Free piston device and method for operating a free piston device

Patent metadata

Field	Value
Publication number	US-10612380-B2
Application number	US-201816192291-A
Country	US
Kind code	B2
Filing date	Nov 15, 2018
Priority date	May 17, 2016
Publication date	Apr 7, 2020
Grant date	Apr 7, 2020

Abstract

A free piston apparatus includes a piston receptacle in which a piston device having a piston is reciprocable along an axis. The piston receptacle includes a combustion chamber delimited by a wall arrangement forming an inlet opening for the supply of fresh gas and an outlet opening for the removal of exhaust gas. The free piston apparatus includes an inflow device, which has the inlet opening and is configured such that fresh gas flowing into the combustion chamber is directed to an incident flow region in the combustion chamber arranged offset axially to the inlet opening, which incident flow region is arranged off-center relative to the axis. A method for operating a free piston apparatus includes operating an inflow device which has an inlet opening configured such that fresh gas is directed to an incident flow region in a combustion chamber offset axially to the inlet opening.

First claim

The invention claimed is:

1. A free piston apparatus comprising a piston receptacle in which at least one piston device having a piston is arranged so as to be reciprocable along an axis, wherein the piston receptacle comprises or forms a combustion chamber delimited by a wall arrangement in which at least one inlet opening for the supply of fresh gas and, spaced apart therefrom in axial direction, at least one outlet opening for the removal of exhaust gas are formed, wherein the free piston apparatus comprises an inflow device for fresh gas, which has the at least one inlet opening and is configured in such a way that fresh gas flowing into the combustion chamber is directed to an incident flow region in the combustion chamber arranged offset axially to the at least one inlet opening in the direction of the at least one outlet opening, which incident flow region is arranged off-center relative to the axis.

2. The free piston apparatus according to claim 1 , wherein the inflow device is configured such that a tumble-shaped movement of the inflowing fresh gas in the combustion chamber is achievable, wherein inflowing fresh gas rolls about a tumble axis which is aligned transverse to the axis.

3. The free piston apparatus according to claim 2 , wherein the tumble axis is arranged centrally or substantially centrally between the at least one inlet opening and the at least one outlet opening.

4. The free piston apparatus according to claim 1 , wherein the incident flow region is arranged in axial direction approximately centrally between the at least one inlet opening and the at least one outlet opening, or wherein the incident flow region is arranged upstream of a center between the at least one inlet opening and the at least one outlet opening in the direction of the at least one inlet opening.

5. The free piston apparatus according to claim 1 , wherein the at least one inlet opening is configured tilted relative to the axis for achieving an axial movement component of inflowing fresh gas.

6. The free piston apparatus according to claim 5 , wherein a plurality of inlet openings is provided, which are configured tilted relative to the axis.

7. The free piston apparatus according to claim 1 , wherein a plurality of inlet openings spaced apart from each other in circumferential direction of the axis is provided.

8. The free piston apparatus according to claim 7 , wherein the plurality of inlet openings are formed at the same position on the wall arrangement in axial direction.

9. The free piston apparatus according to claim 8 , wherein the inlet openings are arranged and configured on the wall arrangement so as to be mirror-symmetrical to each other with respect to a central longitudinal plane of the piston receptacle containing the axis.

10. The free piston apparatus according to claim 1 , wherein an inlet opening is provided which is directed radial to the axis and towards a side of the wall arrangement opposite the inlet opening, with respect to a section plane transverse to the axis, wherein the incident flow region is arranged on the side of the combustion chamber opposite the inlet opening.

11. The free piston apparatus according to claim 10 , wherein no inlet opening is formed on the wall arrangement on a side opposite said inlet opening, with respect to the axis.

12. The free piston apparatus according to claim 1 , wherein an inlet opening is provided which, with respect to a section plane transverse to the axis, is not directed radial to the axis, but rather to a region of the combustion chamber which has an angular distance to the inlet opening of less than 180° in circumferential direction of the axis.

13. The free piston apparatus according to claim 12 , wherein associated with the inlet opening is a corresponding inlet opening aligned as a mirror image thereto with respect to a central longitudinal plane of the piston receptacle.

14. The free piston apparatus according to claim 12 , wherein at least one further inlet opening is provided which is directed to the same region of the combustion chamber which has a smaller angular distance to the further inlet opening in circumferential direction of the axis than the first mentioned inlet opening.

15. The free piston apparatus according to claim 14 , wherein the greater the angular distance between the inlet opening and the region of the combustion chamber is, the greater a volumetric flow of inflowing fresh gas is.

16. The free piston apparatus according to claim 1 , wherein the inflow device comprises or forms an inflow chamber which surrounds the wall arrangement and which is able to be acted upon with fresh gas by way of a supply conduit and which opens into the combustion chamber via the at least one inlet opening.

17. The free piston apparatus according to claim 1 , wherein the free piston apparatus has an actuator at at least one inlet opening, by way of which the inflow direction for fresh gas into the combustion chamber is adjustable.

18. The free piston apparatus according to claim 1 , wherein the piston receptacle comprises a housing and a piston bushing which is inserted into the housing and comprises or forms the wall arrangement, wherein the piston is reciprocable in the piston bushing and at least the at least one inlet opening is formed in the piston bushing.

19. The free piston apparatus according to claim 1 , wherein the piston is movable at least partially over the at least one inlet opening and wherein the latter is at least partially unblockable upon the piston adopting the bottom dead center.

20. The free piston apparatus according to claim 1 , wherein the free piston apparatus comprises a further piston device having a piston, wherein the pistons of both piston devices are positioned in opposed piston arrangement, wherein the combustion chamber is formed between the pistons.

21. The free piston apparatus according to claim 20 , wherein the piston of the further piston device is movable at least partially over the at least one outlet opening and wherein the latter is at least partially unblockable upon the piston adopting the bottom dead center.

22. The free piston apparatus according to claim 1 , wherein the free piston apparatus comprises an energy coupling device which is coupled to the piston device and by way of which energy is able to be decoupled from the piston device or by way of which energy is able to be coupled into the piston device.

23. The free piston apparatus according to claim 22 , wherein the energy coupling device comprises at least one linear generator.

24. A method for operating a free piston apparatus that comprises a piston receptacle in which at least one piston device having a piston is arranged so as to be reciprocable along an axis, wherein the piston receptacle comprises or forms a combustion chamber delimited by a wall arrangement in which at least one inlet opening for the supply of fresh gas and, spaced apart therefrom in axial direction, at least one outlet opening for the removal of exhaust gas are formed, wherein an inflow device for fresh gas is provided, which has the at least one inlet opening and is configured in such a way that fresh gas flowing into the combustion chamber is directed to an incident flow region in the combustion chamber arranged offset axially to the at least one inlet opening in the direction of the at least one outlet opening, which incident flow region is arranged off-center relative to the axis.

Assignees

• Deutsch Zentr Luft & Raumfahrt

Inventors

• Schneider Stephan

Classifications

• F01B11/007 Primary

  in which the movement in only one direction is obtained by a single acting piston motor, e.g. with actuation in the other direction by spring means · CPC title

• F02B71/04

  Adaptations of such engines for special use; Combinations of such engines with apparatus driven thereby · CPC title

• F02B2075/025

  two · CPC title

• F01B11/00

  Reciprocating-piston machines or engines without rotary main shaft, e.g. of free-piston type · CPC title

• F02B31/00 Primary

  Modifying induction systems for imparting a rotation to the charge in the cylinder (air intakes or induction systems for internal-combustion engines F02M35/10) · CPC title