Hydrostatic radial piston unit with cam lobe structure

Abstract

The application provides a hydrostatic radial piston unit with cam lobe structure, comprising: a non-rotating fixed housing, the fixed housing comprising a through hole, the through hole defining a rotation axis of the hydrostatic radial piston unit; a rotating housing rotatably mounted to the fixed housing in an axially overlapping area; a parking brake mechanism comprising at least two brake discs adjacently arranged in the overlapping area; an end cover pre-tightening a disc spring against a disc-shaped brake piston to generate an axial elastic force, the disc spring and the brake piston being located in a rear end portion of the fixed housing, the elastic force being able to be transmitted by the brake piston to at least one brake pin arranged in an axial hole in the fixed housing to press the brake discs against each other when the brake piston opposite to the disc spring is not driven to move towards the end cover.

Description

Technical Field

[0001] This application relates to hydrostatic radial piston units, and more specifically to cam cam motors or pumps, or cycloidal motors or pumps. More specifically, this application relates to a braking mechanism for a hydrostatic radial piston unit with a cam cam structure. Background Technology

[0002] Radial piston units, namely radial piston pumps and radial piston motors, are widely used in the field, for example, in heavy-duty applications. For instance, radial piston units are used in construction, agricultural, or forestry equipment. A characteristic of radial piston units is that, when supplied with pressurized hydraulic fluid (in the case of a radial piston motor), their working pistons move radially relative to a central longitudinal / rotation axis. Typically, radial piston units are used in hydraulic applications that do not require high rotational speeds but do require high torque. Radial piston units exhibit advantages over axial piston units (due to reduced axial structural space).

[0003] One specific application of radial piston units is the movement of work vehicles (e.g., tracked loaders). Often, a radial piston unit is mounted on either side of the frame / body of the work vehicle. Therefore, the geometry of the frame and propulsion mechanism is significantly influenced by the size of the radial piston unit. In many applications, the location where the radial piston unit transmits torque to the drive mechanism is predetermined by other components, rather than by the radial piston unit interacting with the drive mechanism. However, radial piston units in the known art exhibit relatively large axial lengths and diameters. Since the radial piston unit driving the work vehicle must be integrated into the vehicle frame, the frame must be designed to accommodate the fixed components of the radial piston unit (e.g., a fixed housing) to support the torque generated / applied under operating conditions. Therefore, it is desirable to minimize the size of the radial piston unit used (especially its axial dimension) to reduce the design fit of the frame on which the radial piston unit is mounted.

[0004] When hydrostatic radial piston units are used in propulsion applications, a parking brake is often required to ensure fault-protection operation of the unit. In this case, the brakes only allow vehicle movement when actively released. When the parking brake is inactive, movement of both the hydrostatic radial piston unit and the vehicle is prevented. In the prior art, different approaches exist for providing a parking braking mechanism for the hydrostatic radial piston unit, such as disc brakes attached to the outside of the unit housing. Alternatively, the brakes can be arranged inside the unit housing, where they are protected from dirt or similar negative influences. Disadvantageously, this arrangement significantly increases the axial length of the hydrostatic radial piston unit.

[0005] WO 2013 / 160145 A2 discloses a radial piston machine with a rotating output shaft. To reduce the axial length of the radial piston machine, at least a portion of a parking brake is arranged between the housing and a portion of the output shaft. The output shaft is designed to rotate, for example, for driving a wheel, which can be secured to an output flange at the output shaft. Summary of the Invention

[0006] The purpose of this application is to provide a radial plunger unit with reduced dimensions, particularly a reduced axial length, and a reduced radial dimension / diameter. Simultaneously, the provided radial plunger unit will include a parking brake mechanism arranged within the radial plunger unit housing, such that neither the axial nor radial dimensions of the radial plunger unit significantly increase.

[0007] To achieve the above objectives, the hydrostatic radial piston unit with a cam cam angle structure provided in this application includes:

[0008] A non-rotating fixed housing, the fixed housing including a through hole defining the axis of rotation of the hydrostatic radial piston unit;

[0009] A cylindrical rotating housing is rotatably mounted to a non-rotating fixed housing in an axially overlapping region, wherein the front end portion of the non-rotating fixed housing and the rear end portion of the rotating housing overlap, enabling the rotating housing to rotate relative to the fixed housing about the rotation axis.

[0010] A parking brake mechanism, comprising at least two brake discs arranged adjacent to each other in the overlapping area, wherein one brake disc is fixed relative to the fixed housing in the rotational direction, and the other brake disc is fixed relative to the rotating housing in the rotational direction;

[0011] An end cap that closes the fixed housing on the rear end side of the hydrostatic radial piston unit away from the rotating housing;

[0012] The end cap preloads the disc spring against the disc brake piston to generate an axial spring force. Both the disc spring and the brake piston are located in the rear end portion of the fixed housing. The spring force can be transmitted through the brake piston to at least one brake pin arranged in an axial hole in the fixed housing, so that the brake discs press against each other when the brake piston facing the disc spring is not driven to move toward the end cap.

[0013] The hydrostatic radial piston unit according to this application includes a fixed housing with a through-hole defining a longitudinal axis, which is also the axis of rotation of the hydrostatic radial piston unit. The fixed housing is configured to be connected to the frame of a work vehicle; that is, as understood in this specification, the fixed portion of the radial piston unit according to this application forms a rear end region that can be securely fastened to, for example, a frame or support.

[0014] In this specification, the terms "radial" and "axial" refer to directions relative to the longitudinal axis of a fixed shaft. Within the scope of this application, "fixed" means: not rotating about the longitudinal axis, for example, when the radial plunger unit is mounted to a work vehicle.

[0015] A cylindrical rotating housing is rotatably mounted to a non-rotating fixed housing in an axially overlapping region. In this region, the front end portion of the fixed housing and the rear end portion of the rotating housing overlap in the axial direction. Therefore, in the overlapping region, at least a portion of the rotating housing is arranged radially outward or inward of the fixed housing. Thus, when the rotating housing is capable of rotating relative to the fixed housing about the rotation axis of the radial plunger unit, the rear end portion of the rotating housing seals against the front end portion of the fixed housing. The seal between the rotating housing and the fixed housing is achieved in such a way that the two housings together form a closed, liquid-tight cavity. The connection between the rotating housing and the fixed housing allows the rotating housing to rotate relative to the fixed housing about the rotation axis (i.e., the longitudinal axis).

[0016] Essentially, the axial position of the seal between the fixed housing and the rotating housing defines a sealing surface orthogonal to the axis of rotation. Therefore, viewed from the outside, the sealing surface divides the hydrostatic radial plunger unit housing into a fixed portion (rear end portion) on one side of the sealing surface and a rotating portion (front end portion) on the other side of the sealing surface.

[0017] In a preferred embodiment of this application, the fixed housing accommodates the fixed shaft in a torsion-resistant manner at its rear end. This means that neither the fixed shaft nor the fixed housing will rotate relative to each other. The fixed shaft is arranged coaxially with the axis of rotation within the cavity formed by the fixed housing and the rotating housing. At the front end of the fixed shaft, which protrudes from the fixed housing, a fixed cylinder is arranged for torsion-resistant connection with the fixed shaft. The cylinder includes a plurality of cylinder bores, each extending radially inward from the circumferential surface of the cylinder.

[0018] The hydrostatic radial piston unit according to this application further includes a parking brake mechanism comprising at least two brake discs arranged adjacent to each other in an overlapping area, wherein one brake disc is fixed to a fixed housing in the rotational direction and the other brake disc is fixed to a rotating housing in the rotational direction, thereby at least one brake disc being axially movable. If the hydrostatic radial piston unit includes more than two brake discs, each brake disc is alternately fixed to the fixed housing and the rotating housing in the rotational direction, wherein it must be configured to be axially movable so that: a braking effect can be achieved by pressing the brake discs together (compressing them), and the brake can be released by reducing the pressing force. According to this application, the parts fixed in the rotational direction cannot rotate relative to each other.

[0019] The parking brake mechanism includes a blocking position and a rotating position. In the blocking position, the brake discs press against each other, and in the rotating position, the rotating housing is fixed relative to the fixed housing. According to a preferred embodiment of this application, the brake discs may be arranged in the axially overlapping area between the fixed housing and the rotating housing, axially close to the sealing surface.

[0020] The parking brake mechanism can be preloaded toward its blocking position using a disc spring, which provides a preload force acting on the brake piston in the axial direction and is supported, for example, by an end cap / end cover fixed to the rear end of the fixed housing. The end cap closes the non-rotating fixed housing on the end side of the hydrostatic radial plunger unit away from the rotating housing (i.e., away from the axial overlap area where the rotating housing is mounted to the fixed housing).

[0021] The axial preload of the disc spring can be transmitted to the brake disc via the brake piston using at least one brake pin (which extends axially between the brake piston and the brake disc). The at least one brake pin is preferably arranged in an axial bore in a non-rotating, fixed housing, located on the side of the brake piston opposite the disc spring. Thus, the brake piston transmits the preload of the disc spring to the brake pin, which presses the brake discs together.

[0022] Those skilled in the art will select the number, shape, and arrangement of the brake pins and corresponding axial holes according to different application requirements. For example, it may be preferable to arrange at least three brake pins, equidistantly distributed on an arc centered on the axis of rotation.

[0023] Different methods can be used to switch the parking brake mechanism to the open / release position. As a first method, a brake pin seal is used to form a chamber, for example, in a fixed portion of the housing at the rear end of the radial plunger unit. This chamber can also be formed by multiple parts (e.g., via a shaft, via a fixed housing, via a brake pin, and via a brake piston).

[0024] Therefore, the rear end of the brake pin is preferably attached to the brake piston in a liquid-sealed manner. An additional seal is provided between the front end of the brake pin and the fixed housing. Thus, a pressure chamber is formed by the fixed housing, the rear end of the fixed shaft, the brake pin guide hole, and the brake piston. If pressurized hydraulic fluid is supplied to this pressure chamber, a force is generated on the release surface of the brake piston to counteract the preload of the disc spring and release the brake. This releases the clamping force of the brake pin from the brake disc, allowing the rotating housing to rotate relative to the fixed housing. The opening pressure required to release the brake depends on the size of the brake pin piston release surface (compared to the preload provided by the disc spring). The spring preload can be adjustable, for example, by adjusting the relative position of the brake piston and the end cap (achieved via an adjustable shoulder or adjusting screw in the end cap / end cap). Alternatively, the length of the brake assembly, i.e., the number of brake discs, can also be adjusted.

[0025] Preferably, the rear end of the brake pin facing the brake piston has a larger diameter than the front end of the brake pin. This design of the brake pin ensures that the pin is always in contact with the brake piston, regardless of whether the brake prevents relative rotation between the stationary and rotating housings. In the stopped position or when the hydrostatic radial piston unit moves toward the stopped position, the brake piston pushes the brake pin against the brake disc, which is then compressed, for example, against the shoulder of the stationary housing.

[0026] If pressurized hydraulic fluid is supplied to the aforementioned pressure chamber to generate force on the release surface of the brake piston, the same pressure is applied to the end surface of the brake pin. This pressure generates a force acting on the end surface of the brake pin. Because the rear end of the brake pin has a larger diameter, a greater force will be generated on that side. Therefore, the brake pin moves in the direction of the brake piston until it contacts the brake piston. The brake pin then remains in contact with the brake piston, even as the brake piston moves in the direction toward the disc spring (i.e., along the direction of the fixed housing end cap).

[0027] In a second embodiment embodying an alternative embodiment of this application, a pressure chamber is formed within an axial bore (in which the brake pin is disposed and guided in the axial direction). Seals are provided at the front and rear ends of the brake pin to close the pressure chamber. Preferably, also in this embodiment, the rear end of the brake pin facing the brake piston has a larger diameter than the front end. If pressure is supplied to the pressure chamber, a larger force will be generated at the rear end of the brake pin due to the larger diameter. Therefore, the brake pin moves in the direction of the rear end of the hydrostatic radial plunger unit (i.e., in the direction of the brake piston). If there is a gap between the brake pin and the brake piston, the brake pin will move rearward until it contacts the brake piston. The force generated by the pressure in the pressure chamber is then transmitted to the brake piston via the brake pin. If the generated force is large enough to overcome the preload of the disc spring, the disc spring is compressed and the parking brake is released.

[0028] In one embodiment according to this application, the non-rotating fixed housing includes an annular groove on the inner surface of the through-hole, the annular groove forming a first annular passage together with a first groove on the outer circumferential surface of the non-rotating fixed shaft. According to this application, a brake pin is used to bridge the axial clearance between the brake piston and the brake disc (which may be arranged in the axially overlapping region). Preferably, the axial hole with the brake pin is arranged radially outward of the first annular passage in the fixed housing. This ensures that sufficient space is provided for the annular groove on the outer surface of the shaft and sufficient space is provided for the first groove on the inner surface of the fixed housing.

[0029] The braking design according to this application allows the centrally located brake disc to be positioned close to the area where the rotating and fixed portions of the hydrostatic radial piston unit overlap. Simultaneously, the hydraulic connection required to supply hydraulic fluid to the pressure chamber of the braking device for brake release can be arranged in the fixed portion of the hydrostatic radial piston unit and the mechanical portion of the parking brake mechanism, except for the rotating brake disc fixed to the rotating component. The brake pin provides a functional connection between the overlapping area / brake disc near the rotating component and the pressure chamber of the fixed component. Therefore, it is unnecessary to supply hydraulic fluid with brake release pressure from the fixed component to the rotating component. Consequently, fewer sealing connections are required, and the complexity of assembling and manufacturing the hydrostatic radial piston unit according to the invention is reduced. Furthermore, the number of potential leakage points is reduced.

[0030] The stationary cylinder at the front end of the radial plunger unit includes multiple cylinder bores extending radially inward from the circumferential surface of the cylinder body. Multiple working plungers are arranged radially movable within these cylinder bores, with each cylinder bore housing one working plunger. Each working plunger seals a pressure chamber within the cylinder bore, which is supplied with pressurized hydraulic fluid via a hydraulic passage to generate a force on the head of the associated working plunger, causing it to move radially outward. Furthermore, when the working plunger is mechanically driven inward (e.g., using a cam), hydraulic fluid can be discharged from the cylinder bore via a hydraulic passage.

[0031] The rotating housing includes an internal cam lobe surface. When pressurized fluid is supplied to the pressure chamber, the working plunger is driven against the cam lobe surface. When the cylinder block is fixed and supported by the fixed housing via a fixed shaft, the radially outward movement of the working plunger generates a force on the cam lobe surface that causes the rotating housing to rotate relative to the fixed housing.

[0032] To direct pressurized fluid into a pressure chamber, this application provides a rotary distributor comprising a hollow shaft portion and a disc-shaped portion, the disc-shaped portion and the hollow shaft portion being integrally formed but also potentially connected to each other, for example, by a fluid seal. The disc-shaped portion is anti-torsionally connected to a rotating housing, i.e., connected to the rotating housing for rotation together. In a preferred embodiment, the disc-shaped portion of the rotary distributor exhibits a radial protrusion that matches the convex angle of the cam convex angle surface. The rotary distributor further includes a timing hole in the disc-shaped portion for supplying and discharging hydraulic fluid through a hydraulic passage into and from a cylinder bore in the cylinder block. Furthermore, the rotary distributor includes a second internal groove that, together with a second groove on the outer surface of a non-rotating fixed shaft, forms a second annular passage. The second groove on the outer surface of the fixed shaft connects to the first annular passage via an internal passage in the shaft. The operating principle of a radial plunger unit is well known to those skilled in the art, and therefore the function of the radial plunger unit here need not be described in further detail.

[0033] According to this application, paired roller bearings rotatably support a rotating housing on a fixed housing. The roller bearings are arranged radially outward from the rotating distributor, but at approximately the same axial position as the hollow shaft portion of the distributor, near the rear end of the rotating housing and the front end of the fixed housing, respectively. In other words, the roller bearings allow for relative movement between the rotating and fixed housings and are positioned near or close to the sealing surface to avoid large tilting moments between the two housings, which also facilitates sealing of the two housings.

[0034] According to this application, the roller bearings are arranged in pairs, and in one embodiment, they are preferably close to or adjacent to each other. Arranging them at approximately the same axial position as the hollow shaft portion of the rotary distributor means that the bearings are axially positioned in a region adjacent to the side of the cylinder facing the fixed housing, and at least partially surround the rotary distributor (e.g., in the cylindrical portion of the rotary distributor). Moreover, in this region, the fixed housing and the rotary housing overlap, or at least extensions or protrusions of one or both housings overlap each other axially, while being coaxially arranged such that the rotating portion (e.g., the rotary housing or rotary distributor) is rotatable relative to the fixed portion (e.g., the fixed housing or fixed shaft). The paired bearings may have a different axial length than the distributor. When the bearings are arranged radially (relative to the longitudinal axis) outside the hollow shaft portion of the distributor and at least partially overlap the distributor axially (rather than being adjacent to it axially), the axial length of the hydrostatic radial piston unit is reduced. Those skilled in the art will understand that the use of roller bearings is only a preferred embodiment. However, this application also covers the use of sliding bearings to rotatably support the rotary housing relative to the fixed housing.

[0035] According to a preferred embodiment of this application, the fixed housing of the radial plunger unit may include a fixed extension that extends axially beyond the sealing surface into the volume of the rotating housing and has a generally cylindrical shape. This extension, for example, mounts the inner housing of a bearing. When a pair of bearings is accommodated in the space between the rotating housing and the rotary distributor, the extension provides fixed support for the pair of bearings, for example, radially outside the rotary distributor. Therefore, the extension is radially positioned in the space between the two rotating parts (the rotary distributor and the rotating housing).

[0036] In one embodiment of this application, the extension may be integrally formed with the fixed housing. However, in another embodiment of this application, the extension is configured as an additional component and attached to the fixed housing. The extension may be attached to the fixed housing, for example, by screwing, welding, bonding, press-fitting, heat shrinking, clamping, crimping, or plastic deformation. The connection between the fixed housing and the additional extension must be a torsion-resistant connection so that the bearing support force can be statically transmitted to the fixed housing via the extension. This split design increases the feasibility of designing and assembling the radial plunger unit according to this application. Preferably, the extension comprises a hollow cylindrical sleeve shape, wherein its outer surface is adapted to mount a pair of bearings (preferably in an O-type arrangement). To support the bearing in the axial direction, the extension may include: a bearing securing mechanism on the outer surface of the extension, such as a shoulder for supporting the bearing in the axial direction, a groove for receiving a retaining ring, and / or threads for screwing on a shaft nut.

[0037] According to this application, the paired roller bearings can be located not only at or near the same axial position as the distributor, but also at the same axial position as the flange, sprocket, or similar torque transmission device on the outer peripheral surface of the rotating housing. In motor operation mode, the rotating part (such as a wheel or sprocket) can be driven by a hydrostatic radial piston unit. In pump operation mode, the rotating part can drive the hydrostatic radial piston unit. The torque transmission device serves as an interface to which the rotating part, track / track, or chain can be fixed. When the bearings are arranged at the same axial position as the torque transmission device, there is no or at least a reduction in the tilting moment of the rotating housing relative to the longitudinal axis, which is related to the position of the paired bearings. Therefore, the bearings can be designed to be smaller and have a lower load factor. This results in lower bearing costs and further reduces the production cost of the hydrostatic radial piston unit. Simultaneously, the bearing arrangement according to this application reduces the axial length of the radial piston unit and the distance required between the torque transmission location and the fixing mechanism of the fixed housing (whereby the radial piston unit can be mounted, for example, to the frame of a vehicle).

[0038] In another embodiment according to this application, the hydrostatic radial piston unit includes a fixed (non-rotating) two-speed, three-speed, or multi-speed control valve. The control valve (e.g., in a two-speed embodiment) is switchable between a first position and a second position. In the first position, for example, all cylinder bores are used to generate torque on the rotating housing, i.e., fluid at high pressure (e.g., operating pressure) can be supplied to the cylinder bores. This means that supplying high-pressure hydraulic fluid to the cylinder bores forces the pistons arranged in the cylinder bores to move radially outward. When the pistons move radially inward due to the cam shape following the cam lobe surface, the corresponding cylinder bore connects to the outlet timing port, and hydraulic fluid is discharged from the cylinder bore. In the second position, for example, only a portion of the cylinder bores exhibits the same operating behavior as in the first position, i.e., only a portion of the cylinder bores can be supplied with high-pressure hydraulic fluid via the inlet timing port. However, another portion of the cylinder bores is supplied with depressurized (e.g., filling pressure) hydraulic fluid, regardless of the movement of the working pistons. Here, for example, the group of cylinder bores can also be hydraulically short-circuited at reduced hydraulic pressure.

[0039] In other words, in the first position of the control valve, the working volume of the hydrostatic radial piston unit is the sum of all working volumes enclosed between each cylinder bore and its corresponding working cylinder. In the second position, only a portion of the cylinder bores is supplied with high-pressure fluid. Therefore, only this portion of the working pistons and their corresponding cylinder bores contributes to the working volume of the radial piston unit. The other working pistons are supplied with reduced pressure, sufficient to ensure contact between the piston rollers and the cam lobe surface of the rotating housing; they do not contribute to the actual working volume of the radial piston unit because the corresponding pressure chambers are not supplied with high-pressure hydraulic fluid. In a short-circuit condition, the hydraulic fluid volume necessary for one piston to move outward is replaced by another piston moving inward.

[0040] In another preferred embodiment according to this application, the cam lobe surface is integrally formed with the rotating housing. If the housing were to be assembled from multiple parts, the necessary connections and seals would require additional radial and axial space. Integrating the rotating housing with the cam lobe surface reduces the complexity of the assembly process. Furthermore, this integral forming approach allows for a reduction in the diameter, i.e., the radial dimension, of the hydrostatic radial piston unit, as connections between the parts can be eliminated. This also saves on manufacturing and assembly costs, as precision-machined connecting surfaces and additional assembly steps are avoided.

[0041] The synchronizing pin is accommodated in the axial bore of the rotating housing, preferably in an extension of the convex angle, and engages with a corresponding hole in one of the radial protrusions of the disc-shaped portion of the dispenser. Thus, the synchronizing pin can interact simultaneously with both the rotating housing and the rotary dispenser. Therefore, when the dispenser is mounted in the rotating housing, the synchronizing pin ensures the correct orientation of the dispenser (or more precisely, the disc-shaped portion of the rotary dispenser). Furthermore, the synchronizing pin synchronizes the rotation of the dispenser with the rotation of the rotating housing, i.e., prevents relative movement between the two parts.

[0042] According to this application, the radial plunger unit may further include: distributor springs to press the disc-shaped portion of the rotary distributor toward the cylinder body. According to this application, these distributor springs are preferably received in axially extending bores in the rotating housing at the axial extension of the lobe. Preferably, the disc-shaped portion of the rotary distributor exhibits a disc-shaped extension facing the stationary cylinder body and displays a profile complementary to the lobe surface. The distributor springs press the rotary distributor toward the cylinder body. Thus, the front surface of the disc-shaped portion of the rotary distributor and the adjacent front surface of the cylinder body form a hydrostatic bearing between the disc-shaped portion of the rotary distributor and the stationary cylinder body.

[0043] The hydrostatic bearing is supplied with pressurized fluid via a timing orifice (located in the front surface of the disc-shaped portion of the rotary distributor, through which hydraulic fluid can be supplied to or discharged from the cylinder bore in the cylinder block). Arranging the distributor spring within the rotating housing (which provides an anti-torsion connection to the distributor) ensures that there is no relative movement in the circumferential direction between the distributor spring and the distributor. If relative movement exists between the two components, the spring is likely to experience severe wear and / or deformation. Furthermore, axially accommodating the distributor spring in the elongated / extended portion of the cam cam face reduces the load and stress on the synchronizing pin caused by frictional resistance between the rotary distributor and the fixed shaft.

[0044] Another benefit is achieved when the spring is located within the axial thickness of the distributor, which further reduces the axial length of the hydrostatic radial piston motor because the axial bore in the front housing for accommodating the spring is moved to the distributor, thereby reducing the axial length of the front housing.

[0045] The first cylinder may include one or more rows of cylinder bores with radially reciprocating working plungers, each row of cylinder bores being axially spaced from the adjacent rows. The cylinder bores and the corresponding working plungers may be arranged adjacent to each other in adjacent circumferential directions (i.e., having the same direction of rotation) or staggered, and may interact with the surface of the first cam lobe.

[0046] According to this application, the hydrostatic radial piston unit may further include: a second cylinder body, whose working piston interacts with the same cam lobe surface or another cam lobe surface arranged parallel to the first cam lobe surface. The second cylinder body is arranged axially parallel to the first cylinder body on a non-rotating shaft. Providing a cylinder body or a second cylinder body with more than one row of cylinder bores significantly increases the potential working volume, wherein the diameter of the hydrostatic radial piston unit remains the same.

[0047] To customize the behavior of the hydrostatic radial piston unit for a specific application, the number of axially spaced cylinder bores or the number of radially reciprocating working pistons in the second cylinder block may differ from the number of cylinder bores and the number of radially reciprocating working pistons in the first cylinder block.

[0048] In this configuration, a second circumferential cam convex surface may be provided on the radially inner side of the rotating housing. The working plunger of the second cylinder bore or the second or more rows of cylinder bores may interact with the second cam convex surface. In one embodiment, the second circumferential cam convex surface is integrally formed with the rotating housing.

[0049] In a further embodiment according to this application, a reinforced disc cover is attached to the front end of the rotating housing (which is also the front end of the hydrostatic radial piston unit). The cover closes and preferably seals the rotating housing, for example using an O-ring, thereby preventing hydraulic fluid leakage from the cavity formed by the rotating housing and the fixed housing. Furthermore, the front end and the reinforced cover are designed such that the reinforced cover can absorb the radial forces acting on the rotating housing due to the cam cam angle working principle.

[0050] In another embodiment, the reinforcing cover includes a sleeve-shaped collar portion and the rotating housing includes complementary shoulders, or vice versa. The sleeve-shaped collar portion may be arranged to form a closed connection with the complementary shoulders, at least radially. Thus, the rotating housing is radially reinforced. Preferably, the thickness of the reinforcing cover is designed such that it includes a low rotational mass as it rotates with the rotating housing, but provides high radial stiffness. The higher radial stiffness of the reinforcing rotating housing reduces potential deviations between the cam lobe surface and the working plunger (which interacts with the cam lobe surface). The reinforcing cover thus ensures better contact between the cam lobe surface and the working plunger, thereby preventing increased component wear because it facilitates line contact between the plunger rollers and the cam lobe surface during operation of the radial plunger unit.

[0051] In a preferred embodiment according to this application, the hydrostatic radial piston unit operates as a hydraulic motor. A hydraulic motor, for example, drives the track drive or wheels of a work machine (e.g., a tracked loader) using a torque transmission device. Particularly important in the field of tracked drives is the small axial length of the radial piston unit, thereby allowing for the most flexible selection of the work machine design. Attached Figure Description

[0052] The following figures describe exemplary embodiments of the hydrostatic radial piston unit according to this application, as well as specific sub-components of the hydrostatic radial piston unit according to this application. The presented embodiments do not limit the scope of this application. The figures show:

[0053] Figure 1 A first cross-sectional view along the axis of rotation is shown of the hydrostatic radial piston unit according to this application;

[0054] Figure 2 A second sectional view along the axis of rotation is shown of the hydrostatic radial piston unit according to this application;

[0055] Figure 3 A third sectional view perpendicular to the axis of rotation is shown of the hydrostatic radial piston unit according to this application;

[0056] Figure 4 An isometric view of the rotating housing of the hydrostatic radial piston unit according to this application is shown;

[0057] Figure 5 An isometric sectional view of the rotating housing (with a distributor) of the hydrostatic radial piston unit according to this application is shown.

[0058] Figure 6 A partial cross-sectional view of the front end of the hydrostatic radial piston unit according to this application is shown.

[0059] For illustrative and readability purposes only, the same functional parts are indicated by the same reference numerals in all the presented figures.

[0060] Explanation of reference numerals in the attached figures

[0061] 1-Hydrostatic radial piston unit; 3-Housing; 10-Rotating axis; 12-Non-rotating fixed shaft; 13-First groove; 14-Second groove; 15-Axial hole; 20-Non-rotating fixed housing; 22-Annular groove; 24-End side; 25-Extension; 26-Through hole; 28-Axial hole for brake pin; 30-Axial overlap area; 33-First annular passage; 35-Sealing surface; 37-Sealing body; 40-Rotating housing; 42-Front end; 43-Second annular passage; 44-Torque transmission device; 45-Reinforced front cover; 46-Collar portion; 47-Step / Shoulder; 48-Outer peripheral surface; 49-Screw; 50-Cylinder block; 55-Cylinder bore; 60-Working plunger; 65-Roller; 70-Rotary distributor; 71-Disc portion; 72-Distributor spring; 73-Second internal groove; 74-Hollow shaft portion; 75-Axial hole; 77-Timing hole; 78-Synchronizing pin; 80-First cam convex surface; 90-Roller bearing; 100 Parking brake mechanism; 112-Brake disc; 114-Brake pin; 116-Brake piston; 117-Release surface; 118-Disc spring; 120-Dual-speed valve / multi-speed control valve; 130 End cap. Detailed Implementation

[0062] Figure 1 A hydrostatic radial piston unit 1 according to this application is disclosed. The hydrostatic radial piston unit 1 includes: a fixed non-rotating housing 20, the non-rotating housing 20 including a through hole 26 defining a rotation axis 10. The non-rotating housing 20 accommodates a fixed shaft 12, which is coaxially arranged with the rotation axis 10 and anti-torsionally connected to the non-rotating housing 20. A rotating housing 40 is supported by a pair of roller bearings 90, allowing it to rotate about the rotation axis 10 relative to the fixed housing 20. Therefore, the rear end portion of the rotating housing 40 is sealed to the front end portion of the fixed housing 20 by a seal 37. The axial position of the seal 37 is defined by a sealing surface 35 orthogonal to the rotation axis 10. Viewed from the outside, the sealing surface 35 divides the housing 3 of the radial piston unit 1 into a rotating housing portion 40 on one side of the sealing surface 35 and a fixed housing portion 20 on the other side of the sealing surface 35.

[0063] Pairs of roller bearings 90 are arranged on the extension 25 of the fixed housing 20, wherein, according to Figure 1 In the illustrated embodiment, the extension 25 is configured as an additional extension. The extension 25 extends through the sealing surface 35 into the cavity formed by the rotating housing 40. Figure 1In the illustrated embodiment, the roller bearings 90 are arranged in pairs (i.e., substantially adjacent to each other along the axis of rotation) and in an O-type configuration. An O-type bearing configuration is preferred if it is necessary to increase the bearing support spacing (e.g., if a small tilt clearance is required to guide the component) or if large tilting forces must be supported. Otherwise, an X-type configuration or a locating / non-locating bearing arrangement may be chosen.

[0064] According to this application, a pair of bearings 90 are arranged in an axially overlapping region 30, where the fixed portion 20 of the non-rotating housing and the rotating housing 40 overlap. In other words, in the overlapping region 30, the fixed housing 20 and the rotating housing 40 are arranged coaxially, and vice versa. However, the fixed housing 20 and the rotating housing 40 are radially spaced apart from each other. This means that the rotating housing 40 surrounds the fixed housing 20, as is the case in the presented example, or vice versa.

[0065] The rotating housing 40 includes a torque transmission device 44, namely a flange at the outer peripheral surface 48 of the rotating housing. Depending on the application, components may be attached to the flange 44, which may be driven by the hydrostatic radial piston unit 1, or the flange 44 may drive the hydrostatic radial piston unit 1. The torque transmission device 44 is preferably arranged in the same axial position as the paired bearings 90 to reduce axial prying between the bearings 90 and the torque transmission device 49 and thereby eliminate tilting moments that would otherwise occur.

[0066] The rotating housing 40 includes: an inwardly facing cam convex surface 80, and a working plunger 60 that can press against the cam convex surface 80 (see also...). Figure 3 In the presented embodiment, the cam lobe surface 80 is integrally formed with the rotating housing 40, for example, by three-dimensional milling, casting, turning, forging, or other different manufacturing methods. The working plunger 60 is received in the cylinder bore 55 of the cylinder body 50. The cylinder body 50 is designed to be fixed relative to the fixed shaft 12 and the fixed housing 20. Therefore, when the working plunger 60 is pushed / beared against the cam lobe surface 80, a force is generated on the cam lobe surface 80 supported by the fixed cylinder body 50. Due to the shape of the cam lobe, this force causes the rotating housing 40 to rotate.

[0067] To drive the working plunger 60 against the cam lobe surface 80, pressurized fluid is supplied to the cylinder bore 55 of the cylinder body 50. Conversely, if the working plunger 60 is driven radially inward due to conforming to the shape of the cam lobe surface (i.e., the cam), hydraulic fluid is discharged from the corresponding cylinder bore 55. Therefore, the cylinder bore 55 must be alternately connected to the inlet and outlet of the hydrostatic radial plunger unit 1, which is achieved by the rotary distributor 70.

[0068] A rotary distributor 70 (with a T-shaped cross-section) having a disc-shaped portion 711 and a hollow shaft portion 74 is partially arranged in the axially overlapping region 30. Therefore, a pair of bearings 90 can be arranged axially at the same position as the rotary distributor 70, and radially outside the smaller diameter region of the hollow shaft portion 74 of the rotary distributor 70. However, in some designs, the pair of bearings 90 may also be arranged radially inside the hollow shaft portion 74 of the rotary distributor 70.

[0069] Preferably, the rotating housing 40 and the fixed housing 20 seal out the inner cavity. To facilitate the manufacture and installation of the components of the radial plunger unit 1 according to this application, end caps 45, 130 are provided at the rear end side 24 and the front end 42 of the radial plunger unit 1. In addition to its function of sealing the housing cavity, the front cap 45 is designed to reinforce the rotating housing 40 in the radial direction, thereby reinforcing the cam cam surface 80. The front cap 45 comprises a generally flat disc-shaped base from which a hollow cylindrical collar portion 46 extends. Complementing the collar portion 46, a step 47 is provided on the outer circumferential surface 48 of the rotating housing 40. After the front cap 45 is attached to the rotating housing 40, the collar portion 46 provides radial support for the step 47. This additional support ensures that the cam cam surface 80 maintains its shape even when the working plunger 60 presses against the cam cam surface 80. The thickness of the collar portion 46 and the base plate can be selected according to the desired increase in stability.

[0070] Furthermore, the front cover 45 may include a lightweight structure, for example, by providing reinforcing ribs in the main stress areas and cutouts / recesses in the lower stress areas. Those skilled in the art will recognize that the functional principles of the collar portion 46 provided on the front cover 45 and the step provided on the housing 40 can be reversed, such that the front cover 45 may include the step 47 and the housing 40 may include the collar portion 46. However, other stability-enhancing designs capable of absorbing forces acting radially on the rotating housing 40 are also covered by this application. For example, a tenon joint may be provided between the generally flat front cover 45 and the rotating front housing 40.

[0071] In addition to its function of sealing the rear end side 24 of the cavity of the two-part housing of the radial plunger unit 1, the end cap 130 is part of the parking brake mechanism 100 (whose braking mechanism is arranged in the fixed housing 20). The parking brake mechanism 100 includes at least two brake discs 112, one of which is attached to the rotating housing 40 in an anti-torsional manner, and the other is attached to the fixed housing 20 non-rotatably. The brake disc 112 is axially movable relative to the fixed housing 20 and the rotating housing 40. If the parking brake mechanism 100 includes more than two brake discs 112, the brake discs 112 are connected to the fixed housing 20 and the rotating housing 40 in an alternating sequence. The disc spring 118 is supported by the end cap 130 and provides preload to the brake piston 116. As long as the brake piston 116 is not compressed at its release surface 117, the spring force is transmitted via the brake piston 116 to at least one brake pin 114 (the brake pin 114 is arranged in an axial hole 28 in the fixed housing 20).

[0072] Preferably, to provide more balanced brake disc actuation, more than one brake pin 114 is provided. Each brake pin 114 is arranged in one of the circumferentially distributed axial holes 28. At least one brake pin 114 applies / transmits the preload of the disc spring 118 to the brake disc 112, which presses against each other and is supported, for example, by the shoulder of the fixed housing 20 or the extension 25. Thus, relative movement between the rotating housing 40 and the fixed housing 20 can be prevented, for example, when the work vehicle stops.

[0073] If relative movement between the rotating housing 40 and the fixed housing 20 is permitted, hydraulic pressure is applied to the release surface 117 of the brake piston 116, opposite to the disc spring 118. The hydraulic pressure generates a force on the release surface 117 in the direction toward the rear of the fixed housing 20 (i.e., along the direction of the disc spring 118). Since the generated force is opposite to the preload of the disc spring 118, the brake pin 114 is released from the brake disc 112. Thus, relative movement between the brake discs 112 is possible, and consequently, relative movement between the fixed housing 20 and the rotating housing 40 is also possible.

[0074] Preferably, the brake pin 114 has a specific geometry. The end of the brake pin 114 facing the brake piston 116 has a larger diameter than the end facing the brake disc 112. Furthermore, the brake pin 114 is sealed relative to the fixed housing 20 and the fixed shaft 12. Therefore, a pressure chamber is formed between the end face of the brake pin 114 and the housing 20 of the hydrostatic radial piston unit 1. If the brake piston 116 is driven in the direction of the brake disc 112, the brake piston 116 pushes the brake pin 114 against the brake disc 112. In other cases, if pressure is applied to the sealed pressure chamber, a force is generated on the end face of the brake pin 114. Due to the different diameters of the end faces, this pressure generates a force that pushes the brake pin 114 in the direction of the brake piston 116. After the brake pin 114 contacts the brake piston 116, the brake pin 114 causes the brake piston 116 to press against the disc spring 118, thereby releasing the axial force on the brake disc 112.

[0075] However, the concept of this application also encompasses the following: the specific design of the brake pin 114 ensures that the pin 114 is always in contact with the brake piston 116, regardless of whether the release surface is pressurized. In this embodiment, the brake pin 114 is sealed relative to the fixed housing 20 at its end away from the brake piston 116. The rear end of the brake pin 114, having a larger diameter, is received in the brake piston 116, and a seal is provided between the rear end of the brake pin 114 and the brake piston 116. Thus, when the brake piston 116 moves under the force generated by the hydraulic pressure in the pressure chamber (which is formed together by the brake piston 116, shaft 12, the front end of the brake pin 114, and the fixed housing 20), hydraulic pressure can be present at the rear / end face of the brake pin 114. Due to the larger diameter of the end face facing the brake piston 116, the hydraulic pressure generates a greater force on the side away from the brake piston 116, keeping the brake pin 114 in contact with the brake piston 116.

[0076] Figure 2 Showing according to Figure 1 Cross-sectional views of the hydrostatic radial piston unit 1 in different sections. According to Figure 2 The view shows some of the multiple hydraulic passages of the hydrostatic radial piston unit 1 according to this application. At the center of the hydrostatic radial piston unit 1, a non-rotating fixed shaft 12 is provided. The fixed shaft 12 includes a first set of grooves 13 in the region facing the end side 24 of the hydrostatic radial piston unit 1 according to this application. The fixed shaft 12 also includes a second set of grooves 14 in the region facing the front end 42 of the hydrostatic radial piston unit 1. The first set of grooves 13, together with an annular groove 22 provided in the non-rotating fixed housing, forms a first annular passage 33. These first annular passages 33 are used to distribute hydraulic fluid flowing from the inlet of the hydrostatic radial piston unit 1 to the outlet of the hydrostatic radial piston unit 1.

[0077] The second annular passage 43 is formed by the second groove 14 engaging with the second internal groove 73 in the hollow shaft portion 74 of the rotary distributor 70. The first annular passage 33 utilizes a channel arranged in the fixed shaft 12. Figure 2 (Not visible in the middle) The fluid is connected to the second annular passage 43.

[0078] The internal structure of the rotary distributor 70 is from Figure 1 and 2 The rotary distributor 70 can selectively connect the second annular passage 43 to a suitable cylinder bore 55, depending on whether high pressure should be supplied to a particular cylinder bore 55 via a timing orifice or whether hydraulic fluid should be discharged from a particular cylinder bore 55.

[0079] In the embodiment shown in this application, the extension 25 is configured as an additional component attached to the fixed housing 20. In addition to supporting the paired bearings 90, the extension 25 is also provided with a shoulder against which the brake disc 112 can be pressed. Both functions require tight manufacturing tolerances to ensure reliable support and braking of the hydrostatic radial piston unit 1. Achieving these two functions on a relatively small additional component has the advantage of requiring only the machining of a relatively small additional component, eliminating the need for such complex machining of most of the fixed housing 20, which would be necessary if the fixed housing 20 were to provide a shoulder and / or support surface.

[0080] The non-rotating fixed shaft 12 further includes an axial bore 15, which, in the presented example, is arranged coaxially with the rotation axis 10. A two-speed valve 120 is arranged in the axial bore 15. The two-speed valve 120 includes two positions. In the first position, all cylinder bores 55 can be supplied with hydraulic fluid at high pressure. In the second position, only a portion of the cylinder bores 55 can be supplied with hydraulic fluid at high pressure. The other cylinder bores 55 are supplied with a lower pressure sufficient to force the rollers of the working plungers 60 to follow the cam lobe surface. Simultaneously, the cylinder bores 55 supplied with lower pressure can be hydraulically short-circuited. Therefore, in the first position, all cylinder bores 55 contribute to the working volume of the hydrostatic radial plunger unit 1. In the second position, the short-circuited cylinder bores 55 do not contribute to the working volume of the hydrostatic radial plunger unit 1 because for each working plunger 60 that moves outward, another plunger moves inward to the inside of its associated cylinder bore 55.

[0081] In the presented embodiment, the dual-speed valve 120 is hydraulically operated. However, the dual-speed valve 120 may also be mechanically or electromechanically operated. In other embodiments, as those skilled in the art will appreciate, the dual-speed valve 120 may be a multi-speed valve 120 providing more positions to change the rotational speed and torque of the hydrostatic radial piston unit 1 over a wider range.

[0082] Figure 3The image shows a cross-sectional view of the hydrostatic radial piston unit 1 according to this application in a plane orthogonal to the axis of rotation 10. Figure 3 The fixed shaft 12 shown in the middle is anti-torsionally connected to the cylinder body 50. Therefore, the cylinder body 50 is also fixed. The cylinder body 50 includes radially arranged cylinder bores 55, which are equidistantly distributed on the circumferential surface of the cylinder body 50. Each cylinder bore 55 receives a working plunger 60, such that the working plunger 60 can slide radially within the cylinder bore 55. The working plunger 60 includes a roller 65 at its radially outer end. When pressure is supplied to the cylinder bore 55, the roller 65 is pushed to contact a cam cam facet surface 80 formed radially inward on the rotating housing 40. The pressure creates a radially outward force on the working plunger 60. If the rotating housing is driven to rotate, the roller 65 interacts with the cam cam facet surface 80, depending on whether the roller 65 moves from the cam facet to the cam or vice versa. If the roller travels from the cam to the cam (i.e., the cam cam surface shape is radially inward), the roller 65 and the corresponding plunger 60 are driven inward by the shape of the cam cam surface 80, and hydraulic fluid is discharged from the associated cylinder bore 55. Conversely, if the roller travels from the cam to the cam, meaning the cam cam surface 80 shape is radially outward in this region, the roller and the corresponding plunger 60 are driven outward by the pressure within the cylinder bore 55 to follow the cam cam surface.

[0083] Figure 4 An isometric view of the rotating housing 40 for a hydrostatic radial piston unit 1 according to one embodiment of this application is shown. In addition to the features already mentioned, Figure 4 An axial bore 75 is shown, disposed radially inside the cam cam facet surface 80, on a surface perpendicular to the rotation axis 10. The axial bore 75 receives a distributor spring 72, which provides preload to an adjacently arranged rotary distributor 70. The disc-shaped portion 71 of the rotary distributor 70 and the rotating housing 40, combined with the axial bore 75 and the received distributor spring 72, can be rotatably connected using a synchronizing pin 78 disposed in one of the axial bores 75 of the rotating housing 40. Therefore, the rotary distributor 70 and the distributor spring 72 rotate at the same rate.

[0084] according to Figure 1 or Figure 2 Technical personnel in related fields Figure 4 It was found that the axial hole 75 can also be moved to the distributor 70 to be close to the bottom surface of the associated convex corner. Placing the distributor spring 72 in the hole 75 of the distributor 70 can achieve the same function: pressing the disc-shaped part 71 of the distributor 70 against the front surface of the cylinder 50.

[0085] exist Figure 4Also shown is the synchronizing pin 78, arranged on a larger diameter as is customary in this art, which reduces the shearing torque acting on the synchronizing pin 78. These shearing forces are generated during the operation of the hydraulic motor by friction between the outer circumferential surface of the shaft 12 and the inner circumferential surface of the distributor 70, which seals against the surface of the shaft 12 to form an annular distribution channel (see also...). Figure 1 or Figure 2 Here, the synchronizing pin 78 is installed in the axial hole 75 in the front housing 40 and the corresponding hole in the distributor 70.

[0086] Figure 5 A cross-sectional view of a rotating housing 40 is disclosed, in which a rotating distributor 70 is arranged. The outer surface of the disc-shaped portion 71 of the rotating distributor 70 is formed to complement the cam convex surface 80, supporting the function of a synchronizing pin 78 housed within the rotating housing 40. The synchronizing pin 78 ensures that the rotational orientation of the distributor 70 is correct when it is received within the rotating housing 40. Furthermore, the synchronizing pin 78 synchronizes the rotation of the distributor 70 with the rotation of the rotating housing 40. Additionally, how the distributor spring 72 abuts against the bottom of the axial bore 75 and thereby along the direction of the front end 42 (i.e., toward the cylinder block 50) is shown. Figure 5 (Not shown) Squeezing distributor 70. The rotary distributor 70 includes a lightweight design to reduce the rotational inertia of the components. For this purpose, a gap is partially provided at the radially extending disc-shaped portion of the distributor 70. A second internal groove 73 formed at the radially inner side of the distributor 70 is also shown. The second internal groove 73 includes an annular shape and is capable of guiding fluid in and out of a timing hole 77 arranged in the front surface of the distributor 70.

[0087] Figure 6 The illustration shows how the reinforced front cover 45 is attached to the rotating housing 40 using screws (which are equidistantly distributed along an imaginary arc). The combination of the collar portion in the front cover 45, as explained above, and the step in the rotating housing 40 not only reinforces the cam cam surface 80 but also ensures that the cover 45 is precisely centered relative to the rotating housing 40. It should be recognized that other techniques for attaching the cover to the rotating housing are also within the scope of common knowledge for those skilled in the art.

[0088] Based on the foregoing disclosure, accompanying drawings, and claims, it should be recognized that the hydrostatic radial piston unit 1 according to this application provides various feasible solutions and advantages over the prior art. Those skilled in the art will further recognize that further modifications and variations known in the prior art can be made to the radial piston unit 1 according to this application without departing from the spirit of this application. Therefore, all such modifications and variations are within the scope of and covered by the claims. It should be further understood that the above examples and embodiments are for illustrative purposes only, and various modifications, variations, or combinations of embodiments made thereto (which will be suggested by those skilled in the art) are included within the spirit and scope of this application.

Claims

1. A hydrostatic radial piston unit (1) with a cam cam angle structure, comprising: A non-rotating fixed housing (20) includes a through hole (26) that defines the axis of rotation (10) of the hydrostatic radial plunger unit (1). A cylindrical rotating housing (40) is rotatably mounted to the fixed housing (20) in an axial overlap region (30), in which the front end portion of the fixed housing (20) and the rear end portion of the rotating housing (40) overlap, so that the rotating housing (40) can rotate relative to the fixed housing (20) about the rotation axis (10). A parking brake mechanism (100) includes at least two brake discs (112) arranged adjacent to each other in the axial overlap region (30), wherein one brake disc (112) is fixed relative to the fixed housing (20) in the rotational direction and the other brake disc (112) is fixed relative to the rotating housing (40) in the rotational direction. End cap (130) closes the fixed housing (20) on the rear end side (24) of the hydrostatic radial piston unit (1) away from the rotating housing (40). A fixed shaft (12) is coaxially arranged in the inner cavity with the rotation axis (10). The inner cavity is formed by the fixed housing (20), the rotating housing (40), the end cap (130), and the front cover (45). A cylinder (50), non-rotatably housed in the front end portion of the rotating housing (40), is anti-torsionly connected to the fixed shaft (12). The end cap (130) preloads the disc spring (118) against the disc brake piston (116) to generate an axial spring force. The disc spring (118) and the brake piston (116) are both located in the rear end portion of the fixed housing (20). The spring force can be transmitted through the brake piston (116) to at least one brake pin (114) arranged in an axial hole (28) in the fixed housing (20) to press the brake discs (112) against each other when the brake piston (116) opposite to the disc spring (118) is not driven to move toward the end cap (130). The interior of the rotating housing (40) has a cam convex surface (80).

2. The hydrostatic radial piston unit (1) according to claim 1, wherein, The front and rear ends of the at least one brake pin (114) are sealed in the axial hole (28) to form a pressure chamber that can be pressurized to push the brake pin (114) toward the end cap (130) and cause the brake piston (116) to compress the disc spring (118), thereby releasing the clamping force from the brake disc (112).

3. The hydrostatic radial piston unit (1) according to claim 1, wherein, The brake piston (116), the at least one brake pin (114), the fixed shaft (12), and the fixed housing (20) seal out a pressure chamber that can be pressurized to push the brake piston (116) toward the end cap (130) and compress the disc spring (118), thereby releasing the clamping force from the brake disc (112).

4. The hydrostatic radial piston unit (1) according to claim 1, wherein, The at least one brake pin (114) has a larger diameter portion at its end facing the brake piston (116).

5. The hydrostatic radial piston unit (1) according to claim 1, wherein, The fixed housing (20) includes an annular groove (22) on its inner surface, which together with a first groove (13) on the outer surface of the fixed shaft (12) forms a first annular passage (33).

6. The hydrostatic radial piston unit (1) according to claim 5 further includes: A rotary distributor (70) having a disc-shaped portion (71) and a hollow shaft portion (74) is provided. The rotary distributor (70) is arranged around the front end of the fixed shaft (12) by means of the hollow shaft portion (74) and is fixedly housed in the rotating housing (40) in the rotational direction by means of the disc-shaped portion (71). The rotary distributor (70) is connected to a timing hole (77). ） Hydraulic fluid is directed and discharged to the working plunger (60) in the cylinder (50), and the rotary distributor (70) includes a second internal groove (73) inside the hollow shaft portion (74), the second internal groove (73) together with a second groove (14) on the outer surface of the fixed shaft (12) to form a second annular passage (43), the second annular passage (43) being connected to the first annular passage (33) via a fluid passage located in the fixed shaft (12).

7. The hydrostatic radial piston unit (1) according to claim 6, comprising: A pair of roller bearings (90) are used to rotatably mount the rotating housing (40) to the fixed housing (20), wherein the pair of roller bearings (90) are arranged in the axial overlap region (30) between the rotating housing (40) and the fixed housing (20), on the radially outer side of the hollow shaft portion (74) of the rotary distributor (70).

8. The hydrostatic radial piston unit (1) according to claim 7, wherein, The axial overlap region (30) of the front end portion of the radial plunger unit (1) is defined by the extension (25) of the fixed housing (20). The rear end portion of the rotating housing (40) is sealed to the front end portion of the fixed housing (20) by a sealing body (37). The axial position of the sealing body (37) is defined by a sealing surface (35) orthogonal to the rotation axis (10). The extension (25) extends along the rotation axis (10) beyond the sealing surface (35) into the volume of the rotating housing (40) and extends radially between the hollow shaft portion (74) of the rotating distributor (70) and the rotating housing (40). The extension (25) is configured to mate with the inner shell of the paired roller bearing (90).

9. The hydrostatic radial piston unit (1) according to claim 8, wherein, The extension (25) is configured as an additional component and attached to the fixed housing (20).

10. The hydrostatic radial piston unit (1) according to claim 1, further comprising: A fixed multi-speed control valve (120) is available to switch between a first position and a second position, wherein in the first position all cylinder bores (55) are available to be supplied with high-pressure hydraulic fluid from the high-pressure inlet of the hydrostatic radial piston unit (1), and in the second position only a portion of the cylinder bores (55) are available to be supplied with high-pressure fluid, and in the second position, the pairs of cylinder bores (55) are hydraulically short-circuited.

11. The hydrostatic radial piston unit (1) according to claim 10, wherein, The fixed multispeed control valve (120) is arranged in the axial hole (15) in the fixed shaft (12), wherein the axial hole (15) in the fixed shaft (12) is arranged coaxially with the rotation axis (10).

12. The hydrostatic radial piston unit (1) according to claim 10, wherein, The fixed multi-speed control valve (120) is a two-speed control valve (120) or a three-speed control valve (120).

13. The hydrostatic radial piston unit (1) according to any one of claims 1 to 12, wherein, The cam convex surface (80) that the working plunger (60) in the cylinder (50) can act on is integrally formed with the rotating housing (40).

14. The hydrostatic radial piston unit (1) according to claim 6, wherein, The disc-shaped portion (71) of the rotary distributor (70) is biased against the side surface of the cylinder body (50) by a distributor spring (72), the distributor spring (72) being axially housed in the rotary housing (40) or in the disc-shaped portion (71) of the rotary distributor (70).

15. The hydrostatic radial piston unit (1) according to claim 14, wherein, The distributor spring (72) is housed in an axial hole (75) in the rotating housing (40), which is located at a recess in the cam convex surface (80).

16. The hydrostatic radial piston unit (1) according to claim 13, wherein, The cylinder block (50) includes more than one row of cylinder bores that receive radially reciprocating working plungers (60) that are adjacent in the circumferential direction and are capable of interacting with the cam cam surface (80).

17. The hydrostatic radial piston unit (1) according to any one of claims 1 to 12, wherein, The front cover (45) is attached to the front end (42) of the rotating housing (40) away from the fixed housing (20) and closes the rotating housing (40), wherein the front end (42) of the rotating housing (40) and the front cover (45) are configured such that the front cover (45) can at least partially absorb the force acting on the rotating housing (40).

18. The hydrostatic radial piston unit (1) according to claim 17, wherein, The force includes forces in the radial direction.

19. The hydrostatic radial piston unit (1) according to claim 17, wherein, The front cover (45) includes a sleeve-shaped collar portion (46) and the rotating housing (40) includes a complementary shoulder portion (48), or the rotating housing (40) includes a sleeve-shaped collar portion and the front cover (45) includes a complementary shoulder portion.

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