Oscillating piston expander, and method for opening or closing an inlet valve in an oscillating piston expander

Abstract

The invention relates to an oscillating piston expander having a cylinder housing (7), comprising an oscillating piston (1) which is accommodated in a working chamber (2) and is designed to drive an eccentric shaft (8); a high-pressure inlet channel (4) for the working medium to be expanded, said high-pressure inlet channel opening into the working chamber (2); a low-pressure outlet channel (5) for the expanded working medium, said low-pressure outlet channel opening into the working chamber (2); a weighing element assembly; and a piston rod segment (11), which extends perpendicularly from the oscillating piston (1) and can be axially movably received in a receiving area (33) of the weighing element (3), said weighing element assembly comprising an inlet valve. The invention further relates to a method for opening or closing the at least one inlet valve in an oscillating piston expander according to the invention.

Description

[0001] Oscillating piston expander, as well as methods for opening or closing an inlet valve in an oscillating piston expander

[0002] The present invention relates to a oscillating piston expander according to the preamble of claim 1, and to a method for opening or closing the inlet valve in an oscillating piston expander according to the invention according to claim 6.

[0003] Expanders, especially oscillating piston expanders, are used to reduce the pressure of a working medium, thereby performing mechanical work. Typical expander designs include turbo expanders, rotary vane expanders, and radial piston expanders. Concepts for rolling piston expanders and swing piston expanders can also be found in the literature.

[0004] A oscillating piston expander according to the prior art essentially comprises an oscillating piston housed in a working chamber, which is configured to drive an eccentric shaft, a high-pressure inlet channel for the working medium to be depressurized opening into the working chamber, a low-pressure outlet channel for the depressurized working medium opening into the working chamber, and a weighing element assembly comprising a two-part weighing element and a receptacle for rotatably mounting the weighing element in the cylinder housing. Furthermore, the weighing element assembly comprises a piston rod segment which extends perpendicularly from the oscillating piston and is axially displaceable in a receptacle of the weighing element.

[0005] The arrangement of the weighing element, in particular the piston rod segment which is slidably mounted in the weighing element, provides additional guidance to the oscillating piston and also separates the high-pressure chamber from the low-pressure chamber in the working chamber.

[0006] Typically, such oscillating piston expanders include an inlet control in the form of an inlet valve upstream of the high-pressure inlet channel, which regulates the intake of the working fluid to be expanded into the high-pressure inlet channel. Although usable oscillating piston expanders with inlet control are already known, there is still room for improvement.

[0007] This is where the present invention comes in and aims to propose an improved oscillating piston expander, in particular a oscillating piston expander that is compact in design and / or in which a separate valve control can be omitted.

[0008] According to the invention, this problem is solved by a oscillating piston expander with the characterizing features of claim 1. Because the weighing element arrangement includes at least one inlet valve, the existing weighing element can be used as part of the inlet valve. The oscillating piston expander can therefore be designed to be correspondingly compact. Since the rotational angle of the weighing element is dependent on the rotational angle of the eccentric shaft anyway, an inlet valve that is controlled by the rotational angle of the eccentric shaft, i.e., closed or open, can be provided.

[0009] Further advantageous embodiments of the proposed invention arise in particular from the features of the dependent claims. The subject matter or features of the various claims can, in principle, be combined with one another in any way.

[0010] In an advantageous embodiment of the invention, it can be provided that the eccentric shaft has an axis of rotation and the weighing element has an axis of rotation, wherein the axis of rotation of the eccentric shaft and the axis of rotation of the weighing element are aligned parallel to each other.

[0011] In a further advantageous embodiment of the invention, the weighing element can be composed of a component facing the high-pressure inlet channel and a component facing the low-pressure outlet channel. A two-part weighing element offers advantages in terms of production technology. For example, if the receptacle for the piston rod segment is located between the two components, the corresponding surfaces of the components can be machined more easily.

[0012] In a further advantageous embodiment of the invention, it can be provided that the inlet valve comprises a first recess in the weighing element, in particular in the component of the weighing element which faces the high-pressure inlet channel, wherein the first recess is in fluidic communication with the working chamber, wherein the inlet valve comprises a recess in the wall of the receptacle for the weighing element, wherein the recess in the wall of the receptacle is in fluidic communication with the high-pressure inlet channel, and wherein the inlet valve is configured to be opened or closed by changing the rotation angle of the weighing element.

[0013] In a further advantageous embodiment of the invention, the weighing element arrangement, in particular the inlet valve, can be configured such that the first and second recesses can be selectively brought into a fluidic connection or into no fluidic connection by changing the rotation angle of the weighing element. Such a configuration of the first outlet valve can be implemented reliably and with relatively little effort in production. Furthermore, the weighing element is already present and only needs to be modified. It is clear to those skilled in the art that the characteristics of the opening and closing behavior can be adjusted, in particular, by the position and dimensions of the recesses.

[0014] The present invention further relates to a method for opening or closing the inlet valve in a oscillating piston expander according to at least one of claims 2 to 5, which is characterized according to claim 6 in that the inlet valve is selectively opened or closed by rotating the weighing element, wherein the rotational position of the weighing element and / or the axial position of the piston rod segment depends on the rotational angle position of the oscillating piston.

[0015] Further features and advantages of the present invention will become clear from the following description of preferred embodiments with reference to the accompanying figures. The elements or features of the various embodiments can, in principle, be combined with one another as desired. These show:

[0016] Fig. 1 shows a oscillating piston expander according to the prior art in a schematic sectional view;

[0017] Fig. 2 shows a oscillating piston expander according to the invention in a schematic sectional view;

[0018] Fig. 3 shows a detail “A” according to Fig. 2;

[0019] Fig. 4-7 Details of a vibrating piston expander according to the invention in different angular positions of the eccentric shaft during an expansion process;

[0020] Fig. 8-19 shows a vibrating piston expander according to the invention in different angular positions of the eccentric shaft during an expansion process.

[0021] The following reference symbols are used in the illustrations: a) Angle of rotation of the weighing element; ß) Angle of rotation of the eccentric shaft

[0022] S3 Axis of rotation of the weighing element

[0023] S8 axis of rotation of the eccentric shaft

[0024] 2H High-pressure area (of working space 2)

[0025] 2N Low-pressure area (of working space 2)

[0026] 2M medium pressure range (expanding)

[0027] 1 oscillating piston

[0028] 2 workroom

[0029] 3 weighing element

[0030] 4 High-pressure inlet channel 5 Low-pressure outlet channel

[0031] 6 - free -

[0032] 7 Cylinder housings / Expander housings

[0033] 8 eccentric shaft

[0034] 11 Piston rod segment / piston guide web

[0035] 12 Ring

[0036] 31 Inlet-side component (of the weighing element)

[0037] 32 Outlet-side component (of the weighing element)

[0038] 33 Mounting for piston rod segment

[0039] 71 Mounting point for weighing element

[0040] 72 Clearance for piston rod segment

[0041] 321 Recess (in the weighing element)

[0042] 711 Recess (in the recess for the weighing element)

[0043] Features and details described in connection with a method naturally also apply to the device according to the invention, and vice versa, so that the disclosure regarding the individual aspects of the invention always makes or can make reciprocal reference. Furthermore, any described method according to the invention can be carried out with the device according to the invention.

[0044] The terminology used herein serves only to describe certain embodiments and is not intended to limit the disclosure. As used herein, the singular forms "a" and "the" are intended to include the plural forms unless the context otherwise makes clear. It will also be clear that the expressions "indicates" and / or "indicating," when used in this description, specify the presence of the aforementioned features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the expression "and / or" includes any and all combinations of one or more of the associated, listed elements.

[0045] Reference is first made in particular to Fig. 1. Here, a oscillating piston expander according to the prior art is shown in a schematic view.

[0046] A oscillating piston expander essentially comprises an oscillating piston 1 housed in a working chamber 2, which is configured to drive an eccentric shaft 8. The working chamber 2 is housed in a cylinder housing 7. The cylinder housing 7 can also be referred to as the expander housing. The eccentric shaft 8 preferably drives an electric generator. However, other output devices suitable for dissipating or converting the energy of the eccentric shaft are also conceivable.

[0047] The oscillating piston expander further comprises a high-pressure inlet channel 4 for the working medium to be expanded, opening into the working chamber 2, and a low-pressure outlet channel 5 for the expanded working medium, also opening into the working chamber 2. The high-pressure inlet channel 4 for the working medium to be expanded or depressurized can also be described as being in fluidic communication with the working chamber 2. Similarly, the low-pressure outlet channel 5 for the expanded or depressurized working medium, also opening into the working chamber 2, can be described as being in fluidic communication with the working chamber 2.

[0048] Preferably, the working medium to be expanded is a refrigerant. The oscillating piston expander is therefore preferably part of an air conditioning system. Other applications are also conceivable that utilize expansion valves or require the expansion of a gaseous working medium.

[0049] The oscillating piston expander also includes a weighing element arrangement.

[0050] The weighing element assembly essentially comprises a weighing element 3, a receptacle 71 for rotatably mounting the weighing element 3 in the cylinder housing 7, and a piston rod segment 11, which is axially displaceable in a receptacle 33 of the weighing element 3. The weighing element 3 is rotatably mounted about a weighing element rotation axis S3. The weighing element rotation axis S3 is aligned parallel to the eccentric shaft rotation axis S8. The piston rod segment 11 extends radially from the oscillating piston 1 or the eccentric shaft rotation axis S8. Accordingly, the displacement of the piston rod segment 11 in the receptacle 33 with respect to the weighing element rotation axis S3 occurs in the radial direction.

[0051] The weighing element 3 can be a single piece or a multi-part assembly, for example, composed of two components. In this respect, the weighing element 3 can be composed of a component 31 facing the high-pressure inlet channel 4 and a component 32 facing the low-pressure outlet channel 5.

[0052] The oscillating piston 1 essentially comprises a ring 12 and the piston rod segment 11, also called the piston guide web. The receptacle 33 for the piston rod segment 11 is preferably provided between the two components 31 and 32 of the two-part weighing element.

[0053] The sliding mounting of the piston rod segment 11 in the weighing element 3 provides additional guidance to the oscillating piston 1 and also separates the high-pressure chamber 4 from the low-pressure chamber 5 in the working chamber 2.

[0054] To allow sufficient displacement, a clearance 72 is preferably provided for the piston rod segment 11, into which the tip of the piston rod segment 11 can immerse during operation. The clearance 72 is preferably located above the piston rod segment 11, i.e., in particular on the side facing away from the working chamber 2. The ring 12 itself has an oscillating piston outer surface that faces the inner wall of the working chamber 2. The ring 12, or the oscillating piston outer surface, serves in particular as part of the oscillating piston 1 with which the working medium to be depressurized, in particular the refrigerant, is depressurized.

[0055] Particular reference is made below to Figures 2 and 3.

[0056] For a vibrating piston expander according to the invention, the weighing element arrangement includes an inlet valve. The inlet valve comprises a first recess 321 in the weighing element 3, in particular in the component 32 of the weighing element which faces the high-pressure inlet channel 4. The first recess 321 is in fluidic communication with the working chamber 2.

[0057] A fluidic connection, in this context, refers to a connection for transferring the fluid or working medium. A fluid can also be referred to as a working medium.

[0058] Furthermore, the inlet valve includes a recess 711 in the wall of the receptacle 71 of the weighing element 2. The recess 711 in the wall is in fluidic communication with the high-pressure inlet channel 4.

[0059] The opening and closing of the inlet valve is achieved via the angular position a of the weighing element 3. In a first angular position, there is no fluidic connection between the first recess 321 and the second recess 711. In a second angular position of the weighing element 3, there is a fluidic connection between the first recess 321 and the second recess 711, and thus also between the working chamber 2 and the high-pressure inlet channel 4. The weighing element arrangement can therefore be used for inlet control of the oscillating piston expander.

[0060] The rotational angle α of the weighing element 3 depends on the position of the oscillating piston and therefore on the rotational angle β of the eccentric shaft 8. In particular, in combination with the geometry of the weighing element 3, which partially projects into the working chamber 2, it is possible to open and close the working chamber 2, or expansion chamber, in the direction of the high-pressure inlet channel 4 in a rotationally angle-dependent manner. Thus, it is possible to introduce high-pressure gas into the working chamber 2 at the beginning of the operating cycle and then close it. With further rotation of the eccentric shaft 8, the volume of the closed working chamber increases as the high-pressure gas expands.

[0061] Further details of the oscillating piston expander will become apparent in particular from the description of a relaxation process. Reference is made below specifically to Figures 4 to 7. In Figures 4 to 7, the oscillating piston expander according to the invention is schematically depicted in several rotational angular positions of the eccentric shaft. The state shown in Figure 4 corresponds to a position of the oscillating piston at top dead center (TDC), which is assumed to be a rotational position β = 0° of the eccentric shaft 8. A rotation in the direction of the arrow is assumed to be a positive change in the rotational angular position. The cradle element 3 is located in a rotational angular position α = 0°. A rotation to the right is assumed to be positive degrees, a rotation to the left to negative degrees. The arrow in the eccentric shaft 8 is intended to symbolize the direction of rotation of the eccentric shaft.The inlet valve 321, 711 is closed because, due to the rotational angle position of the weighing element 3, there is no fluidic connection between the first recess 321 and the second recess 711.

[0062] The state shown in Fig. 5 corresponds to a rotational angular position β of approximately 90° of the eccentric shaft 8. It can be seen that the weighing element 3 has rotated to the right into a rotational angular position of approximately α = +5°. The inlet valve is now open; in particular, there is a fluidic connection between the first recess 321 and the second recess 711, and thus between the high-pressure inlet channel 4 and the working chamber 2.

[0063] The state shown in Fig. 6 corresponds to a rotational angular position β of approximately 180° of the eccentric shaft 8. This position of the oscillating piston could also be referred to as bottom dead center (BDC). It can be seen that the cradle element 3 has rotated back to the rotational angular position a = 0°. Accordingly, the inlet valve is closed again; in particular, there is no fluidic connection between the first recess 321 and the second recess 711.

[0064] The state shown in Fig. 7 corresponds to a rotational angular position of approximately 270° of the eccentric shaft. It can be seen that the weighing element 3 has rotated to the left into a rotational angular position of approximately α = -5°. The inlet valve is closed; in particular, there is no fluidic connection between the first recess 321 and the second recess 711.

[0065] It is evident that the relative positions of the recesses 321, 711 change depending on the rotational angle of the eccentric shaft 8, thus enabling rotational angle-dependent control of the inlet valve 321, 711. It is further evident that the opening angle range and timing can be essentially adjusted by the arrangement and design of the recesses 321, 711 relative to each other. It is clear to those skilled in the art how the design can be adapted to the technical requirements.

[0066] It is evident that the opening times of the inlet valve depend on the piston position and thus on the rotation angle β of the eccentric shaft 8.

[0067] Geometrically, the opening times can be defined by the shape and / or position of the recess in the weighing element 3 in combination with the shape and / or position of the recess 711 in the weighing element receptacle 71.

[0068] The achievable opening range of the inlet valve preferably focuses on the angular positions between 0° (top dead center) and 180° (bottom dead center), with the maximum deflection, i.e. opening of the inlet valve, being located particularly at 90°.

[0069] The angular position of the inlet valve opening is preferably symmetrical to 90°, which means that the length of the opening area can be varied by the design of the recess 321 in the weighing element and the recess 711 in the receptacle 71 for the weighing element 3.

[0070] In other words, the maximum oscillation angle or maximum deflection of the weighing element is kinematically determined at approximately 90° eccentric wave angle.

[0071] Symmetrical to 90° means that the angular position of the inlet-side weighing element component 31, or of the inlet opening, is the same for any two eccentric angles. For example, Fig. 10 and Fig. 12: 60° and 120° result in the same angular position of the weighing element. 60° = 90° - 30° / 120° = 90° + 30°. The "symmetry" here is 90° ± 30°.

[0072] A later opening of the intake valve generally results in an earlier closing of the intake valve, for example, opening the intake valve at 20° and closing the intake valve at 160°. Particular reference is made below to Figures 8 to 19. In Figures 8 to 19, the oscillating piston expander according to the invention is schematically depicted in several rotational angular positions of the eccentric shaft.

[0073] The following can be seen particularly in Figures 8 and 9:

[0074] As soon as the inlet valve, in particular the recess 321 in the weighing element, releases the connection between high-pressure inlet channel 4 and working chamber 2, the working medium to be expanded (shown here in black) flows into the area of ​​the working chamber which is sealed by the oscillating piston.

[0075] The second, crescent-shaped area in the working chamber 2 contains working medium (shown here in white), which was expanded in the previous working cycle and is now conveyed towards the low-pressure outlet channel 5 by the movement of the oscillating piston.

[0076] The following can be seen particularly in Figures 10 and 11:

[0077] As the rotation angle β of the eccentric shaft 8 increases, the volume of the high-pressure zone 2H, i.e., the zone in the working chamber 2 where the working medium is still at a high pressure, also increases. Conversely, the low-pressure zone 2N of the working chamber 2 is the zone in the working chamber 2 where the working medium is already at a lower pressure. The pressure difference between the high- and low-pressure zones in the working chamber 2 acts on the oscillating piston 1 and generates a moment on the eccentric shaft 8.

[0078] The following can be seen particularly in Figures 12 and 13.

[0079] The working medium, i.e., high-pressure gas, continues to flow into the high-pressure area 2H of the working chamber 2. In contrast, the volume of the low-pressure area 2N decreases and the working medium contained therein continues to be expelled.

[0080] The following can be seen particularly in Figures 14 and 15.

[0081] The weighing element 3 reaches an angular position in which the inlet valve is closed, thus separating the high-pressure inlet channel 4 from the working chamber 2. The high-pressure mass flow is stopped, and the high-pressure area 2H in the working chamber 2 becomes the expansion chamber. Due to the pressure difference, the oscillating piston continues to move; the working medium in the expansion chamber 2M expands under decreasing pressure (intermediate pressure), while the gas on the low-pressure side 2N continues to be expelled.

[0082] The following can be seen particularly in Figures 16 and 17.

[0083] The pressure in the expansion chamber 2M decreases steadily while a moment continues to act on the eccentric shaft 8 and the low-pressure gas is expelled.

[0084] The following can be seen particularly in Figures 18 and 19.

[0085] As soon as the contact between the oscillating piston 1 and the inner wall of the working chamber reaches the low-pressure outlet channel 5, pressure equalization occurs between the medium pressure in the expansion chamber 2M and the low-pressure area 2N. When the oscillating piston 1 is again at top dead center (0°), the large lower area again contains low-pressure gas and the operating cycle begins anew.

Claims

Claims 1. Oscillating piston expander with a cylinder housing (7), comprising - a vibrating piston (1) received in a working space (2), which is designed to drive an eccentric shaft (8), - a high-pressure inlet channel (4) leading into the working chamber (2) for the working medium to be depressurized, - a low-pressure outlet channel (5) leading into the work space (2) for the depressurized working medium, - a weighing element arrangement comprising a two-part weighing element (3), a receptacle (71) for rotatably mounting the weighing element (3) in the cylinder housing (7), and a piston rod segment (11) which extends perpendicularly from the oscillating piston (1) and is axially displaceable in a receptacle (33) of the weighing element (3), characterized in that the weighing element arrangement comprises an inlet valve.

2. Oscillating piston expander according to claim 1, characterized in that the eccentric shaft (8) has an axis of rotation (S8) and the weighing element has an axis of rotation (S3), wherein the axis of rotation (S8) of the eccentric shaft (8) and the axis of rotation (S3) of the weighing element are aligned parallel to each other.

3. Oscillating piston expander according to at least one of the preceding claims, characterized in that the weighing element (3) is composed of a component (31) facing the high pressure inlet channel (4) and a component (32) facing the low pressure outlet channel (5).

4. Oscillating piston expander according to at least one of the preceding claims, characterized in that the inlet valve comprises a first recess (321) in the weighing element (3), in particular in the component (32) of the weighing element which faces the high-pressure inlet channel (4), wherein the first recess (321) is in fluidic communication with the working chamber (2), wherein the inlet valve comprises a recess (711) in the wall of the receptacle (71) for the weighing element (3), wherein the recess (711) in the wall of the receptacle (71) is in fluidic communication with the high-pressure inlet channel (4), wherein the inlet valve (321, 711) is is set up to be opened or closed by changing the rotation angle of the weighing element (3).

5. Oscillating piston expander according to claim 4, characterized in that the weighing element arrangement, in particular the inlet valve, is configured so that the first recess (321) and the second recess (711) can be selectively brought into a fluidic connection or into no fluidic connection by changing the rotation angle of the weighing element (3).

6. Method for opening or closing the at least one inlet valve in a oscillating piston expander according to at least one of claims 1 to 5, characterized in that the inlet valve (321, 711) is selectively opened or closed by rotating the weighing element (3), wherein the rotational position of the weighing element (3) and / or the axial position of the piston rod segment (11) depends on the rotational angle position of the oscillating piston (1).

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