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1. WO2002023040 - ARRANGEMENT AT A PISTON ENGINE AND METHOD OF CONTROLLING THE PISTONS

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[ EN ]

C l a i m s

1. An arrangement at a piston engine in the form of a
piston pump/engine (motor) of the type in which two or more co-operating piston cylinders (14, 14a, 14b,
14c,......), the reciprocating pistons (16, 16a, ) of
which have rods (18, 18a, 18b, 18c, ) that at any time will project more or less outside the respective
cylinders and be influenced by a rotatable body for
controlling each piston, to impart to this a
predetermined displacement in the respective cylinder, which displacement is matched to the corresponding
displacement of the co-operating pistons, and where the controlled reciprocating pistons - in the case of the pump embodiment of the piston engine - contributes to impelling a fluid stream or - in the case of the engine embodiment of the piston engine - is driven by a fluid stream, c h a r a c t e r i s e d i n that the
rotatable controlling body that is designed to control the displacement of the pistons (16, 16a, ) relative to each other, is constituted by a cam (12; 50).

2. An arrangement according to Claim 1 ,
c h a r a c t e r i s e d i n that said cam (12)
consists of a cam ring provided with a 360 degree
encircling course on the outside of a rotatable shaft
(10), the cam-like peripheral surface of which cam ring the piston rod ends abut, directly or indirectly.

3. An arrangement according to Claim 2 , in which a piston cylinder (14, 14a) is provided on either side of the
rotatable shaft/cam (10/12), diametrically opposite each other with regard to the rotational axis of the shaft
(10), the piston rods (18, 18a) of which piston
cylinders are oriented towards each other,
c h a r a c t e r i s e d i n that the cam (12) has s an increasing radius (runs in an eccentric manner),
peripheral curve that exceeds 180 degrees, relative to
the rotational axis of the shaft (10), so that each
power stroke covers a little more than half a rotation
of the drive shaft (10), and an overlap is achieved of o e.g. 30 degrees, where one (e.g.16) of the two pistons
(16, 16a) decelerates steadily towards zero speed and
thereby ends its power stroke, while the other piston
(16a) commences its power stroke and accelerates
steadily towards a full power stroke.

s 4. An arrangement according to claim 1, 2 or 3,
c h a r a c t e r i s e d i n that the free outer end of each piston rod (18, 18a, 18b, 18c, ) is
constituted by that portion of the abutment surface of
the peripheral surface of a rotatable roller (20, 20a, 0 20b, 20c, ) which at any time is furthest out in the
axial direction, which peripheral surface shall at any
time abut the cam surface (12; 52).

5. An arrangement according to Claim 2,
c h a r a c t e r i s e d i n that the cam is
5 constituted by an encircling cam ring (50) arranged on a rotatable drum (44), cylindrical body or similar device, means or structure.

6. An arrangement according to Claim 4,
c h a r a c t e r i s e d i n that said rotatable rollers (20, 20a, 20b, 20c, ) are designed at any time to be kept in elastic/resilient abutment against said cam surface (12; 52).

7. An arrangement according to Claim 6,
c h a r a c t e r i s e d i n that the piston rod ends for support of their respective abutment rollers (20,
20a, 20b,. 20c, ) are formed with a bifurcated head
(18b') designed to accept the abutment roller rotatably between the U-branches with the aid of a transverse bolt (54).

8. An arrangement according to claim 4, 6 or 7,
c h a r a c t e r i s e d i n means (e.g. 56)
designed to ensure the establishment and maintenance of a sufficiently high pressure on the suction side to
compensate for the frictional, gravitational and
inertial forces that seek to lift the abutment roller
(20, 20a, 20b, 20c, ) off the guide surface (52) of the cam (50) .

9. An arrangement according to Claim 8,
c h a r a c t e r i s e d i n that said means are
constituted by spring biasing means, e.g. pneumatic
devices (16A, 14B), mechanical means such as springs
etc.

10. An arrangement according to Claim 7,
c h a r a c t e r i s e d i n that the bifurcated head (18b') at the end of each piston rod (18, 18a, 18b, 18c) supports an axially projecting holder (60) designed to ensure that the abutment roller (20b) is kept in spring loaded contact with the cam surface (52) of the cam.

11. An arrangement according to Claim 8,
c h a r a c t e r i s e d i n that said holder (60)

5 has a U-shaped form, a first U-branch being directed
axially away from the bifurcated outer, free piston rod head (18b'), while the other U-branch, which is
connected to the first U-branch via the U-web that forms a transverse connecting piece, is directed axially o towards the piston rod head (18b') and supports a
contact wheel (56), the peripheral surface of which
abuts the rear ring surface (52a) of the cam ring (50)
in a spring loaded manner, opposite the cam surface (52) of the cam, for the purpose of keeping the abutment s roller (20b) in constant, resilient abutment against the cam surface (52) .

12. An arrangement according to claims 7, 8 and 11
c h a r a c t e r i s e d i n that said bifurcated
head (18a'-18c') is designed for support of both the o abutment roller (20a-20c) and the contact wheel/counter roller (56) on the opposite side of the cam ring (50)
relative to the actual cam surface (52).

13. A method of controlling controllable reciprocating
pistons (16, 16a, ) in piston cylinders (14, 14a, 14b, 5 14c,...) that, numbering two or more, form part of a
piston engine (piston pump/engine (motor)), in which
rotatable means are provided for the mutual control of
the piston strokes, which means influence the pistons
via their projecting piston rods (18,18a, 18b, 18c, ), c h a r a c t e r i s e d i n that each piston (16,
16a, ) is driven at a constant speed through part of its power stroke.

14. A method according to Claim 12,
c h a r a c t e r i s e d i n that the pistons (16,
16a, ...) are driven in such a manner that the piston
speed is changed gradually to or from zero at the end of a power stroke, and in such a manner that when a working piston decelerates to zero speed, the (or one of the) co-operating piston, which at the same time commences a power stroke, is accelerated from zero speed.

15. A method according to Claim 13,
c h a r a c t e r i s e d i n that each piston (16,
16a, .—) decelerates and accelerates linearly at the end and commencement, respectively, of a power stroke, so that the sum of the speed of the pistons during the
change-over phase is constant and equal to the speed at which the piston normally works during the power stroke.

16. A method according to one or more of the preceding
claims 10-11, c h a r a c t e r i s e d i n that a constant, maximum piston speed is established and
maintained through part- of the power stroke.

17. A method according to one or more of the preceding
claims 10-11, where the piston engine is constituted by a pump and work is performed with two diametrically
opposed piston cylinders (14, 14a) and an intermediate cam (12), c h a r a c t e r i s e d i n that each power stroke is brought to cover a little more (e.g. 30 degrees) than 180 degrees rotation of the drive shaft (10), so that both pistons (16, 16a) simultaneously execute part of a power stroke during the overlapping part of a rotation, where one of the pistons is decelerated steadily towards zero and ends this power stroke, while the other piston commences its power stroke and is accelerated steadily towards a full power stroke, and where the return stroke is executed at a higher speed than the actual power stroke.

A method according to any one of claims 10-11,
c h a r a c t e r i s e d i n that at least one piston is driven in a such a manner that its speed profile/curve is asymmetrical, i.e. constant but with different speeds for the power stroke and the return stroke.