# US 9,752,471 B2 · Compression-release engine brake system for lost motion rocker arm assembly and method of operation thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,752,471 B2 - Document ID: US9752471B2 - Status: Granted - Kind: B2 - Application number: 15/241,609 - Filed: 2016-08-19 - Published: 2016-12-08 - Granted: 2017-09-05 - Earliest claimed: 2013-11-25 - Assignees: Pacbrake Company - Applicants: Pacbrake Company - Inventors: Vincent Meneely; Robert Price - Web page: https://patentgrep.com/patent/US9752471B2 ## CPC - F01L 13/065: {Compression release engine retarders of the "Jacobs Manufacturing" type} - F01L 1/18: Rocking arms or levers - F01L 1/181: {Centre pivot rocking arms} - F01L 1/26: characterised by the provision of two or more valves operated simultaneously by same transmitting-gear; peculiar to machines or engines with more than two lift-valves per cylinder (with coaxial valves F01L1/28) - F01L 13/06: for braking - F02B 75/02: Engines characterised by their cycles, e.g. six-stroke - F02D 13/04: using engine as brake - F01L 1/08: Shape of cams - F01L 1/146: {Push-rods} - F01L 1/20: Adjusting or compensating clearance - F01L 2001/054: {Camshafts in cylinder block} - F01L 2013/105: {Hydraulic motors} - F01L 2305/00: Valve arrangements comprising rollers - F01L 2820/01: Absolute values - F02B 2075/027: {four} - F01L: CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES - F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G) - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) ## Abstract A compression-release brake system is provided that includes a lost motion exhaust rocker assembly, an actuation piston, and a reset device. The actuation piston includes an actuation piston body that is slidably received by the rocker arm to define a piston cavity in the rocker arm and is movable between piston retracted and extended positions. The actuation piston is configured to be operatively associated with the exhaust valve to permit unseating of the exhaust valve from the seated state. An actuation piston check valve is configured to move between closed and open positions to permit hydraulic fluid flow through an actuation piston communication port to the piston cavity. The reset device includes a reset check valve and a reset pressure control spring for applying a biasing force to the reset check valve to urge the reset check valve toward an open position. ## Claims ### Claim 1 A compression-release brake system for effectuating a compression-release engine braking operation in connection with an internal combustion engine comprising an engine cylinder that is associated with a four-stroke piston cycle comprising a compression stroke and an expansion stroke and is provided with at least one intake valve, at least one exhaust valve, and at least one exhaust valve return spring exerting a closing force on the exhaust valve to urge the exhaust valve into a seated state, the compression-release brake system comprising: a lost motion exhaust rocker assembly comprising a rocker arm; an actuation piston comprising an actuation piston body slidably received by a first pocket of the rocker arm to define a piston cavity in the rocker arm and movable between a piston retracted position and a piston extended position, the actuation piston configured to be operatively associated with an exhaust valve to permit unseating of the exhaust valve from the seated state, the actuation piston body having an actuation piston communication port and an actuation piston check valve configured to move between a first closed position and a first open position to provide a first hydraulic fluid flow pathway through the actuation piston communication port to the piston cavity; and a reset device received by a second pocket of the rocker atm, the reset device operatively associated with the actuation piston through at least one connecting conduit, and comprising a reset check valve configured to move between a second closed position and a second open position to provide a second hydraulic fluid flow pathway to the piston cavity, the second hydraulic fluid flow pathway comprising the at least one connecting conduit, the reset check valve further comprising a reset pressure control spring for applying a biasing force to the reset check valve to urge the reset check valve toward the second open position. ### Claim 2 (depends on 1) The compression-release brake system of claim 1, wherein the compression-release brake system is configured for installation on the internal combustion engine and operation in a brake-on mode in which the reset device is operatively associated with the actuation piston through the at least one connecting conduit to release a portion of hydraulic fluid from the piston cavity so that the exhaust valve return spring resets the exhaust valve to the seated state by the end of the expansion stroke. ### Claim 3 (depends on 1) The compression-release brake system of claim 1, wherein the at least one connecting conduit comprises a first connecting conduit and a second connecting conduit, wherein the reset device is in communication with a continuous supply conduit through the first connecting conduit, and wherein the reset device is in communication with the piston cavity through the second connecting conduit. ### Claim 4 (depends on 1) The compression-release brake system of claim 1, wherein in the first open position the actuation piston check valve is operable to open the actuation piston communication port to place a continuous supply conduit in fluid communication with the piston cavity through the actuation piston communication port, and wherein the actuation piston check valve is operable to close the actuation piston communication port to prevent backflow of the hydraulic fluid from the piston cavity through the actuation piston communication port. ### Claim 5 (depends on 1) The compression-release brake system of claim 1, wherein the actuation piston further comprises an actuation piston biasing member for urging the actuation piston check valve toward the first closed position. ### Claim 6 (depends on 1) The compression-release brake system of claim 1, wherein: the reset check valve is movable between the second open position and the second closed position relative to a reset communication port of the reset device, wherein in the second open position the reset check valve opens the reset communication port to place a continuous supply conduit in fluid communication with the piston cavity through the at least one connecting conduit and the reset communication port, and wherein in the second closed position the reset check valve closes the reset communication port; and the reset device further comprises a reset trigger and a reset piston, the reset trigger being operatively connected to the reset check valve and the reset pressure control spring and movable between a trigger retracted position and a trigger extended position. ### Claim 7 (depends on 6) The compression-release brake system of claim 6, wherein the rocker arm further comprises a brake-on supply conduit configured to supply activation fluid to the reset device to move the reset trigger from the trigger retracted position to the trigger extended position, wherein the brake-on supply conduit is not in fluid communication with the piston cavity. ### Claim 8 (depends on 6) The compression-release brake system of claim 6, wherein the supply conduit is configured to supply the hydraulic fluid to the reset device to move the reset trigger from the trigger retracted position to the trigger extended position, and wherein the supply conduit is also configured to supply the hydraulic fluid to the piston cavity. ### Claim 9 (depends on 6) The compression-release brake system of claim 6, wherein the compression-release brake system is configured for installation on the internal combustion engine and operation in a brake-on mode so that: the lost motion exhaust rocker assembly is operatively associated with the reset device to cause, during the compression stroke, the reset trigger to be moved from the trigger extended position into the trigger retracted position by relative movement between the pivoting rocker arm and a stop member of the lost motion exhaust rocker assembly to compress the reset pressure control spring while maintaining the reset check valve in the second closed position, the lost motion exhaust rocker assembly is operatively associated with the actuation piston to cause, during the compression stroke, the actuation piston in the piston extended position to exert sufficient force on the exhaust valve to unseat the exhaust valve, and the reset device is operatively associated with the actuation piston so that after unseating of the exhaust valve, and as the hydraulic pressure within the piston cavity decreases, the biasing force of, the reset pressure control spring compressed by the reset trigger and the reset piston moves the reset check valve into the second open position to thereby release a portion of the hydraulic fluid in the piston cavity through the reset communication port so that the closing force of the exhaust valve return spring resets the exhaust valve to the seated state by the end of the expansion stroke. ### Claim 10 (depends on 1) The compression-release brake system of claim 1, wherein the actuation piston contains a variable-volume accumulator cavity. ### Claim 11 (depends on 10) The compression-release brake system of claim 10, wherein the actuation piston further comprises an accumulator connection port configured to place the accumulator cavity into operative communication with the piston cavity to supply the hydraulic fluid from the accumulator cavity to the piston cavity through the actuation piston communication port. ### Claim 12 (depends on 10) The compression-release brake system of claim 10, wherein the actuation piston further comprises an accumulator piston slidable within the actuation piston to vary a volume of the accumulator cavity, and an accumulator spring configured to urge the accumulator piston toward the actuation piston check valve to reduce the volume of the accumulator cavity. ### Claim 13 (depends on 1) An internal combustion engine, comprising: an engine cylinder associated with a four-stroke piston cycle comprising a compression stroke and an expansion stroke, the engine cylinder comprising at least one intake valve, at least one exhaust valve, and at least one exhaust valve return spring exerting a closing force on the exhaust valve to urge the exhaust valve into a seated state; and the compression-release brake system of claim 1. ### Claim 14 (depends on 13) A method of effectuating a compression-release engine braking operation in connection with the internal combustion engine of claim 13, comprising releasing a portion of hydraulic fluid from the piston cavity so that the exhaust valve return spring resets the exhaust valve to the seated state by the end of the expansion stroke. ### Claim 15 A compression-release brake system for effectuating a compression-release engine braking operation in connection with an internal combustion engine comprising an engine cylinder that is associated with a four-stroke piston cycle comprising a compression stroke and an expansion stroke and is provided with at least one intake valve, at least one exhaust valve, and at least one exhaust valve return spring exerting a closing force on the exhaust valve to urge the exhaust valve into a seated state, the compression-release brake system comprising: a lost motion exhaust rocker assembly comprising a rocker arm; an actuation piston slidably received by the rocker arm to define a piston cavity in the rocker arm and movable between a piston retracted position and a piston extended position, the actuation piston being configured to be operatively associated with the exhaust valve to permit unseating of the exhaust valve from the seated state, the actuation piston comprising an actuation piston body containing a variable-volume accumulator cavity; and a reset device received by the rocker arm. ### Claim 16 (depends on 15) The compression-release brake system of claim 15, wherein the compression-release brake system is configured for installation on the internal combustion engine and operation in a brake-on mode in which the reset device is operatively associated with the actuation piston through at least one connecting conduit of the rocker arm to release a portion of hydraulic fluid from the piston cavity so that exhaust valve return spring resets the exhaust valve to the seated state by the end of the expansion stroke. ### Claim 17 (depends on 15) The compression-release brake system of claim 15, wherein the actuation piston further comprises an accumulator connection port configured to place the accumulator cavity into operative communication with the piston cavity to supply hydraulic fluid from the accumulator cavity through the accumulator connection port to the piston cavity. ### Claim 18 (depends on 15) The compression-release brake system of claim 15, wherein the actuation piston further comprises an accumulator piston slidable within the actuation piston to vary a volume of the accumulator cavity, and an accumulator spring configured to urge the accumulator piston toward the piston cavity to reduce the volume of the accumulator cavity. ### Claim 19 (depends on 15) The compression-release brake system of claim 15, wherein the reset device is operatively associated with the actuation piston through at least one connecting conduit and comprises a reset check, valve and a reset pressure control spring for applying a biasing force to the reset check valve to urge the reset check valve toward an open position. ### Claim 20 (depends on 15) The compression-release brake system of claim 15, wherein the actuation piston further contains an actuation piston communication port and an actuation piston check valve configured to move between an open position to permit hydraulic fluid flow from the accumulator cavity through the actuation piston communication port to the piston cavity and a closed position to prevent backflow of the hydraulic fluid from the piston cavity through the actuation piston communication port. ### Claim 21 (depends on 15) An internal combustion engine, comprising: an engine cylinder associated with a four-stroke piston cycle comprising a compression stroke and an expansion stroke and provided with, at least one intake valve, at least one exhaust valve, and at least one exhaust valve return spring exerting a closing force on the exhaust valve to urge the exhaust valve into a seated state; and the compression-release brake system of claim 15. ### Claim 22 (depends on 21) A method of effectuating a compression-release engine braking operation in connection with the internal combustion engine of claim 21, comprising releasing a portion of hydraulic fluid from the piston cavity so that the exhaust valve return spring resets the exhaust valve to the seated state by the end of the expansion stroke. ### Claim 23 A lost motion exhaust rocker assembly, comprising: a rocker arm; and an actuation piston slidably received by a pocket of the rocker anti to define a piston cavity and movable between a piston retracted position and a piston extended position, the actuation piston being configured to be operatively associated with an exhaust valve of an engine cylinder of an internal combustion engine to permit unseating of the exhaust valve from the seated state, the actuation piston comprising an actuation piston body containing a variable-volume accumulator cavity configured to feed hydraulic fluid to the piston cavity. ### Claim 24 (depends on 23) The lost motion exhaust rocker assembly of claim 23, wherein actuation piston body further contains an accumulator connection port configured to place the accumulator cavity into operative communication with the piston cavity to supply the hydraulic fluid from the accumulator cavity to the piston cavity. ### Claim 25 (depends on 23) The lost motion exhaust rocker assembly of claim 23, wherein the actuation piston further comprises an accumulator piston slidable within the actuation piston to vary a volume of the accumulator cavity, and an accumulator spring configured to urge the accumulator piston toward the piston cavity to reduce the volume of the accumulator cavity. ### Claim 26 (depends on 23) The lost motion exhaust rocker assembly of claim 23, wherein the actuation piston body further contains an actuation piston communication port and an actuation piston check valve configured to move between an open position to permit hydraulic fluid flow from the accumulator cavity through the actuation piston communication port to the piston cavity and a closed position to prevent backflow of the hydraulic fluid from the piston cavity through the actuation piston communication port. ### Claim 27 (depends on 23) An internal combustion engine, comprising: an engine cylinder associated with a four-stroke piston cycle comprising a compression stroke and an expansion stroke and provided with at least one intake valve, at least one exhaust valve, and at least one exhaust valve return spring exerting a closing force on the exhaust valve to urge the exhaust valve into a seated state; and a compression-release brake system comprising the lost motion exhaust rocker assembly of claim 23. ### Claim 28 (depends on 27) A method of effectuating a compression-release engine braking operation in connection with the internal combustion engine of claim 27, comprising releasing a portion of hydraulic fluid from the piston cavity so that the exhaust valve return spring resets the exhaust valve to the seated state by the end of the expansio stroke.