US3741175A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable compression ratio internal combustion engines
Assignee: Safran Aircraft Engines SAS
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Filing: 1971-07-29
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Granted: 1973-06-26
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Expires: 1991-07-29
Abstract
Abstract The internal combustion engine comprises at least one main cylinder in which a main piston driving a drive shaft moves, and a cylinder head over the main cylinder. An auxiliary piston slides in an auxiliary cylinder contrived in the cylinder head and communicating with the main cylinder. An actuating mechanism reciprocates the auxiliary piston at half the rate of the main piston piston reciprocation (four-stroke engine) or at the rate of main piston reciprocation (two-stroke engine). Control or adjusting means act on said actuating mechanism so as to vary auxiliary piston travel. The actuating mechanism is so devised that the offset between main piston and auxiliary piston reciprocations is such that the auxiliary piston reaches its inner dead centre position during the exhaust stroke (four-stroke engine) or during the scavenging stroke (two-stroke engine).
Inventors
- 👤 H Rouger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 08:02
CPC Classifications
F; F02; F02D; F02D15/00; F02D15/04; F02B; F02B41/00; F02B75/00; F02B75/02; F02B2075/022; F02B2075/027
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
187 words
In a variable compression ratio four-stroke internal combustion engine comprising: at least one main cylinder in which a main piston slides driving a crank-shaft; a cylinder head covering this main cylinder; an auxiliary cylinder arranged in this cylinder head and in which an auxiliary piston slides; a passage between the auxiliary cylinder and the main cylinder; a control mechanism actuating the auxiliary piston in a reciprocating motion between an inner dead center near the main cylinder and an outer dead center remote from the main cylinder; the improvement wherein the reciprocating motion of the auxiliary piston operates at a rate equal to half the rate of the reciprocating motion of the main piston, the relative offset between the reciprocating motions of the main piston and of the auxiliary piston is such that the inner dead center is reached by the auxiliary piston during or at the end of the exhaust stroke, and adjusting means are provided for varying the stroke of the auxiliary piston such that the inner dead center position is fixed and the variable outer dead center position is a function of the compression ratio.
Claim 2
Dependent Claim
187 words
In a variable compression ratio four-stroke internal combustion engine comprising: at least one main cylinder in which a main piston slides driving a crank-shaft; a cylinder head covering this main cylinder; an auxiliary cylinder arranged in this cylinder head and in which an auxiliary piston slides; a passage between the auxiliary cylinder and the main cylinder; a control mechanism actuating the auxiliary piston in a reciprocating motion between an inner dead center near the main cylinder and an outer dead center remote from the main cylinder; the improvement wherein the reciprocating motion of the auxiliary piston operates at a rate equal to half the rate of the reciprocating motion of the main piston, the relative offset between the reciprocating motions of the main piston and of the auxiliary piston is such that the inner dead center is reached by the auxiliary piston during or at the end of the exhaust stroke, and adjusting means are provided for varying the stroke of the auxiliary piston such that the inner dead center position is fixed and the variable outer dead center position is a function of the compression ratio.
Claim 3
Dependent Claim
46 words
An engine according to claim 1, wherein the inner dead centre position is reached at a time corresponding to an advance of from 90* to 0* crankshaft angle before the top dead centre position of the main piston at the end of the exhaust stroke thereof.
Claim 4
Dependent Claim
175 words
In a variable compression ratio two-stroke internal combustion engine comprising: at least one main cylinder driving a crank-shaft; a cylinder head covering this main cylinder; an auxiliary cylinder arranged in this cylinder head and in which an auxiliary piston slides; a passage between the auxiliary cylinder and the main cylinder; a control mechanism actuating the auxiliary piston in a reciprocating motion between an inner dead center near the main cylinder and an outer dead center remote from the main cylinder, the improvement wherein the reciprocating motion of the auxiliary piston operates at a rate equal to the rate of the reciprocating motion of the main piston, the relative offset between the reciprocating motions of the main piston and of the auxiliary piston is such that the inner dead center is reached by the auxiliary piston during the scavenging stroke, and adjusting means are provided for varying the stroke of the auxiliary piston such that the inner dead center position is fixed and the outer dead center position varies as a function of the compression ratio.
Claim 5
Dependent Claim
175 words
In a variable compression ratio two-stroke internal combustion engine comprising: at least one main cylinder driving a crank-shaft; a cylinder head covering this main cylinder; an auxiliary cylinder arranged in this cylinder head and in which an auxiliary piston slides; a passage between the auxiliary cylinder and the main cylinder; a control mechanism actuating the auxiliary piston in a reciprocating motion between an inner dead center near the main cylinder and an outer dead center remote from the main cylinder, the improvement wherein the reciprocating motion of the auxiliary piston operates at a rate equal to the rate of the reciprocating motion of the main piston, the relative offset between the reciprocating motions of the main piston and of the auxiliary piston is such that the inner dead center is reached by the auxiliary piston during the scavenging stroke, and adjusting means are provided for varying the stroke of the auxiliary piston such that the inner dead center position is fixed and the outer dead center position varies as a function of the compression ratio.
Claim 6
Dependent Claim
28 words
An engine according to claim 3 wherein the inner dead centre position is reached at a time corresponding to the top dead centre position of the main piston.
Claim 7
Dependent Claim
46 words
An engine according to claim 1 wherein the superficial area of the auxiliary piston is less than half the superficial area of the main piston, and the volume swept by the auxiliary piston is less than 10 percent of the volume swept by the main piston.
Claim 8
Dependent Claim
35 words
A four-stroke engine according to claim 1 wherein the inner dead centre position of the auxiliary piston is arranged to give a very reduced residual volume between the main piston, cylinder head and auxiliary piston.
Claim 9
Dependent Claim
23 words
A four-stroke engine according to claim 1 wherein the auxiliary piston actuating mechanism takes the form of linkage driven by the engine camshaft.
Claim 10
Dependent Claim
80 words
An engine according to claim 7 wherein the camshaft has for each auxiliary piston a wrist pin fitted with a rod coupled with a lever, one end of which pivots around a spindle and the other end of which is connected to the end of a rod pivoted to the auxiliary piston, the spindle being movable between two end positions, one corresponding to engine operation at maximum compression ratio and the other corresponding to engine operation at minimum compression ratio.
Claim 11
Dependent Claim
47 words
An engine according to claim 8 wherein the spindle is moved by a pivoting arm, the spindle being mounted at one end of such arm, the other end thereof being rigidly secured to a rotatable shaft whose angular position is controlled by the adjusting or control means.
Claim 12
Dependent Claim
95 words
An engine according to claim 7 wherein the camshaft has for each auxiliary piston a wrist pin on which a rod coupled with a lever and guided in a link is disposed, one end of the lever being formed with an elongated aperture in which a spindle engages, the other end of the lever being connected to the end of a rod pivoted to the auxiliary piston, the spindle being movable between two end positions, one corresponding to engine operation at maximum compression ratio and the other corresponding to engine operation at minimum compression ratio.
Claim 13
Dependent Claim
20 words
An engine according to claim 10 wherein the spindle is displaced through the agency of the control or adjusting means.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |