Variable valve actuator

Patent metadata

Field	Value
Publication number	US-2016290184-A1
Application number	US-201514672916-A
Country	US
Kind code	A1
Filing date	Mar 30, 2015
Priority date	Mar 30, 2015
Publication date	Oct 6, 2016
Grant date	—

Abstract

A valve actuation system is provided. A fluid actuator is configured to selectively prevent a valve from moving to a particular position. A source of fluid is in fluid communication with the fluid actuator. A bi-directional control valve is configured to control a flow of fluid between the source of fluid and the fluid actuator. A fluid passageway connects the bi-directional control valve with the fluid actuator. A relief valve is in fluid communication with the fluid passageway and moveable between a closed position to prevent a flow of fluid therethrough to create a high pressure circuit in the valve actuation system and an open position to allow a flow of fluid therethrough to create a low pressure circuit in the valve actuation system.

First claim

We claim:

1 . A valve actuation system, comprising:
a valve moveable between a first position to prevent a flow of fluid and a second position to allow a flow of fluid; a cam assembly configured to move the valve between the first position and the second position, wherein the cam assembly is mechanically connected to the valve; a fluid actuator configured to selectively prevent the valve from moving to the first position, and further configured to selectively hold the valve at a position between the first position and the second position; a source of fluid in fluid communication with the fluid actuator; a bi-directional control valve configured to control a flow of fluid between the source of fluid and the fluid actuator; a fluid passageway connecting the bi-directional control valve with the fluid actuator; an accumulator in fluid communication with the fluid passageway; a restrictive orifice disposed between the accumulator and the fluid passageway to restrict a flow of fluid between the accumulator and the fluid passageway; and a relief valve in fluid communication with the fluid passageway and moveable between a closed position to prevent a flow of fluid therethrough to create a high pressure circuit in the valve actuation system and an open position to allow a flow of fluid therethrough to create a low pressure circuit in the valve actuation system, wherein the relief valve is actuated between the closed position and the open position based at least on a pressure in the fluid passageway, wherein the high pressure circuit allows the fluid to pass through the fluid passageway to actuate the fluid actuator, and wherein the low pressure circuit allows at least a portion of the fluid in the fluid passageway to drain from the fluid passageway to an external environment.

2 . The valve actuation system of claim 1 , further comprising a controller configured to actuate the bi-directional control valve between an open position and a closed position to control a flow of fluid between the source of fluid and the fluid actuator.

3 . The valve actuation system of claim 1 , wherein the bi-directional control valve is normally biased in an open position.

4 . The valve actuation system of claim 1 , wherein the relief valve includes a seat, a poppet, and a spring acting on the poppet to disengage the poppet from the seat.

5 . The valve actuation system of claim 1 , wherein the fluid actuator includes a piston operatively associated with the valve.

6 . The valve actuation system of claim 1 , further comprising a hydraulic snubbing valve configured to control the rate of fluid flow from the fluid actuator.

7 . The valve actuation system of claim 1 , wherein the accumulator includes a chamber, a piston moveable between a first position where the volume of the chamber is minimized and a second position where the volume of the chamber is maximized, and a spring acting on the piston to bias the piston towards the first position.

8 . The valve actuation system of claim 1 , wherein the bi-directional control valve, the relief valve, and the accumulator are fluidly connected to the fluid passageway in series.

9 . A method of controlling an engine having a piston moveable through an intake stroke followed by a compression stroke, comprising:
rotating a cam to move an intake valve between a first position to prevent a flow of fluid and a second position to allow a flow of fluid during the intake stroke of the piston, wherein the cam is mechanically connected to the intake valve; directing fluid through a bi-directional control valve and a fluid passageway to a fluid actuator associated with the intake valve after the intake valve is moved from the first position, wherein the fluid actuator is configured to selectively hold the intake valve at a position between the first position and the second position; actuating the bi-directional control valve to selectively prevent fluid from flowing through the fluid passageway from the fluid actuator to thereby prevent the intake valve from moving to the first position; and allowing a pressure in the fluid passageway to fall below a threshold pressure to allow a relief valve disposed in fluid communication with the fluid passageway to open and at least a portion of the fluid within the fluid passageway to drain to an external environment.

10 . The method of claim 9 , further comprising:
sensing at least one operating parameter of the engine; and moving the bi-directional control valve to a closed position to prevent fluid from flowing to the fluid actuator based on the sensed operating parameter of the engine.

11 . The method of claim 10 , wherein the at least one operating parameter is at least one of a coolant temperature, an oil temperature, an engine temperature, an ambient air temperature, an engine speed, an engine load, and an intake air pressure.

12 . The method of claim 9 , further comprising closing the bi-directional control valve to prevent fluid from releasing from the fluid actuator to thereby prevent the intake valve from moving to the first position.

13 . The method of claim 9 , further comprising directing fluid from the fluid passageway through a restrictive orifice to an accumulator to inhibit oscillations in the fluid actuator.

14 . An engine, comprising:
an engine block defining at least one cylinder and a cylinder head having at least one intake passageway leading to the at least one cylinder; at least one intake valve moveable between a first position to prevent a flow of fluid through the at least one intake passageway and a second position to allow a flow of fluid through the at least one intake passageway; a cam assembly connected to the intake valve to move the intake valve between the first position and the second position, wherein the cam assembly is mechanically connected to the intake valve; a fluid actuator configured to selectively prevent the intake valve from moving to the first position, and further configured to selectively hold the intake valve at a position between the first position and the second position; a source of fluid in fluid communication with the fluid actuator; a bi-directional control valve configured to control a flow of fluid between the source of fluid and the fluid actuator; a fluid passageway connecting the directional control valve with the fluid actuator; an accumulator in fluid communication with the fluid passageway; a restrictive orifice disposed between the accumulator and the fluid passageway to restrict a flow of fluid between the accumulator and the fluid passageway; a relief valve in fluid communication with the fluid passageway and moveable between a closed position to prevent a flow of fluid therethrough and an open position to allow a flow of fluid therethrough, wherein the relief valve is actuated between the closed position and the open position based at least on a pressure in the fluid passageway, wherein the closed position of the relief valve allows the fluid to pass through the fluid passageway to actuate the fluid actuator, and wherein the open position of the relief valve allows at least a portion of the fluid in the fluid passageway to drain from the fluid passageway to an external environment.

15 . The engine of claim 14 , further comprising a controller configured to actuate the bi-directional control valve between an open position and a closed position to control a flow of fluid between the source of fluid and the fluid actuator.

16 . The engine of claim 14 , wherein the bi-directional control valve is normally biased in an open positi

Assignees

• Caterpillar Inc

Inventors

• Yeager Kendall
• Yacoub Victor
• Schreader Kevin

Classifications

• F01L1/146

  Push-rods · CPC title

• F01L2820/01

  Absolute values · CPC title

• F01L2305/00

  Valve arrangements comprising rollers · CPC title

• F01L1/267

  with means for varying the timing or the lift of the valves · CPC title

• F01L2001/054

  Camshafts in cylinder block · CPC title