This application claims priority to International Patent Application No.: PCT/EP2016/053460 filed on Feb. 18, 2016, and German Patent Application No.: DE 10 2015 204 385.1 11 filed Mar. 11, 2015, the contents of which are incorporated herein by reference.
The present invention relates to an axial piston machine comprising a shaft which is connected in a torque-proof manner to a swashplate. The invention additionally relates to a heat recovery system with such an axial piston machine.
In internal combustion engines it is known that only 40% of the energy stored in the fuel is used for movement of the piston and therefore for driving the internal combustion engine. The remaining energy produced in the course of the combustion is principally removed from the internal combustion engine in the form of heat by escaping combustion exhaust gases. In order to reduce these heat losses and therefore increase the efficiency of the internal combustion engine, it is known to couple an axial piston machine to the internal combustion engine.
DE 10 2011 118 622 A1 teaches, for example, a generic axial piston machine comprising a shaft which is connected in a torque-proof manner to a swashplate. A plurality of cylinders are arranged coaxially to the shaft and annularly around this, in which constructed and hollow pistons are arranged translationally adjustably in each case. Each of these pistons is coupled to the swashplate via an appurtenant spherical bearing and a sliding block, whereby a movement of the respective piston brings about a drive of the swashplate and therefore a driving of the shaft. Via a rotary valve disk having an eccentrically arranged through opening, each inlet opening of a cylinder is swept once during each revolution and working medium is thereby supplied to the respective cylinder. In the central region of the axial piston machine, a cavity is provided, which is delimited by the cylinder head wherein the outlet openings pertaining to the cylinder head are guided through the cylinder block in such a manner that a temporary connection can be made between the cavity and the expansion volume of the cylinder via the off-axis through opening in the circumferential rotary valve disk. In particular, the efficiency should be able to be increased as a result.
WO 2014/128266 A1 teaches another axial piston machine which has a bypass channel for bypassing the same. This bypass channel completely bypasses the axial piston machine so that an extra bypass line and corresponding branches and a bypass valve are to be provided for this.
The present invention is concerned with the problem of providing an improved or at least at alternative embodiment for an axial piston machine of the generic type which in particular enables an improved control of the axial piston machine with simultaneously reduced installation space requirement.
This problem is solved according to the invention by the subject matters of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.
The present invention is based on the general idea of providing an axial piston machine with a bypass channel wherein the bypass channel is integrated in a cylinder head and a housing of the axial piston machine and is thereby optimized in terms of installation space. Compared to axial piston machines known from the prior art, therefore in particular no external separate arrangement of the bypass channel is required. The axial piston machine according to the invention thereby has in a known manner a rotor rotatably mounted in a housing and cylinders arranged in an annular manner and at an angle to the rotor in which pistons are arranged in a translationally adjustable manner. In this case, the cylinders are arranged in a range of +/−30° to the rotor, in particular 0°, i.e. parallel to the rotor. Each cylinder is assigned an inlet opening in the cylinder head and at least one outlet opening in the housing. According to the invention, an inlet channel leading to the inlet opening and an outlet channel connected in a communicating manner to the outlet opening are provided in the housing. Furthermore, a bypass channel is provided which extends from the cylinder head via the housing onto the outlet channel or a swashplate space. Also provided is a bypass valve which is either connected to the cylinder head or is even integrated in this and which apportions an inflow of working medium to the inlet channel and the bypass channel depending on a switching position thereof. In particular the second embodiment in which not only the bypass channel is integrated in the cylinder head and the housing but in addition the bypass valve is integrated in the cylinder head is an embodiment which is particularly optimized in terms of installation space. Compared to axial piston machines known from the prior art, however, the first-mentioned alternative in which the bypass valve is arranged on the cylinder head or is connected to this is already an appreciable improvement since the bypass channel is completely integrated in the cylinder head and the housing and as a result separate laying of a corresponding bypass line or a corresponding bypass channel is no longer required. The axial piston machine according to the invention can thus be controlled or regulated particularly exactly and as a result of the previously described integration of the bypass channel in the cylinder head and the housing, is extremely compact. In the axial piston machine according to the invention, a separation of lubricant contained in the working medium is additionally made possible as is already provided in active operation with the result that in particular a lubrication of a swashplate can be particularly advantageously ensured. As a result of the improved lubrication, a significant improvement can be achieved when restarting. As a result of the bypass channel integrated at least partially in the housing, a more rapid heating of the axial piston machine can be achieved whereby the efficiency thereof is improved and thus an earlier switch-on of the axial piston machine can be achieved.
If the bypass valve is integrated in the cylinder head, as already explained previously, a particularly compact embodiment can be achieved which allows an improved heat transfer compared to the axial piston machine known from the prior art. On the one hand, external lines can be omitted which otherwise mean an unnecessary heat loss and on the other hand, as a result of the direct structural proximity the heat input is directly in or on the housing of the axial piston machine.
Expediently the bypass valve is fastened to the outside of the cylinder head via a decoupling element. Such an attached design in particular also allows the provision of the bypass valve as merely an optional component since this can for example be flange-mounted in a modular fashion and in particular can also be retrofitted. In order to be able to thermally decouple the bypass valve from the cylinder head, the decoupling element is configured for example as a plastic part, in particular as an elastomer element.
In another advantageous embodiment of the solution according to the invention, a braking device for braking the rotor and for fixing the same in a predefined rotational position is provided in the cylinder head wherein the braking device for example can be actuated by means of compressed air or by means of the working medium. In this case, it can be provided that a braking channel is arranged in the cylinder head which is connected at one end to the bypass valve and at the other end to the braking device so that the braking device can be actuated via the bypass valve. By means of the braking device, it is possible for example to fix the rotor in a predefined rotational position in which an eccentric opening of a rotary valve disk connected in a torque-proof manner to the rotor is aligned with an inlet opening of a cylinder wherein the piston of this cylinder is located in the area of an upper dead point and is displaced in the direction of the lower dead point when working medium flows in. A reliable and forceful starting of the axial piston machine is thereby possible.
Expediently the braking device comprises a pin which in the predefined rotational position engages in a recess arranged on the rotary valve disk and fixes this. Such a recess can be arranged, for example on an external edge of the rotary valve disk. Purely theoretically a braking action could be achieved by means of the bypass valve even without the braking channel if the bypass valve specifically switches a counterpressure when the respective piston, in the outlet opening of which working medium is blown, rests in the lower dead point. In this case, the inlet opening of this cylinder is closed so that the bypass stream flowing in via the outlet opening builds up a pressure and prevents travel of the piston as far as the upper dead point.
In a further advantageous embodiment of the solution according to the invention, a connecting channel is provided between the inlet channel and the bypass channel in which an overpressure valve is arranged. By means of such an overpressure valve, the axial piston machine can be closed off at a predefined overpressure independently of the bypass valve since working medium can then be blown out directly from the inlet channel via the connecting channel into the bypass channel. As a result, the axial piston machine is shut off until a subcritical pressure is again present and specifically without the bypass valve itself needing to be switched. This therefore enables a particularly rapid switching.
In an advantageous embodiment the bypass channel is arranged at right angles to the respective external surfaces in each case and thereby enables a particularly simple and cost-effective manufacture of the bypass channel.
In an advantageous embodiment of the solution according to the invention corresponding to the second alternative, in which the bypass channel opens into the swashplate space, this has a nozzle at its end facing the swashplate space or such a nozzle is arranged there. This nozzle is directed onto an impact surface of a sliding foot connected to the piston and thus serves as a starting aid whereby a vapour jet emerging therefrom presses the piston downwards. When starting the axial piston machine, a translational starting impulse can be applied to the sliding foot and a rotational starting impulse can be applied to the swashplate via the nozzle.
Further important features and advantages of the invention are obtained from the subclaims, from the drawings and from the relevant description of the figures with reference to the drawings.
It is understood that the features mentioned previously and to be explained further hereinafter can be used not only in the respectively given combination but also in other combinations or alone without departing from the scope of the present invention.
Preferred exemplary embodiments of the invention are presented in the drawings and are explained in detail in the following description, where the same reference numbers relate to the same or similar or functionally the same components.
In a schematic representation, not to scale:
According to
By integrating the bypass channel 13 in the cylinder head 7 and the housing 3, this can be arranged in a manner optimized in terms of installation space, wherein at the same time further components such as for example lines and branches as would be necessary in external bypass channels known from the prior art can be omitted.
If
If
In the axial piston machine according to
If the embodiment of the axial piston machine 1 according to
If the embodiment of the axial piston machine 1 according to
With the axial piston machine 1 according to the invention, not only an arrangement of the bypass channel 13 in the cylinder head 7 or in the housing 3 which is optimized in terms of installation space is possible but the bypass channel 13 enables a media guidance comparatively close to real operation without the axial piston machine 1 being actuated.
Thus, for example, it is possible to separate lubricant contained in the working medium as is already provided in active operation. As a result, the axial piston machine 1 can be optimally lubricated when restarting, in particular lubrication of the swashplate 23 is possible. As a result of the bypass channel 13 being guided through the housing 3, a more rapid heating of the housing 3 can be achieved.
If the bypass valve 14 is attached to the outside of the cylinder head 7 as shown according to
Number | Date | Country | Kind |
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10 2015 204 385 | Mar 2015 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2016/053460 | 2/18/2016 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2016/142144 | 9/15/2016 | WO | A |
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Entry |
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English abstract for DE-102011118622. |
Number | Date | Country | |
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20180045173 A1 | Feb 2018 | US |