluid and contract, thereby decreasing the length of the tappet and increasing the amount of lost motion between the means for opening and the valve.

Claim 31

In an internal combustion engine valve actuation system, a hydraulic system for controlling the amount of lost motion between a means for opening an engine cylinder valve and a valve, comprising: a source of pressurized hydraulic fluid having an outgoing fluid feeding conduit; a variable length tappet having an internal expansible chamber in communication with the fluid feeding conduit and with a fluid bleeding conduit, and being adapted to assume a minimum operable length; and means for selectively blocking and unblocking said fluid bleeding conduit at a sufficient rate to vary the length of the tappet at least once per cycle of the engine independent of the position of the means for opening the engine cylinder valve, wherein the blocking of the fluid bleeding conduit causes said chamber to retain fluid and expand thereby increasing the length of the tappet and decreasing the amount of lost motion between the means for opening and the valve, and wherein the unblocking of the fluid bleeding conduit causes said chamber to drain off fluid and contract, thereby decreasing the length of the tappet and increasing the amount of lost motion between the means for opening and the valve.

Claim 32

The system of claim 29 wherein said means for opening an engine cylinder valve comprises a Y-shaped rocker arm having common operable connection with first and second tappets.

Claim 33

An internal combustion engine comprising: a valve train including a hydraulic linkage operably coupled between an engine cylinder valve and an engine cam, said valve train and hydraulic linkage being provided to transmit a force for opening the valve from one or more lobes on said cam to the valve; and a hydraulic linkage control for selectively controlling the length of said hydraulic linkage to selectively modify the openings of said valve in response to a force transmitted from said cam lobes, said hydraulic linkage control being carried out independent of the position of the engine cam wherein said hydraulic linkage comprises a master piston and a slave piston, each of which are slidably disposed in the hydraulic linkage relative to each other such that the hydraulic linkage may selectively assume plural lengths, and wherein said engine cylinder valve is an exhaust valve and said lobes include one or more of the group consisting of an exhaust lobe, a compression release lobe and an exhaust gas recirculation lobe, and wherein said hydraulic linkage control is responsive to whether said engine is in a positive power mode of operation or a compression release engine braking mode of operation by controlling the length of the hydraulic linkage so that the exhaust valve opens in response to one or more of the group consisting of said compression release lobe and said exhaust gas recirculation lobe only when said engine is in said compression release engine braking mode.

Claim 34

An internal combustion engine comprising: a valve train including a hydraulic linkage operably coupled between an engine cylinder valve and an engine cam, said valve train and hydraulic linkage being provided to transmit a force for opening the valve from one or more lobes on said cam to the valve; and a hydraulic linkage control for selectively controlling the length of said hydraulic linkage to selectively modify the openings of said valve in response to a force transmitted from said cam lobes, said hydraulic linkage control being carried out independent of the position of the engine cam wherein said hydraulic linkage comprises a master piston and a slave piston, each of which are slidably disposed in the hydraulic linkage relative to each other such that the hydraulic linkage may selectively assume plural lengths, and wherein said engine cylinder valve is an exhaust valve and said lobes include one or more of the group consisting of an exhaust lobe, a compression release lobe and an exhaust gas recirculation lobe, and wherein said hydraulic linkage control is responsive to whether said engine is in a positive power mode of operation or a compression release engine braking mode of operation by controlling the length of the hydraulic linkage so that the exhaust valve opens in response to one or more of the group consisting of said compression release lobe and said exhaust gas recirculation lobe only when said engine is in said compression release engine braking mode.

Claim 35

In an internal combustion engine valve actuation system, a method of controlling the amount of lost motion between a means for opening an engine cylinder valve and a valve during engine operation, comprising the steps of: a) providing hydraulic fluid to an internal expansible chamber of a variable length tappet disposed in a valve train linking the means for opening and the valve; and b) selectively bleeding hydraulic fluid from the expansible chamber to decrease the amount of hydraulic fluid in the chamber and decrease the length of the tappet, to thereby increase the amount of lost motion between the means for opening and the valve, wherein the step of selectively bleeding is controlled such that the amount of hydraulic fluid in the chamber may be varied one or more times per cycle of the engine and independently of the position of the means for opening an engine cylinder valve.

Claim 36

In an internal combustion engine valve actuation system, a method of controlling the amount of lost motion between a means for opening an engine cylinder valve and a valve during engine operation, comprising the steps of: a) providing hydraulic fluid to an internal expansible chamber of a variable length tappet disposed in a valve train linking the means for opening and the valve; and b) selectively bleeding hydraulic fluid from the expansible chamber to decrease the amount of hydraulic fluid in the chamber and decrease the length of the tappet, to thereby increase the amount of lost motion between the means for opening and the valve, wherein the step of selectively bleeding is controlled such that the amount of hydraulic fluid in the chamber may be varied one or more times per cycle of the engine and independently of the position of the means for opening an engine cylinder valve.

Claim 37

The method of claim 32 wherein the step of selectively bleeding is controlled such that the tappet is capable of assuming one of three or more different lengths corresponding with different amounts of lost motion.