WO2020038609A1 - Frein de purge passif à base de pont - Google Patents

Frein de purge passif à base de pont Download PDF

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Publication number
WO2020038609A1
WO2020038609A1 PCT/EP2019/025279 EP2019025279W WO2020038609A1 WO 2020038609 A1 WO2020038609 A1 WO 2020038609A1 EP 2019025279 W EP2019025279 W EP 2019025279W WO 2020038609 A1 WO2020038609 A1 WO 2020038609A1
Authority
WO
WIPO (PCT)
Prior art keywords
assembly
plunger
valve
reset pin
valvetrain
Prior art date
Application number
PCT/EP2019/025279
Other languages
English (en)
Inventor
Mark VANWINGERDEN
Andrew Lee
Original Assignee
Eaton Intelligent Power Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eaton Intelligent Power Limited filed Critical Eaton Intelligent Power Limited
Publication of WO2020038609A1 publication Critical patent/WO2020038609A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/12—Transmitting gear between valve drive and valve
    • F01L1/14—Tappets; Push rods
    • F01L1/146—Push-rods
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/12—Transmitting gear between valve drive and valve
    • F01L1/18—Rocking arms or levers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/12—Transmitting gear between valve drive and valve
    • F01L1/18—Rocking arms or levers
    • F01L1/181—Centre pivot rocking arms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/20—Adjusting or compensating clearance
    • F01L1/22—Adjusting or compensating clearance automatically, e.g. mechanically
    • F01L1/24—Adjusting or compensating clearance automatically, e.g. mechanically by fluid means, e.g. hydraulically
    • F01L1/2422—Adjusting or compensating clearance automatically, e.g. mechanically by fluid means, e.g. hydraulically by means or a hydraulic adjusting device located between the push rod and rocker arm
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/26—Valve-gear or valve arrangements, e.g. lift-valve gear 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F01L13/06—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for braking

Definitions

  • the present disclosure generally relates to valvetrain assemblies in internal combustion engines and, more particularly, to a valvetrain assembly having a passive bleeder engine brake system.
  • Engine braking can be used to retard forces within an engine to ultimately slow a vehicle down.
  • an exhaust valve is actuated by a rocker arm which engages the exhaust valve by means of a valve bridge.
  • the rocker arm rocks in response to a cam on a rotating cam shaft and presses down on the valve bridge which itself presses down on the exhaust valve to open it.
  • One form of engine braking includes a bleeder brake.
  • Bleeder brakes can be used as auxiliary brakes, in addition to wheel brakes, on relatively large vehicles, for example trucks, powered by heavy or medium duty diesel engines.
  • a bleeder brake typically includes a piston that selectively extends to a full stroke. In the full stroke, the piston can maintain an exhaust valve open a fixed amount throughout an engine cycle.
  • a valve bridge assembly for a valvetrain assembly configured to selectively perform a bleeder brake operation.
  • the valve bridge assembly is configured to be selectively engaged by a rocker arm to open at least one of a first and second engine valve.
  • the valve bridge assembly includes a bridge main body having a fluid supply passage and including a first end configured to engage the first engine valve, and a second end configured to engage the second engine valve.
  • a plunger assembly is disposed at least partially within the hydraulic chamber in fluid communication with the fluid supply passage. The plunger assembly is configured to selectively move from a retracted position to an extended position where the plunger assembly engages and partially opens the first engine valve to perform the bleeder brake operation.
  • the described valve bridge assembly may include one or more of the following features: a hydraulic chamber formed in the bridge main body first end, wherein the plunger assembly is at least partially disposed within the hydraulic chamber; wherein the plunger assembly comprises a plunger and a reset pin; a first biasing mechanism disposed between the plunger and the valve bridge assembly, and a second biasing mechanism disposed between the plunger and the reset pin; wherein the reset pin includes a discharge port configured to selectively drain hydraulic fluid from a hydraulic chamber, the discharge port including a first portion intersected by a second portion; and wherein reset pin includes a first end and a second end, and the discharge port first portion defines an inlet on the first end of the reset pin, wherein the discharge port second portion defines a plurality of outlets defined in an outer surface of the reset pin extending between the first and second ends of the reset pin.
  • a valvetrain assembly configured to selectively perform a bleeder brake operation.
  • the assembly includes a rocker shaft that defines a pressurized fluid supply conduit, a rocker arm that receives the rocker shaft and is configured to rotate about the rocker shaft, the rocker arm having a fluid supply passage defined therein, and a valve bridge assembly operably associated with the rocker arm and configured to be selectively engaged by the rocker arm to open at least one of a first and second engine valve.
  • a plunger assembly is disposed at least partially within the valve bridge assembly and is in fluid communication with the fluid supply passage. The plunger assembly is configured to selectively move from a retracted position to an extended position where the plunger assembly engages and partially opens the first engine valve to perform the bleeder brake operation.
  • the described valvetrain assembly may include one or more of the following features: a cam lobe configured to impart motion to the rocker shaft through a hydraulic lash adjustment (HLA) lifter and a push tube; wherein the plunger assembly comprises a plunger and a reset pin; a first biasing mechanism disposed between the plunger and the valve bridge assembly; a second biasing mechanism disposed between the plunger and the reset pin; and wherein the reset pin includes a discharge port configured to selectively drain hydraulic fluid from a hydraulic chamber.
  • HLA hydraulic lash adjustment
  • the described valvetrain assembly may include one or more of the following features: wherein the discharge port includes a first portion intersected by a second portion; wherein reset pin includes a first end and a second end, and the discharge port first portion defines an inlet on the first end of the reset pin; wherein the discharge port second portion defines a plurality of outlets; wherein the plurality of outlets are defined in an outer surface of the reset pin that extends between the first and second ends of the reset pin; wherein the plunger assembly is at least partially disposed in a hydraulic chamber formed in the valve bridge assembly.
  • valvetrain assembly may include one or more of the following features: wherein the valve bridge assembly includes a bridge main body, and a bridge fluid supply conduit fluidly coupled to the rocker arm fluid supply passage; wherein the valve bridge assembly further includes a check valve disposed on the bridge fluid supply conduit, and wherein the rocker arm includes an adjustable screw configured to selectively prevent the reset pin from translating out of the hydraulic chamber.
  • FIG. 1 is a schematic side view of a valvetrain assembly constructed in accordance to one example of the present disclosure
  • FIG. 2 is a schematic side view of the valvetrain assembly shown in FIG. 1 in a braking condition
  • FIG. 3 is a schematic side view of the valvetrain assembly shown in FIG. 1 in main lift condition
  • FIG. 4 is a schematic side view of the valvetrain assembly shown in FIG. 1 in a reset during the main lift condition;
  • FIG. 5 is a schematic side view of the valvetrain assembly shown in FIG. 1 with valves closing during the main lift condition;
  • FIG. 6 is a graph illustrating an example valve lift of the operation of the valvetrain assembly shown in FIGS. 1 -5.
  • the assembly can include a rocker arm and a valve bridge.
  • the rocker arm can include a central pivot, a cam interfacing end, an end interfacing with the center of the valve bridge, and an adjustable screw positioned above the inboard valve (closest to the pivot).
  • the valve bridge can include two ends for interfacing with an engine valve. One end has a hydraulic chamber for a plunger and plunger spring designed to expand when the engine valve floats.
  • the hydraulic chamber also includes a check ball, a reset sliding pin, and a pin spring which interfaces with the adjustable screw on the rocker arm.
  • a hydraulic passage connects an engine oil supply through the rocker arm to the hydraulic chamber within the bridge.
  • a flap or variable geometry turbo creates a restriction in the exhaust, which raises exhaust manifold pressure.
  • High exhaust manifold pressure causes exhaust valves to float when a differential between in-cylinder pressure and the manifold creates a force which overcomes the valve spring.
  • the hydraulic plunger in the bridge expands, filling with oil from the supply feed, while the valve is floating and “catches” the valve by becoming hydraulically solid. This creates a bleeder brake function.
  • the reset pin will begin to open and allow the hydraulic chamber to dump pressure. The plunger then collapses, and the valves begin to move in parallel as controlled by a standard bridge.
  • valvetrain assembly 10 constructed in accordance to one example of the present disclosure is shown and generally identified at reference 10.
  • the valvetrain assembly 10 can generally include a cam shaft with one or more lobes 12 configured to indirectly drive a first end of a rocker arm 14 via a pushrod 16.
  • a hydraulic lash adjuster (HLA) lifter 18 can be implemented between the cam lobe 12 and the pushrod 16 to remove any lash or gap that develops between the components in the valvetrain assembly.
  • HLA hydraulic lash adjuster
  • the rocker arm 14 pivots about a fixed rocker shaft 20 and the opposite second end of the rocker arm 14 actuates one or more engine valves 22, 24 via a valve bridge assembly 26.
  • the rocker arm 14 generally includes a first end 28 and an opposite second end 30.
  • the first end 28 is configured to be engaged by the pushrod 16, and the second end 30 is configured to engage the valve bridge assembly 26 via a spigot assembly 32 to thereby actuate valves 22, 24.
  • a pin or adjustable screw 34 extends through a bore 35 formed in the rocker arm 14.
  • the adjustable screw 34 can be threaded to a nut 36 for selectively adjusting and positioning the adjustable screw 34.
  • the rocker shaft 20 can define a pressurized fluid (e.g., oil) supply conduit 38, and the rocker arm 14 can define a rocker arm supply conduit 40 that is configured to deliver oil (or other fluid) from the pressurized fluid supply conduit 38, through the spigot assembly 32, and to the valve bridge assembly 26.
  • a pressurized fluid e.g., oil
  • the rocker arm 14 can define a rocker arm supply conduit 40 that is configured to deliver oil (or other fluid) from the pressurized fluid supply conduit 38, through the spigot assembly 32, and to the valve bridge assembly 26.
  • the valve bridge assembly 26 includes a plunger assembly 42 disposed within a bridge main body 44.
  • the bridge main body 44 includes a first end 46 and a second end 48.
  • the first end 46 can be configured to engage valve 24, and the plunger assembly 42 can be received in a hydraulic chamber 50 formed in the second end 48.
  • a bridge fluid supply conduit 52 is formed in bridge main body 44 and is configured to deliver fluid from the rocker arm supply conduit 40 to the chamber 50.
  • a one-way check valve 54 is configured to prevent oil in the bridge fluid supply conduit 52 from travelling back toward the rocker arm 14.
  • the plunger assembly 42 can generally include a plunger 60, a first biasing mechanism 62 (e.g., a spring), a reset pin 64, and a second biasing mechanism 66 (e.g., a spring).
  • the plunger 60 is slidingly disposed within chamber 50 and generally includes a first end 68 and an opposite second end 70.
  • the first end 68 is configured to engage engine valve 22, and the second end 70 defines a bore 72.
  • the first biasing mechanism 62 is at least partially disposed or seated within bore 72 and is configured to bias plunger 60 out of the chamber 50 toward engine valve 22.
  • the reset pin 64 is disposed at least partially within chamber 50 and bore 72, and extends through an aperture 74 formed in the bridge main body 44.
  • Second biasing mechanism 66 is disposed at least partially within the bore 72 and is configured to bias reset pin 64 through aperture 74 toward adjustable screw 34.
  • reset pin 64 includes a first end 76 and an opposite second end 78 having a shoulder or stop 80 configured to limit the distance reset pin 64 can extend into aperture 74.
  • a discharge port 82 extends through reset pin 64 and is configured to discharge or bleed oil from the chamber 50, as described herein in more detail.
  • the discharge port 82 includes a vertical or substantially vertical portion 84 intersected by a horizontal or substantially horizontal portion 86 such that discharge port 82 is generally T-shaped cross-section.
  • vertical portion 84 defines an inlet 88 and the horizontal portion 80 defines a plurality of outlets 90 disposed on an outer surface or outer diameter 92 of the reset pin 64 rather than on the top 76 of the reset pin 64. Due to this arrangement, the described system advantageously obviates the requirement for an additional component (e.g., screw 34) to block or cover any outlet formed in the valve bridge main body 44 or reset pin 64.
  • valvetrain assembly 10 includes a hydraulic system that is always in place (e.g., no oil control valve).
  • a controller creates an increased backpressure in the exhaust manifold (not shown), for example, by closing a VGT, an exhaust flap, etc.
  • controller refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.
  • ASIC application specific integrated circuit
  • processor shared, dedicated, or group
  • memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.
  • valve 22 When the pressure in the exhaust manifold is higher than the pressure in the cylinder (not shown), the exhaust valve 22 floats open. During this valve float, as shown in FIG. 2, the plunger 60 extends toward the valve 22 due to biasing mechanism 62 and/or hydraulic fluid being supplied to the chamber 50. In this extended position, the plunger 60 catches and holds the valve 22 open through at least a portion of the compression stroke. It will be appreciated that valve 22 may be kept open during other portions of the piston stroke.
  • the plunger 60 is configured to hold valve 22 open until the next main exhaust event where rocker arm 14 is pushed by upward movement of pushrod 16 to subsequently rotate clockwise about rocker shaft 20 (as viewed in the Figures). This causes spigot assembly 32 to press downward on the valve bridge assembly 26 and open exhaust valves 22, 24. During continued operation, as shown in FIG. 3, the hydraulic pressure in chamber 50 pushes the reset pin 64 upward. However, in this position, the reset pin 64 is limited in upward movement due to the adjustable screw 34.
  • valve bridge assembly 26 As shown in FIG. 4, further downward movement of valve bridge assembly 26 enables further upward movement of reset pin 64, thereby exposing discharge port outlets 90 and allowing hydraulic fluid to drain from the chamber 50.
  • the rocker arm 14 begins to rotate counterclockwise about rocker shaft 20 to allow upward movement of the valve bridge assembly 26 and opening of the exhaust valves 22, 24. This causes adjustable screw 34 to force reset pin 64 back into chamber 50. Since the hydraulic fluid has been drained or at least partially drained from chamber 50, plunger 60 is able to collapse back into the chamber 50 into a collapsed or withdrawn position. The system then returns to the starting position on the base circle of the cam shaft 12 with plunger 60 in the withdrawn position similar to that shown in FIG. 1 .
  • FIG. 6 illustrates an example valve lift during the operation of valvetrain assembly 10.
  • Intake valve lift is shown by line 100
  • piston movement is shown by line 1 10
  • typical exhaust valve lift is shown by line 120.
  • the lift of at least one exhaust valve follows line 130.
  • the exhaust valve 22 begins to float and plunger 60 is extended to catch the exhaust valve 22.
  • reset pin 64 discharges hydraulic fluid from chamber 50 to reset plunger 60 and enable normal exhaust lift along line 120.
  • valve bridge in a diesel engine valvetrain such as, for example, a four-valve engine primarily built into the valve bridge and grounding through an adjustable pin in the rocker arm.
  • the system does not require external grounding, such as a bolt-on structure external to the valvetrain, and is compatible with HLA.
  • the valve bridge includes a hydraulic plunger and reset pin each biased by a spring seated within the hydraulic plunger, thereby providing a compact arrangement.
  • the reset pin includes port outlets disposed on the outside of the reset pin rather than a top, thereby enabling the valve bridge to block the outlets until the reset pin extends out of the valve bridge.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve Device For Special Equipments (AREA)

Abstract

L'invention concerne un ensemble dispositif de commande des soupapes qui est configuré pour effectuer de manière sélective une opération de frein de purge et qui comprend un arbre de culbuteur qui définit un conduit d'alimentation en fluide pressurisé, un culbuteur qui reçoit l'arbre de culbuteur et qui est configuré pour tourner autour de l'arbre de culbuteur, l'arbre de culbuteur ayant un passage d'alimentation en fluide défini en son sein, et un ensemble pont de soupape fonctionnellement associé au culbuteur et configuré pour être sélectivement mis en prise par le culbuteur afin d'ouvrir au moins l'une d'une première et d'une seconde soupape de moteur. Un ensemble de piston est disposé au moins partiellement à l'intérieur de l'ensemble pont de soupape et est en communication fluidique avec le passage d'alimentation en fluide. L'ensemble de piston est configuré pour se déplacer de manière sélective d'une position rétractée à une position étendue dans laquelle il vient en prise et ouvre partiellement une première soupape de moteur pour effectuer une opération de frein de purge.
PCT/EP2019/025279 2018-08-20 2019-08-20 Frein de purge passif à base de pont WO2020038609A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201862719891P 2018-08-20 2018-08-20
US62/719,891 2018-08-20

Publications (1)

Publication Number Publication Date
WO2020038609A1 true WO2020038609A1 (fr) 2020-02-27

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PCT/EP2019/025279 WO2020038609A1 (fr) 2018-08-20 2019-08-20 Frein de purge passif à base de pont

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070144472A1 (en) * 2005-12-28 2007-06-28 Zhou Yang Method and system for partial cycle bleeder brake
US20100170471A1 (en) * 2009-01-05 2010-07-08 Zhou Yang Engine braking apparatus with two-level pressure control valves
CN202140128U (zh) * 2011-02-25 2012-02-08 奚勇 集成式的泄气型发动机制动装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070144472A1 (en) * 2005-12-28 2007-06-28 Zhou Yang Method and system for partial cycle bleeder brake
US20100170471A1 (en) * 2009-01-05 2010-07-08 Zhou Yang Engine braking apparatus with two-level pressure control valves
CN202140128U (zh) * 2011-02-25 2012-02-08 奚勇 集成式的泄气型发动机制动装置

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