US5080054A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rocker arm arrangement for variable timing valve train
Assignee: Nissan Motor Co Ltd
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Filing: 1991-02-28
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Granted: 1992-01-14
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Expires: 2011-02-28
Abstract
Abstract A main rocker arm which is pivotally mounted on a rocker shaft has a sub-rocker arm pivotally mounted thereon. The main rocker arm is arranged to open and close at least one poppet valve. A hydraulic lash adjuster or adjusters are arranged at the free end of the main rocker arm to reduce valve clearance to zero. The sub-rocker arm can be selectively locked to the main one by way of hydraulically operated plunger arrangement. The main rocker arm is provided with a roller type cam follower which follows a low speed cam. The sub-rocker arm is provided with a follower which engages a high speed cam. The low speed cam follower is arranged to project above the high speed one when the two rocker arms are interlocked so that the low speed cam follower engages the base circle of the low speed cam and a clearance is developed between the high speed cam follower and the base circle of the high speed cam. This eliminates the need for sudden changes in lash adjuster length when the valve train operation switches between high and low speed operation.
Inventors
- 👤 Makoto Nakamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 09:05
CPC Classifications
F; F01; F01L; F01L1/00; F01L1/26; F01L1/267; F01L1/20; F01L1/22; F01L1/24; F01L1/2411
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
210 words
In an internal combustion engine having a cylinder head a first rocker arm pivotally mounted on the cylinder head; a second rocker arm pivotally mounted on said first rocker arm; hydraulically operated engagement means for selectively connecting said first and second rocker arms in a manner wherein relative movement therebetween is prevented; a first cam follower on said first rocker arm, said first cam follower being arranged to operatively engage a first cam which has a base circle portion and a profile portion, the profile portion being suited for low speed engine operation; a second cam follower on said second rocker arm, said second cam follower being arranged to operatively engage a second cam which has a base circle portion and a profile portion which is suited for high speed engine operation; and wherein said first cam follower and the base circle portion of said first cam are so constructed and arranged that when said hydraulic operated engagement means connects said first and second rocker arms in a manner which prevents relative movement therebetween, a predetermined clearance is established between the base circle portion of said second cam and said second cam follower while the first cam follower is in engagement with the base circle portion of said first cam.
Claim 2
Dependent Claim
210 words
In an internal combustion engine having a cylinder head a first rocker arm pivotally mounted on the cylinder head; a second rocker arm pivotally mounted on said first rocker arm; hydraulically operated engagement means for selectively connecting said first and second rocker arms in a manner wherein relative movement therebetween is prevented; a first cam follower on said first rocker arm, said first cam follower being arranged to operatively engage a first cam which has a base circle portion and a profile portion, the profile portion being suited for low speed engine operation; a second cam follower on said second rocker arm, said second cam follower being arranged to operatively engage a second cam which has a base circle portion and a profile portion which is suited for high speed engine operation; and wherein said first cam follower and the base circle portion of said first cam are so constructed and arranged that when said hydraulic operated engagement means connects said first and second rocker arms in a manner which prevents relative movement therebetween, a predetermined clearance is established between the base circle portion of said second cam and said second cam follower while the first cam follower is in engagement with the base circle portion of said first cam.
Claim 3
Dependent Claim
35 words
An internal combustion engine as claimed in claim 1 further comprising: a hydraulic lash adjuster operatively mounted on said first rocker, said hydraulic lash adjuster being arranged to engage a stem of the poppet valve.
Claim 4
Dependent Claim
85 words
An internal combustion engine as claimed in claim 1 wherein the first and second cams are on a single cam shaft and the base circles of said first and second cams have the same diameter, and wherein said first cam follower is arranged to project above said second cam follower when said first and second rocker arms are interlocked by said hydraulic operated engagement means, so that said first cam follower engages the base circle of said first cam and the predetermined clearance is established.
Claim 5
Dependent Claim
42 words
An internal combustion engine as claimed in claim 1 further comprising: a lost motion spring mounted on said first rocker arm and arranged to engage said second rocker arm in a manner which biases said second rocker arm against said second cam.
Claim 6
Dependent Claim
195 words
An internal combustion engine as claimed in claim 4 wherein said hydraulically operated engagement means comprises: a first bore formed in said first rocker arm; a first plunger reciprocatively disposed in said first bore in a manner to define a hydraulic chamber which is in fluid communication with said second passage; a second bore formed in said second rocker arm, said second bore being formed in said second rocker arm so as to be alignable with said first bore; a second plunger reciprocatively disposed in said second bore, said second plunger having first end which is abutable with an end of said first plunger, said second plunger having a length which is essentially the same as the length of the bore; a third bore formed in said first rocker arm, said third bore being formed so as to be alignable with said second bore; a third plunger reciprocatively disposed in said third bore, said third plunger having a first end which is abutable with a second end of said second plunger; and a return spring disposed in said third bore and arranged to produce a bias which acts on a second end of said plunger.
Claim 7
Dependent Claim
53 words
An internal combustion engine as claimed in claim 5 wherein said first, second and third plungers are formed with tapered portions which facilitate the engagement of the first and second rocker arms when the first, second and third bores in which the first, second and third plungers are respectively disposed, are slightly misaligned.
Claim 8
Dependent Claim
64 words
An internal combustion engine as claimed in claim 5 further comprising: a retainer which is disposed between said lost motion spring and second rocker arm, said retainer and said first rocker arm being so constructed and arranged that the movement of said retainer toward said second rocker arm is limited and is selected to facilitate the alignment of said first, second and third bores.
Claim 9
Dependent Claim
44 words
A valve train as claimed in claim 5 further comprising passage means defined in said first rocker arm and the rocker shaft on which said first rocker arm is pivotally mounted, said passage means being arranged to supply control pressure to said hydraulic chamber.
Claim 10
Dependent Claim
182 words
In a gear train for an internal combustion engine a cam shaft operatively mounted on a cylinder head; a first rocker arm pivotally mounted on the cylinder head; a second rocker arm pivotally mounted on said first rocker arm; hydraulically operated engagement means for selectively connecting said first and second rocker arms in a manner wherein relative movement therebetween is prevented; a first cam follower on said first rocker arm, said first cam follower being arranged to operatively engage a first cam which has a base circle portion and a profile portion, the profile portion being suited for low speed engine operation; a second cam follower on said second rocker arm, said second cam follower being arranged to operatively engage a second cam which has a base circle portion and a profile portion which is suited for high speed engine operation; and wherein said first cam follower is arranged to project further toward said cam shaft than said second cam follower when said hydraulic operated engagement means connects said first and second rocker arms in a manner which prevents relative movement therebetween.
Claim 11
Dependent Claim
182 words
In a gear train for an internal combustion engine a cam shaft operatively mounted on a cylinder head; a first rocker arm pivotally mounted on the cylinder head; a second rocker arm pivotally mounted on said first rocker arm; hydraulically operated engagement means for selectively connecting said first and second rocker arms in a manner wherein relative movement therebetween is prevented; a first cam follower on said first rocker arm, said first cam follower being arranged to operatively engage a first cam which has a base circle portion and a profile portion, the profile portion being suited for low speed engine operation; a second cam follower on said second rocker arm, said second cam follower being arranged to operatively engage a second cam which has a base circle portion and a profile portion which is suited for high speed engine operation; and wherein said first cam follower is arranged to project further toward said cam shaft than said second cam follower when said hydraulic operated engagement means connects said first and second rocker arms in a manner which prevents relative movement therebetween.
Claim 12
Dependent Claim
26 words
An internal combustion engine as claimed in claim 9 wherein said first cam follower is a roller which is rotatably supported on said first rocker arm.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-01-13 | 1995-07-15 | 1996-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-01-13 | 1999-07-15 | 2000-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-01-13 | 2003-07-15 | 2004-01-14 | $7700.00 | Window Closed / Lapsed |