WO1999051864A2

WO1999051864A2 - Hydraulic lash adjuster with compression release brake

Info

Publication number: WO1999051864A2
Application number: PCT/US1999/007322
Authority: WO
Inventors: Thomas J. Bresnahan; Bruce N. Swanbon; James N. Usko
Original assignee: Diesel Engine Retarders, Inc.
Priority date: 1998-04-03
Filing date: 1999-04-02
Publication date: 1999-10-14
Also published as: EP1068432A2; JP2002510770A; WO1999051864A3; JP4567188B2; KR20010042444A

Abstract

The present invention is directed to an improved assembly for operating at least one exhaust valve (710) and at least one intake valve (710) in a cylinder in an engine. The assembly (10) includes a rocker shaft (200), an intake rocker arm (100) pivotally mounted on the rocker shaft for operating at least one intake valve of the engine cylinder, an exhaust rocker arm pivotally mounted on the rocker shaft for operating at least one exhaust valve of the engine cylinder. The improved assembly includes a lash adjusting assembly (300) for adjusting a lash between at least one of the intake rocker arm and the at least one intake valve, and the exhaust rocker arm and the at least one exhaust valve. The improvement further includes an energy supply assembly for supplying energy to the lash adjusting assembly to operate the lash adjusting assembly. The improved assembly further includes a control assembly (500) for controlling the operation of the supply assembly in response to predetermined engine operating conditions.

Description

HYDRAULIC LASH ADJUSTER WITH COMPRESSION RELEASE BRAKE

Cross Reference To Related Patent Application

This application relates to and claims priority on provisional application serial number 60/080,606, filed April 3, 1998.

Field of the Invention

The present invention relates generally to a hydraulic lash adjuster assembly for use in a diesel engine having a compression release retarder. In particular, the present invention is directed to a system that permits an engine to operate under positive power with a hydraulic lash adjuster to remove unwanted lash and to disable the hydraulic lash adjuster when operating within a compression release retarder.

Background of the Invention

Today the use of hydraulic lash adjusters in heavy duty diesel engines is nonexistent or in limited use at best. However, with the technological advancements and discussions of hydraulic overheads, camless engines with hydromechanical valve control, and lost motion devices, the hydraulic lash adjuster is sure to be standard equipment before any of the other mechanisms mentioned. The hydraulic lash adjuster mechanism is a standard component in most automotive gasoline engines on the road today, and has become reliable for that industry. The use of a hydraulic lash adjuster on the exhaust rocker arms of an engine equipped with an engine brake will not work. The constant flow of oil to the hydraulic lash adjuster will cause the hydraulic lash adjuster plunger to protrude further out of its assembly during the brake operation, resulting in the valve not seating at the end of the engine cycle. A commonly used device added to the heavy duty diesel engine is a compression release retarder. This device actuates one or more exhaust valve in its mode of operation. Objects of the Invention

It is an object of the present invention to provide a hydraulic lash adjuster in a diesel engine having a compression release retarder.

It is another object of the present invention to provide a hydraulic lash adjuster in a diesel engine to remove unwanted lash during positive power.

It is another object of the present invention to provide a hydraulic lash adjuster in a diesel engine that can be disabled during a compression release retarding operation.

It is another object of the present invention to provide a hydraulic lash adjuster in an engine to permit modification of valve timing during positive power. It is another object of the present invention to provide a hydraulic lash adjuster in an engine to permit modification of lift during positive power.

It is another object of the present invention to provide a hydraulic lash adjuster in a diesel engine for improved emissions during positive power.

Summary of the Invention

The present invention is directed a system for use in a diesel engine having a compressionreleaseretarder. The system includes a hydraulic lash adjustor assembly located on at least one of an intake rocker arm and an exhaust rocker arm. The rocker arms are pivotally mounted on a rocker shaft. The rocker shaft includes a passageway for each of the intake rocker arm and the exhaust rocker arm to provide a supply of hydraulic fluid to operate the hydraulic lash adjusters on the intake rocker arm and the exhaust rocker arm. At least one solenoid valve on the rocker shaft is provided to control the flow of hydraulic fluid through the passageways to operate the hydraulic lash adjusters on the exhaust and intake rocker arms. A control assembly is provided to control the operation of the solenoid valves. The control assembly controls the operation of the solenoid valves to permit operation of the adjusters during positive power and to deactivate the adjusters during a compression release retarding operation. Furthermore, the operation of the control assembly permits the lash adjusters to be operated to adjust valve timing during positive power. The system also includes a brake rocker arm assembly having its own cam lobe or a conventional engine brake to facilitate engine braking.

The present invention is directed to an improved assembly for operating at least one exhaust valve and at least one intake valve in a cylinder in an engine. The assembly includes a rocker shaft, an intake rocker arm pivotally mounted on the rocker shaft for operating at least one intake valve of the engine cylinder, an exhaust rocker arm pivotally mounted on the rocker shaft for operating at least one exhaust valve of the engine cylinder. The improved assembly includes a lash adjusting assembly for adjusting a lash between at least one of the intake rocker arm and the at least one intake valve, and the exhaust rocker arm and the at least one exhaust valve. The improvement further includes an energy supply assembly for supplying energy to the lash adjusting assembly to operate the lash adjusting assembly. The improved assembly further includes a control assembly for controlling the operation of the supply assembly in response to predetermined engine operating conditions.

The lash adjusting assembly may be located on the intake rocker arm, wherein the lash adjusting assembly adjusts the lash between the intake rocker arm and the at least one intake valve. The lash adjusting assembly may be located on the exhaust rocker arm, wherein the lash adjusting assembly adjusts the lash between the exhaust rocker arm and the at least one exhaust valve. Finally, the improved assembly may include a pair of the lash adjusting assemblies to adjuv the lash between the exhaust rocker arm and the at least one exhaust valve and between the intake rocker arm and the at least one intake valve.

The energy supply assembly may supply hydraulic fluid to the lash adjusting assembly to operate the lash adjusting assembly. The energy supply assembly may comprise a fluid passageway to supply hydraulic fluid to the lash adjusting assembly, and an assembly for controlling the flow of hydraulic fluid within the fluid passageway. The energy supply assembly may be located on the rocker shaft.

The control assembly may operate the supply assembly to supply energy to the lash adjusting assembly during positive power. The control assembly may operate the supply assembly to deactivate the lash adjusting assembly during an engine braking operation. The control assembly may operate the supply assembly to deactivate the lash adjusting assembly after the control assembly senses a predetermined engine operating condition. The control assembly is capable of operating the supply assembly to operate the lash adjusting assembly to modify valve timing of at least one of the at least one exhaust valve and the at least one intake valve. Furthermore, the control assembly is capable of operating the supply assembly to operate the lash adjusting assembly to modify valve lift of at least one of the at least one exhaust valve and the at least one intake valve. Additionally, the control assembly is capable of operating the supply assembly to operate the lash adjusting assembly to modify overlap of the at least one exhaust valve and the at least one intake valve.

Brief Description of the Drawings

The invention will be described in conjunction with the following drawings in which like reference numerals designate like elements and wherein:

Fig. 1 is a schematic of the hydraulic lash adjuster system in accordance with the present invention; Fig. 2 is an exploded schematic view of the hydraulic lash adjuster system in accordance with the present invention; and

Fig.2 is a graph depicting the modified valve timing achieved in accordance with the present invention.

Detailed Description of the Preferred Embodiments

Fig. 1 illustrates a rocker arm assembly 10 for use in operating at least one cylinder valve in a diesel engine. A single rocker arm assembly 10 is depicted for illustrative purposes only. It i to be understood that a separate rocker arm assembly 10 is provided to operate at least one exhaust valve and to operate at least one intake valve associated with a cylinder. The rocker arm assembly 10 includes a pivoting rocker arm 100 that is pivotably mounted on a rocker shaft 200. The rocker arm assembly 10 further includes a hydraulic lash adjuster assembly 300 that is mounted on the rocker arm 100. The rocker arm assembly 10 further includes at least one valve 400 for controlling the operation of the hydraulic lash adjuster assembly 300. The operation of the valve 400 is controlled by a control assembly 500.

The rocker shaft 200 includes at least two passages therein. A first passage 210 supplies lubrication, such as, for example, hydraulic fluid to the moving components in the valve train. A second passage 220 supplies hydraulic fluid to the hydraulic lash adjuster 300 located on the rocker arm 100.

The rocker arm 100 includes a first end 110 and a second end 120. the hydraulic lash adjuster 300 is located within a cavity 111 within the first end 110 of the rocker arm 100, as shown in Fig. 2. A passageway 130 extends within the rocker arm 100 from the cavity 111 in the first end 110 to the rocker shaft 200 such that the hydraulic lash adjuster 300 is fluidically connected to the second passage 220. The second end 120 of rocker arm 100 includes a follower assembly 121. The follower assembly 121 is adapted to follow the profile of a cam lobe assembly 600.

The hydraulic lash adjuster 300 will now be described. The lash adjuster 300 is mounted within the cavity 111 within the first end 110 of the rocker arm 100, as shown in

Fig. 2. The lash adjuster 300 includes an inner plunger 310 and an outer plunger 320. The outer plunger 320 is slidably received within the cavity 111. The inner plunger 310 is slidably received within the outer plunger 320.

In operation, hydraulic fluid flows into the cavity 111 from passageway 130. A check valve 311 in the inner plunger 310 is biased downward to permit the flow of fluid into a cavity 312 is filled with fluid, a second check valve 313 located in the lower end of the cavity 312 is biased downward to permit the flow of fluid into a cavity 330 formed by the lower end of the inner piston 310 and the upper end of the outer piston 320. As the cavity 330 fills with fluid, the outer piston 320 moves downward to an extended position to engage a crosshead pin 700. The crosshead 700 is then capable of operating at lest one valve 710. the downward movement of the outer piston 320 is limited by surface 321 engaging surface 112 in the cavity 111.

The control assembly 500 controls the operation of the valve 400 to supply hydraulic fluid to the lash adjuster assembly 300. The control assembly 500 may be integrated into the control assembly of the engine. Alternatively, the control assembly 500 may be a separate control assembly. The valve 400 is preferably a normally open three-way solenoid valve. the control assembly 500 sense engine speed, fuel on/off mode, clutch engagement, and various positive power conditions to identify the need to reduce valve. The operation of the rocker arm assembly 10 will now be described. During positive power operation, hydraulic fluid flows through the first passage 210 of the rocker shaft 200 to lubricate including but not limited to the rocker arm bushing, the follower assembly 121 and the valve train, the control assembly 500 operates the valve 400 to supply hydraulic fluid through the second passage 220 to the passageway 130 to operate the hydraulic lash adjuster assembly 300. The lash adjuster assembly 500 extends to take up any unwanted lash. This allows the engine to operate in a valve timing mode that is optimized for a particular engine speed.

When the engine brake is activated, the control assembly 500 operates the valve 400 to deactivate flow of hydraulic fluid to the hydraulic lash adjuster assembly 300. The fluid within the cavity 111 and the passageway 130 is permitted to drain which allows the inner plunger 310 and outer plunger 320 to retreat to a collapsed position. The engine brake rocker arm, now shown, can then be operated to operate the at least one exhaust valve as an engine brake.

If the control assembly 500 determines that a change in valve overlap is necessary during positive power, the control assembly 500 can activate the valve 400 in the rocker shaft

200 and cause the lash adjuster assembly 300 to collapse and change valve timing, overlap and lift, as shown in Fig. 3. With additional valves the exhaust and intake could be operated separately, allowing only the exhaust or intake valve timing vary from a set condition.

While this invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined in the following claims.

Claims

What Is Claimed Is:

1. In an assembly for operating at least one exhaust valve and at least one intake valve in a cylinder in an engine, said assembly including a rocker shaft, an intake rocker arm pivotally mounted on the rocker shaft for operating at least one intake valve of the engine cylinder, an exhaust rocker arm pivotally mounted on the rocker shaft for operating at least one exhaust valve of the engine cylinder, the improvement comprising: lash adjusting means for adjusting a lash between at least one of the intake rocker arm and the at least one intake valve, and the exhaust rocker arm and the at least one exhaust valve; energy supr ly means for supplying energy to said lash adjusting means to operate said lash adjusting means; and control means for controlling the operation of said supply means in response to predetermined engine operating conditions.

2. The assembly according to Claim 1 , wherein said lash adjusting means is located on the intake rocker arm, wherein said lash adjusting means adjusts the lash between said intake rocker arm and said at least one intake valve.

3. The assembly according to Claim 1, wherein said lash adjusting means is located on the exhaust rocker arm, wherein said lash adjusting means adjusts the lash between said exhaust rocker arm and said at least one exhaust valve.

4. The assembly according to Claim 1 , wherein said assembly includes a pair of said lash adjusting means to adjust the lash between the exhaust rocker arm and the at least one exhaust valve and between the intake rocker arm and the at least one intake valve.

5. ' lie assembly according to Claim 1, wherein said energy supply means supplies hydraulic fluid to said lash adjusting means to operate said lash adjusting means.

6. The assembly according to Claim 5, wherein said energy supply means comprises: a fluid passageway to supply hydraulic fluid to said lash adjusting means; and means for controlling the flow of hydraulic fluid within said fluid passageway. DP-236

7. The assembly according to Claim 5, wherein said energy supply means is located on the rocker shaft.

8. The assembly according to Claim 1, wherein said control means operates said supply means to supply energy to said lash adjusting means during positive power.

9. The assembly according to Claim 1, wherein said control means operates said supply means to deactivate said lash adjusting means during an engine braking operation.

10. The assembly according to Claim 1 , wherein said control means operates said supply means to deactivate said lash adjusting means after said control means senses a predetermined engine operating condition.

11. The assembly according to Claim 10, wherein said control means is capable of operating said supply means to operate said lash adjusting means to modify valve timing of at least one of said at least one exhaust valve and said at least one intake valve.

12. The assembly according to Claim 10, wherein said control means is capable of operating said supply means to operate said lash adjusting means to modify valve lift of at least one of said at least one exhaust valve and said at least one intake valve.

13. The assembly according to Claim 10, wherein said control means is capable of operating said supply means to operate said lash adjusting means to modify overlap of said at least one exhaust valve and said at least one intake valve.