US3703937A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiple rpm range tuned exhaust pipe and silencer for two-cycle engine
Assignee: Individual
•
Filing: 1971-05-21
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Granted: 1972-11-28
•
Expires: 1991-05-21
Abstract
Abstract An expansion chamber exhaust system operative to obtain high power output from two-cycle engines at more than one engine rpm range. The exhaust system includes automatic or manual means to change the effective range of engine rpm at which it is providing power increase. At least one valve member is provided, which is open in a low speed position, to permit substantially unrestricted passage of the exhaust gases and exhaust gas pressure waves past the valve member, and which closes at higher engine rpm to provide a pressure wave reflecting surface so positioned to reflect a positive pressure wave to arrive at the exhaust port of the two-cycle engine just before the port closes, at the desired higher rpm range of the engine. The exhaust systems can be made with a fixed positive wave reflecting surface downstream from the valve member, or they may open directly to atmosphere downstream from the valve member, and they may include a silencing muffler, is desired.
Inventors
- 👤 William L Tenney
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 16:00
CPC Classifications
F; F01; F01N; F01N13/00; F01N13/08; F01N1/00; F01N1/16; F01N1/165; F01N1/166; F02; F02B; F02B27/00; F02B27/04; F02B27/06; F01N2590/00; F01N2590/04; F02B75/00; F02B75/02; F02B2075/022; F02B2075/025; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
134 words
An exhaust system for two-cycle engines including an exhaust port, a tubular exhaust duct member including a portion generally expanding in cross sectional area in direction of exhaust gas flow from said exhaust port and in communication therewith, and having an exhaust gas outlet, valve means positioned in said tubular exhaust duct member, means to move the valve meanS between a first position wherein said valve means does not substantially influence exhaust gas flow through said tubular member, and a second position where it forms a pressure wave reflecting surface so positioned with respect to said exhaust port as to reflect a positive pressure wave timed to arrive back at the exhaust port of said engine immediately prior to closing of said exhaust port when said engine is operating in a preselected speed range.
Claim 2
Dependent Claim
134 words
An exhaust system for two-cycle engines including an exhaust port, a tubular exhaust duct member including a portion generally expanding in cross sectional area in direction of exhaust gas flow from said exhaust port and in communication therewith, and having an exhaust gas outlet, valve means positioned in said tubular exhaust duct member, means to move the valve meanS between a first position wherein said valve means does not substantially influence exhaust gas flow through said tubular member, and a second position where it forms a pressure wave reflecting surface so positioned with respect to said exhaust port as to reflect a positive pressure wave timed to arrive back at the exhaust port of said engine immediately prior to closing of said exhaust port when said engine is operating in a preselected speed range.
Claim 3
Dependent Claim
35 words
The combination as specified in claim 1 wherein said valve means comprises a blade member pivotally mounted about an axis positioned in a preselected relationship with respect to exhaust gas flow in said exhaust system.
Claim 4
Dependent Claim
36 words
The combination as specified in claim 2 wherein said means for moving said valve means toward its first position comprises bias means acting to create a moment about the axis of pivot of said blade member.
Claim 5
Dependent Claim
15 words
The combination as specified in claim 3 wherein said bias means comprises a weight member.
Claim 6
Dependent Claim
14 words
The combination as specified in claim 3 wherein said bias means comprises a spring.
Claim 7
Dependent Claim
80 words
The combination as specified in claim 3 wherein said blade member is positioned at a preselected angle of attack with respect to direction of normal exhaust gas flow through said exhaust system, means mounting said blade member so that said exhaust gas flowing across said blade member creates a lift on a portion of said blade member to move said blade toward said second position when the exhaust gas flow across said blade member has substantially reached a preselected velocity.
Claim 8
Dependent Claim
31 words
The combination of claim 4 wherein said weight member is mounted directly on said blade member adjacent the leading edge thereof with respect to the direction of flow of exhaust gas.
Claim 9
Dependent Claim
42 words
The combination as specified in claim 2 wherein the axis of mounting of said blade member is offset with respect to a transverse bisecting line of said blade member and the major portion of said blade member is upstream from the axis.
Claim 10
Dependent Claim
24 words
The exhaust system of claim 1 further characterized in that means forming an engine noise silencing device is mounted downstream from said valve means.
Claim 11
Dependent Claim
24 words
The exhaust system of claim 9 wherein said noise silencing device forms a fixed wave reflecting surface located farther downstream from said valve means.
Claim 12
Dependent Claim
37 words
The combination as specified in claim 1 and a chamber wall forming a fixed positive pressure wave reflecting surface spaced in downstream direction away from said valve means with respect to the direction of exhaust gas flow.
Claim 13
Dependent Claim
22 words
The combination as specified in claim 1 and manually operable means to operate the valve means between its first and second positions.
Claim 14
Dependent Claim
47 words
The combination as specified in claim 2 wherein said blade is mounted onto a shaft, said shaft being pivotally mounted in said tubular duct member, a lever on said shaft, bias means acting through said lever and arranged to bias said blade member toward its open position.
Claim 15
Dependent Claim
38 words
The combination as specified in claim 13 and means to permit adjustment of said bias means with respect to the axis of rotation of said shaft to change the effective moment of said bias means on said shaft.
Claim 16
Dependent Claim
43 words
The combination as specified in claim 2 and stop means to stop said blade member in its first position at a preselected angle with respect to the direction of exhaust gas flow and permit said blade member to move to its second position.
Claim 17
Dependent Claim
24 words
The combination as specified in claim 2 and stop means to stop said blade member when said blade member moves to its second position.
Claim 18
Dependent Claim
35 words
The combination as specified in claim 2 and separate bias means urging said blade member from its second position toward its first position during at least initial portions of blade travel from its second position.
Claim 19
Dependent Claim
110 words
The combination as specified in claim 1 and at least one second valve means located in said tubular member a different distance from the exhaust port than said first valve means, said second valve means being movable from a first position wherein It does not substantially influence flow of gases through the exhaust system, to a second position where it forms a pressure wave reflecting surface so positioned with respect to said exhaust port as to reflect a positive pressure wave timed to arrive back at the exhaust port of said engine immediately prior to closing of said exhaust port when said engine reaches a second preselected speed of operation.
Claim 20
Dependent Claim
43 words
The combination as specified in claim 1 and power means to operate said valve means, an engine speed sensor means to actuate said power means at a preselected engine speed to selectively move said first valve means to its first and second positions.
Claim 21
Dependent Claim
14 words
The combination as specified in claim 19 wherein said power means comprises a solenoid.
Claim 22
Dependent Claim
17 words
The combination as specified in claim 19 wherein said power means comprises a fluid pressure actuated cylinder.
Claim 23
Dependent Claim
30 words
The combination of claim 1 wherein said valve means comprises a blade member, and guide means to support said blade member for sliding movement between said first and second positions.
Claim 24
Dependent Claim
45 words
The combination of claim 1 and rim members positioned around the inner periphery of said tubular exhaust member, said valve means comprising a pivoting blade member, said blade member at least partially engaging said rim members when said blade member pivots to its second position.
Claim 25
Dependent Claim
56 words
The combination of claim 1 and an outlet pipe positioned in said tubular member, said valve member comprising a blade having a U-shaped opening that fits over said pipe when said valve member moves to its second position whereby exhaust gases will be discharged from said pipe when the valve member is in its second position.
Claim 26
Dependent Claim
33 words
The combination of claim 1 wherein said tubular exhaust duct member has a central flow axis that changes direction, and muffler means positioned generally within the space defined by the tubular duct member.
Claim 27
Dependent Claim
28 words
The combination of claim 25 wherein said tubular duct member bends into a generally ''''U'''' shape, and said muffler means is positioned between the legs of the ''''U.''''
Claim 28
Dependent Claim
26 words
The combination as specified in claim 25 wherein said muffler means and curved tubular exhaust duct member are formed with divider walls inside a common housing.
Claim 29
Dependent Claim
23 words
The combination as specified in claim 2 and dashpot means coupled to said pivoting blade member to dampen movement of said blade member.
Claim 30
Dependent Claim
30 words
The combination of claim 1 and bias means to exert a force urging said valve means toward its first position when the valve means has substantially reached said second position.
Claim 31
Dependent Claim
74 words
The combination as specified in claim 1 wherein said valve means comprises a pair of blade members, each pivotally mounted in said exhaust duct member, means operating said blade members together for coordinated movement whereby in said first position of said valve means the blade members are substantially parallel to the flow of exhaust gases and in said second position cooperate to form a surface means converging in the direction of exhaust gas flow.
Claim 32
Dependent Claim
136 words
An exhaust system for two-cycle engines having an exhaust port, an exhaust pipe open to said exhaust port and having an exhaust gas outlet, and blade valve means positioned within said exhaust pipe, means to hold the blade means in a first predetermined position wherein it does not substantially influence exhaust gas flow through said tubular member, and means to move said blade means to a second position wherein it forms a pressure wave reflecting surface so positioned with respect to said exhaust port as to reflect a positive pressure wave timed to arrive back at the exhaust port of said engine shortly prior to closing of said exhaust port when said engine is operating in a speed range preselected to be a higher speed range than when said blade means is in its first position.
Claim 33
Dependent Claim
136 words
An exhaust system for two-cycle engines having an exhaust port, an exhaust pipe open to said exhaust port and having an exhaust gas outlet, and blade valve means positioned within said exhaust pipe, means to hold the blade means in a first predetermined position wherein it does not substantially influence exhaust gas flow through said tubular member, and means to move said blade means to a second position wherein it forms a pressure wave reflecting surface so positioned with respect to said exhaust port as to reflect a positive pressure wave timed to arrive back at the exhaust port of said engine shortly prior to closing of said exhaust port when said engine is operating in a speed range preselected to be a higher speed range than when said blade means is in its first position.
Claim 34
Dependent Claim
79 words
The exhaust system as specified in claim 31 wherein said blade means is pivotally mounted about an axis substantially transverse to the direction of exhaust gas flow through said exhaust piPe, and stop means to support said blade means in its first position at a preselected angle of attack with respect to exhaust gas flow whereby when exhaust gas flow reaches a predetermined velocity said blade means will be moved to its second position by action of aerodynamic forces.
Claim 35
Dependent Claim
36 words
The exhaust system as specified in claim 32 wherein said means for holding said blade means in its first position comprises bias means to create a moment about the axis of pivot of said blade means.
Claim 36
Dependent Claim
30 words
The combination of claim 27 and bias means to exert a force urging said blade means toward its first position when the blade means has substantially reached said second position.
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) | 1975-11-28 | 1976-05-29 | 1976-11-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-28 | 1980-05-29 | 1980-11-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-28 | 1984-05-29 | 1984-11-28 | $7700.00 | Window Closed / Lapsed |