The present invention relates to an axial piston machine comprising a housing, in which a vapor chamber, a cylinder chamber and a wobble-plate chamber are provided. Moreover, the invention relates to a heat recovery system in a motor vehicle comprising at least one such axial piston machine.
A plurality of generic axial piston machines comprising a housing is known from the prior art, in which a vapor chamber, a cylinder chamber as well as a wobble-plate chamber are provided. A rotor comprising a shaft as well as the wobble plate arranged thereon in a rotationally fixed manner and a valve disk, which is also connected to the shaft in a rotationally fixed manner, are also arranged in the housing. The wobble plate, which is in each case coupled to one of the pistons via a cup and ball bearing and which is coupled to the shaft in a rotationally fixed manner, is arranged in the wobble-plate chamber itself. Such axial piston machines are in particular used in so-called heat recovery systems in motor vehicles, in which they convert thermal energy into mechanical energy.
However, the comparatively extensive and expensive production is a disadvantage of the piston machine known from the prior art.
The invention at hand thus deals with the problem of specifying an improved or at least an alternative embodiment for an axial piston machine of the generic type, which is characterized in particular by a structurally simple and cost-efficient production.
According to the invention, this problem is solved by means of the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.
The present invention is based on the general idea of now embodying a housing of an axial piston machine, which is comparatively extensive and thus expensive to produce until now, in several parts and to thus disentangle the extremely complex production process. In a known manner, the axial piston machine according to the invention thereby has a housing, in which a vapor chamber, a cylinder chamber and a wobble-plate chamber are arranged. Cylinders, in which pistons are arranged in a translationally movable manner, are provided annularly around a shaft in the cylinder chamber. A valve disk, which is connected to the shaft in a rotationally fixed manner and which connects the vapor chamber so as to communicate with one of the cylinders or separates it therefrom, depending on the rotational position of the vapor chamber, is arranged in the vapor chamber itself. A wobble plate, which is connected to one of the pistons via a cup and ball bearing each and which is coupled to the shaft in a rotationally fixed manner, is arranged in the wobble-plate chamber. According to the invention, the housing now has a steam-chamber housing part, a cylinder housing part and a wobble-plate housing part, which are connected to one another. Moreover, a cylinder sleeve comprising a radially protruding collar is provided in at least one cylinder, wherein the cylinder sleeve is retained by means of its collar in a cut-out in the cylinder housing part, which adjoins a parting plane between the vapor-chamber housing part and the cylinder housing part. The vapor chamber itself is closed by means of a first cover, which is connected to the vapor-chamber housing part and which is designed as a shaped sheet-metal part. By means of the at least three housing parts, which, in the mounted state, form the housing of the axial piston machine, the individual housing parts can be produced in a simpler and more lightweight manner, wherein an insertion of the cylinder sleeve into the cylinder is additionally possible from the vapor-chamber housing part. By means of the cylinder sleeve, which is inserted into the respective cylinders, the load capacity of the axial piston machine according to the invention can be increased significantly and the production effort thereof can be reduced significantly, because an individual post-processing of the cylinder tracks, which can only be accomplished with difficulties in the case of the housings, which have been provided to date, can now be forgone completely. Via the first cover, by means of which the vapor chamber can be closed off, a cover, which has been formed integrally with the vapor-chamber housing part until now, can also be forgone, whereby the production can be simplified, in turn. By designing the first cover as shaped sheet-metal part, this cover can moreover not only be designed in a more cost-efficient manner, but also thinner, because such a shaped sheet-metal part is able to reliably bear higher forces, as compared to a cover, for example, which is designed as a cast part. By segmenting the housing into the individual housing parts, in particular a comparatively simple and, associated therewith, a cost-efficient production of the individual housing parts and, via the latter, of the entire housing, is thus also possible.
In the case of an advantageous further development of the solution according to the invention, the cylinder sleeve is made of stainless steel. Such a cylinder sleeve made of stainless steel is in particular wear- and corrosion-resistant, whereby a permanent use in an axial piston machine, which is driven by means of steam, is feasible without any problems. As an alternative to this, the cylinder sleeve can also be made of a steel alloy with the following components, 3.20-3.50% by weight of C, 1.60-2.10% by weight of Si, 0.60-0.80% by weight of Mn, 0.35-0.50% by weight of P, maximally 0.06% by weight of S, 0.20-0.40% by weight of Cr, 0.30-0.50% by weight of Mo and iron for the remainder.
In the case of a further advantageous embodiment of the solution according to the invention, the wobble-plate chamber is closed off by a second cover, which is designed as shaped sheet-metal part. Analogous to the first cover, which is designed as shaped sheet-metal part and which, together with the vapor-chamber housing part, defines the vapor chamber, the wobble-plate chamber can thus also be closed off by means of such a cover on the axially opposite side, which also contributes to designing the wobble-plate housing part more cost-efficiently and more easily here.
In the case of an advantageous further development of the solution according to the invention, the cup and ball bearing, via which the individual pistons of the axial piston machine are connected to the wobble plate, has a collar, which protrudes radially outwards. The cylinder sleeve, in turn, has a cut-out, which is open towards the front side and into which the cut-out of the cup and ball bearing, which protrudes radially outwards, can dip. Provision is moreover made on the cup and ball bearing itself for two sliding feet, which are arranged adjacent to the cut-out and which are supported on the guide bushing. An exact translational adjustment of the respective cup and ball bearing can be forced by means of such an embodiment, because said cup and ball bearing is guided via its cut-out, which protrudes radially outwards, in the cylinder sleeve-side cut-out. The guide can thereby be supplemented in that a guide bushing comprising a cut-out, which is only open between the cylinder housing part and the wobble-plate housing part, is arranged in the wobble-plate housing part, wherein the cut-out of the cup and ball bearing, which protrudes radially outwards, is also guided in this cut-out in terms of a lock against rotation. The cut-out of the cylinder sleeve and the cut-out of the guide bushing thus form the entire guide track for the cut-out of the cup and ball bearing, which protrudes radially outwards.
Advantageously, provision is made for at least one blind plug for one of the cylinders, which can be inserted into one of the cylinders instead of a cylinder sleeve and which closes the inlet opening thereof, which faces the vapor chamber. A power reduction of the axial piston machine according to the invention can hereby in particular be attained in a comparatively simple manner, because not all cylinders are used to generate power any longer, but only those, which are not closed by such a blind plug. By selecting the number of the used blind plugs, the respectively desired power of the axial piston machine can thus be influenced individually.
In the case of an advantageous further development of the solution according to the invention, the first cover has projections, which are embossed in the direction of the vapor chamber, which reduce the volume of the vapor chamber. The volume in the vapor chamber itself can be dimensioned exactly via these projections, which can also be used as reinforcement for the cover, whereby tests have shown that in particular a coordination, for example of the volume of the vapor chamber, of a displaced volume of a cylinder, as well as of a cross section of an inlet into the vapor chamber, has a significant influence on the efficiency of the axial piston machine. Particularly preferably, the volume of the vapor chamber is thereby between 30 cm3 and 100 cm3, while a cross section of an inlet into the vapor chamber is between 78 mm2 and 200 mm2. The displaced volume of the cylinder is between 25 cm3 and 75 cm3. This applies in particular for an axial piston machine comprising six cylinders. The three above-mentioned variables, thus the volume of the vapor chamber, the cross section of the inlet and the displacement volume of the cylinder, are thereby dependent on one another and thus do not only determine the efficiency, but also the response behavior of the axial piston machine significantly. In order to be able to obtain a response behavior, which is as quick as possible, the working chamber should have as little dead volume as possible. So that pressure fluctuations nonetheless do not result in the case of reduced steam volume in the working chamber, the inlet needs to be chosen to be correspondingly large. The quick provision of steam thereby also has a positive effect on a quick response behavior of the axial piston machine. The displaced volume of a cylinder thereby determines the required amount of steam per actuation. Moreover, the volume of the vapor chamber is also linked to the speed of the rotor, which determines the number of actuations per time. Optimal conditions both with regard to the response behavior and also with regard to the efficiency can be obtained thereby within the above-mentioned ranges of the volume of the vapor chamber, of the cross section of the inlet, and of the displaced volume of the cylinder.
In the case of a further advantageous embodiment of the solution according to the invention, the first cover has at least two connections for connecting in particular a pressure sensor or a temperature sensor, which are attached to a flat front surface of the first cover. A small sealing surface and a comparatively simple mounting can be obtained by arranging the connections on the flat surface of the first cover.
In the case of an advantageous embodiment of the solution according to the invention, partial ribs are arranged on the wobble-plate housing, wherein these ribs, for example together with the wobble-plate housing part, can be designed as integral cast part. The ribs themselves can thereby serve as reinforcement or also to enlarge the surface, whereby an improved cooling can be obtained. This cooling effect is in particular desired in the area of the wobble-plate housing, all the way to the discharge channels.
In the case of a further advantageous embodiment of the solution according to the invention, at least one of the housing parts has a corrosion-protection layer on an inner side. By means of such a corrosion-protection layer, in particular a corrosion process, triggered by the vapor used in the axial piston machine to drive the latter, can at least be reduced. In addition or in the alternative, provision can also be made for an insulating element, in particular a so-called insulating plate, which surrounds at least the vapor chamber, preferably also the cylinder chamber all the way to the outlets, by forming an air gap. By means of such an insulating element, an insulating layer of air can be created in particular around the vapor chamber, whereby the steam remains hot for a longer period of time in the vapor chamber itself, and a comparatively high efficiency can thus be obtained.
Further important features and advantages of the invention follow from the subclaims, from the drawings, and from the corresponding figure description by means of the drawings.
It goes without saying that the above-mentioned features and the features, which will still be discussed below, cannot only be used in the respectively specified combination, but also in other combinations or alone, without leaving the scope of the invention at hand.
Preferred exemplary embodiments of the invention are illustrated in the drawings and will be discussed in more detail in the description below, whereby the same reference numerals refer to the same or to similar or functionally identical components.
In each case schematically,
According to
The cylinder sleeve 18 can thereby be made of stainless steel and can thus not only have a comparatively high wear resistance, but also an insensitivity to corrosion, which is highly advantageous in particular for the axial piston machine 1, which is operated by means of steam. In addition or in the alternative, the cylinder sleeve 18 can also be provided with a coating, in particular a polymer coating or a DLC coating, which reduces the wear and/or the friction. Moreover, the cylinder sleeve 18 can be designed in such a way that an at least partial immersion of the wobble plate 14 is made possible. In particular a more compact design can be obtained through this.
When taking a closer look at the cylinder sleeve 18, it can be seen that the latter has at least two passage openings 22 and 22′ in the area of a lower dead center of the piston 9, via which steam can be discharged. The passage openings 22, 22′ thereby communicate with a respectively corresponding discharge channel 23, 23′, lead into the wobble-disk chamber 6 and are defined by the cylinder housing part 16 on the one side and the cylinder sleeve 18 on the other side. Moreover, the cylinder sleeve 18 preferably has at least a third passage opening 38, which serves as auxiliary outlet and vents the cylinder 8 in response to a movement of the piston 9 to the upper dead center (OT).
Downwards, the wobble-plate chamber 6 is closed off by a second cover 24′, which is designed as shaped sheet-metal part and which is illustrated in
When taking a closer look at
Moreover, provision can be made for at least one blind plug 28 for one of the cylinders 8, which can be inserted into the cylinder 8 instead of a cylinder sleeve 18 and which closes the inlet opening 12 facing the vapor chamber 4, as it is illustrated according to
When taking a closer look at the first cover 24, it can be seen that the latter is embodied so as to be substantially flat and has projections 29 embossed in the direction of the vapor chamber 4, which reduce the volume of the vapor chamber 4 and effect an additional reinforcement of the first cover 24. By providing corresponding projections 29, the volume of the vapor chamber 4 can also be determined exactly by means of a simple design of the first cover 24.
A volume of the vapor chamber 4 of between 30 cm3 and 100 cm3, a cross section of an inlet 30 of between 78 mm2 and 200 mm2 as well as a displaced volume of a cylinder 8 of between 25 cm3 and 75 cm3 has proven to be particularly advantageous. The three above-mentioned variables, that is, the volume of the vapor chamber 4, the cross section of the inlet 30 and the displacement volume of the cylinder 8, are thereby dependent on one another and thus determine the response behavior of the axial piston machine 1 as well as the efficiency thereof significantly. The working chamber should thereby have as little dead volume as possible, in order to improve the response behavior. So that pressure fluctuations nonetheless do not result in the case of reduced vapor volume in the working chamber, the inlet needs to be chosen correspondingly large. It goes without saying that the volume of the travel of the piston 9 then determines the required amount per actuation. In addition, this is then also linked to the speed, which determines the number of actuations per time. A large vapor chamber 4 would be ideal for a quick actuation, because sufficient steam is then always present and because pressure fluctuations do not result.
When taking a closer look at
Provision can moreover be made in the wobble-plate housing part 17 for a guide bushing 33 comprising a cut-out 26′, which is open only between the cylinder housing part 16 and the wobble-plate housing part 17 and into which the cut-out 25 dips. The guide bushing 33 can thereby also be made of stainless steel and can thus be designed to be wear-resistant as well as corrosion resistant. Particularly advantageously, it can also be provided with a friction and/or wear-reducing coating. In the mounted state, the cut-out 26′ of the guide bushing 33 is thereby aligned with the cut-out 26 of the cylinder bushing 18 and thus forms a guide track for the cut-out 25 of the cup and ball bearing 13, which protrudes radially outwards.
To be able to also reliably mount the guide bushing 33 in the housing 3 of the axial piston machine 1, said guide bushing has a radially protruding collar 19′, via which it is retained in a separating plane 20′ between the cylinder housing part 16 and the wobble-plate housing part 17. For mounting purposes, the guide bushing 33 is thereby inserted into the wobble-plate housing 17 from the top (based on
On an inner side, at least one of the housing parts 15, 16, 17 can additionally have a corrosion protection layer 34, by means of which the corrosion resistance can also be increased.
When taking a closer look at
When looking at the axial piston machine 1 of
Finally,
A particularly simple and thus also cost-efficiently constructed axial piston machine 1 can be realized by means of the axial piston machine 1 according to the invention, which, due to the housing, which is designed in several parts, is also extremely flexible, in particular with regard to a possible adaptation. Moreover, it is a large advantage that, by means of the first cover 24, which is designed as cast part, the vapor-chamber housing part 15 can also be designed more easily and more cost-efficiently as compared to common housing parts installed therein.
Number | Date | Country | Kind |
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10 2015 207 909.0 | Apr 2015 | DE | national |
This application claims priority to International Patent Application No. PCT/EP2016/059693, filed on Apr. 29, 2016, and German Patent Application No. DE 10 2015 207 909.0, filed on Apr. 29, 2015, the contents of both of which are incorporated herein by reference in their entireties.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2016/059693 | 4/29/2016 | WO | 00 |