CN110582620B

CN110582620B - Leaf spring sliding contact for power latch rocker arm assembly

Info

Publication number: CN110582620B
Application number: CN201880029778.1A
Authority: CN
Inventors: 吉里·塞克勒; 黛尔·雅顿·斯特雷奇; 迈克尔·J·坎贝尔
Original assignee: Eaton Intelligent Power Ltd
Current assignee: Eaton Intelligent Power Ltd
Priority date: 2017-05-08
Filing date: 2018-05-08
Publication date: 2022-11-04
Anticipated expiration: 2038-05-08
Also published as: CN110582620A; WO2018208857A1; DE112018001953T5

Abstract

A valve train includes a rocker arm assembly and a power transfer module that provides power to the rocker arm assembly. The power transfer module includes a mounting frame and a leaf spring. The mounting frame holds the leaf spring against contacts on the rocker arm of the rocker arm assembly. The contacts on the rocker arm may be provided by contact pins. The mounting frame may be mounted about a pivot for the rocker arm assembly. A contact frame on the rocker arm may hold a conductor of the circuit extending from the contact.

Description

Leaf spring sliding contact for power latch rocker arm assembly

Technical Field

The present teachings relate to valvetrains, particularly valvetrains that provide Variable Valve Lift (VVL) or Cylinder Deactivation (CDA).

Background

Variable Valve Lift (VVL) or Cylinder Deactivation (CDA) is achieved using hydraulically actuated latches on some rocker arm assemblies. For example, some Switching Roller Finger Followers (SRFFs) use hydraulically actuated latches. In these systems, pressurized oil from an oil pump may be used for latch actuation. The flow of pressurized oil may be regulated by an Oil Control Valve (OCV) under supervision of an internal combustion Engine Control Unit (ECU). Separate feeds from the same source provide oil for hydraulic lash adjustment. In these systems, there are two hydraulic feeds per rocker arm assembly, which requires a degree of complexity and equipment cost.

The oil requirements of these hydraulic feeds may be close to the limits of existing supply systems. By replacing the hydraulic latching rocker arm assembly with an electric latching rocker arm assembly, the complexity and need for oil in certain valve train systems may be reduced. The power latching rocker arm assembly requires electrical power. There is a continuing need for reliable structures for transferring power to rocker arm assemblies.

Disclosure of Invention

The present teachings relate to a valve train suitable for use in an internal combustion engine including a combustion chamber, a movable valve having a seat formed in the combustion chamber, and a camshaft. The valve train includes a rocker arm assembly having a rocker arm, a cam follower configured to engage a camshaft-mounted cam as the camshaft rotates, and an electrical circuit including an electrical device mounted to the rocker arm. These teachings provide a structure for powering or communicating with electrical devices. If conventional wiring is used to power electrical equipment, the wires may become stuck, pinched or fatigued and thereby short circuited.

According to some aspects of the present teachings, the circuit includes a connection formed by an abutment between surfaces of two different portions. The rocker arm assembly operates to move one of the two abutment surfaces relative to the other abutment surface in response to actuation of the rocker arm assembly by the cam follower. One of the abutment surfaces is formed by a leaf spring. In some of these teachings, the leaf spring is mounted to a different portion than the rocker arm assembly. In some of these teachings, the portion is a mounting frame that rests against a cylinder head of the engine. In some of these teachings, the portion is a mounting frame that fits around a pivot that provides a fulcrum for the rocker arm assembly. In some of these teachings, the leaf spring is retained by a mounting frame abutting two or more pivot shafts that provide a fulcrum for a rocker arm assembly of the valve train. The mounting frame may be overmolded around the leaf spring. The leaf spring mounted to a different portion of the rocker arm assembly may be larger than the leaf spring mounted on the rocker arm. The mounting frame of the present disclosure provides a structure that retains the leaf spring reliably and with proper positioning, while efficiently utilizing the limited space around the rocker arm assembly.

In some of these teachings, a portion adjacent to the leaf spring is retained to the rocker arm. In some of these teachings, the portion held to the rocker arm is a contact pin. In some of these teachings, the portion retained to the rocker arm is retained to one side of the rocker arm. In some of these teachings, the circuit includes a second electrical connection formed by abutment between surfaces of two different portions, the second connection being formed by contacts held to opposite sides of the rocker arm. In some of these teachings, the contacts held to the rocker arm are held by a contact frame that extends over the rear of the rocker arm and around the side of the rocker arm to the point where it holds the contacts. In some of these teachings, the contact frame is partially fitted within an opening formed in the rear portion of the rocker arm. In some of these teachings, conductors of an electrical circuit that travel from contacts at the side of the rocker arm are enclosed within a contact frame. In some of these teachings, the contact frame snaps around the side of the rocker arm. In some of these teachings, the contact frame must be deformed to be placed in or removed from its position on the rocker arm. In some of these teachings, the combination of protrusions and indentations on the contact frame and rocker arm require deformation. In some of these teachings, contact pins are directed into the side of the rocker arm to maintain stability. The contact frame is a compact structure for maintaining the electrical connections and their wiring. It is particularly suitable for adapting a latching rocker arm assembly designed for hydraulic actuation for use with electrical actuation. Having contacts on both sides of the rocker arm may balance the forces placed on the rocker arm assembly by the contacts.

In some of these teachings, the rocker arm assembly is configured to pivot generally on an axis and bring an electrical connection proximate the axis when actuated by the cam follower. In some of these teachings, pivoting causes movement of the rocker arm assembly at the electrical connection location that is 10% or less of the simultaneous movement of the rocker arm assembly at a point on the rocker arm assembly away from the axis.

In some of these teachings, the abutting surfaces of the two distinct portions are electrically isolated from ground. In some of these teachings, the ground corresponds to a cylinder head of an engine in which the valvetrain is mounted. In some of these teachings, an electrical connection couples an electrical device with a power source. In some of these teachings, the electrical device is an electromagnetic latch assembly. In some of these teachings, the electromagnetic latch assembly switches the rocker arm assembly between a first configuration and a second configuration. In a first configuration, the rocker arm assembly operates to actuate the movable valve in response to rotation of the camshaft to produce a first valve lift profile. In a second configuration, the rocker arm assembly operates to actuate the movable valve in response to rotation of the camshaft to produce a second valve lift curve that is different than the first valve lift curve, or the movable valve is deactivated. In some of these teachings, the processor is operatively coupled to communicate with the electrical device through an electrical connection.

In some of these teachings, the valve train is operable to move the rocker arm assembly in a manner that causes the contact area of the electrical connection to move between the first and second portions of the minimal spring surface, and the electrical circuit resistance varies depending on which of the first and second portions of the surface is connected through. In some of these teachings, a second portion of the surface of the leaf spring is provided with a coating that increases electrical resistance. These structures may be used to provide on-board diagnostic feedback.

Some aspects of the present teachings relate to an internal combustion engine having a valvetrain according to the present teachings mounted therein. An internal combustion engine includes a cylinder head. In some of these teachings, the electrical connection is electrically isolated from the cylinder head. In some of these teachings, a mounting frame that holds one of two different portions rests on the cylinder head. In some of these teachings, a mounting frame rests on the cylinder head adjacent to the pivot for the rocker arm assembly. In some of these teachings, the mounting frame rests on the cylinder head above the rocker arm assembly.

The primary purpose of this summary is to present some concepts of the inventor in a simplified form to facilitate an understanding of the more detailed description that follows. This summary is not an extensive overview of each and every concept of the inventors that may be considered an "invention" or a combination of concepts of the inventors. Other concepts of the present inventors will be conveyed to one of ordinary skill in the art by the following detailed description in conjunction with the accompanying drawings. The details disclosed herein may be summarized, reduced, and combined in various ways with the final statements by which the inventors claim that their invention is reserved for the claims that follow.

Drawings

FIG. 1 is a perspective view of a portion of a valvetrain according to aspects of the present teachings.

Fig. 2 is a perspective view of a mounting frame holding spring-loaded contacts in the valve train of fig. 1.

FIG. 3 is a perspective view of one of the rocker arm assemblies of the valve train of FIG. 1.

Fig. 4 is another perspective view of the valve train of fig. 1.

Fig. 5 is a perspective view of the valve train of fig. 1 installed in an engine.

Fig. 6 is a perspective view of a contact frame for the rocker arm assembly of fig. 3.

Fig. 7 is a perspective view of the rocker arm assembly of fig. 3 mated with the contact frame of fig. 6.

Detailed Description

Fig. 1-5 illustrate a valvetrain 104 according to aspects of the present teachings. Fig. 1 provides a perspective view of a portion of a valve train 104 including two rocker arm assemblies 106, two pivots 140, and a power transfer module 223. A power transfer module (as that term is used in this disclosure) is a mounting frame that holds electrical contacts in a position adjacent to a rocker arm assembly. The power transfer module 223 is shown separately in fig. 2. The rocker arm assembly 106 is shown in isolation in fig. 3. Fig. 4 provides another view of the valve train 104, which includes a camshaft 109 and a cam 107 configured to actuate the rocker arm assembly 106. Fig. 5 provides a top view of a portion of a valve train 104 installed in an engine 100 having a cylinder head 102. A pivot 140, which may be a hydraulic lash adjuster, provides a fulcrum for the rocker arm assembly 106.

The rocker arm assemblies 106 each include two pivotally connected

rocker arms

103E and 103F. The

swing arms

103E and 103F are selectively engaged by latch pins of an electromagnetic latch assembly 122 mounted to the swing arm 103E. The electromagnetic latch assembly 122 includes a coil. Energizing the coil with DC current in the forward direction actuates the latch pin to the engaged position. Energizing the coil with DC current in the opposite direction actuates the latch pin to the unengaged position. The coils receive power via contact pins 211 that are mounted to and held on the side of the rocker arm 103E. The contact pin 211 may be positioned in a guide hole formed in a side surface of the rocker arm 103E. In any event, insulation may be provided to prevent electrical contact between contact pin 211 and rocker arm 103E.

The power transfer module 223 includes the leaf spring 215. The leaf spring 215 is an electrical conductor. The power transfer module 223 is designed to keep the leaf spring 215 in abutment with the contact pins 211. Electrical connections are made between the contact pins 211 and the leaf springs 215 through which the electromagnetic latch assembly 122 may be powered. Electrical contact is maintained even when the contact pin 211 slides on the surface of the leaf spring 215 in conjunction with actuation of the rocker arm assembly 106 by the cam 107 in conjunction with the camshaft 109, or in conjunction with lash adjustment by extension and retraction of the pivot 140.

The rocker arm assembly 106 is configured to undergo pivotal movement when it is actuated by the cam 107. The pivoting occurs substantially on an axis. In some of these teachings, the contact pin 211 is located near this axis to keep the relative motion between the contact pin 211 and the leaf spring 215 small. The range of motion induced by the cam 107 over the contact pin 211 may be 10% or less of the range of motion induced by the cam 107 over the portion of the rocker arm assembly 106 furthest from the axis. In some of these teachings, the range of motion of the contact pin 211 is 2% or less of the motion induced on the portion of the rocker arm assembly 106 furthest from the axis.

On the other hand, in some of these teachings, a particular range of motion between the contact pin 211 and the leaf spring 215 is desired. A portion of the surface of the leaf spring 215 may be coated with a material that significantly increases the resistance of the electrical circuit comprising the connection between the contact pin 211 and the leaf spring 215. The material may be, for example, diamond-like carbon. The contact pin 211 can move to the high resistance surface only when the cam 107 lifts the rocker arm 103E. The increase in resistance may be detected and used to provide rocker arm position information, which may in turn be used for diagnostics or control operations.

As can be seen in fig. 2, the leaf spring 215 has an outwardly arched portion 221 adapted to press against the contact pin 211. The power transfer module 223 may be adapted to maintain the arcuate portion 221. These adaptations may include structures that hold the leaf spring 215 above and below the bowed portion 221. In some of these teachings, the power transfer module 224 is overmolded around the leaf spring 215, wherein the overmolding secures the leaf spring 215 to the power transfer module 224. In some of these teachings, a portion of the leaf spring 215 is bent, and the bent portion abuts the power transfer module 224 to prevent the leaf spring 215 from extending.

The contact plug 219 may be used to couple the power transfer module 224 to the electrical system of the vehicle. The raised position, such as a position above the height of the rocker arm assembly 106, facilitates coupling with the vehicle electrical system because the wires connected to the contacts 219 have a short travel distance before passing through the valve cover (not shown). The electrical wire may pass through the valve cover adjacent the spark plug tower. One option is to lead wires into and out of the spark plug towers so that they pass through the valve cover inside the spark plug towers.

The power transfer module 224 has a lower portion 241 that rests against the cylinder head 102 adjacent the pivot 140, and an upper portion 243 that fits over and may rest on a raised portion 245 of the cylinder head 102. The raised portion 245 may be above the rocker arm assembly 106. "above" is used in the following sense: the rocker arm assembly 106 is "above" the combustion chambers contained within the cylinder head 102. The pivot 140 fits through an opening 225 in the power transfer module 224. The opening 225 abuts the pivot 140 and helps position the power transfer module 224. The opening 225 may fit closely around the pivot 140 so that the pivot 140 may be engaged to the power transfer module 224 prior to installation.

An opening 233 may be formed in the lower portion 241 of the power transfer module 224 and used to bolt the power transfer module 224 to the cylinder head 102. Alternatively or in addition, an opening may be formed in the upper portion 243 of the power transfer module 224 and used to bolt the power transfer module 224 to a raised portion 245 of the cylinder head 102.

The rocker arm assembly 106 may be less than 25mm wide, and preferably less than 22mm wide. As shown in fig. 7, contact pins 212 may be held on the sides of rocker arms 103E by contact frame 249. Contact frame 249 is shown in isolation in fig. 6. Electrical wires 227 connect the contact pins 211 to electrical equipment within the rocker arm 103E. The wires 227 may be enclosed within the contact frame 249. The wires 227 and/or contact pins 211 may be overmolded within the contact frame 249.

An electromagnetic latch assembly 122 may be mounted in the swing arm 103E through an opening 116 formed in the rear of the swing arm 103G. The contact frame 249 may be mounted in the opening 116. The contact frame 249 may be retained to the swing arm 103E by contact with the opening 116. Alternatively or additionally, contact frame 249 may cooperate with the sides of rocker arm 103E to form an interference fit. The interference fit may require that the contact frame 249 deform outward before it can slide over and be allowed to snap into place on the rocker arm 103E. The interference fit may be formed by an inward projection on contact frame 249 and a corresponding indentation on rocker arm 103E, or any other suitable combination of projections and indentations on both portions.

The components and features of the present disclosure have been shown and/or described in accordance with certain teachings and examples. Although a particular component or feature or a broad or narrow expression of that component or feature may have been described in connection with only one embodiment or example, all components and features, whether broadly or narrowly expressed, may be combined with other components or features as long as such combination is considered logical by those of ordinary skill in the art.

Claims

1. A valve train for an internal combustion engine of the type having a combustion chamber, a movable valve having a seat formed in the combustion chamber, and a camshaft, the valve train comprising:

a rocker arm assembly including a rocker arm and a cam follower configured to engage a cam mounted on a camshaft as the camshaft rotates; and

an electrical circuit comprising an electrical device mounted to the rocker arm;

wherein the circuit comprises an electrical connection formed by abutment between surfaces of two different parts;

the rocker arm assembly operative to slide one of the two abutment surfaces over the other abutment surface in response to actuation of the cam follower; and is

One of the two abutment surfaces is formed by a leaf spring.

2. The valve train of claim 1, wherein the leaf spring is mounted to a different portion than the rocker arm assembly.

3. The valve train according to claim 2, wherein the surface abutting the leaf spring is provided by a portion mounted on the rocker arm.

4. The valve train of claim 2, wherein the electrical connection is made between the leaf spring and a contact pin mounted on the rocker arm.

5. The valvetrain of claim 1, wherein the leaf spring is retained by a mounting frame that rests against a cylinder head of an engine.

6. The valvetrain of claim 1, wherein the leaf spring is retained by a mounting frame that fits about a pivot shaft that provides a fulcrum for the rocker arm assembly.

7. The valve train of claim 1, wherein the leaf spring is retained by a mounting frame abutting two or more pivot shafts that provide a fulcrum for a rocker arm assembly of the valve train.

8. The valve train according to claim 1, wherein the other of the two abutment surfaces is a contact held to one side of the rocker arm.

9. The valve train according to claim 8, wherein:

the circuit further comprises a second electrical connection formed by abutment between surfaces of the two different parts; and is

The second electrical connection is formed by a second contact held to an opposite side of the rocker arm.

10. The valve train of claim 9, wherein the contacts held to the rocker arm are adjoined by a contact frame that extends from one contact on one side of the rocker arm to another contact on the opposite side of the rocker arm.

11. The valve train of claim 10, wherein conductors of the electrical circuit that travel from the contacts at the side of the rocker arm are enclosed within the contact frame.

12. The valve train of claim 11, wherein the contact frame snaps around the side of the rocker arm.

13. The valve train of claim 10, wherein the contact frame must be deformed to be placed in or removed from its position on the rocker arm.

14. The valve train of claim 1, wherein the electrical connection is isolated from ground.

15. The valve train of any of claims 1-14, wherein the leaf spring is retained by a mounting frame overmolded around the leaf spring.