WO2014198527A1

WO2014198527A1 - Radial piston compressor

Info

Publication number: WO2014198527A1
Application number: PCT/EP2014/060867
Authority: WO
Inventors: Michael Krug; Christian Heine; Tilo SCHÄFER
Original assignee: Magna Powertrain Bad Homburg GmbH
Priority date: 2013-06-13
Filing date: 2014-05-26
Publication date: 2014-12-18
Also published as: BR112015030857A2; CN105378279A; DE112014002794A5

Abstract

Radial piston compressor having at least one cylinder, in which a piston is arranged, wherein the piston has a shoulder section and a guide section, having a drive shaft which, on one end, has an eccentric section, on which a lifting element which has at least one flattened portion parallel to the longitudinal axis thereof is mounted rotatably, wherein the piston is supported on the at least one flattened portion by way of that side of the shoulder section which faces the drive shaft, and is connected to the lifting element by way of a return device, wherein the return device engages at least partially behind the shoulder section and the piston is secured such that it cannot be displaced in the direction of the longitudinal axis thereof and such that it can be displaced transversely with respect to the longitudinal axis thereof in relation to the return device.

Description

Radial piston compressor

The invention relates to a radial piston compressor according to the preamble of patent claim 1.

Such compressors are known. As a rule, in this design, one or more cylinders are arranged radially around a drive shaft. The drive shaft has, for example, an element for the cylinder movement, which is mounted eccentrically and connected to the piston. Internally supported radial piston compressors are characterized in that the pistons are in contact with a lifting element mounted on the drive shaft. The pistons are set into an oscillating motion as a result of the eccentricity of the lifting element bearing on the drive shaft. The piston stroke is constant and corresponds to twice the amount of eccentricity of Hubelementlagerung the drive shaft.

In order to achieve the longest possible service life of the drive unit, it is necessary for the pistons to be in secure contact with the lifting element. Otherwise, there is an increased wear of the contact surfaces when the pistons can lift off the lifting element. It is known to provide in piston pumps and compressors on the piston means on which coil springs can be supported, which are aligned parallel to the longitudinal axis of the pistons and press them continuously against the lifting element. DE 42 16 877 C2 shows a radial piston pump with a plurality of cylinders, in which piston reciprocate and each supported on a shoe and a captive, which prevents uncontrolled separation between the piston and the shoes. The sliding shoe is in permanent contact with a lifting element designated as a control disk and allows a reciprocating relative movement, caused by the eccentrically mounted control disk, to occur. rich in sliding contact surfaces. Such devices require in addition to the space for the cylinder and piston additional space for the coil spring, which is larger in diameter than the piston, since the coil spring surrounds the piston and also must be designed durable.

Furthermore, it is known to use a return device in reciprocating compressors having a plurality of cylinders, which is formed by a spring band which extends in the circumferential direction around the lifting element and in which an opening for attachment is provided for each piston.

A radial piston pump is known from DE 198 16 044 C2, which has a ring eccentrically mounted on a drive shaft, which cooperates with pistons of the respective cylinder, wherein the cylinder ends pointing towards the ring each have a plate and wherein the plates are connected by a spring band, which extends in the circumferential direction around the ring held. The spring bands have to be made individually for each pump variant as well as for the different number of cylinders. The invention is now based on the object to propose a return device, which is designed as compact and inexpensive as possible and, moreover, is universally applicable.

The object is achieved by a radial piston compressor, which has at least one cylinder in which a piston is arranged, wherein the piston has a shoulder portion and a guide portion, with a drive shaft having an eccentric portion on one end, on which a lifting element which at least one flattening is parallel to its longitudinal axis, is rotatably mounted, wherein the piston is supported with the drive shaft side facing the shoulder portion on the at least one flattening, and is connected by a return device with the lifting element, wherein the return Holeinrichtung the shoulder portion at least partially engages behind and the piston with respect to the retractor in the direction of its longitudinal axis is not slidably supported and transversely to its longitudinal axis slidably. This ensures that the piston is always pressed with one end face, or axially fixed, against the lifting element, whereas transverse to its longitudinal axis a sliding movement is possible lent to the relative movement resulting from the eccentricity of a shaft portion at the end of Drive shaft results to compensate. By engaging behind it is to be understood that the piston interacts with the return device in such a way that the piston can not be released from the return device in its axial direction.

In a further embodiment of the invention, the return device is in one piece and spans the shoulder portion at least partially. This results in a compact design, as no additional elements are necessary to allow attachment of the return device on the piston. By overstretching, it is meant that the shoulder portion of the piston is supported on one side by the retractor. In a preferred embodiment of the invention, the return device has a holding section and at least one attachment section. The attachment portion serves to fix the piston at least in the axial direction on the lifting element. This results in a simple and inexpensive installation. In addition, the mounting method is unique and thereby assembly errors are avoided.

In a further embodiment of the invention, the one piston has at least one circumferential groove in the circumferential direction, which forms the shoulder portion, wherein the return device engages with the holding portion in the groove. This also allows a compact design and a positive fit of the piston. Furthermore, the assembly of the drive unit of the radial piston compressor is much easier. Alternatively, the piston may also have at the end of a larger diameter, which forms the shoulder portion, so that the retractor engages with the holding portion of the larger diameter. This has the advantage that just-if a secure positive connection is achieved, but no cross-sectional tapering occurs by the grooving of a groove and thus a positive effect on the fatigue strength is achieved. Furthermore, there is a more favorable ratio in terms of surface pressure and thus an improvement in the fatigue strength of the return device.

In another embodiment of the invention, the lifting element at least a first and a second undercut, in which engage the mounting portions of the retractor. This ensures that the attachment areas of the return device have a sufficient and secure fit and that the installation can be done as simply as possible, for example by lateral insertion.

A particularly preferred embodiment of the invention comprises a Rückholein- direction of wire, preferably made of spring steel wire, which is a closed

Has contour. This has the advantage that the retrieval device can be manufactured on a numerically controlled wire bending machine, which is particularly cost-effective and can be made of either a wire ring or a wire section. When using a wire section, a joining process, for example a welding process, can follow at the end of the shaping in order to obtain a closed contour. Alternatively, an open contour can also be used. As a result, the manufacturing costs can be further reduced and there is also a further degree of freedom in terms of geometry and the spring force.

In an alternative embodiment of the invention, the retaining element has at a first end an axis of rotation, which are formed for example by the ends of the wire and at the second end a clamping portion. This has the advantage that the retaining element rotatably attached to the lifting element with the axis of rotation. can be taken and so only a pivoting movement is required for mounting until the mounting portion engages behind the undercut.

In a further embodiment of the invention, the return device is made of spring steel sheet. This makes a production in a punching and bending tool possible. This is especially efficient in making great

Quantities.

Advantageously, the holding region of the return device consists of two webs which connect the attachment regions spaced apart from one another. The distance is so wide that the base diameter of the groove extending in the circumferential direction on the piston is not touched by the webs. In order to improve or simplify the assembly and the guiding capability of the return device and to reduce the surface pressure, the webs are formed in the holding area substantially wider than the other areas of the retractor.

A preferred embodiment of the invention has a hinge region on the lifting element, on which the rotary joint of the retractor is rotatably mounted.

The invention will now be explained with reference to schematic drawings. Show it:

1 is a sectional view of a partial view of the radial piston compressor

2a shows a three-dimensional view of the drive unit and the return device made of wire with an open contour

2b a return device with a closed contour 2c shows a return device according to the invention with an alternative embodiment of the open contour

Fig. 3 shows another embodiment of the drive unit with a return device made of sheet metal material

Fig. 4 shows an alternative embodiment of the return unit in the form of a metal cap Fig. 5a an alternative embodiment of the metal cap with beads on the mounting portions

Fig. 5b shows an alternative embodiment of the metal cap in which the mounting portions are designed similar to locking fingers

Fig. 6a, the lifting element with two shoulders in detail Fig. 6b an alternative embodiment of the lifting element with a shoulder and a bore for receiving the retractor

Fig. 6c a lifting element with a partially circumferential groove for use together with a metal cap with beads

7 shows an alternative embodiment of the piston. The radial piston compressor shown in simplified form in section in a partial view in FIG. 1 is used in particular in the field of refrigeration and air conditioning technology. The radial piston compressor comprises a drive shaft 3 mounted in a housing 1 with an eccentrically formed shaft section 4 on which a lifting element 7 is rotatably mounted. The lifting element 7 comprises at least one flattening 8, against which a piston 5 is supported. The piston 5 is received in a cylinder bore 1 1 and stored movable back and forth. When the drive shaft 3 rotates, the piston 5 moves in the cylinder bore 1 1 due to the eccentric mounting of the lifting element 7 back and forth. The piston 5 has a shoulder portion 15 which comprises a plate 14 which rests against the flattening 8 arranged on the lifting element 7. Due to the movement characteristic of the lifting element 7 during rotation of the drive shaft 3, the piston 5 moves back and forth. At the same time, however, the plate 14 must be able to slide on the flattening 8 transversely to the longitudinal axis 6 of the drive shaft 3. This lateral movement is permitted by the return device 13 according to the invention.

FIG. 2a shows the drive unit in a three-dimensional view in isolation for better understanding. It can be clearly seen in FIGS. 1 and 2a that on the end of the piston 5 directed towards the drive shaft 3 there is a shoulder section 15 which consists of a circumferential groove 16 and the plate 14 results. The plate 14 abuts against the associated flattening 8 of the lifting element 7. The lifting element 7 itself performs, as already described above, due to the eccentric shaft section 4, a circular path movement about the center axis 6 of the drive shaft 3, but without rotating itself. As a result, the at least one piston 5 is moved back and forth along its longitudinal axis 10 and thus exerts the suction and pressure stroke movement. As a result of the return device 13, which in FIG. 2a is designed as a wire spring clip 13a with a holding section 19 and two fastening sections 17a and 17a ', the at least one piston 5 with its plate 14 is pressed against the flattening 8 of the lifting element 7. The compressive force results from an elastic deformation of the return device 13a, which in turn is determined by the wire thickness, the wire material and the geometry of the return device 13a. It can be z. B. the wire spring clip 13a have different shapes. The special design as well as the use of wire for the production of the return device allows an open 13a, 13c (Fig. 2a, 2c) or a closed contour 13b (Fig. 2b). In this case, the wire spring clip 13a can be designed in a first embodiment, it engages in each case one of the shoulders 31 of the lifting element 7, each with a fastening section 17a, 17a '.

In another embodiment of the wire spring clip 13b, which is shown in Fig. 2b, it is provided that the wire spring clip 13b is made with a closed contour. This variant can be produced, for example, starting from a ring by deformation. Alternatively, the contour can first be made of a wire section on a wire bending machine, so that an embodiment results, as shown in Fig. 2c. In a last step, the two end sections 20a can then be connected so that a closed contour results. Suitable joining methods are, for example, welding methods such as arc welding, pressure welding or laser welding. Alternatively, however, the end sections can also be connected by a mechanical joining method. It is conceivable, e.g. Joining by forming.

As an alternative to the solutions shown in FIGS. 2a and 2b, a further use, which is shown in FIG. 2c, results in combination with the lifting element 7 'shown in FIG. 6b. The wire ends 20c of the open side are directed towards each other and can be inserted into a bore 35 of the lifting element 7 'shown in FIG. 6b. In this way, a hinge is formed, which makes it possible to attach the wire spring clip 13c with a pivoting movement on the lifting element 7 '. For this purpose, the wire spring clip 13c at the end opposite the open end has a fastening section 17c which can be latched behind the shoulder 31 with a rotational movement about the axis Z. Previously, the piston 5 can be simply pushed with its shoulder portion 15 on the holding portion 19 of the wire spring clip 13c and then together with the wire spring clip 13c with a pivoting movement against the flattening 8 of the lifting element 7 'are arranged.

Fig. 3 shows an alternative embodiment 13d of the retrieval device 13. Instead of a wire section, a sheet metal section is used. The use of sheet metal offers the advantage that cost-effectively complex shapes can be produced by stamping and bending technology. The sheet metal strips or sheet metal sections required for producing the return device 13d can, for example, be produced from a slit strip. This has advantages, in particular with regard to the corrosion behavior, since slit strip can be used with a corrosion protection layer already applied at the factory. This can be costly subsequent corrosion protection measures can be saved. Furthermore, the manufacturing method offers the option of making the holding section 19d geometrically different than the fixing section 17d, 17d '. For example, the webs 18 of the holding portion 19d are made wider than in the curvature region of the mounting portion 17d, 17d '. This results in a better manufacturability. Furthermore, a different spring characteristic or rigidity of the return device 13d can be adjusted in this way, whereby the guidance of the piston 5 is improved and can be inserted laterally during assembly of the piston 5.

In FIGS. 1, 2 a and 3 it can be seen that the piston has a circumferential groove 16 which forms the shoulder section 15. The shoulder portion 15 indicates

its end a plate 14 which is axially fixed in the mounted state by the retractor 13, 13a, 13d with the flattening 8 of the lifting element 7 in connection. The webs 18 of the holding portion 19d engage over the top of the plate 14 in the manner of a secant. In addition, it can be ensured that it does not come to tilting and thus interference in the back and forth sliding of the piston 5 on the flattening 8.

The return device 13e according to the embodiment of FIG. 4 can also be produced in a progressive composite tool from a sheet metal strip. Characteristic of this variant is that the retraction device 13e has a central bore 25 and at least one fastening section 17e, wherein the retracting device 13e can be set like a cap on the shaft section 4 of the drive shaft 3. With the at least one attachment portion 17e, the return device 13e is additionally fixed to the lifting element 7. The fastening portion 17e is formed from at least one sheet metal tab which is angled at 90 °. The holding section 19e is formed by a sheet metal tab 21 which has a region bent through 90 ° The width of the holding portion 19e corresponds at least to the extreme positions of the piston which it occupies in its reciprocating motion on the flat 8 due to the eccentricity of the shaft portion 4 5a and 5b show alternative embodiments of the return device 13f, 13g, and Fig. 5a shows a return device 13f with at least one attachment section 17f, which has at least one bead 22. The introduction of a suture is relatively easy For example, a further tool stage can be provided in the progressive tool The bead 22 increases the holding force on the lifting element 7 in particular when the lifting element 7 has an at least partially circumferential groove. Fig. 5b shows an embodiment in which at least one fastening portion 17g is designed in the manner of a spring finger and at its lower end has a latching edge 23 which engages behind the underside of the lifting element 7. Thus, the lifting element 7 is axially secured. If a return device 13e, 13f, 13g according to FIGS. 4, 5a and 5b is used, the assembly of the piston 5 can take place parallel in the direction of the longitudinal axis 6 of the drive shaft 3. For this purpose, the return device 13e is placed in advance on the lifting element 7 with the at least one fastening section 17e. In an alternative embodiment, the attachment portions 17f, g are designed like snap hooks or latching fingers. The length of the latching hook or the snap finger corresponds to the thickness 33 of the lifting element 7 shown in FIG. 6a. As a result, the latching fingers 23 engage behind the underside of the lifting element 7 and latch, so that the lifting element 7 is secured axially. 6a and 6b each show a detailed view of the lifting element 7. For simplicity, only the lifting element for a single-cylinder compressor will be described here. However, the same applies equally to a multi-cylinder compressor. The lifting element 7 is preferably made in one piece. Due to the thermal and mechanical stress, steel, for example tempered steel, has proven to be an advantageous material. However, it is also conceivable to produce the lifting element 7 from a sintered material. The cylindrical opening 29, which is arranged substantially centrally, serves to receive a bearing bush. Preferably, a sliding bearing is used. Alternatively, a needle bearing is also conceivable here. A first embodiment of the lifting element 7 is shown in Fig. 6a. The lifting element 7 has at least one shoulder 31 on the flattening 8. The positions of the shoulders 31 are selected such that the retracting means 13a, 13b, 13d are securely locked behind the shoulders and aligned parallel to the flat 8. The lifting element 7 can be tempered as a whole or it is only the flattening 8 subjected to a surface heat treatment. An alternative embodiment shown in Fig. 6b, in addition to the at least one shoulder 31 at least one bore 35 to cooperate with the return means and to form in this way a hinge. For assembly, the return device 13c shown in FIG. 2c is first inserted into the bore 35. For this purpose, the wire ends 20c are moved apart so that they can be guided over the lifting element 7 'and can dive into the bore 35. Now, the wire ends 20c and the bore 35 form a hinge. Subsequently, piston 5 and return device 13c can be pivoted together about the axis Z shown in FIG. 2a until the fastening section 17a latches behind the other shoulder 31. 6c shows an embodiment of the lifting element 7 "which has an at least partially encircling groove 37 on the lateral surface 12. The groove 37 interacts with the bead 22, 22 ', 22" shown in FIG. The bead 22, 22 ', 22 "locked in the groove 37. Thus, the holding force is increased again. Fig. 7 shows an alternative embodiment of the piston 5 '. Instead of a circumferential groove 16, this shape of the piston 5 'has a plate 14' whose diameter is substantially larger than the piston diameter. Such an embodiment is preferably used where appropriate space for the larger diameter is available. It is advantageous that the cross section is not weakened by the insertion of a significant groove. Furthermore, the surface pressure is cheaper compared to a smaller diameter. The piston 5 'is combined with the return device by the webs or the sheet metal tab overlap at least on one side the shoulder 31 of the shoulder portion 15.

LIST OF REFERENCE NUMBERS

1 housing

3 drive shaft

4 shaft section

5 pistons

6 center axis, longitudinal axis

7 lifting element

T lifting element

7 "lifting element

8 flattening

10 longitudinal axis

1 1 cylinder bore

12 guide section

13 return device

13a return device

13b return device

13c return device

13d return device

13e return device

13f return device

13g return device

14, 14 'plate

14a top of the plate

15 shoulder section

16 circumferential groove, recess

17 attachment section

17a attachment section

17a 'attachment section

17b attachment section 17c attachment portion 7d attachment portion

17d 'attachment section

17e attachment section

17e 'attachment section

17e "attachment section 7f attachment section

17f attachment section

17f "attachment section

17g attachment section

18 bars

19 holding section

19b holding section

19c holding section

19d holding section

19e holding section

19f holding section

19g holding section

20a ends

20c ends

21 sheet metal tab +

22-22 'bead

23 locking edge

25 centric bore

29 opening

31 shoulders

33 material thickness

35 bore

37 groove

Z axis

Claims

claims

A radial piston compressor with at least one cylinder, in which a piston (5, 5 ') is arranged, wherein the piston (5, 5') has a shoulder portion (15) and a guide portion (12), with a drive shaft (3), which on one end having an eccentric portion (4) on which a lifting element (7, 7 ', 7 "), which parallel to its center axis (6) and perpendicular to the longitudinal axis (10) of the piston (5, 5') at least one flat (8), is rotatably mounted, wherein the piston (5, 5 ') with the drive shaft (3) facing side of the shoulder portion (15) on the at least one flattening (8) is supported, and by a return device (13, 13a, 13b, 13c, 13d, 13e, 13f, 13g) is connected to the lifting element (7, 7 ', 7 "), characterized in that the return device (13, 13a, 13b, 13c, 13d, 13e, 13f, 13g) at least partially spans the shoulder portion (15) and the piston (5, 5 ') with respect to the return means (13, 13a, 13b, 13c , 13d, 13e, 13f, 13g) is non-displaceable in the direction of its longitudinal axis (10) and displaceably mounted transversely to its longitudinal axis (10).

2. Radial piston compressor according to claim 1, characterized in that the

Return device (13, 13a, 13b, 13c, 13d, 13e, 13f, 13g) has a holding section (19, 19e, 19f, 19g) for the piston (5, 5 ') and at least one attachment section (17, 17a, 17a', 17b, 17c, 17d, 17d ', 17e, 17e', 17e ", 17f, 17f, 17f") for the lifting element (7, 7 ', 7 ").

3. radial piston compressor according to claim l or 2, characterized in that the piston (5) has at least one circumferentially circumferential groove (16) which delimits the shoulder portion (15) from the guide portion (12), wherein the retractor (13, 13a, 13b, 13c, 13d, 13e, 13f, 13g) engages the retaining portion (19, 19a, 19b, 19c, 19d, 19e, 19f, 19g) in the groove (16).

4. Radial piston compressor according to one of the preceding claims, characterized in that the piston (5 ') at its first, the lifting element (7, 7', 7 ") facing the end, with respect to the second, in the cylinder (1 1) guided guide section (12) having a larger diameter forming said shoulder portion (15), said retracting means (13, 13a, 13b, 13c, 13d, 13e, 13f, 13g) being connected to said holding portion (19, 19a, 19b, 19c, 19d , 19e, 19f, 19g) spans the larger diameter.

5. Radial piston compressor according to one of the preceding claims, characterized in that the lifting element (7, 7 ', 7 ") at least a first and a second shoulder (31) into which the fastening portions (17, 17 a, 17 a', 17 b, 17c, 17d, 17d ', 17e, 17e', 17f, 17f ') of the return device (13, 13a, 13b, 13c, 13d, 13e, 13f, 13g) rest.

6. Radial piston compressor according to one of the preceding claims, characterized in that the return device (13, 13a, 13b, 13c, 13d, 13e, 13f, 13g) is designed to be latchable or clipped.

7. Radial piston compressor according to one of the preceding claims, characterized in that the return device (13a, 13c,) made of wire, preferably spring wire, is made and has an open contour.

8. Radial piston compressor according to one of the preceding claims, characterized in that the return device (13b) made of wire, preferably spring wire, and has a closed contour. Radial piston compressor according to one of the preceding claims, characterized in that the return device (13d, 13e, 13f, 13g) is made of sheet metal, preferably of spring steel sheet.

Radial piston compressor according to one of the preceding claims, characterized in that the holding portion (19) of the return device (13d) from

two webs (18) are formed, which in parallel spaced from each other, the fastening portions (17, 17 a, 17 a ', 17 b, 17 c, 17 d, 17 d') connect.

Radial piston compressor according to claim 10, characterized in that the webs (18) in the holding portion (19d) are formed substantially wider than the remaining areas of the retractor (13d).

Radial piston compressor according to one of the preceding claims, characterized in that the return device (13a, 13c) is made in one piece.

Radial piston compressor according to one of the preceding claims, characterized in that the lifting element (7, 7 ', 7 ") has at least one bore (35) on which the ends (20a, 20c) of the return device (13a, 13c) can be inserted.

A radial piston compressor according to claim 13, characterized in that the return means (13, 13a, 13b, 13c, 13d, 13e, 13f, 13g) act at a first end of wire ends (20a, 20c) acting as a hinge and at the second end Attachment portion (17a, 17c). Radial piston compressor according to one of the preceding claims, characterized in that the shoulder portion (15) in the direction of the longitudinal axis (10) of the piston (5, 5 ') axially fixed to the piston (5, 5') is connected.