HYDRAULIC BEARING BUSHING

Description

[0001] The invention relates to a method for manufacturing a hydraulic bearing bushing, in particular for railway bogies, wherein the hydraulic bearing bushing has the following features: an inner bushing for receiving a bearing journal, an annular rubber body which substantially comprises the inner bushing and is vulcanized over its outer circumference, and two annular support rings vulcanized to both axial ends of the rubber body, preferably made of metal, an outer annular housing on whose inner circumference the support rings are supported, preferably at the two axial ends of the outer annular housing, and at least two chambers formed in the circumferential direction between the annular rubber body and the annular housing, each extending over partial regions of the circumference and fillable with a hydraulic fluid, wherein the chambers are connected to each other via at least one equalization and throttling channel, wherein the inner bushing consists of at least two coaxially nested hollow cylindrical bodies and the equalization and throttling channel is formed essentially in the connection area (contact area) of the hollow cylindrical bodies, wherein the equalization and throttling channel runs helically over at least a partial length of the inner bushing, wherein the annular rubber body seals the coaxially nested hollow cylindrical bodies to the outside, wherein the rubber body has passages or channels for connection between the equalization and throttling channel provided in the connection area of ​​the hollow cylindrical bodies and the respective fillable chamber.

[0002] Hydraulic bearing bushings of this type, used to influence and / or adjust the damping behavior of bearings on vehicles, particularly rail vehicles, are already known in various designs. These bearing bushings, also known as wheelset guide bushings, are used for the elastic mounting of moving parts, such as components of a vehicle's running gear, especially a rail vehicle.

[0003] Typically, such a rubber-metal bearing consists of an inner rubber-metal element encased in a metal sleeve. The outer metal sleeve is connected to the vehicle's body, for example, while the inner rubber-metal element accommodates a pin that belongs to a part of the chassis.

[0004] Between the elastomeric / rubber part of the rubber-metal element and the metal sleeve as the housing element, chambers extending over partial areas of the circumference and fillable with hydraulic fluid are arranged, often kidney-shaped over a portion of the bearing's circumference. These fillable chambers are interconnected or connected to a compensating chamber by at least one connecting channel.

[0005] When the hydraulic bushing is under load, the compression of the rubber component reduces the size of one chamber, causing some of the hydraulic fluid in that chamber to flow through the connecting channel into the other chamber or into the compensating chamber. The connecting channel then acts as a hydraulic throttle, specifically as a throttle channel. The flow through this specially designed throttle channel generates dissipation and thus damping work.

[0006] A hydraulic fluid is thus provided in chambers arranged approximately diametrically opposite each other and at least partially surrounded by the rubber-elastic material to provide further vibration-absorbing properties. The connecting channel, with its throttling function, serves as a vibration damper or to provide dynamic stiffness in the corresponding load direction.

[0007] The damping characteristics of such hydraulic bushings are frequency-dependent due to their design. Typically, low-frequency vibrations, i.e., vibrations with frequencies below approximately 2 Hz, which generally occur with amplitudes of approximately 10 mm, are strongly damped, while high-frequency vibrations, i.e., vibrations in the frequency range above this value, pass through almost undamped due to the inertia and incompressibility of the hydraulic fluid and the rubber spring. These properties are utilized by adjusting the damping and stiffness of the connecting channel in a frequency-dependent manner.

[0008] The elastic behavior, based on the vibrational behavior of a hydraulic fluid column, can be adjusted in terms of stiffness and damping along the length of the connecting channel. With a long overflow channel, forces originating from the bushing can only be transmitted sufficiently well from one chamber to the other via the hydraulic fluid and the overflow channel if the time interval between impacts or vibrations is large, i.e., the frequency of the vibrations is low. If, on the other hand, the mechanical loads occur at a high frequency, the inertia and incompressibility of the hydraulic fluid, the available channel cross-section, and the channel length prevent the flow through or overflow channel from the connecting or overflow channel from occurring quickly enough between two successive impacts to provide elasticity through an overflow from the loaded chamber to the unloaded chamber.

[0009] This effect is used, for example, in rail vehicles to provide greater stiffness at high speeds, where there is a rapid succession of irregularities on the track and the resulting mechanical shocks occur. This ensures safe operation at high speeds through a rigid bearing structure and thus prevents excessive flex.

[0010] At low speeds, i.e., when cornering and the like, low stiffness is advantageous, and the corresponding flexibility is achieved by allowing the hydraulic fluid column to be transferred from one chamber to the other between two successive impacts. The cutoff frequency, which distinguishes the stiff behavior from the damping behavior of a soft bearing, is determined by the channel length such that the longer the overflow channel, the lower the cutoff frequency above which a stiff bearing with a hard bushing is observed.

[0011] In the prior art, hydraulic wheelset guide bushings are known that consist of a metal-rubber body for achieving static stiffness and two integrated chambers with a connecting channel. Fluid is exchanged through this defined connecting channel, resulting in a dynamic stiffness that varies at different frequencies, for example, in the direction of travel. The current state of the art describes a hydraulic wheelset guide bushing consisting of a metal-rubber body for achieving static stiffness and two integrated chambers with a connecting channel. Fluid is exchanged through this defined connecting channel, resulting in a dynamic stiffness that can be varied at different frequencies as desired, in the direction of travel.

[0012] German patent application DE 103 10 633 A1 describes a bushing for a bearing for the elastic connection of parts of a running gear. The bushing, intended particularly for railway vehicles, has an inner housing around which an outer housing is radially spaced to form an annular gap. Within this annular gap is a rubber-elastic element that defines two diametrically opposed chambers filled with a hydraulic fluid and connected to each other via an overflow channel designed as a vibration damper. The overflow channel can be helical and run along the outer and / or inner circumference of the bushing or its housing parts, but at least partially passes through either the inner or outer part of the bearing.

[0013] A preferred embodiment of the bushing is characterized by the fact that the overflow channel is formed between an inner wall of the inner housing part and a groove that is approximately helical and cut into an outer surface of a bolt-shaped element enclosed by the bushing. Cutting grooves on the outer surface of the bearing bolt, such as a circumferential groove on a control arm bolt of an axle link, is complex and partially shifts the function or design of the bearing into the design of the axle link itself. This makes replacing or replacing the bearing more difficult.

[0014] Document US4763884 also discloses a generic bearing bushing.

[0015] The invention therefore aims to design the generic bearing bushing in such a way that a dynamic stiffness behavior can be easily specified by changing the length of the connecting channel. The hydraulic bearing bushing should achieve soft stiffnesses in the low frequency range and high stiffnesses in the direction of travel at defined higher frequencies. It should also achieve cost-effective manufacturing by avoiding notch effects in load-bearing components, thereby allowing the use of inexpensive materials, simple designs, and simple manufacturing processes. The hydraulic wheelset guide bushing should achieve soft stiffnesses at low frequencies and high stiffnesses at higher frequencies in the direction of travel.

[0016] The problem is solved by a special manufacturing process for the hydraulic bearing bushing.

[0017] The inner bushing consists of at least two coaxially nested hollow cylindrical bodies, and the compensating and throttling channel is essentially formed in the connection area, i.e., in the contact area of ​​the hollow cylindrical bodies. The design of such a connection channel allows for very simple variants for varying static and dynamic stiffnesses, since the contact areas—that is, the surfaces of the hollow cylindrical bodies facing each other—can be easily machined before assembly. For example, grooves can be machined into the surfaces, or raised or recessed areas can be created, which, after assembly, form cavities through which a compensating and throttling channel is formed. A "common parts principle" can also be easily implemented here, for example, by using one of the hollow cylindrical bodies identically for different bearing types.

[0018] This also allows for very simple variants for variable static and dynamic stiffnesses.

[0019] The inner bushing consists of a hollow cylindrical body with a pressed-on outer sleeve, preferably a metallic bushing with an outer plastic sleeve. Such a plastic sleeve can be easily machined using an abrasive or forming process as described above and can then simply be pressed / slid onto the metallic bushing. Following the principle of identical parts, for example, the inner metallic bushing can remain the same, while the plastic sleeve can be adapted as needed.

[0020] The compensating and throttling channel is designed as a recess or depression in the inner surface of the respective outer hollow cylindrical body or sleeve. As explained above, this design allows for simple manufacturing of the compensating or throttling channel.

[0021] The compensating and throttling channel runs helically over at least a portion of the inner bushing. This allows for a wide range of channel length adjustments, thus affecting the damping. The connecting channel can be designed, for example, as a flat screw or as a series of interlocking screws. This allows for a space-saving arrangement of the connecting channel, as well as a design that is essentially arc-shaped or consists of arc-shaped sub-channels. For example, the respective ends of the channel system can be connected to the two opposing chambers by two or more channels.

[0022] The ring-shaped rubber body seals the coaxially nested hollow cylindrical bodies to the outside. The rubber body features passages or channels for connecting the compensating and throttling channel located in the junction area of ​​the hollow cylindrical bodies to the respective fillable chamber. Due to the vulcanization and bonding of the two hollow cylindrical bodies—for example, a plastic sleeve and a metallic inner ring—no additional sealing of the channel system is required. This ensures a consistent seal of the channel system both internally and externally. Simple, air-free filling is also possible.

[0023] Such a design is particularly suitable in combination with an advantageous method for manufacturing a hydraulic bearing bushing, in which the inner bushing is formed from an inner hollow cylindrical body with a pressed-on outer plastic sleeve, on the inner surface of which the compensating and throttling channel is formed as a recess or depression, characterized in that the outer plastic sleeve is produced by a 3D printing process, then pressed onto the inner hollow cylindrical body and afterwards the annular rubber body is vulcanized on.

[0024] As already explained, the application of the hydraulic bearing bushing manufactured according to the invention as a wheelset guide bushing within a chassis for a rail vehicle is particularly advantageous. Here, with a component of very small dimensions, it is possible to significantly influence the stiffness depending on the frequency of the acting loads / forces.

[0025] Further advantages arise from the very simple modification of the kidney-shaped chambers and their relationship to the rubber-metal component or the rubber pad geometry. Likewise, the dynamic stiffness and the stiffness ratio (Cstatic to Cdynamic) can be easily varied. Depending on the required dynamic stiffness, multiple channel layers, channel cross-sections, and various channel lengths are possible within the channel system. The use of materials such as aluminum or plastic is also possible.

[0026] Furthermore, different liquids with varying viscosities can be used. Due to its temperature insensitivity, glycol is currently used. The design according to the invention also allows for simple, cost-effective, and yet process-reliable assembly.

[0027] The static stiffness of the hydraulic bearing bushing can be varied by modifying the kidneys, i.e., the fillable hydraulic chambers and the rubber pad geometry. Depending on the required dynamic stiffness, different channel cross-sections and lengths are possible within the channel system. Furthermore, the use of various hydraulic fluids with different viscosities at defined temperatures is possible. Filling is achieved through a suitable filling bore using a filling device, possibly even under vacuum.

[0028] The invention will be explained in more detail using an exemplary embodiment.

[0029] Fig. 1 Figure 1 shows a hydraulic bearing bushing 1 for a rail bogie (not shown in detail here). The hydraulic bearing bushing has an inner bushing 2 for receiving a bearing journal 12, as well as an annular rubber body 3, which essentially encompasses the inner bushing 2 and is vulcanized to it over its outer circumference, and two annular metallic support rings 4 and 5 vulcanized to both axial ends of the rubber body.

[0030] The hydraulic bearing bushing also has an outer annular housing 6, on the inner circumference of which, namely at the two axial ends of the housing, the support rings 4 and 5 are supported and fixed with corresponding retaining rings.

[0031] The Fig. 1The figure also shows that the hydraulic bearing bushing 1 has two chambers 7 and 8, formed circumferentially between the annular rubber body and the annular housing. Each chamber extends over partial areas of the circumference and can be filled with hydraulic fluid. These chambers are connected to each other via a compensating and throttling channel 9. The direction of travel 14 lies in or parallel to the vertical axis of the drawing, and the kidney-shaped chambers are deformed to a greater or lesser extent by radial forces during operation of the bearing bushing, allowing the hydraulic fluid contained therein to flow into the other chamber via the compensating and throttling channel 9. The inner bushing 2, or in this case the outer sleeve 10 of the inner bushing 2, naturally has corresponding inlet bores 13 that connect the respective channel inlets to the corresponding chambers.The rubber body 3 naturally also has corresponding bores and inlets that correspond to the inlet bores 13.

[0032] In the embodiment according to the invention, the inner bushing 2 consists of two coaxially interlocked hollow cylindrical bodies, namely a metallic bushing 11 provided with an outer plastic sleeve 10.

[0033] The compensating and throttling channel 9 is formed as a recess in the inner surface of the plastic sleeve 10 and runs helically over a portion of the inner bushing. The compensating and throttling channel 9 is thus essentially located in the connection or contact area between the plastic sleeve 10 and the metallic bushing 11. Reference symbol list:

[0034] 1 Hydraulic bearing bushing 2 Bushing 3 Rubber body 4 Support ring 5 Support ring 6 Ring-shaped housing 7 Fillable chamber 8 Fillable chamber 9 Compensation and throttling channel 10 Plastic sleeve 11 Metal bushing 12 Bearing pin 13 Inlet bore 14 Direction of travel

Claims

1. A method for the manufacture of a hydraulic bearing bushing, in particular for rail running gear, wherein the hydraulic bearing bushing has the following characteristics:-an inner bushing (2) to accommodate a bearing pin (12),- a ring-shaped rubber body (3) which substantially encompasses the inner bushing (2) and is vulcanized over its outer circumference, and - two annular support rings vulcanized at both axial ends of the rubber body (4, 5), preferably of metal, - an outer ring-shaped housing (6), on the inner circumference of which the support rings (4, 5) are supported, preferably at the two axial ends of the outer ring-shaped housing, as well as at least two chambers formed in the circumferential direction between the ring-shaped rubber body (3) and the ring-shaped housing (6), each extending over parts of the circumference and being filled with a hydraulic fluid (7, 8), wherein the chambers (7, 8) are connected to each other via at least one compensating and throttling channel (9), wherein the inner bushing (2) consists of at least two hollow cylindrical bodies (10, 11) coaxially joined into each other and the compensating and throttling channel (9) is formed essentially in the connecting region (contact area) of the hollow cylindrical bodies (10, 11), wherein the compensating and throttling channel (9) are helically shaped over at least one part length of the inner bushing (2) , wherein the ring-shaped rubber body (3) seals the coaxially interconnected hollow cylindrical bodies (10, 11) outwards, wherein the rubber body has passages or channels for the connection between the compensating and throttling channel (9) provided in the connection area of the hollow cylindrical bodies and the respective fillable chamber (7, 8), in which the inner bushing is formed from an inner hollow cylindrical body with a pressed-on outer plastic sleeve, on the inner surface of which the equalization and throttle channel is formed as a recess or recess, characterized in that the outer plastic sleeve is produced by a 3D printing process, then pressed onto the inner hollow cylindrical body and then the ring-shaped rubber body is vulcanized.