hydrostatic radial piston machine

Abstract

A hydrostatic radial piston machine includes a front housing component that accommodates a drive shaft through a bearing device so that the drive shaft can rotate around a central axis relative to the front housing component. A rear housing component is attached to the front housing component on one side and is closed on the other side to define an internal volume. A cylinder body is arranged in the internal volume and is attached to the drive shaft in a torque-guaranteed manner. An axially arranged timing hole in the cylinder body connects the radially oriented working volume in the cylinder body with the front surface of the cylinder body, which is arranged perpendicular to the central axis and faces away from the front housing component. An internal annular flow channel is integrally formed in the rear housing component, which is connected to the inlet and outlet of the radial piston machine and extends substantially in a circumferential direction around the central axis. An internal distribution passage is also integrally formed in the rear housing component, and the internal distribution passage is configured to hydraulically connect the internal annular flow channel to the timing hole of the cylinder body.

Description

Technical Field

[0001] The present invention relates to a hydrostatic radial piston machine, and more particularly to a cam lobe motor or pump, or a gerotor motor or pump, respectively. Background Art

[0002] Radial piston motors are widely used in the art and are characterized by the fact that their working pistons move in a radial direction relative to the drive shaft when supplied with pressurized hydraulic fluid. For example, cam lobe and gerotor motors are used in heavy-duty applications. In general, radial piston machines are used for hydraulic applications that do not require high rotational speeds. However, compared to axial piston machines, radial piston machines show the advantage of having a smaller axial construction space.

[0003] Although radial piston motors with cam lobe or cycloidal configurations are well known in the art, there is a continuing goal to reduce the external dimensions, particularly the axial dimensions of such radial piston machines while maintaining or even improving their performance characteristics.

[0004] DE 10 2016 214 967 A1 discloses a hydrostatic radial piston machine with a rotating cylinder. The hydrostatic radial piston machine can operate with six different volume flows per revolution of the cylinder and comprises a multi-part housing. An annular channel is formed in one part of the housing.

[0005] FR 3 048 473 A1 shows a hydraulic motor equipped with a brake arranged in a separate housing. The brake is prestressed by a leaf spring arranged between a pressurizable piston and a housing cover. An annular channel is formed in the housing of the hydraulic motor by means of an internal groove and a distributor. Summary of the invention

[0006] The object of the present invention is therefore to improve the known radial piston machines with cam lobes or cycloid configurations. By doing so, a high robustness should be maintained and manufacturing costs and maintenance workload should be reduced. Further, the radial piston machine according to the present invention should be improved in terms of operational flexibility, smooth operation, low wear and convenient and reliable operating state control.

[0007] The object of the invention is solved by a hydrostatic radial piston machine according to the invention, preferred embodiments of which are disclosed hereinafter.

[0008] The object of the present invention is solved by a hydrostatic radial piston machine according to the present invention having a cam lobe or cycloidal configuration, the hydrostatic radial piston machine comprising a front housing part accommodating a drive shaft. The drive shaft is mounted in the front housing by means of a bearing device so that the drive shaft can rotate around a central axis relative to the front housing part. A rear housing part is attached to one side of the front housing part, and the opposite side of the rear housing part facing away from the front housing is closed to define an internal volume, which is preferably hydraulically sealed. Within this internal volume, usually in the area of ​​the front housing part, the cylinder body is attached to the drive shaft in a torque-guaranteed manner, wherein, in an exemplary embodiment, the drive shaft further extends toward the rear housing part. In the cylinder body, a substantially axially oriented timing hole is provided. These timing holes connect the radially oriented working volume in the cylinder body with the front surface of the cylinder body arranged perpendicular to the central axis and facing away from the front housing (i.e., facing the rear housing part).

[0009] According to the invention, in the rear housing part, internal annular flow channels are formed integrally with the rear housing part, which extend in a circumferential direction around a central axis and are configured to be hydraulically connected to the inlet and outlet of the radial piston machine. The internal annular flow channels are also connected to generally axially oriented internal distribution passages, which, according to the invention, are also integrally formed in the rear housing part. Unlike the known prior art, the present invention utilizes a rear housing part in which the circumferentially extending annular flow channels and the axially oriented distribution passages for supplying and discharging hydraulic fluid to the working volume of the radial piston machine are integrally formed in the rear housing part.

[0010] By applying the rear housing part according to the present invention, which is integrally formed with an annular flow channel and an axial distribution passage, more design freedom of the rear housing is provided compared with the rear housing solution of the prior art. A major difference is that the rear housing part of the present invention is a single piece and does not require a separate distribution element as provided for the known radial piston machine in the prior art. In general, annular flow channels and distribution passages are necessary to provide a hydraulic fluid connection between the inlet and outlet and the cylinder. Usually, in the rear housing of the prior art, the annular flow channel is split, which is partially composed of a radially inwardly opening channel in the rear housing and a radially outwardly opening channel in an additional so-called fluid distributor (usually in the form of a stepped cylinder). This stepped design of the fluid distributor of the prior art is due to the fact that at least two annular flow channels with two different pressure levels must be completed by two corresponding annular distributor channels in order to form at least two annular flow channels. On the other hand, the axially oriented distributor channels connecting the (two) annular flow channels with the timing holes of the cylinder must have the same reference diameter. Since half of the number of distributor channels are connected to one annular flow channel at a first pressure level, and the other half of the number of distributor channels are connected to another annular flow channel at a second pressure level, and further, since the distributor channels with different pressure levels are arranged alternately around the reference diameter, the connections of the distributor channels to the respective two annular flow channels must have different reference diameters. This may result in a stepped design of the radial inner side of the rear housing according to the prior art, and thus in a stepped design of the distributor component.

[0011] Furthermore, the stepped distributor component according to the prior art must be mounted in the rear housing component using a plurality of (annular) seals in order to fluidically separate the annular flow channels from one another and to seal them from the interior of the rear housing behind. Thus, at least three seals are required to separate two annular channels from one another and to seal them from the interior volume of the rear housing.

[0012] Unlike the prior art multi-component solutions for forming the annular flow channel, the present invention forms the annular flow channel together with the distribution channel in one piece in the rear housing part. By doing so, a great degree of freedom in the design of the rear housing part is achieved, resulting in a number of advantageous embodiments which compensate for the higher effort involved in manufacturing the one-piece rear housing part, since a separate fluid distributor element and a seal for sealing the distributor to the rear housing part are no longer required.

[0013] A person skilled in the art recognizes that manufacturing such a one-piece rear housing component with a dead angle in the demoulding direction requires production methods such as sand casting or additive manufacturing processes. A person skilled in the art will know many other possibilities for manufacturing such a rear housing component according to the present invention, and therefore, all of these possibilities are covered by the concept of the present invention.

[0014] According to the prior art, at least two (cast) parts and at least three seals are required to provide the same function as the one-piece rear housing part according to the present invention. Further, the two housing parts according to the prior art must be machined very accurately in order to obtain a good surface quality of the sealing surfaces, which must be able to withstand the high pressure conditions usually applied in radial piston machines. Since the housing parts are usually manufactured by casting, in order to machine concentric surfaces and circumferential inner and outer grooves in the two housing parts, additional preparatory work is required to generate (auxiliary) reference surfaces on these housing parts in order to achieve precise clamping of these parts, for example for milling and turning in a machine tool. Therefore, by integrating the annular flow channel into the rear housing, the processing time and costs can also be significantly reduced. In addition, the logistics and assembly costs of assembling the distributor and the rear housing part in a sealed manner can also be reduced, because it is no longer necessary to transport and assemble the two housing parts and at least three seals.

[0015] As described above, the integration of the annular flow channel in the rear housing part of the radial piston machine housing not only eliminates separate distributor elements and seals, it also provides greater design freedom in arranging functional elements as part of the radial piston machine. For example, such integration provides the possibility of moving the annular flow channel toward the radial outside of the rear housing part, thereby releasing radially inner construction space that can be used to arrange other components, thereby increasing the compactness of the radial piston machine and, for example, reducing the axial length.

[0016] In the prior art, the annular flow channel is usually shown as a stepped arrangement so that the internal components of the rear housing are used as distribution elements to provide hydraulic fluid flows into and out of the working volume, and in particular to keep the external radial dimensions of the radial piston machine as small as possible. By integrating the distribution channels as internal distribution passages in the rear housing as in the present invention, these passages can be arranged to have a reference diameter that is closer to the reference diameter of the internal annular flow channel. Further, in a preferred embodiment, the annular flow channels according to the present invention can be arranged closer to each other in the axial and radial directions, because no sealing and / or mounting surfaces are required. Here, according to the present invention, the radial connecting holes connecting the annular flow channel to the fluid distribution passage in the radial direction can be much shorter than the radial connecting holes realized, for example, by machining on a separate distributor element according to the prior art. Therefore, the combination of the annular flow channel and the connecting channel according to the present invention shows a very compact design, which can also be moved more toward the radial outside of the radial piston machine, with the benefit that the radial inner area of ​​the rear housing component can be used to accommodate other parts or elements of the radial piston machine (such as parking brake mechanisms or parts thereof), distribution plates or pistons, bearings, sensors, etc.

[0017] By moving the combination of the annular flow channel and the distribution passage (where the distribution passage is preferably arranged radially inside the annular flow channel) toward the radial outside of the radial piston machine, the timing hole at the cylinder body can also be moved toward the radial outside, and thereby toward the bottom surface of the working cylinder, thereby providing the following possibility: increasing the number of working volumes while maintaining the volume size of the radial piston machine. To achieve this, the single working volume / stroke and diameter of the working plunger can be reduced, and the axial length of the cylinder body can be reduced thereby. By doing so, the ratio of the working plunger height to the working plunger diameter should be considered to avoid tilting the working plunger. When implementing a smaller working volume, in particular when the stroke of the working plunger is reduced, the radial inner area of ​​the cylinder body can be used to at least partially accommodate other components of the radial piston machine, thereby further contributing to reducing the axial length of the radial piston machine. For example, an axial space for a bearing or a portion of a bearing (preferably a tapered bearing) can be found in the cylinder body. Moreover, for example, the pressure distribution plate can be at least partially received in a recess adjacent to the through hole in the cylinder body, wherein the drive shaft of the radial piston machine is received in the above-mentioned through hole.

[0018] The above also leads to another beneficial point of the inventive concept, for example, enabling the use of a simple disc-type pressure distributor plate to provide a sliding surface for the cylinder front surface, on which the timing holes for supplying and discharging hydraulic fluid to the working volume are arranged. Such a pressure distributor for reducing friction and wear at the sliding contact surface can be disc-shaped or plate-shaped, with simple through holes for guiding the hydraulic fluid from the internal distribution passage to the timing holes at the cylinder. Here, the through holes in the pressure distribution plate can be oriented parallel or obliquely with respect to the rotation axis of the drive shaft (i.e. the central axis of the radial piston machine).

[0019] By using such a plate distributor rotatably fixed to the one-piece rear housing component, the difference in the reference diameter of the timing hole in the cylinder and the distribution passage can be compensated. To this end, the through holes in the pressure distributor plate can be arranged to be inclined relative to the axial direction, that is, they can have a radial component. In another embodiment, the distributor plate can include radially oriented holes and axially oriented blind holes located on both sides of the distributor plate to connect the timing holes at the front surface of the cylinder on one side and the distribution passage on the other side (rear housing component side). This allows the designer to arrange the internal distribution passage radially outside the internal annular flow channel.

[0020] By applying the concept according to the invention, the annular flow channel and the distribution passage are integrated into the rear housing part, and a control hole can be integrated in the one-piece rear housing, which is used for a 2-speed or 3-speed control unit for controlling the rotation speed of a radial piston machine, and the control hole has a control valve core with a larger diameter than the radial piston machine of the prior art with comparable volume dimensions. Similar to the prior art, the control unit is connected to the inlet, the outlet and the annular flow channel. The control valve core in the control hole is movably accommodated and can guide the hydraulic fluid from the inlet to at least one of the annular flow channels and guide the hydraulic fluid from the other annular flow channel to the outlet through a control recess arranged at the outer surface of the control valve core.

[0021] Unlike the prior art, the diameter of this control valve core can be larger than the diameter of a similar control valve core of a radial piston machine of comparable volume size according to the prior art. In general, another direction of effort in the field is to use a control valve core with as large a diameter as possible in order to improve the ratio of flow force to valve core force, which reduces the position error of the control valve core. The larger the diameter of the control valve core, the greater the valve core force generated by the hydraulic force acting on at least one front surface of the control valve core. The greater the valve core force, the better the controllability of the valve core position. By increasing the control valve core diameter to improve the position accuracy, the radial piston machine has better controllability of 2-speed or even 3-speed. By implementing this larger radial control valve core, the radial piston machine can be switched more accurately from the full torque operating state to the partial torque state, in which the entire working volume is filled with high pressure, and in the partial torque state, only two-thirds, half or one-third of the working volume is filled with high pressure. When the control plunger changes from the full torque position to the low torque position, the number of working volumes filled with high pressure is reduced, and the speed of the radial piston machine is changed accordingly. The remaining working volumes are "short-circuited" so that the hydraulic fluid in these unpressurized working volumes moves from one low-pressure working volume to another low-pressure working volume without generating mechanical energy.

[0022] Another preferred embodiment of the present invention is derived from the increased diameter of the control valve core, wherein at the surface of the control valve core, a smooth recess extending axially from at least one of the control recesses can be changed in shape and in size so as to provide a fluid connection with a reduced cross section between the inlet or outlet and the internal annular flow channel. This recess is provided to reduce the drastic changes when changing from one operating state to another. This occurs in particular when the radial piston machine is operated using a cold hydraulic fluid. According to the present invention, the recess can be formed to have a constant cross section or a monotonically reduced cross section. In the prior art, due to the small available space at the outer surface of the control valve core and / or taking into account the positioning error of the control valve core, such a recess often has a stepped design. Since the diameter of the control valve core according to the present invention can be increased and the position accuracy of the control valve core can be improved, the recess on the control valve core can use a constant cross section without negatively affecting the operation of the radial piston machine or endangering other components of the radial piston machine due to sudden pressure changes in the annular flow channel, such as the seal used in the prior art for sealing the distributor element and the rear housing component.

[0023] In a further embodiment of the invention, a check valve arrangement can be implemented in the inner bore of the control spool, which in the low torque position of the control spool can ensure the hydraulic path if the pressure in one of the internal annular flow channels drops below a predetermined threshold amount. Such a check valve ensures that the working plunger in the working volume cannot move without displacing the hydraulic fluid, which eliminates the risk of hard physical contact of the working plunger roller with the cam lobe. The arrangement of such a safety check valve in the control spool is possible because the outer diameter of the control spool according to the invention can be increased and sufficient space radially inside the control spool is available, which is ultimately due to the compact design of the combination of the internal annular flow channel and the internal distribution passage in the rear housing part according to the invention.

[0024] In another preferred embodiment of the present invention, due to the availability of the radially inner side of the space of the rear housing part, at least a part of the brake mechanism can be located in the internal volume due to the disappearance of the distributor element used in the radial piston machine of the prior art. Preferably, at least the brake disc of this brake mechanism can be arranged in this area radially inner side of the rear housing part, in particular radially inner side of the combination of the annular flow channel and the distribution passage. When the elements of this brake mechanism are axially moved into the interior of the one-piece rear housing part, the total axial length of the axial piston machine can be reduced. Therefore, there is actually no need to make further changes to the design of the parking brake mechanism of the existing radial piston machine. Basically, it is only necessary to shift the parking brake mechanism axially toward the front housing.

[0025] In a further embodiment of the present invention, an additional bearing device or one of the two bearing devices (usually located in the front housing component) can be placed in the available space radially inside the obtained rear housing component in order to reduce the axial length of the front housing component and thereby reduce the total axial length of the radial piston machine. This also improves the bearing state of the drive shaft with the attached cylinder body, because it enables the cylinder body to be supported on both sides. Another benefit achieved by placing a bearing to the rear housing component is that the drive shaft can be extended to the parking brake mechanism as a one-piece drive shaft. In the prior art, the shaft for the parking brake mechanism is usually separated from the drive shaft to avoid transmitting the vibration and alignment errors of the parking brake mechanism to the distributor element located in the rear housing component, which will at least cause a sealing problem between the separate distributor element and the rear housing. Moreover, when the drive shaft extends to the rear end of the radial piston machine in an unsupported manner in the overhanging bearing device as a continuous shaft, the mass imbalance of the parking brake mechanism, in particular the mass imbalance of the brake disc, or the force associated with the inaccuracy or error of the balance or the force caused by the imbalance is easily transmitted to the cylinder body. According to the present invention, since one bearing can be arranged in the rear housing part, it is possible to provide a continuous drive shaft that receives the parking brake disc. Since the rear bearing is directly supported in the rear housing part, it does not negatively affect the sealing surface, and it provides a stable and strong bearing support for the drive shaft and the brake mechanism.

[0026] According to the above description, those skilled in the art can conclude that the axial length of the radial piston machine can be significantly reduced by integrally forming an annular flow channel and a distribution passage in the rear housing component and moving the annular flow channel and the distribution passage toward the radial outside of the rear housing component. By implementing the concept of the present invention, other components of the radial piston machine can be shifted to the internal radial space / volume obtained in the rear housing component. Embodiments not described above or below but within the knowledge of those skilled in the art are also covered by the concept of the present invention. Therefore, the new design of the rear housing component with an integrally formed internal annular flow channel and an integrally formed internal distribution passage according to the present invention provides a variety of design improvements for reducing the axial length of the radial piston machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention outlined above is now described in further detail with the aid of the accompanying drawings, in which preferred embodiments and preferred design possibilities are shown; however, these preferred embodiments do not limit the scope of the inventive concept. Further modifications within the possibilities of the knowledge of a person skilled in the art may be implemented without departing from the spirit of the invention. In addition, the preferred embodiments shown may be combined with each other without departing from the spirit of the invention. In the accompanying drawings, it is shown:

[0028] Figure 1shows a longitudinal sectional view of a radial piston machine according to the prior art;

[0029] Figure 2 A longitudinal sectional view of a radial piston machine according to a first embodiment of the present invention is shown;

[0030] Figure 3 A longitudinal sectional view of a radial piston machine according to a second embodiment of the present invention is shown;

[0031] Figure 4 Shown according to Figure 2 Cross section of a radial piston machine;

[0032] Figure 5 A detailed view shows the Figure 2 A control unit of an embodiment. DETAILED DESCRIPTION

[0033] exist Figure 1 , a radial piston machine according to the prior art is shown. In the front housing part 10, the drive shaft 3 is mounted via a bearing arrangement 16 so that the drive shaft 3 can rotate about the center axis 5. The drive shaft 3 extends toward the rear housing part 20, wherein at its freely projecting end, a cylinder 30 is fixed to the drive shaft 3 in a torque-guaranteed manner. Figure 1 It can be seen that the drive shaft 3 is designed in two parts, wherein the connection / transition part between the two parts of the drive shaft 3 is located in the area of ​​the cylinder 30, so that the two parts of the drive shaft 3 can be driven by the cylinder 30 / can drive the cylinder 30. Those skilled in the art know that if there is no parking brake mechanism 70 at the radial piston machine, the second part of the drive shaft 3 can be omitted, because the function of the second part of the drive shaft 3 is mainly to mechanically connect the cylinder 30 with the parking brake mechanism 70. Figure 1 It can also be seen that the drive shaft 3 - whether in one or two pieces - is supported only in the front housing part 10 and projects towards the parking brake mechanism 70 in the rear housing part 20 where the drive shaft 3 is not supported.

[0034] As seen in the longitudinal / axial direction (ie, along the central axis 5), Figure 1 The radial piston machine of the present invention arranges a separate fluid distributor element 80 axially rearward of the cylinder body 30 and radially inside the rear housing component 20. The fluid distributor element 80 is designed in a stepped cylindrical shape, wherein at each step, a circumferential groove opening in the radial direction is formed on the outside. The circumferential groove on the fluid distributor element 80 and the circumferentially extending radially inwardly opening annular groove in the rear housing component 20 together form an annular flow channel 82. Figure 1The two annular channels 82 shown in the figure are at different pressure levels, which are indicated by different colors. The annular flow channel 82 is connected to the timing hole 37 located on the front surface of the cylinder 30, which faces the rear housing part 20, via a distribution path 84 formed in the fluid distributor element 80. In order to operate the radial piston machine, half of the number of distribution paths 84 are filled with high pressure, and the other half of the distribution paths 84 guide the low pressure to the outlet 62. In order to enable half of the distribution path 84 to be connected to one of the annular channels 82 and the other half of the distribution path 84 to be connected to the other annular flow channel 82, the annular flow channel 82 can have different reference diameters. Therefore, the fluid distributor element 80 is designed in a stepped cylindrical shape. Typically, in the prior art, for example, for a radial piston machine with a (total) volume size of, for example, 600 cc to about 950 cc, eight or ten working volumes 36 are provided in the cylinder 30.

[0035] Axially rearwardly of the rear housing part 20, the radial piston machine 1 according to the prior art shows a parking brake mechanism 70 comprising a plurality of brake discs 72. Since the function of such a parking brake mechanism 70 is known to a person skilled in the art, further details are omitted.

[0036] exist Figure 2 In Figure 1 The radial piston machine according to the prior art is shown in a longitudinal section in substantially the same orientation as that of the radial piston machine according to the prior art. Figure 2 It can be seen that there is no separate fluid distributor element 80. According to the present invention, the function of the distributor element 80 of the prior art is realized integrally by the rear housing component 20. In particular, the internal annular flow channel 22 and the internal distribution passage 24 are integrally formed in the rear housing component 20, and these internal distribution passages connect the internal annular flow channel 22 with the timing hole 37 located at the front surface 32 of the cylinder body 30. Since the internal distribution passage 24 and the internal annular flow channel 22 are designed as cavities in the rear housing component 20, each of the internal distribution passages 24 can be designed separately with greater design freedom, because it is not necessary to process these annular flow channels 22 and internal distribution passages 24, nor is it necessary to process the fluid distribution components.

[0037] Due to the greater design freedom in arranging the inner annular flow channel 22 and the inner distribution passage 24, these elements can be combined closer to each other and / or can be moved towards the radial outside of the rear housing part 20. As a result, more internal space is available on the radial inside of the rear housing 20. According to the invention, this larger internal volume in the rear housing part 20 can be used for other components of the radial piston machine 1, for example in order to reduce the overall axial length of the radial piston machine 1.

[0038] exist Figure 2 In the figure, various possibilities for reducing the overall axial length of the radial piston machine 1 according to the invention are shown, which possibilities can be implemented individually or in combination with one another, depending on the requirements / functions that the radial piston machine 1 has to fulfill.

[0039] In an exemplary embodiment, the brake disc 72 of the parking brake mechanism 70 is arranged inside the rear housing member 20, that is, radially inside the inner annular flow channel 22 and the inner distribution passage 24. In the prior art, a fluid distributor element 80 is arranged at this location.

[0040] exist Figure 2 In another preferred embodiment shown, a pressure distribution plate 40 is arranged between the cylinder body 30 and the rear housing part 20 on the side of the timing hole 37 of the cylinder body front surface 32 (i.e., the side of the cylinder body 30 facing the rear housing part 20). This pressure distribution plate 40 acts, for example, as a running surface of the cylinder body 30. Since the pressure distribution plate 40 does not have to fulfill the sealing function of isolating from the rear housing part 20 like the distribution elements known in the prior art, the pressure distribution plate 40 can be designed specifically to achieve its main function, that is, to reduce the friction of the rotating cylinder body 30. For this purpose, the pressure distribution plate can be designed in the shape of a disk as a basic standard molded part of a specific material that reduces friction and wear at the cylinder body 30. Since the pressure distribution plate 40 has a simple geometry, it can also be considered to be designed as a wear part. Since the pressure distribution plate does not have to meet other sealing requirements in the radial direction (as the fluid distribution elements in the prior art need to meet), the diameter of the pressure distribution plate 40 can be selected to be larger in order to increase the running surface, which reduces the friction and gives the cylinder body 30 greater axial stability.

[0041] like Figure 2 As shown, the pressure distribution plate 40 shows a through hole 42 for connecting the internal distribution passage 24 in the rear housing member 20 with the timing hole 37 of the cylinder 30. Further, the pressure distribution plate 40 is fixed to the rear housing member 20 in the axial direction, for example, in a floating manner; at the same time, it is actuated by the pressure distribution piston 44 (such as Figure 332 and the pressure distribution plate 40. The distribution piston 44 is a piston rod 46, which is a piston rod 47, and a piston rod 48. The piston rod 46 is a piston rod 48, which is a piston rod 49. The piston rod 49 is a piston rod 49, which is a piston rod 49, and a piston rod 49. The piston rod 49 is a piston rod 49, which is a piston rod 49. The piston rod 49 is a piston rod 49, which is a piston rod 49. The piston rod 49 is a piston rod 49, which is a piston rod 49. The piston rod 49 is a piston rod 49, and a piston rod 49 ... The pressure piston 44 is mounted in the rear housing part 20, for example in a blind hole 46, and is pressed against the pressure distribution plate by means of a spring 48. A person skilled in the art knows that this is only one of many possibilities for pressing the pressure distribution plate 40 against the cylinder 30. Therefore, the inventive concept covers other possibilities, such as the use of disc springs or the filling of the pressure piston with a pressurized (e.g. high pressure or housing pressure) hydraulic fluid, or any other possibilities. A further possibility is to arrange the hollow pressure piston 44 at the end of the internal distribution passage 24, so that the hydraulic fluid can pass through the pressure piston 44 and, at the same time, generate a pressure at the annular surface facing the internal distribution passage 24, thereby forcing the pressure piston 44 against the pressure distribution plate 40 and further forcing the pressure distribution plate 40 against the cylinder front surface 32.

[0042] In another embodiment of the embodiment of the present invention, the cylinder 30 may be provided with a recess 33 on the side thereof facing the front housing part 10. In this recess 33 adjacent to the through hole 38 through which the drive shaft 3 passes, the inner shell of the bearing 16 may be at least partially accommodated, so that the total axial length of the front housing part 10 and the total axial length of the radial piston machine 1 may be reduced. This is also achieved by the effect of the present invention, that is, the internal distribution passage 24 may be arranged to have a larger reference diameter than it may have in the case of the prior art design. Therefore, the working volume 36 may be arranged radially outside, leaving space for the recess 33.

[0043] As the working volumes 36 move to the radially outer region, their diameter, i.e. the diameter and height of the working plunger 34, can be reduced without reducing the available torque. By reducing the diameter of the working volumes 36, the number of working volumes 36 arranged around the circumference can be increased, for example 12 working volumes 36. Thus, the total volume size can be maintained or even increased compared to radial piston machines of the prior art with comparable radial outer dimensions. Thus, the available torque can be maintained or even increased relative to radial piston machines known in the prior art.

[0044] In such Figure 3 In another embodiment of the present invention shown, one of the two bearings 16 used in the prior art for supporting the drive shaft 5 in a cantilevered manner in the area of ​​the front housing component 10 can be moved to the area of ​​the rear housing component 20 according to the present invention. This is possible because there is no longer a separate fluid distributor component 80 in the area of ​​the rear housing component 20. In radial piston machines of the prior art, it was not possible to implement the arrangement of such a bearing 16 in the area of ​​the rear housing component 20, in order not to endanger the sealing state between the separate fluid distributor part 80 and the rear housing component 20. According to the present invention, since the distribution system is integrally formed in the rear housing component 20, one of the two bearings 16 - typically a roller bearing or a needle bearing - can be moved to the area of ​​the rear housing component 20. This significantly reduces the axial length of the front housing component 10 without increasing the axial length of the rear housing component 20. It is also obvious to those skilled in the art that the above-mentioned embodiment of the present invention can be seen in FIG. Figure 3 It is found that a very compact axial piston machine design with a minimum axial length is achieved when the bearing 16 is arranged at the rear housing part 20 and when the parking brake mechanism 70 is not required. Figure 3 As depicted, both component groups, namely the bearing arrangement 16 and the parking brake mechanism 70 , can be integrated at least partially radially inwardly of the rear housing part 20 . As a result, the axial length is significantly reduced compared to radial piston machines according to the prior art.

[0045] I'm here too Figure 3In another embodiment shown in FIG. 2 , the control unit 50 can also be integrally formed in the rear housing part 20. Such a control unit 50 includes a control hole 52, in which a control valve core 54 is movably arranged in the axial direction of the control hole 52. The control valve core 54 includes one or more control recesses 55 for opening and closing the inlet 60 and the outlet 62 of the radial piston machine 1, respectively. Such a control unit 50 is well known in the prior art, so an explanation of its function can be omitted. However, the control unit 50 according to the present invention is different from the known control unit in that the diameter of the control hole 52 and the corresponding diameter of the control valve core 54 can be selected to be larger than the control unit 50 integrally formed in the rear housing of the radial piston machine known in the prior art with comparable radial outer dimensions. This is particularly suitable for radial piston machines with comparable volume dimensions. For example, for radial piston machines with a volume range between 600 cc and 950 cc in the prior art, a control valve core with a diameter of approximately 18 mm is used. In the radial piston machine according to the present invention, the control valve core diameter can reach approximately 30 mm or more. Obviously, in a larger rear housing of a radial piston machine with a larger volume, a larger control unit can be implemented. However, when comparing the rear housing according to the invention with a rear housing according to the prior art with approximately the same radial outer dimensions, the inventive concept of integrating the internal flow channel 22 and the internal distribution channel 24 into the rear housing part 20 provides more space for the control unit 50. As a result, a larger control valve core diameter can be used.

[0046] When using such a control spool 54 with an increased diameter, the radial piston machine 1 can be better controlled, because, as known to the skilled person, a larger control surface or control ring surface, or a larger difference between two control surfaces or control ring surfaces, can be achieved. Further, a larger control surface provides a greater control force and thus provides a higher positioning accuracy of the control spool, a lower hysteresis and a higher displacement speed.

[0047] Due to the increase in the diameter of the control valve core 54, the smooth recess 56, which extends axially in the axial direction from at least one recess 55 at the control valve core 54 and has an end, can be redesigned and optimized to achieve better function. Such smooth recesses 56 are also known in the prior art and are introduced into the control valve core 54 in order to smooth the change of operating state (for example, switching from the full torque operating state of the radial piston machine to the half torque / dual speed operating state). This is particularly important when the hydraulic fluid used is still cold and exhibits high viscosity. At this point, it is obvious to those skilled in the art that the cross-section of such smooth recesses 56 has a great influence when changing from one operating state to another. By applying the inventive concept to the radial piston machine, these smooth recesses 56 can be designed as constant recesses or continuously reduced recesses, and the continuously reduced recesses may have a cross-sectional reduction amount that increases toward the end of the smooth recess 56. In the prior art, these recesses are designed in a stepped manner.

[0048] In another embodiment of the radial piston machine according to the present invention, the internal distribution passage 24 can also be moved radially outside the internal annular flow channel 22, that is, the internal annular flow channel 22 is moved radially inside the internal distribution passage 24. By doing so, the timing hole 37 in the cylinder 30 can also be moved radially outside the cylinder 30. Thereby (if necessary) reducing the working volume 36 in the cylinder 30. In order not to lose the volume size of the radial piston machine, the number of working spaces 36 (that is, the number of cylinders and working pistons 36) can be increased because the working volume 36 can be arranged on a larger reference diameter. Therefore, for example, for a radial piston machine of 600 cc to 950 cc, the number of working pistons 34 can be increased to 12. For example, for this exemplary range of volume sizes, so far in the prior art, due to the use of a cam disc with six cam lobes, the number of working volumes is limited to ten. According to the present invention, for example, for a radial piston machine having a comparable volume size, by increasing the number of working pistons 34 to twelve and using a cam plate 12 having nine cam lobes 13, a 3-speed radial piston machine can be realized.

[0049] As is known from the prior art, when some of the working volumes will not be charged with high pressure (i.e., no high pressure is supplied to a portion of the timing holes), the torque of the radial piston machine decreases, however, its speed increases. Here, it must be ensured that a sufficient number of working volumes are charged with high pressure. For example, the other non-pressurized working volumes are usually short-circuited and the hydraulic fluid is not discharged to the outlet. When a cylinder with 12 working volumes is used, it is conceivable to have an operating state in which only 8 or 4 of the 12 working volumes are charged with high pressure. Finally, by applying the inventive concept to a radial piston machine, three operating states of full torque, two-thirds of the full torque or only one-third of the full torque can be achieved. Accordingly, in order to meet the performance equation of volume size multiplied by speed, the speed increases accordingly as the working volume charged with high pressure decreases.

[0050] In another embodiment according to the present invention, since the control valve core 54 of the integrated control unit 50 is increased in diameter relative to the corresponding situation in the prior art, a check valve device 58 (also called an anti-cavitation device) can be introduced inside the control valve core 54 to ensure that a minimum pressure is maintained in the internal annular flow channel 22 (i.e., at least in the internal annular flow channel of the short-circuited working volume 36) when the radial piston machine operates under low torque conditions.

[0051] From the above disclosure as well as the drawings and claims, it can be understood that the hydraulic radial piston machine 1 according to the present invention provides many possibilities and advantages compared to the prior art. All modifications and changes within the scope of the claims should be covered. It should also be understood that the examples and embodiments described above are for illustrative purposes only, and various modifications, changes or combinations based on these examples and embodiments that will occur to those skilled in the art are included in the spirit and scope of the present application.

[0052] Reference numerals list

[0053] 1 Hydrostatic radial piston motor

[0054] 3 Drive shaft

[0055] 5 Central axis

[0056] 10 Front housing part

[0057] 12 Cam plate

[0058] 13 Cam lobe

[0059] 14 Inner cam surface

[0060] 16 Bearing assembly

[0061] 18 Housing cover

[0062] 20 Rear housing parts

[0063] 22 Internal annular flow channel

[0064] 24 Internal distribution channels

[0065] 30 Cylinder

[0066] 32 Cylinder front surface

[0067] 33 recess

[0068] 34 Working plunger

[0069] 36 Working volume / cylinder bore

[0070] 37 Timing hole

[0071] 38 Through Holes

[0072] 40 Pressure distribution plate

[0073] 42 Through Holes

[0074] 44 Pressure piston

[0075] 46 blind holes / holes

[0076] 48 Spring

[0077] 50 Control Unit

[0078] 52 Control hole

[0079] 54 Control valve core

[0080] 55 Control recess

[0081] 56 Notch

[0082] 57 External surface

[0083] 58 Check valve device

[0084] 60 Entrance

[0085] 62 Exit

[0086] 70 Parking brake mechanism

[0087] 72 Brake disc

[0088] 80 Distributor element

[0089] 82 Annular channel

[0090] 84 Assignment path.

Claims

1. A hydrostatic radial piston machine (1), comprising: - a front housing part (10) which accommodates the drive shaft (3) via a bearing arrangement (16) such that the drive shaft (3) can rotate relative to the front housing part (10) about a central axis (5); - a rear housing part (20) attached on one side to the front housing part (10) and closed on the other side to define an internal volume; - a cylinder (30) arranged in the inner volume and attached to the drive shaft (3) in a torque-secure manner, wherein an axially arranged timing hole (37) in the cylinder (30) connects a radially oriented working volume (36) in the cylinder (30) with a cylinder front surface (32) arranged perpendicular to the center axis (5) and facing away from the front housing part (10); An internal annular flow channel (22) and an internal distribution passage (24) are integrally formed in the rear housing component (20), the internal annular flow channel being connected to an inlet (60) and an outlet (62) of the radial piston machine (1) and extending substantially in a circumferential direction around the central axis (5), the internal distribution passage being configured to hydraulically connect the internal annular flow channel (22) with a timing hole (37) of the cylinder body, Characterized in that the hydrostatic radial piston machine comprises a parking brake mechanism (70) located on the rear side of the internal volume, wherein a brake disc (72) of the parking brake mechanism (70) is axially arranged in the rear housing component (20) and at least partially arranged radially inwardly of the inner annular flow channel (22).

2. The hydrostatic radial piston machine (1) according to claim 1, further comprising a pressure distribution plate (40) fixed to the rear housing part (20) between the cylinder block (30) and the rear housing part (20), the pressure distribution plate comprising a through hole (42) connecting the timing hole (37) of the cylinder block with the internal distribution passage (24), wherein the through hole (42) is oriented parallel or obliquely relative to the center axis (5).

3. The hydrostatic radial piston machine (1) according to claim 1 or claim 2, further comprising a control hole (52) in the rear housing component (20), the inlet (60), the outlet (62) and the internal annular flow channel (22) being connected to the control hole, so that a control valve core (54) movably accommodated in the control hole (52) can guide the hydraulic fluid from the inlet (60) to the internal annular flow channel (22) via a control recess (55) arranged at the outer surface of the control valve core (54), and guide the hydraulic fluid from the internal annular flow channel (22) to the outlet (62).

4. The hydrostatic radial piston machine (1) according to claim 3, wherein: In the full torque position of the control valve spool (54), the timing hole (37) is connected to the inlet (60) and the outlet (62) in an alternating sequence through the internal distribution passage (24), and wherein, in a low torque position of the control valve spool (54), less internal distribution passage (24) is connected to the inlet (60) than in the full torque position of the control valve spool (54).

5. The hydrostatic radial piston machine (1) according to claim 3, wherein: The control valve core (54) comprises at least one recess (56) which extends axially from at least one of the control recesses (55) on the outer surface (57) so that a fluid connection of reduced cross-section can be established between the inlet (60) or the outlet (62) and the inner annular flow channel (22).

6. The hydrostatic radial piston machine (1) according to claim 5, wherein: The depth and / or width of the recess (56) in the axial direction is constant, or increases or decreases monotonically toward the end of the recess.

7. The hydrostatic radial piston machine (1) according to claim 3, wherein: Compared to a control valve core of a prior art hydraulic radial piston machine having a comparable displacement volume but without an internal annular flow passage integrally formed in the rear housing component, the outer surface (57) of the control valve core (54) has an increased diameter.

8. The hydrostatic radial piston machine (1) according to claim 4, wherein: A check valve arrangement (58) is arranged inside the control spool (54) such that in the low torque position, hydraulic fluid can be supplied to one of the inner annular flow passages (22) if the pressure in the inner annular flow passages (22) drops below a predetermined threshold.

9. The hydrostatic radial piston machine (1) according to claim 1, wherein: The parking brake mechanism (70) is fail-safe and can be actuated hydraulically or electromechanically.

10. The hydrostatic radial piston machine (1) according to claim 1, wherein: The rear housing part (20) is closed by a housing cover (18) on the side facing away from the front housing part (10).

11. The hydrostatic radial piston machine (1) according to claim 1, wherein: The working volume (36) in the cylinder (30) is sealed by a radially movable working piston (34) arranged in the working volume (36), and wherein, in the operating state of the radial piston machine (1), the piston movement is guided by a cam lobe (13) on an inner cam surface (14) of a cam disk (12) against which the working piston (34) abuts, wherein the working volume (36) and / or the working piston (34) further comprise a surface-finished surface.

12. The hydrostatic radial piston machine (1) according to claim 11, wherein: Compared to a prior art radial piston machine having a comparable displacement volume but without an internal annular flow passage integrally formed in the rear housing component, the number of the working pistons (34) and the number of cam lobes (13) on the cam plate (12) are increased.

13. The hydrostatic radial piston machine (1) according to claim 11 or 12, wherein: The cam plate (12) is formed integrally with the front housing component (10).

14. The hydrostatic radial piston machine (1) according to claim 1, wherein: One bearing arrangement (16) is located in the rear housing part (20) and another bearing arrangement is located in the front housing part (10).

15. The hydrostatic radial piston machine (1) according to claim 2, wherein: When the radial piston machine (1) is in operation, the opening force exerted on the pressure distribution plate (40) by the fluid pressure in the timing hole (37) of the cylinder body is balanced by the pressure piston (44), which abuts against the pressure distribution plate (40) and is pressed against the pressure distribution plate (40) by a pressure spring (48) and / or by fluid pressure.

16. The hydrostatic radial piston machine (1) according to claim 15, wherein: The pressure piston (44) is arranged coaxially in the internal distribution passage (24).

17. The hydrostatic radial piston machine (1) according to claim 1, wherein: The rear housing component (20) is manufactured by sand casting, additive manufacturing technology or lost core preforming technology.

18. The hydrostatic radial piston machine (1) according to claim 2, wherein: The cylinder body (30) comprises, at least on one side, an axially concave recess (33) adjacent to an axial through hole (38) for receiving the drive shaft (3), wherein the at least one recess (33) is configured to receive a portion of a bearing inner shell or a bearing outer shell and / or at least partially accommodate the pressure distribution plate (40).

Images