Patent Grant
10221850
The present invention relates to a piston machine which comprises a housing with a chamber which has a substantially circle sector-shaped cross-section, a pivotal piston which is designed as a pivoting element, is arranged in the housing, and comprises a first working surface, wherein the housing and the piston define at least one first variable working chamber; a drive or output which is connected to the piston; and an outlet which is arranged in the working chamber for discharging a working fluid.
Piston machines of the type as mentioned in the preamble, which are employed as working machines in the form of piston pumps and piston compressors or as power machines in the form of internal combustion engines, compressed gas motors or hydraulic motors for converting pressure generated in the working chamber into motion, are known from prior art.
For instance, DE 10 2008 040 574 A1 discloses a piston machine which has a piston being designed as a dual-pivot plate. The piston, which is arranged in a substantially circle sector-shaped housing, is pivotably mounted with the aid of a rotary cylinder formed thereon, and divides the housing into two separate working chambers which are each furnished with inlet and outlet valves.
DE 10 2010 036 977 B3 equally discloses a piston machine. The piston machine is equipped with two pistons which are designed as dual-pivot plates. A housing of the piston machine is formed from two or more integrally joined housing parts which are each circular cylindrical segment-shaped, but turned by 180 degrees, and form a common cavity, with pistons which are assigned to each housing part, are synchronically driven in respectively opposite directions and are arranged in parallel to one another, said pistons each defining an outer working chamber between the twin-piston plates with third and fourth inlet and outlet valves formed in a housing rear wall at the height of an imaginary separating line between the adjacent housing parts.
It is an object of the present invention to further develop a piston machine of the type as mentioned in the preamble so that it can be operated with greater efficiency. This object is attained by means of a piston machine being formed in accordance with the features of the main claim. Functional further developments of the application are the subject-matter of the subclaims and the exemplary embodiments.
The piston machine comprises a housing with a chamber which has a substantially circle sector-shaped cross-section, as well as a pivotal piston which is designed as a pivoting element, is arranged in the housing and comprises a first working surface, wherein the housing and the piston define at least one first variable working chamber. Furthermore, the piston machine comprises a drive or output, which is connected to the piston, and an outlet which is arranged in the working chamber for discharging a working fluid. The housing has a cooling opening in at least one housing wall, said opening leading to the chamber, at least for convectively cooling a piston side opposite the first working surface by means of a coolant. A coolant can be introduced into the chamber through the cooling opening, whereby temperature of the piston and/or the working fluid and/or the housing and/or the chamber can be reduced. In this way, efficiency of the piston machine can be increased. Typically, the cooling opening in fact reduces a work volume of the variable working chamber. However, the piston machine can only be operated by cooling with greater efficiency. Depending on the position of the cooling opening, besides the abovementioned surface of the piston, for instance further surfaces of the piston as well as one or more housing walls or parts of the chamber can be intensively cooled as well.
In one further development, the chamber is delimited by a wall which has a circular arc-shape in cross-section. In the following, said wall having a circular arc-shape in cross-section will be referred to as “circular arc-shaped wall”. The cooling opening for instance can be provided in the circular arc-shaped wall. The opening in the circular arc-shaped wall makes it possible to flush the chamber by means of a coolant, whereby efficient cooling of the chamber can be realized. For instance, hot re-expansion gases can be removed from the chamber after compression in the chamber with the aid of a flushing process using the coolant. In this way, efficiency of the piston machine can be further enhanced.
A pivot angle (cf. e.g. angle α in
Typically, a center angle in a circle is indicated by the ratio of a circular arc with respect to the radius r of the associated circle. It can be provided that the opening in the circular arc-shaped wall is defined by a first center angle (cf. e.g. angle β in
Typically, the piston can be pivoted about a pivot axis. Here, the pivot axis can define an axial direction. A radial direction can be defined perpendicular to the axial direction and perpendicular to the pivot direction. For instance, it can be provided that the opening in the circular arc-shaped wall extends over an entire axial length of the circular arc-shaped wall.
In one embodiment, a pivot movement of the piston defines a pivot plane. Preferably, the chamber is delimited by a front wall and a rear wall, wherein the front wall and the rear wall can be formed in parallel to the pivot plane. It can be provided that the cooling opening is formed in the front wall and/or in the rear wall. This design makes it possible to attain cooling in a similar manner as with the abovementioned design of the cooling opening in the circular arc-shaped wall. The cooling opening in the rear wall and/or front wall for instance extends over an entire radial length of the rear wall and/or the front wall.
The drive or output typically comprises at least one crank shaft with a crank pin. The crank pin for instance engages into a connecting rod eye of a connecting rod being connected to the piston or into a guide groove of a connecting rod loop being firmly connected to the piston. It is known to the skilled person that there are many options available for constructing the drive or the output. A rotational speed of the crank shaft is typically more than 1500 min−1. The rotational speed can even be up to 8000 min−1 or more.
The working surface of the piston is typically the surface of the piston by means of which or on which work is performed. Moreover, it can be provided that the piston has a second working surface on a side opposite the first working surface, and the piston and the housing define a second variable working chamber with a second outlet valve arranged therein, wherein the cooling opening separates the cooling opening of the first working chamber from the second working chamber and is located at least on a separating line between the first working chamber and the second working chamber. Then, in each case work can be performed alternately by the first working surface and the second working surface, depending on which variable working chamber is closed or open at the moment. Convective cooling using the coolant then usually takes place at least at the respectively opposite side of the working surface of the piston. The cooling opening is preferably located in the circular arc-shaped wall, e.g. in the center of the arc-shaped wall, and/or in the front wall and/or in the rear wall. The two working chambers are alternately closed and opened typically during one complete pivot movement or turn of the crank shaft by 360°. The opened working chamber is flushed for instance by means of a coolant, while a working fluid can be fed or compressed in the closed working chamber. Thus, this design of the piston machine makes it possible to carry out the entire flushing and cooling process particularly efficiently.
In another embodiment, the working chamber is open or closed as a function of the pivot position of the piston. When the working chamber is open, the coolant preferably flows into the working chamber and at least convectively cools the piston side opposite the working surface and/or flushes the working chamber.
The chamber further can be delimited by a first side wall facing away from the first working surface, whereby the cooling opening is provided in the first side wall. Typically, the chamber is delimited by a second side wall facing the first working surface. Moreover, the variable working chamber can be delimited by the piston, the second side wall, the circular arc-shaped wall, the front wall and the rear wall. If the cooling opening is only provided in the first side wall facing away from the working surface, flushing of the working chamber using the coolant usually does not take place. Instead, this design enables continuous convective cooling of the piston side opposite the working surface.
The cooling opening in the first side wall can extend over an entire radial and/or axial length of the side wall. Preferably, the cooling opening extends even over the entire first side wall, i.e. the first side wall is omitted. In this way, it is possible to further enhance the cooling effect.
To form the cooling opening in the housing, one or several housing walls can be removed completely or partly, whereby work volume of the chamber in fact is reduced, but overall work quality of the piston machine can be improved.
It can be provided that the circular arc-shaped wall and/or the front wall and/or the rear wall and/or the abovementioned side wall are separated into two parts by the cooling opening. The cooling opening in particular can be provided in a housing wall, where space is available and good flow of the coolant is ensured. The cooling opening can be formed in the housing wall in various shapes, such as e.g. a groove, a circular sector or a circle or any other shape. It is also possible to provide several cooling openings in respectively different walls, e.g. in the circular arc-shaped wall and/or the front wall and/or the rear wall and/or the side wall. The abovementioned cooling openings can be combined with each other.
If several cooling openings are provided, one cooling opening can be designed as a coolant inlet and the other cooling opening can be designed as a coolant outlet. For instance, in one embodiment, a cooling opening is each formed in the rear wall and in the front wall. For instance, the coolant can be introduced into the chamber through the cooling opening of the rear wall or the front wall and can be discharged through the cooling opening of the front wall or the rear wall. Furthermore, the cooling opening can also be provided in the circular arc-shaped wall and in the rear wall and/or in the front wall. In this embodiment, for instance, the coolant can be introduced into the chamber through the cooling opening in the circular arc-shaped wall and can be discharged through the cooling opening in the rear wall and/or in the front wall. Other combinations of cooling openings in respectively different housing walls are also conceivable, in which the coolant is introduced into the chamber through a cooling opening and is discharged from the chamber through the respectively other cooling opening. In these embodiments, the chamber can be flushed particularly well by means of the coolant.
If several cooling openings are provided, they can have different sizes or can even be divided. The cooling openings can be differently designed in width and length.
The employed coolant or working fluid for instance can be air, CO2 or other gases or can be a liquid, such as water. It is evident for the skilled person that the selection of the coolant and the working fluid depends on the respective design of the piston machine. The piston machine for instance can be operated as a pump, vacuum pump, compressor or engine/motor.
In another embodiment, a second wall, which is circular arc-shaped in cross-section, can be attached to the piston which is arranged on a smaller radius than a maximum radial length of the piston, and which engages into a passage of a side wall at least in a pivot position of the piston, wherein the cooling opening is preferably equally provided in this side wall. In one embodiment, the cooling opening forms the inlet for the second wall which is circular arc-shaped in cross-section. The cooling opening, which is provided in the side wall, can be provided above or below the second circular arc-shaped wall, viewed from the pivot axis. Preferably, the second circular arc-shaped wall is equally cooled by the coolant. Then, a second variable working chamber can be defined at least by the second arcuate wall, the piston and the side wall. With this embodiment, for instance, two-stage compression can be realized.
In another embodiment, an inlet valve is arranged in the working chamber at least for introducing the working fluid into the working chamber. Typically, the cooling opening differs from the inlet valve. In a preferred embodiment, the outlet is designed as an outlet valve. Typically, the cooling opening differs from the outlet valve. Thus, an inlet and outlet valve can be arranged in the working chamber, for instance in the rear wall, front wall, side wall and/or in the circular arc-shaped wall. Alternatively, the inlet valve can also be omitted. When the chamber is open, the chamber and/or the piston is/are at least convectively cooled and/or flushed by means of the coolant. As the pivot movement of the piston advances, the chamber subsequently closes. The coolant which still remains in the chamber then can be removed through the outlet valve.
In another embodiment, the piston features cooling fins for convective cooling. Preferably, the cooling fins are located on the piston side opposite the working surface. Furthermore, the piston can be designed as a cavity. The cooling fins and/or the cavity design make/makes it possible to further enhance cooling of the piston.
In another embodiment, a size of the cooling opening can be variably controlled or adjusted, preferably by means of a control member or slide or throttle valve being arranged in a housing wall. In this way, a size of the opening can be controlled or reduced or enlarged so as to influence or regulate cooling air flow rate. Hence, the piston machine can be adapted to various performance requirements, whereby the cooling effect can be controlled during operation. The variably controllable cooling opening can be opened or closed mechanically to a more or lesser degree as required, for instance via the motion of a camshaft. The variably controllable cooling opening can also be controlled by an electronic control device so as to change a size of the cooling opening as required during operation of the piston machine. In another embodiment, a pressure sensor and/or a temperature sensor is/are provided in the chamber and/or in the piston, which can be connected to the control device and/or an evaluation device. Upon reaching a threshold of a temperature and/or a pressure in the chamber and/or in the piston, the cooling opening can be opened or closed to a more or lesser degree and the size thereof can be enlarged or reduced, respectively. If the measured temperature for instance is less than a specific threshold, the cooling opening can be closed so as to increase a feed volume of the piston machine. Hence, it is possible to influence feed volume of the piston machine, coolant flow rate, pressure and temperature during operation of the piston machine using the variably controllable cooling opening so as to enhance efficiency of the piston machine.
The coolant can be drawn in through the cooling opening by means of the motion of the piston. Moreover, a cooling device, preferably a blower or a pump, can be provided for feeding the coolant through the opening of the housing and into the chamber. Cooling can be made even more efficient in this way. In order to further increase cooling air flow rate, a Venturi tube can be provided at the cooling opening, which makes it possible to considerably enhance flow rate.
It is evident for the skilled person that several chambers can be connected in succession or side-by-side. Hence, the housing for instance can have two or more joined housing parts, which are each circle sector-shaped, but turned by 180°, and form a common cavity, wherein a piston is assigned to each housing part. Then, two adjacent housing parts together with their pistons define at least one variable working chamber. Further details can be found for instance in document DE 10 2010 036 977 B3. Here, a cooling opening can be provided in at least one chamber. However, several or all chambers can have cooling openings as well.
A piston machine being designed as a compressor for instance enables compression to 10 bar or more, e.g. up to 20 bar, using one-stage compression. Moreover, the piston machine allows oil-free operation, which is desirable in particular for application as a vacuum pump, compressor or expansion motor.
Exemplary embodiments of the invention will be described in greater detail with reference to the attached drawings, wherein:
In the figures, recurring features are furnished with same reference numerals.
In the following, reference is firstly made to
As illustrated in
The above described piston machine can operate as a piston pump or piston compressor as follows, but can also function as an internal combustion engine, the function thereof being not described here, with inner or outer combustion: During rotary movement of a crank shaft 19, a crank pin 18 moving on a crank radius 11 slides in a guide groove 17 of a connecting rod 16 which thereby transmits a pivot movement to the piston 15. When a pivot movement of the piston 15 is performed from the position as shown in
The piston 15 thus operates as a twin-piston with two working surfaces 29 and 30, which executes two pivot movements during one turn of the crank shaft 19, this means from the left dead center at the left side wall 5 to the right dead center at the right side wall 6 and back. The oil sump 12 effects lubrication of the crank mechanism, this means the guide groove 17 and the crank pin 18 sliding therein, which, incidentally, can also be formed with rolling bearings and sliding blocks.
As is known from DE 2008 040 574 A1, the guide groove 17 can also be arranged in the piston 15. Thus, a highly compact design can be realized.
Alternatively, it can also be provided that the crank pin 18 of the crank shaft 19 engages in a connecting rod eye of a connecting rod which is articulately connected to the piston. The drive and output of the piston machine thus is not limited to the illustrated embodiments.
The embodiment of
While the piston 15 of
The piston machine of
The embodiment of
In the embodiment of
In the embodiment of
As can be seen from
The piston machine of
d further differ from
Unlike the piston machine according to
Hereinafter, reference is made to
According to
The integrally formed housing 103 comprises—indicated by a dashed line X—two joined housing parts 103a, 103b which, however, are turned by 180° and have a substantially circle sector-shaped cross-section, in which the rotary cylinders of the pistons 101 and 102 are once mounted at the upper housing wall 111 and once at the lower housing wall 112. A chamber A1 and A2 enclosed by the housing thus has the shape of two equisized circle sectors which lie side-by-side so as to be opposed to each other. The housing 103 further comprises a housing rear wall 114 and a housing cover 113 as well as a first side wall 115 and a second side wall 116. The two twin-pistons 101, 102, which are aligned in parallel to one another in every position, are disposed in an initial position, as shown in
For instance, in case of the function as a pump, a feed medium, which is located in the inner large working chamber A3 between the two twin-piston plates 101 and 102 and which has been previously drawn in via the inlet valve 18c, is discharged from the working chamber A3 again during the pivot movement of the twin-piston plates 101 and 102 toward the separating line X. During this pivot movement (discharge), a feed medium is simultaneously drawn into the two outer (smaller) working chambers A1 and A2, which are each formed between the twin-piston plates 101 and 102 and the side walls 115 and 116, via the inlet valves 18a and 18b. When the two twin-piston plates 101 and 102 subsequently move in the direction of the side walls 115 and 116, the feed medium, which has been previously drawn into the working chambers A1 and A2, is discharged through the outlet valves 19a, 19b and at the same time, feed medium is drawn into the large working chamber A3 via the inlet valve 18c. In this way, efficient feed operation is ensured with the aid of two interacting twin-piston plates 101 and 102 and three working chambers A1, A2 and A3 in one and the same housing 103. The maximum volume of the two small outer working chambers A1 and A2 corresponds to the maximum volume of the larger inner working chamber A3. The above-described piston machine can be operated as a compressor or expansion motor or as a combination thereof with equally high efficiency. For instance, the medium-large—working chamber A3 can operate as an expansion motor, while the two outer smaller—working chambers A1 and A2 operate as compressor or pump and are driven by the expansion motor. When the described piston pump is used as a compressor, the inner working chamber A3 and an outer (left) working chamber A1 can be operated as a first compressor stage, and the other outer working chamber A2 can be operated as second compressor stage. Hence, the working chambers A1, A2 and A3 can each fulfil different functions as compressor, pump and engine/motor.
The embodiment of
The embodiment of
In
Moreover, an optional blower or a cooling device is each provided in the embodiments of
The embodiments in
The drive or output of the piston machine is not limited to the illustrated embodiments of
The features disclosed in the exemplary embodiments of the different embodiments can be combined and can be claimed individually.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 208 939 | May 2014 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/060500 | 5/12/2015 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2015/173255 | 11/19/2015 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 1363423 | Le Pierre | Dec 1920 | A |
| 3408991 | Davis | Nov 1968 | A |
| 5228414 | Crawford | Jul 1993 | A |
| 5666912 | McLachlan | Sep 1997 | A |
| 5979163 | Hanners et al. | Nov 1999 | A |
| Number | Date | Country |
|---|---|---|
| 23 53 008 | Apr 1975 | DE |
| 37 05 313 | Oct 1987 | DE |
| 10 2008 040 574 | Jan 2010 | DE |
| 10 2010 036 977 | Nov 2011 | DE |
| 486 745 | Jun 1938 | GB |
| 486745 | Jun 1938 | GB |
| 9508055 | Mar 1995 | WO |
| Entry |
|---|
| Translation of the International Preliminary Report on Patentability issued in PCT/EP2015/060500; dated Nov. 24, 2016; 11pp. |
| International Search Report issued in PCT/EP2015/060500; dated Aug. 10, 2015. |
| Office Action issued in the related Chinese Patent Application No. 201580038189.6 dated Jul. 4, 2018; 16 pages. |
| Number | Date | Country | |
|---|---|---|---|
| 20170138359 A1 | May 2017 | US |
