AXIAL PISTON MACHINE

Abstract

An axial piston machine may include a rotor mounted rotatably in a housing. The axial piston machine may also include a plurality of cylinders in which a plurality of pistons are disposed such that the plurality of pistons are translationally movable. The plurality of cylinders may be arranged in a ring-like manner around the rotor. Further, the axial piston machine may include a starter device configured to exert a pulse-like torque on the rotor to initiate a starting operation. The starter device may be couplable to the rotor.

Claims

1. An axial piston machine comprising: a rotor mounted rotatably in a housing; a plurality of cylinders in which a plurality of pistons are disposed such that the plurality of pistons are translationally movable, the plurality of cylinders arranged in a ring-like manner around the rotor; and a starter device configured to exert a pulse-like torque on the rotor to initiate a starting operation, wherein the starter device is couplable to the rotor.

2. The axial piston machine according to claim 1, wherein: the starter device includes a sleeve, the sleeve including at least one internal elevation; and a shaft of the rotor includes at least one radially outwardly spring-biased roller tappet extending along an inner track disposed within the sleeve on which the at least one internal elevation is arranged.

3. The axial piston machine according to claim 2, wherein: the sleeve includes two opposing internal elevations; and the shaft of the rotor includes at least two radially outwardly spring-biased roller tappets extending along the inner track on which the two opposing elevations are arranged.

4. The axial piston machine according to claim 2, wherein the at least one elevation includes a steep flank and a gently sloping opposite flank.

5. The axial piston machine according to claim 2, further comprising an output shaft, wherein the sleeve is integrally arranged on the output shaft.

6. The axial piston machine according to claim 5, further comprising a freewheel device configured to at least one of 1) connect the rotor with the output shaft in a driving manner and 2) disconnect the rotor from the output shaft.

7. The axial piston machine according to claim 2, wherein the at least one elevation has a height from 2.0 mm to 5.0 mm, particularly h approximately 3.7 mm.

8. The axial piston machine according to claim 1, wherein the starter device configured to provide a pulse-like torque from 1 to 2 Nm.

9. A motor vehicle comprising: an internal combustion engine coupled to a drivetrain via a transmission; a heat recovery system including a vaporiser; and an axial piston machine including a rotor rotatably mounted within a housing, a plurality of cylinders arranged in a ring-like manner around the rotor, and a starter device couplable to the rotor, the plurality of cylinders including a plurality of translationally movable pistons disposed therein, the starter device configured to exert a pulse-like torque on the rotor to initiate a starting operation; wherein the vaporiser is heatable by exhaust gas of the internal combustion engine, a pump, a condenser, and the axial piston machine.

10. The motor vehicle according to claim 9, wherein the internal combustion engine is a diesel engine.

11. A method for starting an axial piston machine in a motor vehicle comprising: starting an internal combustion engine coupled to a drivetrain via a transmission; heating and vaporising a working medium disposed within a vaporiser of a heat recovery system via exhaust gas discharged from the internal combustion engine; heating a housing of an axial piston machine via directing the working medium vaporised in the vaporiser through the housing of the axial piston machine via a bypass; feeding the working medium vaporized into an opened cylinder of the axial piston machine after the vaporised working medium reaches at least one of a predefined temperature and a predefined pressure, wherein the opened cylinder is one of a plurality of cylinders arranged in a ring-like matter around a rotor rotatably mounted within the housing, the plurality of cylinders including a plurality of translationally movable pistons disposed therein; starting the axial piston machine via exerting a pulse-like torque on the rotor via an output shaft of the axial piston machine and a starter device coupled to the rotor; and closing a freewheel device of the axial piston machine and connecting the axial piston machine to the drivetrain in a driving manner after the rotor reaches a predefined rotating speed.

12. The axial piston machine according to claim 7, wherein the at least one elevation has a height of approximately 3.7 mm.

13. The axial piston machine according to claim 3, wherein at least one of the two opposing internal elevations includes a steep flank and a gently sloping opposite flank.

14. The axial piston machine according to claim 13, further comprising an output shaft, wherein the sleeve is integrally arranged on the output shaft.

15. The axial piston machine according to claim 14, further comprising a freewheel device configured to at least one of 1) connect the rotor with the output shaft in a driving manner and 2) disconnect the rotor from the output shaft.

16. The axial piston machine according to claim 15, wherein the two opposing internal elevations has a height from 2.0 mm to 5.0 mm.

17. The motor vehicle according to claim 9, wherein: the starter device includes a sleeve, the sleeve including at least one internal elevation; and a shaft of the rotor includes at least one radially outwardly spring-biased roller tappet extending along an inner track disposed within the sleeve on which the at least one elevation is arranged.

18. The motor vehicle according to claim 17, wherein the at least one internal elevation includes a steep flank and a gently sloping opposite flank.

19. The motor vehicle according to claim 18, further comprising an output shaft, wherein the sleeve is integrally arranged on the output shaft.

20. The motor vehicle according to claim 19, further comprising a freewheel device configured to at least one of 1) connect the rotor with the output shaft in a driving manner and 2) disconnect the rotor from the output shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the drawing, of which the figures are all diagrammatical:

[0019] FIG. 1 shows a longitudinal section through an axial piston machine according to the invention,

[0020] FIG. 2 shows a cross section through the axial piston machine along sectional plane A-A,

[0021] FIG. 3 shows a motor vehicle with an internal combustion engine and a heat recovery system, in which an axial piston machine as represented in FIG. 1 is integrated,

[0022] FIG. 4 is a view as in FIG. 2, but with two opposing internal elevations and two radially outwardly spring biased roller tappets.

DETAILED DESCRIPTION

[0023] As shown in FIG. 1, an axial piston machine 1 according to the invention includes a rotor 3 mounted rotatably in a housing 2. Cylinders 4 in which pistons 5 are translationally movable are arranged in a ring around rotor 3. Not shown are, for example, a cylinder head and a swash plate, via which the individual pistons 5 are coupled with rotor 3 and a shaft 6 of rotor 3 in torque-transmitting manner. According to the invention, a starter device 7 is provided which may be coupled to rotor 3 and to shaft 6 and which is designed such that it exerts a pulse-like torque on rotor 3 for starting axial piston machine 1.

[0024] Starter device 7 is furnished with a sleeve 8 (see also FIG. 2) having at least one inner elevation 9, for example a raised cam (see also FIG. 2). Starter device 7 also may also include a sleeve 8 with two opposing inner elevations 9 (see FIG. 4). Shaft 6 of rotor 3 in turn has a radially outwardly spring-biased roller tappet 10 which runs along an inner track 11 inside sleeve 8, wherein elevation 9 is also arranged on this inner track 11 (see FIG. 2), wherein alternatively it may also be provided here that shaft 6 of rotor 3 has two or more radially outwardly spring-biased roller tappets 10. If FIG. 4 is viewed in this context, it is evident that the two roller tappets 10 are guided into one another. Sleeve 8 is connected in torque-transmitting manner to an output shaft 12 of axial piston machine 1. Sleeve 8 may also form an form an integral part of said output shaft 12.

[0025] The at least one elevation 9 has a radial height h between 2 mm and 5 mm, for example, preferably approximately 3.7 mm. In this case, the at least one elevation 9 has one steep flank 31 and one gently sloping flank 32 (see FIG. 2), and sleeve 8 rotates relative to shaft 6 of rotor 3 in such a manner so that the roller 21 of roller tappet 10 first runs onto elevation 9 up the steep flank 31 and runs off elevation 9 down the gently sloping flank 32, so that elevation 9 is also actually able to exert a pulse-like torque on rotor 3.

[0026] A free-wheel device 13 is also provided, connecting rotor 3 and shaft 6 to the output shaft 12 in driving manner or disconnecting them therefrom. In particular, freewheel device 13 may serve to prevent an internal combustion engine 14 (see FIG. 3) from driving not only wheels 17 of a motor vehicle 18 via a drivetrain 15 and a differential 16, but also axial piston machine 1.

[0027] The one or more roller tappet(s) 10 is/are themselves arranged in a groove 19 of shaft 6, and biased with the respective roller 21 against inner track 11 by means of a spring element 20, for example a low-cost helical spring. Theoretically, of course the roller tappet 10 may also be embodied as a sliding tappet or with a ball in this case. FIG. 4 shows that it is even possible to bias both roller tappets 10 against the inner track 11 with a single spring element 20.

[0028] Now regarding motor vehicle 18 according to FIG. 3, besides the internal combustion engine 14 the vehicle includes a heat recovery system 22 with a vaporiser 23 which is heatable by the exhaust gas from the internal combustion engine 14, a pump 24 and a condenser 25. Vaporiser 23 is embodied as a heat exchanger which transfers thermal energy from the exhaust gas 26 to a working medium 27. The heated and vaporised working medium 27 may be sued not only to heat but also to drive axial piston machine 1. Internal combustion engine 14 may be in the form of a diesel engine, for example. Additionally, a transmission 28 is typically disposed between internal combustion engine 14 and drivetrain 15.

[0029] The axial piston machine 1 according to the invention in motor vehicle 18 is started as follows:

[0030] First, internal combustion engine 14 of motor vehicle 18 is started, and the exhaust gas 26 discharged thereby is passed into vaporiser 23 where it used to warm or heat the working medium 27 of heat recovery system 22. The working medium 27 which is vaporised in vaporiser 23 is initially routed past housing 2 of the axial piston machine 1 via a bypass 29, heating the housing. When working medium 27 has reached a predefined temperature and/or a predefined pressure, it is introduced into the open cylinder 4 of axial piston machine 1 in order to start it. In this state, freewheel device 13 still idling. Since the vapour pressure introduced may not be sufficient to reliably start the axial piston machine 1 in the presence of a correspondingly strong breakaway friction, in the inventive method, the internal combustion engine 14 now exerts a pulse-like torque on rotor 3 and shaft 6 thereof via the drive train 15, the output shaft 12 of the axial piston machine 1 and the starter unit 7, whereby the breakaway friction may be reliably overcome and the axial piston machine 1 can be reliably started.

[0031] When rotor 3 reaches a predefined speed, freewheel device 13 is then closed, so that axial piston machine 1 is connected in driving manner to drive train 15 of motor vehicle 18. When freewheel device 13 is closed, the rotating speeds of drivetrain 15 on the one hand and output shaft 12 on the other are synchronised simultaneously. In theory, output shaft 12 of axial piston machine 1 may be coupled with drivetrain 15 via a corresponding transmission 30, and said transmission 30 may also be equipped with a freewheel device, not further described here.

[0032] With the axial piston machine 1 according to the invention, it is thus reliably possible to start axial piston machine 1 unfailingly, even in the presence of a not inconsiderable breakaway friction, so that a motor vehicle 18 equipped therewith may be operated as efficiently as possible.