Pumps – Motor driven – Internal-combustion engine
Patent
1994-05-18
1996-09-17
Gluck, Richard E.
Pumps
Motor driven
Internal-combustion engine
417380, F02B 7104, F02B 7102, F01B 1102
Patent
active
055562620
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a free-piston engine having a fluid energy unit.
In a known embodiment of such a free-piston engine (see EP-A-0 254 353), the supply and discharge means of the displacement chambers consist of a supply and discharge channel having a non-return valve. At the end of the movement of the piston from the second to the first position, that is at the end of the expansion stroke, the non-return valve of the discharge channel closes so that the pressure in the respective chamber becomes lower than the pressure in the accumulator together with the spring pressure of the valve. The closing action of the non-return valve should take place quickly because otherwise hydraulic liquid will flow back to the chamber which will cause the piston to move back to the second position along some distance, while it is the intention to retain the piston in its first position until a new compression and expansion stroke is required. The quick closing action of the non-return valve necessitates a high spring pressure in the non-return valve. This results, however, in a high flow resistance when hydraulic liquid flows through this non-return valve during the expansion stroke of the piston causing substantial flow losses.
The object of the present invention is to provide a free-piston engine having a fluid energy unit in which this disadvantage is removed in an effective way.
SUMMARY OF THE INVENTION
Due to the features according to the invention, the discharge channel means having a LOW FLOW resistance are used during the first part of the expansion stroke so that low hydraulic losses occur. At the end of the expansion stroke, when the speed of the piston is reduced substantially, the first discharge channel means are put out of action and the discharge of hydraulic liquid from the chamber only takes place through the second discharge channel means having a quick non-return valve and a small waste volume. In this manner, both opposite objectives of low flow resistances and small rebound of the piston from the bottom dead centre are obtained in an effective way.
NL-A-6 814 405 discloses a free-piston engine having a fluid energy unit, which comprises separate first and second discharge channel means operating in a first and second part of the expansion stroke, respectively, and in a second and first part of the compression stroke. The first discharge channel means has a low flow resistance and the second discharge channel means includes a regulator to control the speed of the piston in the first part of the compression stroke to thereby control the stroke frequency of the engine.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will hereafter be elucidated with reference to the drawings showing embodiments of the free-piston engine according to the invention by way of example.
FIG. 1 is a very schematic longitudinal section of a free-piston engine showing a simplified scheme of the corresponding hydraulic unit.
FIG. 2 is a longitudinal sectional view of a more realistic structural embodiment of the free-piston engine having the hydraulic energy unit of FIG. 1.
FIG. 3 is a sectional view corresponding to FIG. 1 but showing a second embodiment of the free-piston engine together with a hydraulic energy unit.
FIG. 4 is a diagram illustrating the piston displacement as a function of time.
FIG. 5A, B illustrate the waste volume of hydraulic liquid in a displacement chamber at the end of the expansion stroke of the piston.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows schematically a first exemplary embodiment of a free-piston engine having a hydraulic energy unit according to the present invention. This free-piston engine includes a cylinder 1 and a piston 2 arranged within the cylinder 1, bordering one side of a combustion room 3 and reciprocating in the cylinder 1 between a first position in which the volume of the combustion room 3 in the cylinder 1 is at a maximum (the so-called bottom dead centre, BDC), and a second position in which the volume of the combust
REFERENCES:
patent: 3216651 (1965-11-01), King et al.
patent: 3606591 (1971-09-01), Potma
patent: 4210046 (1980-07-01), Beerens
patent: 4307999 (1981-12-01), Vanderlaan
patent: 4705460 (1987-11-01), Braun
patent: 4791786 (1988-12-01), Stuyvenberg
Achten Peter A. J.
Potma Theodorus G.
Gluck Richard E.
Innas Free Piston B.V.
LandOfFree
Free-piston engine having a fluid energy unit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Free-piston engine having a fluid energy unit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Free-piston engine having a fluid energy unit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-409444