Methods and apparatus to use engine valves as both intake and exhaust valves
Methods and apparatus to selectively use engine valves as both intake and exhaust valves and to selectively operate the engine as a 2 cycle or as a 4 cycle engine. In a disclosed embodiment, the intake valves and the exhaust valves, are manifolded together through a small manifold, with the manifold being connectable to the intake manifold or the exhaust manifold through two-way valves. In preferably a camless engine, the engine valves may be controlled to operate the intake valves as intake valves only or to operate as both intake valves and exhaust valves, and to operate the exhaust valves as exhaust valves only or to operate the exhaust valves as both intake valves and exhaust valves. Exemplary embodiments are disclosed.
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This application claims the benefit of U.S. Provisional Patent Application No. 60/775,387 filed Feb. 21, 2006.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to the field of the operation and control of engine valves in piston engines.
2. Prior Art
The present invention is based on the fact that at higher engine speeds and higher power outputs, engines have more difficulty breathing, that is, their volumetric efficiency goes down. Typically modern engines may include, by way of example, two intake valves and two exhaust valves per cylinder to attempt to increase the volumetric efficiency. However, there is a limit as to how much this can achieve, as all four valves must generally fall within a circle of a diameter approximately equal to the piston diameter.
BRIEF DESCRIPTION OF THE DRAWINGS
The preferred embodiments of the present invention are intended to be used on diesel engines, though this is not a limitation of the invention, as the invention is also applicable to gasoline engines, or engines intended to operate on other fuels. Also, while the present invention is preferably to be used on turbocharged engines, this too is not a limitation of the invention, as the present invention is also applicable to non-turbocharged engines. Further, the preferred embodiments are intended to be used on engines having multiple intake and multiple exhaust valves, as is characteristic of most modern engines, though this too is a preference, not a limitation of the invention.
The present invention is intended to increase the volumetric efficiency of engines, in the exemplary embodiments disclosed herein, engines having two intake valves and two exhaust valves per cylinder, by selectively using all four valves, the two intake and the two exhaust valves, as both the intake valves and as the exhaust valves for that cylinder. For this purpose, much larger valves external to each combustion chamber are used to switch the coupling of the valves (intake and exhaust) between an intake manifold and an exhaust manifold. Thus the intake valves may be coupled as intake valves or exhaust valves, depending on whether it is an intake stroke or an exhaust stroke. Similarly, the exhaust valves may be coupled between the exhaust manifold and the intake manifold, depending on whether they are then currently functioning as exhaust valves or intake valves. Because these external valves can be large, they can be made to have low flow resistance, with the net result providing much better intake and exhaust breathing for the engine.
The preferred embodiments of the invention are intended to be used in what are referred to as camless engines, wherein the timing and operation of the engine valves may be electronically controlled (see for instance, U.S. Pat. No. 6,739,293 entitled Hydraulic Valve Actuation Systems and Methods, the disclosure of which is hereby incorporated herein by reference). While the preferred embodiments use electronically controlled hydraulic valve actuation, other types of camless engine engine valve operation could equally as well be used. Because of that degree of control, an engine such as a diesel engine may be operated as a four cycle engine, or for higher power output, switched to two cycle operation, as desired. Consequently, in a typical application of the present invention, a diesel engine may be operated as a conventional four stroke engine using two intake valves and two exhaust valves at idle and at low engine outputs, at higher engine speeds and outputs, perhaps operated with all valves functioning as both intake and exhaust valves as described, and at still higher engine outputs operating as a two stroke engine, again with all valves functioning as both intake and exhaust valves as described. This is merely one example of the combinations of operating modes possible with the present invention.
In
The hydraulic control valves for the hydraulically controlled engine valves and switch valves in this embodiment are shown schematically at the top of
A top schematic view of the exemplary assembly of
Now referring to
While in the preferred embodiments, when desired, all valves are used for both intake and exhaust, note that one could always use the intake valves for intake and switch only the exhaust valves between functioning as exhaust and intake valves, or vice versa, thereby eliminating the need for switching valves on the engine intake valves or the engine exhaust valves, respectively. The advantage, particularly with respect to increasing the volumetric efficiency on intake, is two-fold. First, less energy is lost by the pressure drop through the intake valves, and secondly, more air is ingested, allowing injection of greater amounts of fuel to obtain greater engine output. Thus both efficiency and maximum power output are increased.
Thus the present invention has a number of aspects, which aspects may be practiced alone or in various combinations or sub-combinations, as desired. Also while certain preferred embodiments of the present invention have been disclosed and described herein for purposes of exemplary illustration and not for purposes of limitation, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
Claims
1. A piston engine comprising:
- at least one intake valve and at least one exhaust valve per piston engine cylinder; and,
- a flow control valve system for controllably coupling the at least one intake valve to an intake manifold or to an exhaust manifold, and for controllably coupling the at least one exhaust valve to an exhaust manifold or to an intake manifold;
- the at least one intake valve and at least one exhaust valve per piston engine cylinder being actuated by camless actuators.
2. The piston engine of claim 1 wherein the flow control system comprises two, two-way valves per cylinder.
3. The piston engine of claim 2 wherein for each intake valve, a first two-way valve controllably couples the intake valve to the intake manifold or blocks the coupling of the intake valve to the intake manifold, and for each exhaust valve, a second two-way valve controllably couples the exhaust valve to the exhaust manifold or blocks the coupling of the intake valve to the exhaust manifold, the at least one intake valve and the at least one exhaust valve being manifolded together.
4. The piston engine of claim 3 wherein a first two-way valve controllably couples the at least one intake valve to the intake manifold or blocks the coupling of the at least one intake valve to the intake manifold, and a second two-way valve controllably couples the at least one exhaust valve to the exhaust manifold or blocks the coupling of the at least one intake valve to the exhaust manifold, the at least one intake valve and the at least one exhaust valve being manifolded together.
5. The piston engine of claim 1 further comprising a control system for controlling the camless actuators and the flow control valve system to operate the engine as a four cycle engine or as a two cycle engine.
6. The piston engine of claim 1 further comprising a control system for controlling the camless actuators and the flow control valve system to operate the engine using the intake valves for intake and the exhaust valves for exhaust, and to operate the engine using the intake valves for both intake exhaust and the exhaust valves for both intake and exhaust.
7. The piston engine of claim 1 wherein the flow control system couples the intake valves to the intake manifold or blocks the coupling of the intake valves to the intake manifold, and couples the exhaust valves to the exhaust manifold or blocks the coupling of the exhaust valves to the exhaust manifold, the at least one intake valve and the at least one exhaust valve being manifolded together.
8. The piston engine of claim 1 wherein the piston engine is a camless engine further comprising:
- a control system for each cylinder to control the intake and exhaust valves so that;
- at times, the piston engine operates as a 4 cycle engine using the at least one intake valve as intake valves and the at least one exhaust valve as exhaust valves; and
- at other times, the piston engine operates as a 4 cycle engine using all the intake and exhaust valves as intake valves and all intake and exhaust valves as exhaust valves.
9. The piston engine of claim 8 further comprising at still other times, the control system controls the intake and exhaust valves so that the piston engine operates as a 2 cycle engine.
10. The piston engine of claim 9 wherein the piston engine sometimes operates as a 2 cycle engine using all the intake and exhaust valves as intake valves and all intake and exhaust valves as exhaust valves.
11. A method of operating a camless piston engine having at least one intake valve and at least one exhaust valve per cylinder comprising:
- for each cylinder;
- at times, operating the piston engine as a 4 cycle engine using the at least one intake valve as intake valves and the at least one exhaust valve as exhaust valves; and
- at other times, operating the piston engine as a 4 cycle engine using all the intake and exhaust valves as intake valves and all intake and exhaust valves as exhaust valves.
12. The method of claim 11 further comprising at still other times, operating the piston engine as a 2 cycle engine.
13. The method of claim 12 wherein the piston engine is sometimes operated as a 2 cycle engine using all the intake and exhaust valves as intake valves and all intake and exhaust valves as exhaust valves.
14. In a piston engine, the improvement comprising:
- at least one intake valve and at least one exhaust valve per piston engine cylinder; and,
- a flow control system for each cylinder for controllably coupling the at least one intake valve to an intake manifold or to an exhaust manifold, and for controllably coupling the at least one exhaust valve to an exhaust manifold or to an intake manifold.
15. The improvement of claim 14 wherein the flow control system comprises one two-way valve per intake valve and one two-way valve per exhaust valve.
16. The improvement of claim 15 wherein for each intake valve, a first two-way valve controllably couples the intake valve to the intake manifold or blocks the coupling of the intake valve to the intake manifold, and for each exhaust valve, a second two-way valve controllably couples the exhaust valve to the exhaust manifold or blocks the coupling of the exhaust valve to the exhaust manifold, the at least one intake valve and the at least one exhaust valve being manifolded together.
17. The improvement of claim 15 wherein the piston engine includes multiple intake valves and multiple exhaust valves, the flow control system having an air flow area at least as large as the combined intake and exhaust valve air flow area when coupling the intake and exhaust valves to an intake manifold, and when coupling the intake and the exhaust valves to an exhaust manifold.
18. The improvement of claim 14 wherein the flow control system couples the intake valves to the intake manifold or blocks the coupling of the intake valves to the intake manifold, and couples the exhaust valves to the exhaust manifold or blocks the coupling of the exhaust valves to the exhaust manifold, the at least one intake valve and the at least one exhaust valve being manifolded together.
Type: Application
Filed: Feb 20, 2007
Publication Date: Sep 20, 2007
Applicant:
Inventor: Oded Sturman (Woodland Park, CO)
Application Number: 11/708,939
International Classification: F01L 9/02 (20060101); F01L 9/04 (20060101);