WO2015003954A1

WO2015003954A1 - Axial piston machine

Info

Publication number: WO2015003954A1
Application number: PCT/EP2014/063915
Authority: WO
Inventors: Asmus Carstensen; Artur Semke; Thomas Schulenburg; Andreas Herr; Marcus Dallmann; Jörg Volkmann; Thomas Maischik; Bernd Hupfeld
Original assignee: Volkswagen Aktiengesellschaft
Priority date: 2013-07-11
Filing date: 2014-07-01
Publication date: 2015-01-15
Also published as: EP3019702B1; EP3019702A1; CN105378224A; DE102013213614A1; CN105378224B

Abstract

An axial piston machine having a cylinder body (10) in which at least three cylinders (12) are formed, and having pistons (14) movably guided in said cylinders (12), said pistons (14) being connected to a swash plate (18) that rotatably abuts a swash plate foot (20), and a flow of fluid into and out of the cylinders (12) being controlled by means of inlet and outlet valves, is characterized by varying distributions between the connections of the pistons (14) to the swash plate (18) and/or varying opening times for the inlet and/or outlet valves.

Description

description

axial piston

The invention relates to an axial piston machine and in particular a

Axial piston engine for a cycle device for the use of waste heat of an internal combustion engine.

Motor vehicles are currently mostly driven by internal combustion engines in which fuels are burned and the heat energy released thereby is partially converted into mechanical work. The efficiency of reciprocating internal combustion engines, which are used almost exclusively for the drive of motor vehicles, is about one third of the primary energy used. Thus, two-thirds of the heat energy released during combustion is waste heat, either through the engine cooling system or the exhaust system as heat loss to the

Environment is delivered.

Utilization of this waste heat represents a possibility to increase the overall efficiency of a drive unit of the motor vehicle and thus to reduce fuel consumption.

DE 10 2008 028 467 A1 describes a device for utilizing waste heat of an internal combustion engine. This is in the exhaust system of the

Internal combustion engine, a first heat exchanger, the evaporator, a

Integrated steam cycle process device. The heat energy transferred in the heat exchanger from the exhaust gas to a working medium of the steam cycle device is partially converted into mechanical energy in an expansion device which can be used, for example, to assist the propulsion of a motor vehicle or to generate electrical energy. Downstream of the expansion device, the working medium is cooled in a second heat exchanger, the condenser, where it condenses. About a feed pump is a pressure increase of the

Working medium and its supply to the evaporator. As an expansion device in such a system for waste heat utilization, an axial piston motor can be used, as is known from DE 10 2010 052 508 A1.

Axial piston engines have a cylinder body in which a plurality of cylinders are formed in a uniform pitch. In each of the cylinders, a piston is movably guided, wherein a phase offset is provided in the piston positions, based on a movement cycle of the piston ("piston cycle": OT-> UT-> OT or

UT-> OT-> UT) corresponds to the division between the cylinders. About inlet and

Exhaust valves are used to perform a power stroke (OT-> UT) of each piston, a pressurized fluid sequentially introduced into the corresponding cylinder, where appropriate, (in a pneumatic axial piston engine) expands and causes movement of the respective piston. In one to the work cycle

subsequent exhaust stroke (UT-> OT) of each piston will return the fluid

pushed out. The movements of the pistons are inclined at an angle to the

Longitudinal axes of the cylinder arranged plate to which the pistons are connected directly or via connecting rods, transmitted to an output shaft.

Axial piston compressors or pumps have one to Axialkolbenmotoren in

Essentially identical structure, with mechanical drive power transmitted from the shaft via the obliquely arranged plate on the piston, while a rotational movement of the shaft or an associated drive motor is translated into the cyclic movement of the piston. In the working stroke (UT-> OT) of the individual pistons, a fluid previously introduced into the cylinders during an intake stroke (OT-> UT) is displaced and / or compressed and expelled.

Axial piston machines (axial piston motors and axial piston compressors or pumps) are regularly executed in one of three designs.

In the swash plate and the bent axis design of the cylinder body rotates together with the piston. In the swashplate design, the shaft is arranged parallel to the cylinder body and rotatably connected thereto. The movement of the piston controlling oblique plate is fixed. In the

Oblique-axis design, the longitudinal axes of the shaft, including the flange ("oblique plate") on which attack the piston, and the cylinder obliquely to each other. In the swash plate type, the cylinder body does not rotate with the pistons guided therein. The same applies to a swash plate to which the pistons are connected via connecting rods. The swash plate is rotatably mounted on a swash plate, wherein the support surface of the swash plate and thus the orientation of the swash plate is aligned obliquely with respect to the longitudinal axes of the cylinder. The swash plate is rotatably connected to the shaft.

In axial piston machines of the swash plate type is regularly provided, an unintentional co-rotation of the swash plate with the swash plate by a rotationally fixed fixation of the swash plate in or on the housing

Ensure axial piston machine. For this purpose, a groove is regularly provided at one or more points on the outer or inner circumference of the annular swash plate, which engages in an elongated, curved extending projection of the housing or a component connected to the housing. These groove-protrusion connections prevent the swash plate from rotating, but at the same time permit movement along the course of the protrusion, thereby enabling the tumbling motion of the swash plate.

The intake and exhaust valves of axial piston engines are regularly formed in the form of a rotary valve which is non-rotatably connected to the shaft and temporarily connects intake and exhaust ports of the individual cylinders to an intake and exhaust passage depending on the respective piston positions.

Based on this prior art, the present invention seeks to provide a Taumelscheibenbauart axial piston machine, which is characterized by the highest possible efficiency and / or a uniform course.

This object is achieved by an axial piston machine according to independent claim 1. Advantageous embodiments thereof are the subject of the dependent claims and will become apparent from the following description of the invention.

The invention is based on the finding that in an axial piston machine of the swash plate design as a result of the fixation of the swash plate to prevent rotation, a nonuniformity in the tumbling motion is generated, which leads to a

results in non-uniform phase offset in the piston positions of adjacent pistons and in a non-uniform velocity profile of adjacent pistons. Thereby arise on the one hand rotational irregularities. On the other hand, the performance and efficiency of the axial piston machine is adversely affected, since the movement of individual pistons no longer fits exactly to the provided and provided by the rotational movement of the shaft valve timing. For example, it can be provided that the intake valves for all cylinders should be opened as exactly as possible at top dead center (TDC) of the respective piston. The inlet openings of all cylinders are arranged and formed identical with respect to the respective cylinders in conventional axial piston machines. Accordingly, the successive opening of the inlet openings takes place by the rotating with the shaft rotary valve after always the same, the division between the cylinders corresponding partial rotation of the shaft. The non-uniformity, which is introduced by the translation of the rotational movement of the shaft in the cyclic linear movement of the piston is not taken into account. This can thus lead to the inlet openings being opened by the rotary valve in individual cylinders before the associated piston reaches the TDC or after it has already passed the TDC. This leads to a deteriorated filling of these cylinders.

The basic idea of the invention is to compensate for the non-uniformity in the piston movements, which is due to the translation of the rotational movement of the shaft into the cyclical linear movement of the piston.

This is in a generic axial piston machine having a cylinder body in which a plurality (preferably at least three) cylinders are formed, as well as in the cylinders movably guided pistons, wherein the pistons are connected to a swash plate which rotatably bears against a swash plate, and wherein a fluid flow into and out of the cylinders is controlled by means of inlet and outlet valves, according to the invention achieved by varying divisions between the (in particular fixed) connections of the piston to the swash plate and / or varying opening times for the inlet and / or outlet valves

are provided.

By varying the pitches of the connections of the piston to the swash plate, a translation of the total movement of the pistons, which is justified in the translation, can be compensated, so that, as a result, the pistons always reach their TDC and / or BDC after a constant partial rotation of the shaft. By varying the opening times for the intake and / or exhaust valves can be achieved that, despite the non-uniformity caused by the translation in the piston movements, the opening times as closely as possible to the respective

Adjust piston positions.

In particular, it may be provided that the varying opening times are adapted such that the inlet and / or the exhaust valves of all cylinders open and / or close at identical piston position of the associated piston. Thereby, the filling of the cylinder and thus the performance and possibly also the efficiency of the axial piston machine can be improved. For example, it can be provided that the opening times of the intake valves of all cylinders are matched to the TDCs of the respective pistons by a cylinder-selective adaptation.

Furthermore, it can be provided that the varying opening times are adapted such that the opening duration of the inlet and / or outlet valves of at least some of the cylinders is different. As a result, in particular the influence which the different speed profiles of the piston movements can have on the filling of the cylinders with the fluid can be compensated. Preferably, it is therefore provided that the different opening duration (ie the angular ranges of the part rotations of the shaft between the opening and re-closing of the inlet or outlet valves, defined by the sum of the respective angle α (length of the inlet and outlet openings 28) and the angle γ (length of the inlet opening of the rotary valve 38, see Fig. 8)) is adapted such that the masses of the in each case a piston cycle in the cylinders enclosed subsets of the fluid are as equal as possible.

In a preferred embodiment of the axial piston machine according to the invention can be provided that the inlet and / or the exhaust valves in the form of a

(Multiple) rotary valve are formed. Thus, the intake and / or exhaust valves may include intake and / or exhaust ports for the individual cylinders, which are temporarily released and covered by a rotary valve. The varying opening times (and thus also varying opening duration of the individual intake and / or exhaust valves) can then be determined by a varying pitch between the inlet and / or outlet openings of individual cylinders and / or by different lengths (relative to the direction of movement relative to the

Rotary valve) of the inlet and / or outlet openings of the cylinder can be achieved.

It can, if the phase relationship between inlet and outlet of all cylinders may be constant, only one (combined) inlet and outlet opening per cylinder be provided. If different phase relationships between inlet and outlet are to be provided for the individual cylinders, at least one inlet and at least one outlet opening may be provided at different radii per cylinder, which are temporarily released by corresponding openings of the rotary valve.

The invention will be described below with reference to the drawings

Embodiments explained in more detail. In the drawings shows:

1 shows an embodiment of an axial piston motor according to the invention in a perspective view;

Fig. 2: the axial piston motor in a plan view;

3: the axial piston motor in a section along the plane III - III in Fig. 2;

FIG. 4 shows the axial piston motor in a section along the plane IV-IV in FIG. 2; FIG.

5 shows an enlarged section of the axial piston motor in a section along the plane V-V in FIG. 2;

Fig. 6: the rotary valve of the axial piston motor in a perspective

Presentation;

Fig. 7: the rotary valve in a view from above;

8 shows the rotary valve in a view from below;

FIG. 9 shows the rotary valve in a section along the plane IX-IX in FIG. 7; FIG.

10: the rotary valve in a section along the plane X - X in Fig. 7;

Fig. 1 1: the rotary valve in a section along the plane XI - XI in Fig. 7;

Fig. 12: the cylinder head plate of the axial piston motor in a plan view; 13 shows a swash plate for an axial piston machine according to the invention in a plan view;

Fig. 14: the course of the piston movements in a generic

Axial piston machine with six cylinders;

Fig. 15: the course of the cylinder fillings in a generic

Axial piston machine with six cylinders; and

16: the course of the cylinder fillings in an inventive

Axial piston machine with six cylinders.

FIGS. 1 to 12 show an embodiment of a device according to the invention

Axial piston machine in the form of an axial piston motor. The axial piston motor can be used, for example, in a cycle device for utilizing waste heat of an internal combustion engine of a motor vehicle. In this case, a vaporized and superheated and pressurized working medium expands in the axial piston motor, whereby part of the thermal and potential energy of the working medium is converted into mechanical energy.

The axial piston motor is designed in swash plate design. This comprises a cylinder body 10 having a plurality (here: six) of parallel to each other

aligned, extending through the entire cylinder body 10 cylinders 12 is formed. In each of the cylinders 12, a piston 14 is movably guided. The pistons 14 are connected via a connecting rod 16 with an annular swash plate 18. The swash plate 18 is rotatably mounted on a swash plate 20 which is rotatably connected to a (output) shaft 22 of the axial piston motor.

The swash plate 18 and the swash plate 20 have (coaxial) longitudinal axes which are inclined at a defined angle to the longitudinal axes (and the axis of rotation of the shaft 22) of the cylinder 12. This angle is by means of a

Adjusting pin 24 adjustable. For this purpose, the adjusting screw 24 provided with an external thread is guided in a threaded opening of the shaft 22.

The pressure of the successively entering into the individual cylinder 12 working medium leads due to the inclination of the swash plate 18 to a directed in the circumferential direction force component in the connection points of the connecting rod 16 at the Swash plate 18. This force component causes the desired rotation of the shaft 22. As a result of the rotation of the shaft 22 and the thus rotatably connected

Swashplate leg 20, the swash plate 18 is set in a tumbling motion, which leads to an up and down movement of the connected to the swash plate 18 via the connecting rod 16 piston 14. In this case, each of the pistons 14 cyclically moves between a top dead center (TDC) and a bottom dead center (TDC).

The pistons 14 work with two clocks. The movement between the TDC and the TDC of each piston 14 is influenced by the inflow into the respective cylinders 12

Working medium causes (working cycle). When guided by the swash plate 18 movement of the piston 14 between the UT and the TDC is the relaxed

Working medium from the respective cylinders 12 ejected (exhaust stroke). The

Inflow and discharge of the working fluid at the designated timing is realized by means of intake and exhaust valves for each of the cylinders 12 formed by a rotary valve device.

The rotary valve device comprises a cylinder head plate 26 which abuts the cylinder body 10 on the front side on the side remote from the swash plate 18. The cylinder head plate 26 has a combined intake and exhaust port 28 for each of the cylinders 12 (see Fig. 12). Further openings 30 serve to receive screws 32, through which a housing head 34, the cylinder head plate 26, the

Cylinder body 10 and a swash plate 18 and the swash plate 20 surrounding housing 36 are interconnected. On the cylinder head plate 26 is a rotary valve 38, which is rotatably connected to the shaft 22 and thus rotates relative to the cylinder head plate 26 during operation of the axial piston motor. Characterized the inlet and outlet openings 28 of the cylinder head plate 26 are alternately and once per revolution of the shaft 22 in registration with an inlet port 40 and with an outlet opening 42 of the rotary valve 38 is brought. The inlet opening 40 and the outlet opening 42 are for this purpose on the same circular path around the center (the

Rotary axis) of the rotary valve 38 is arranged. At a coverage with the

Inlet opening 40 is supplied to the respective cylinder 12 via a central inlet 44 and an integrated into the rotary valve 38, radially extending inlet channel 46, the vaporous working medium. When overlapping with the outlet opening 42, the working fluid is expelled from the respective cylinder 12 and discharged through outlets 48 from the axial piston motor. Here is the length of

Inlet opening 40 of the rotary valve 38 (with respect to the direction of rotation relative to the cylinder head plate 26) selected such that an overlap (and thus Inlet valve opening) with the inlet and outlet opening 28 is always given only a cylinder 12, while the much longer (only interrupted by reinforcing struts 60) outlet opening 42 of the rotary valve 38, a simultaneous opening of several outlet valves (by covering with the corresponding inlet and outlet openings 28th the cylinder head plate 26) provides.

The inlet channel 46 of the rotary valve 38 is formed for manufacturing reasons open to the outside. During assembly of the axial piston motor, this opening is closed by means of a spherical closure body 50 (see FIG. 5).

To prevent the swash plate 18 from the rotational movement of the

Taumelscheibenfußes 20 is taken, is provided to connect these rotationally fixed (with respect to the axis of rotation of the shaft 22) with the cylinder body 10. For this purpose, a securing sleeve 52 is provided which is non-rotatably connected via securing pins 54 (with respect to the axis of rotation of the shaft 22) to the cylinder body 10. The

Locking sleeve 52 is also a cardan-like joint arrangement with the

Swash plate 18 connected. The hinge assembly 18 rotatably binds the swash plate 18 (with respect to the axis of rotation of the shaft 22) to the locking sleeve 52 and thus to the cylinder body 10, but at the same time allows the wobble of the swash plate. The joint arrangement comprises a joint ring 56 which is rotatable about a first axis about the two bearing pins 58 with the securing sleeve 52 (see Fig. 3) and about a second axis perpendicular to the first axis rotatable with the swash plate 18 (see FIG 4).

In known, to the invention described axial piston motor in

Substantially functionally identical axial piston machines are provided to arrange the cylinders 12 in a uniform pitch in the cylinder body 10 and to provide a corresponding arrangement of the connection of the connecting rods 16 to the swash plate 18. In addition, identical inlet and outlet openings 28 are provided in the cylinder head plate 26 for the individual cylinders 12. This leads due to the rotationally fixed connection of the swash plate 18 with the cylinder body 10 to non-uniform piston movements and - resulting - to an uneven phase offset between

Thus, in an axial piston machine with six cylinders 12, the pitch between all adjacent cylinders is 60 °. However, the phase offset of the piston movements, ie the partial rotation of the shaft 22, after the adjacent piston 14 each reach their TDC or UT, is not exactly 60 °, but up to a few degrees more or less. Fig. 14 visualizes this effect. There is shown over a revolution of the shaft 22, the movement of the six pistons 14 (solid lines). In addition, a sinusoidal comparison movement is entered with dashed line for each piston 14. FIG. 14 shows that all real piston movements deviate from the respective sinusoidal comparison movement, the deviations of the individual ones

In addition, piston movements are sometimes different. Only in the

Cylinder body 10 opposite, i. Displaced by 180 ° arranged piston 14 have identical (only 180 ° out of phase) piston movement curves. Further, FIG. 14 illustrates the different phase offsets in the movements of adjacent pistons 14, different from the pitch of 60 °.

is, based on the movement of reaching its OT at 180 ° piston 14, the phase offset to the movements of the two adjacent pistons several degrees less than the 60 ° due to the expected part 60 °. For those in the

Cylinder body 10 respectively opposing piston 14 is the phase offset, however, corresponding to the pitch 180 °. The non-uniformity and the phase offset in or between the piston movements tends to increase with increasing inclination angle of the swash plate 18.

The phase offset between the movements of adjacent pistons 14 in conjunction with the symmetrical arrangement of the inlet and outlet ports 28 in the

Cylinder head plate 26 of conventional axial piston engines results in the intake and exhaust valves not always opening exactly to the intended position of the respective piston 14 (e.g., in TDC). This as well as the different courses of the

Piston movements lead to a different filling of the cylinder 12, which remains at least some of the cylinder 12 below the intended filling. This results in a lower power and possibly also in a lower efficiency of the axial piston machine.

FIG. 15 visualizes the differences in the filling of the individual cylinders 12 in a generic axial piston machine. There, over one revolution of the shaft 22, the course of the filling of the cylinders 12, i. the change in the mass of the

Working medium in the individual cylinders 12, shown. There, too, it appears that the course of the filling is the same (only 180 ° out of phase) only with cylinders 12 located opposite one another in the cylinder body 10. To avoid this problem, it is provided in the axial piston motor according to the invention that the individual cylinders 12 associated inputs and

Outlet openings 28 of the cylinder head plate 26 are individually adapted such that a substantially identical filling results for all cylinders 12 (see Fig. 12). On the one hand it is provided that the division between the individual

adjacent inlet and outlet openings 28 (relative to their central axes) may be different, so that, for example, ßi + ß ₂ . In particular, the arrangement of the inlet and outlet openings 28 and thus the pitch is selected such that all inlet valves substantially always open in the TDC of the respective piston 14 (by an incipient overlap of the inlet and outlet openings 28 of

Cylinder head plate 26 with the inlet opening 40 of the rotary valve 38). In addition, the lengths of the inlet and outlet openings 28 relative to the direction of the

Relative movement between the cylinder head plate 26 and the rotary valve 38 different. As a result of the rotating relative movement of the rotary valve 38 and the cylinder head plate 26, the lengths of the inlet and outlet openings 28 as

Indicated angle ranges. Accordingly, for example, αι + a ₂ . In principle, it may be provided that a longer opening duration should be provided for piston movements which are relatively flat in the region of their OTs, in order to achieve an identical filling in comparison to piston movements that are relatively acute in the OTs. FIG. 16 shows that, according to the invention, essentially identical filling progressions can be realized for all cylinders 12.

Alternatively or additionally to an adaptation of the opening times of the inlet valves, it may also be provided to adapt the divisions between the connections of the connecting rods 26 to the swash plate 18, whereby different phase shifts of the (total) movements of adjacent pistons 14 can be avoided. Fig. 13 shows a correspondingly formed swash plate 18, which in a

Axial piston engine according to FIGS. 1 to 1 1 can be used. It may be useful not only to adapt the pitches between the connections of the piston 14 to the swash plate 18, but also according to the pitches between adjacent cylinders 12 in the cylinder body 10, which may then be identical to that of the swash plate 18. An axial piston machine according to the invention with an adapted connection of the pistons 14 to the swash plate 18 can

preferably with an adjusted opening duration of the individual valves, i. For example, with regard to their length adapted inlet and outlet openings 28 in the

Cylinder head plate 26 are combined, so that in addition a compensation of the different courses of the piston movements can be done. LIST OF REFERENCE NUMBERS

cylinder body

cylinder

piston

pleuel

swash plate

Taumelscheibenfuß

wave

adjusting

Cylinder head plate

Inlet and outlet opening

opening

screw

housing head

casing

rotary vane

inlet port

outlet

inlet

inlet channel

outlet

closure body

securing sleeve

safety pin

joint ring

bearing pin

reinforcing strut

Claims

claims

1 . Axial piston machine comprising a cylinder body (10) in which a plurality of cylinders (12) are formed, and with the piston (14) movably guided in the cylinders (12), the pistons (14) being connected to a swash plate (18) which is rotatable abutting a swashplate base (20), and wherein fluid flow into and out of the cylinders (12) is controlled by inlet and exhaust valves, characterized by varying divisions between the connections of the pistons (14) to the swashplate (18) and / or varying opening times for the intake and / or exhaust valves.

2. axial piston machine according to claim 1, characterized in that the pitches are adapted such that adjacent pistons (14) always after a constant partial rotation of the swash plate (20) reach their TDC and / or UT.

3. Axial piston machine according to claim 1 or 2, characterized in that the opening times are adapted such that the inlet and / or

Open and / or close the exhaust valves of all cylinders (12) with identical piston position of the associated pistons (14).

4. Axial piston machine according to one of the preceding claims, characterized in that the opening times are adapted such that the opening duration of the intake and / or the exhaust valves of at least some of the cylinders (12) is different.

5. Axial piston machine according to claim 4, characterized in that the different opening duration is adjusted such that the masses of in a cycle in the individual cylinders (12) enclosed subsets of the fluid are as equal as possible.

6. Axial piston engine according to one of the preceding claims, characterized in that the inlet and / or the exhaust valves comprise inlet and / or outlet openings (28) for the cylinder (12), which temporarily by means of a Rotary vane (38) are released and covered, wherein the varying opening times by varying pitches between the inlet and / or outlet openings (28) of adjacent cylinders (12) and / or by varying lengths of the inlet and / or outlet openings (28) is achieved ,