Actuator control system for bi-stable electric rocker arm latches

Patent metadata

Field	Value
Publication number	US-11274579-B2
Application number	US-201816761973-A
Country	US
Kind code	B2
Filing date	Nov 2, 2018
Priority date	Nov 7, 2017
Publication date	Mar 15, 2022
Grant date	Mar 15, 2022

Abstract

An actuator control system suitable for providing single wire control of electromagnetic latch assemblies providing for cylinder deactivation or variable valve actuation in a valvetrain system. The system is adapted to control electromagnetic latch assemblies that require DC current in a first direction for latching and DC current in a reverse of the first direction for unlatching. The actuator control system includes an inverting DC/DC converter and switching elements. In some embodiments, the inverting DC/DC converter uses capacitors to store energy that drives the inverted current. In some embodiments, the inverting DC/DC converter serves a plurality of distinct groups of the electromagnets.

First claim

The invention claimed is:

1. A valvetrain for an internal combustion engine of a type that has a combustion chamber, a moveable valve having a seat formed in the combustion chamber, and a camshaft, the valvetrain comprising:
a plurality of rocker arm assemblies, each comprising a rocker arm, a latch pin, and a cam follower configured to engage a cam mounted on a camshaft as the camshaft rotates;
a plurality of electromagnets each having first and second terminals and each operative to actuate a distinct one of the latch pins; and
an actuator control system comprising a first electronic device and one or more switching elements;
wherein, when coupled to a DC power source, the actuator control system is operative to provide to the first terminals of any selected one of a plurality of distinct groups comprising one or more of the plurality of electromagnets a DC current that is selectively either in a first direction or a second direction;
the second direction is a reverse of the first direction;
the first electronic device is a device that when powered by a DC current having a first polarity is operative to provide a DC current having a second polarity, which is opposite that of the first polarity;
the first electronic device provides the DC current in the second direction;
the second terminals of the electromagnets are grounded; and
the first electronic device comprises one or more capacitors operative to supply the DC current in the second direction.

2. The valvetrain of claim 1 , wherein the actuator control system provides the DC current in the second direction from the first electronic device to the electromagnets through one or more half-bridge circuits.

3. An engine, comprising:
a cylinder head; and
the valvetrain of claim 1 ;
wherein the second terminals of the electromagnets are grounded to the cylinder head.

4. The valvetrain of claim 1 , wherein the second terminals are grounded through structures of the rocker arm assemblies.

5. The valvetrain claim 1 , further comprising permanent magnets that retain the latch pins in both extended and retracted positions.

6. The valvetrain claim 1 , wherein:
the electromagnets are mounted on the rocker arms;
electrical connections between the actuator control system and the electromagnets are made by abutment between surfaces of distinct parts, a first of which is mounted to the rocker arm bearing the electromagnet and a second of which is mounted to a distinct part such that the rocker arm assembly is operative to move the first of the abutting surfaces relative to the second in response to actuation of the rocker arm assembly through the cam follower; and
the electrical connections are isolated from ground.

7. A valvetrain for an internal combustion engine of a type that has a combustion chamber, a moveable valve having a seat formed in the combustion chamber, and a camshaft, the valvetrain comprising:
a plurality of rocker arm assemblies, each comprising a rocker arm, a latch pin, and a cam follower configured to engage a cam mounted on a camshaft as the camshaft rotates;
a plurality of electromagnets each having first and second terminals and each operative to actuate a distinct one of the latch pins; and
an actuator control system comprising a first electronic device and one or more switching elements operative to provide the first terminal of one of the electromagnets with a DC current that is selectively in either a first direction or a second direction;
wherein the second direction is a reverse of the first direction;
the first electronic device comprises one or more capacitors operative to provide the DC current in the second direction; and
the second terminals are grounded.

8. The valvetrain of claim 7 , wherein the actuator control system provides the DC current in the second direction from the first electronic device to the electromagnets through one or more half-bridge circuits.

9. An engine, comprising:
a cylinder head; and
the valvetrain of claim 7 ;
wherein the second terminals of the electromagnets are grounded to the cylinder head.

10. The valvetrain of claim 7 , wherein the second terminals are grounded through structures of the rocker arm assemblies.

11. The valvetrain of claim 7 , further comprising permanent magnets that retain the latch pins in both extended and retracted positions.

12. The valvetrain of claim 7 , wherein:
the electromagnets are mounted on the rocker arms;
electrical connections between the actuator control system and the electromagnets are made by abutment between surfaces of distinct parts, a first of which is mounted to the rocker arm bearing the electromagnet and a second of which is mounted to a distinct part such that the rocker arm assembly is operative to move the first of the abutting surfaces relative to the second in response to actuation of the rocker arm assembly through the cam follower; and
the electrical connections are isolated from ground.

13. A method of operating electromagnets each having first and second terminals and each operative to actuate a distinct group of one or more latch pins in rocker arm assemblies in a valvetrain for an internal combustion engine of a type that has a combustion chamber, a moveable valve having a seat formed in the combustion chamber, and a camshaft, the method comprising:
over a first period, coupling a DC power source to the first terminals of a first set of the electromagnets to provide a current in a first direction to those terminals;
over a second period during which the DC power source is not coupled to the first terminals of the first set of the electromagnets, coupling the DC power source to the first terminals of a second set of the electromagnets, wherein the electromagnets in the second set are distinct from those in the first;
storing energy from the DC power source in a first electronic device;
over a third period, coupling the first electronic device to the first terminals of the first set of the electromagnets to provide a current in a second direction to those first terminals, wherein the second direction is a reverse of the first;
over a fourth period during which the first electronic device is not coupled to the first terminals of the first set of the electromagnets, coupling the first electronic device to the first terminals of the second set of the electromagnets; and
keeping the second terminals grounded over the first period, the second period, the third period, and the fourth period.

14. A method according to claim 13 , wherein:
wherein storing energy in the first electronic device comprises storing the energy in one or more capacitors of the first electronic device; and
the current in the second direction is driven by the energy stored in the capacitors.

15. A method according to claim 14 , wherein:
the current in the first direction actuates the latch pins from first positions to second positions; and
the current in the second direction actuates the latch pins from the second positions to the first positions.

16. The method of claim 13 , further comprising installing the first electronic device as part of the valvetrain.

17. The method of claim 13 , wherein the first electronic device is used exclusively by the valvetrain.

Assignees

• Eaton Intelligent Power Ltd

Inventors

• Kucera Pavel
• Liskar Petr
• Fojtik Pavel

Classifications

• F01L9/21 Primary

  actuated by solenoids · CPC title

• F01L2001/467

  Lost motion springs · CPC title

• F01L2009/2163

  Connectors · CPC title

• F01L13/0005

  Deactivating valves · CPC title

• F01L2800/08

  Timing or lift different for valves of different cylinders · CPC title