A disc-type hydraulic rotary joint

Abstract

The application discloses a disc type hydraulic rotary joint and belongs to the technical field of hydraulic transmission. The disc type hydraulic rotary joint comprises an inner ring, an outer ring, a bearing, a circumferential combined sealing assembly and a self-heat-dissipation structure. The inner ring and the outer ring are coaxially arranged and can rotate relative to each other. A radial hydraulic flow channel is arranged between the inner ring and the outer ring. The hydraulic flow channel comprises an oil supply channel and an oil return channel. The bearing is arranged between the inner ring and the outer ring and serves as a rotary support. The circumferential combined sealing assembly is arranged between the inner ring and the outer ring and serves as a dynamic seal. The self-heat-dissipation structure is arranged on a shell of the outer ring. The radial flow channel layout compresses the axial dimension. The oil storage groove and the oil storage hole are arranged, and the self-lubricating sealing material is designed to inhibit dry grinding of the dynamic seal. The self-heat-dissipation structure actively controls temperature. The multiple features cooperatively form a complete technical closed loop, and the compactness, reliability and service life of the rotary joint are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of hydraulic transmission technology, specifically to a disc-type hydraulic rotary joint, which is particularly suitable for applications with stringent requirements for installation space, sealing reliability, thermal management, and rotational accuracy, such as hydraulic systems for electronic device antenna mounts and rotary joints for engineering machinery. Background Technology

[0002] Hydraulic rotary joints are key components for enabling continuous transmission of hydraulic oil between relatively rotating parts. In existing technologies, mainstream products generally adopt a "shoulder-sleeve" structure, characterized by: a rotating shaft nested within a fixed sleeve, hydraulic flow channels arranged axially along the device, deep groove ball bearings for support, and dynamic seals relying on mechanical seals or rubber-plastic seals.

[0003] However, as hydraulic systems develop towards higher pressure and greater integration, traditional structures have revealed the following inherent defects: First, the axial flow channel layout, based on physical principles, makes it difficult to compress the axial dimensions of the joints, failing to meet the extreme requirements of modern equipment for installation space height (low profile); second, to withstand complex radial and axial loads, large-sized or paired bearings are often required, contradicting the goal of compact design; third, traditional sealing structures are prone to severe wear under dry friction or poor lubrication conditions, leading to seal failure; in addition, there is a lack of effective solutions to the problem of frictional heat accumulation, and heat-induced seal failure has become a key bottleneck restricting reliability.

[0004] To address the aforementioned issues, there is an urgent need in this field for an integrated solution that is compact, reliably sealed, and capable of thermal management. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: how to solve the problems of the difficulty in compressing the axial dimension of the joint in the prior art, the inability to meet the extreme requirements of modern equipment for the height direction of the installation space (low profile) and the failure of sealing, and to provide a disc hydraulic rotary joint.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution: The present invention includes an inner ring, an outer ring, a bearing, a circumferential combined sealing assembly, and a self-heating structure; the inner ring and the outer ring are coaxially arranged and can rotate relative to each other, and a radially arranged hydraulic flow channel is provided between the inner ring and the outer ring, the hydraulic flow channel including an oil supply channel and an oil return channel; the bearing is disposed between the inner ring and the outer ring as a rotational support; the circumferential combined sealing assembly is disposed between the inner ring and the outer ring as a dynamic seal; the self-heating structure is disposed on the shell of the outer ring.

[0007] Furthermore, the circumferential combined sealing assembly consists of three sets, arranged radially in sequence, and respectively located on both sides of the oil supply channel and the inner side of the oil return channel.

[0008] Furthermore, the inner ring, outer ring, and three sets of circumferential sealing components form two annular cavities, namely an oil supply cavity and an oil return cavity. The oil supply cavity and the oil return cavity are arranged parallel to each other and spaced apart in the radial direction. The high-pressure inlet of the oil supply cavity is located on the inner ring, and the high-pressure outlet is located on the outer ring. The low-pressure inlet of the oil return cavity is located on the outer ring, and the low-pressure outlet is located on the inner ring.

[0009] Furthermore, the circumferential combined sealing assembly includes a circumferential combined sealing ring, an oil reservoir, an oil reservoir hole, a sealing groove, and a contact portion on the outer ring that contacts the circumferential combined sealing ring. The circumferential combined sealing ring is disposed within the sealing groove, which is located on the inner ring. The oil reservoir is disposed on the side of the circumferential combined sealing ring adjacent to the sealing interface. The oil reservoir hole is located on the surface of the oil reservoir near the circumferential combined sealing ring and communicates with the oil reservoir. The oil reservoir holes are evenly distributed along the circumference of the oil reservoir.

[0010] Furthermore, the disc-type hydraulic rotary joint also includes a first overflow chamber, a second overflow chamber, a first overflow pipe, and a second overflow pipe. The first overflow pipe is connected to the circumferential combined sealing assembly on the outside of the oil supply channel and the first overflow chamber, and the second overflow pipe is connected to the circumferential combined sealing assembly on the inside of the oil return channel and the second overflow chamber.

[0011] Furthermore, the inner ring has an upper fork at the top and a lower fork at the bottom, and the upper and lower forks are perpendicular to each other in the axial direction and do not contact each other.

[0012] Furthermore, the self-heating structure includes a coolant flow channel, a fin structure, a coolant inlet, and a coolant outlet. The coolant flow channel is located inside the outer ring shell, and the fin structure is located inside the coolant flow channel. The coolant inlet and coolant outlet are located on the outer ring shell and communicate with the coolant flow channel. The coolant flow channel is an annular spiral flow channel, and the fin structure is a plate-shaped fin, integrally formed with the outer ring shell.

[0013] Furthermore, the coolant flow channels and the hydraulic flow channels are arranged radially in space, and the coolant flow channels are located at the outermost edge of the radial space without increasing the radial envelope dimension and axial dimension of the disc hydraulic rotary joint.

[0014] Furthermore, the ratio of the axial profile height to the radial diameter of the disc-type hydraulic rotary joint is less than 1:3.

[0015] Furthermore, the bearing is a single-row crossed cylindrical roller bearing with a thin-walled structure, and its axial thickness is less than 1 / 7 of the bearing's radial inner diameter.

[0016] The present invention has the following advantages over the prior art:

[0017] 1. Revolutionary structural compactness. By changing the hydraulic flow channels to a radial arrangement (high-pressure oil supply channels and low-pressure oil return channels are arranged in parallel radial directions) and combining them with thin-walled single-row crossed cylindrical roller bearings, the axial dimension of the joint is fundamentally reduced. In a typical embodiment, the ratio of axial profile height to radial diameter is less than 1:3, reducing the axial dimension by more than 35% compared to the traditional bushing structure, allowing it to be directly embedded in low-profile spaces.

[0018] 2. Multi-layer adaptive self-lubricating dynamic seal protection with strong dry friction suppression capability. Three sets of circumferential combined sealing components are arranged radially to form independent sealing protection for high-pressure and low-pressure oil. Each sealing component is equipped with an oil reservoir and an oil reservoir hole. During start-up, shutdown, or poor lubrication, the working medium stored in the oil reservoir is slowly released to the corresponding circumferential combined sealing component, forming a lubricating film at the sealing interface to maintain lubrication and significantly reduce starting torque and wear rate.

[0019] 3. Active thermal management with controllable temperature rise. The self-heating structure integrated into the housing rapidly dissipates heat generated by sealing friction through the synergistic effect of coolant channels and fins. The coolant channels are arranged near the sealing installation area to achieve "precise cooling." Tests show that under the same operating conditions, the joint with the integrated self-heating structure can reduce the operating temperature of its sealing interface by more than 40%, fundamentally inhibiting thermal aging and thermal wear.

[0020] 4. Dual leakage prevention mechanism. The first overflow chamber is located between the first circumferential combined sealing assembly and the bearing, and the second overflow chamber is located between the two sets of dynamic seals in the third circumferential sealing assembly. When a trace amount of medium penetrates the two sets of main seals, it can be guided out through the corresponding overflow chamber and overflow pipe, and then recycled and reused after passing through the filter device, preventing the medium from accumulating and leaking to the outside, thus forming secondary protection.

[0021] 5. Integrated torque transmission and angle limiting. The coordinated design of the upper and lower shift forks achieves torque transmission and relative rotation angle limiting without adding extra components, further enhancing integration.

[0022] 6. The synergistic effect of various features forms a virtuous cycle: the oil reservoir provides localized lubrication, reducing heat generation → the self-heating structure removes excess heat → the sealing material maintains its performance → the oil reservoir remains effective → wear is further reduced. This positive cycle stands in stark contrast to the vicious cycle of "wear → increased heat generation → aggravated wear" in existing technologies. Attached Figure Description

[0023] Figure 1 This is a first three-dimensional structural schematic diagram of the disc-type hydraulic rotary joint described in this invention;

[0024] Figure 2This is a schematic diagram of the second three-dimensional structure of the disc-type hydraulic rotary joint described in this invention;

[0025] Figure 3 This is a bottom view of the disc-type hydraulic rotary joint described in this invention.

[0026] Figure 4 This is a top view of the disc-type hydraulic rotary joint described in this invention.

[0027] Figure 5 for Figure 3 Sectional view at point AA;

[0028] Figure 6 for Figure 3 Sectional view at point BB;

[0029] Figure 7 for Figure 6 A partially enlarged structural diagram of the first circumferential sealing assembly.

[0030] Figure 8 for Figure 6 Sectional view at CC;

[0031] Figure 9 for Figure 8 A partially enlarged structural diagram of the first oil storage hole in the middle section;

[0032] Figure 10 This is a schematic diagram illustrating the hydraulic oil flow principle during the operation of the disc-type hydraulic rotary joint of the present invention.

[0033] The numbers in the diagram represent:

[0034] 1-Inner ring; 2-Outer ring; 3-Bearing end cap; 4-Bearing; 5-Locking nut; 6-First circumferential combined sealing assembly; 7-Second circumferential combined sealing assembly; 8-Third circumferential combined sealing assembly; 9-Rotary oil seal; 10-Static sealing ring; 11-Adjusting shim; 12-Connecting assembly; 13-Center hole; 14-Mounting hole; 101-High pressure inlet; 102-Low pressure outlet; 103-Upper shift fork; 104-Lower shift fork; 105-First Overflow chamber; 106-Second overflow chamber; 107-First overflow pipe; 108-Second overflow pipe; 201-High pressure outlet; 202-Low pressure inlet; 203-Coolant inlet; 204-Coolant outlet; 205-Coolant flow channel; 206-Fin structure; 301-Oil supply chamber; 302-Oil return chamber; 601-First circumferential combined sealing ring; 602-First oil reservoir; 603-First oil reservoir hole; 604-First sealing groove. Detailed Implementation

[0035] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0036] like Figures 1 to 9 As shown, this embodiment provides a technical solution: a disc-type hydraulic rotary joint, including an inner ring 1 and an outer ring 2 coaxially arranged and rotatable relative to each other. The inner ring 1 is provided with a high-pressure inlet 101 (hydraulic oil), a low-pressure outlet 102 (hydraulic oil), an upper shift fork 103, a lower shift fork 104, a first overflow chamber 105, a second overflow chamber 106, a first overflow pipe 107, and a second overflow pipe 108. The outer ring 2 is provided with a high-pressure outlet 201 (hydraulic oil) and a low-pressure inlet 202 (hydraulic oil).

[0037] The inner ring 1 and the outer ring 2 are supported by a bearing 4 to achieve relative rotation between the inner ring 1 and the outer ring 2, while ensuring the relative position between the inner ring 1 and the outer ring 2 is limited. The inner ring of the bearing 4 is pressed by a locking nut 5 with a set screw, and the outer ring of the bearing 4 is pressed by a bearing end cover 3 equipped with a rotating oil seal 9 and a static sealing ring 10 and an adjusting shim 11. The outer ring 2 and the bearing end cover 3 are connected as a whole by a connecting assembly 12. The connecting assembly 12 can use a reasonable structure such as screws to achieve the connection state between the outer ring 2 and the bearing end cover 3.

[0038] Several circumferential combined sealing components (first circumferential combined sealing component 6, second circumferential combined sealing component 7 and third circumferential combined sealing component 8) are provided at the contact position between the inner ring 1 and the outer ring 2 to ensure the sealing of the space between the inner ring 1 and the outer ring 2.

[0039] The outer ring 2, inner ring 1, first circumferential combined sealing assembly 6, second circumferential combined sealing assembly 7 and third circumferential combined sealing assembly 8 form two annular cavities—oil supply cavity 301 and oil return cavity 302. The oil supply cavity 301 and oil return cavity 302 are arranged parallel and spaced apart in the radial direction.

[0040] In this embodiment, the high-pressure inlet 101, the oil supply chamber 301 and the high-pressure outlet 201 form a connected oil supply channel; the low-pressure inlet 202, the oil return chamber 302 and the low-pressure outlet 102 form a connected oil return channel; the oil supply channel is arranged radially outside the oil return channel, and the two channels are independent of each other.

[0041] It should be noted that the positions of the high-pressure inlet 101 and the low-pressure outlet 102 can be set to appropriate dimensions according to the actual usage; that is, the high-pressure inlet 101 and the low-pressure outlet 102 can be set at any relative position where the disc hydraulic rotary joint will not interfere with each other.

[0042] It should be noted that the positions of the high-pressure outlet 201 and the low-pressure inlet 202 can be set to appropriate dimensions according to the actual usage; that is, the high-pressure outlet 201 and the low-pressure inlet 202 can be set at any relative position where the disc hydraulic rotary joint will not interfere with each other.

[0043] In this embodiment, the circumferential combined sealing assembly is configured as three sets: a first circumferential combined sealing assembly 6, a second circumferential combined sealing assembly 7, and a third circumferential combined sealing assembly 8, arranged radially in sequence. These are respectively located on both sides of the (high-pressure) oil supply channel and on the inner side of the low-pressure oil return channel to ensure the sealing of the space between the inner ring 1 and the outer ring 2. The first circumferential combined sealing assembly 6 is located on the outermost ring of the inner ring 1, i.e., on the side of the oil supply chamber 301 closest to the bearing 4, and the third circumferential combined sealing assembly 8 is located on the innermost ring of the inner ring 1, i.e., on the side of the oil return chamber 301. 2. On the side near the central hole 13; the first circumferential combined sealing assembly 6 and the third circumferential combined sealing assembly 8 prevent the oil supply chamber 301 and the oil return chamber 302 from communicating with the outside atmosphere; the second circumferential combined sealing assembly 7 is located between the oil supply chamber 301 and the oil return chamber 302 to prevent communication between the oil supply chamber 301 and the oil return chamber 302; through the setting of the first circumferential combined sealing assembly 6, the second circumferential combined sealing assembly 7 and the third circumferential combined sealing assembly 8, the independent sealing effect of the oil supply chamber 301 and the oil return chamber 302 is guaranteed.

[0044] In this embodiment, the first overflow pipe 107 is connected to the first circumferential combined sealing assembly 6 and the first overflow cavity 105; the second overflow pipe 108 is connected to the third circumferential combined sealing assembly 8 and the second overflow cavity 106; it is used to indicate the leakage status of the first circumferential combined sealing assembly 6 and the third circumferential combined sealing assembly 8, that is, the leakage medium of the first circumferential combined sealing assembly 6 and the third circumferential combined sealing assembly 8 is collected by the first overflow cavity 105 and the second overflow cavity 106 respectively, and further discharged through the guiding effect of the first overflow pipe 107 and the second overflow pipe 108 after flowing through the filter device for recycling and reuse, so as to prevent the medium from accumulating and leaking to the outside.

[0045] In this embodiment, the first circumferential combined sealing assembly 6, the second circumferential combined sealing assembly 7, and the third circumferential combined sealing assembly 8, taking the first circumferential combined sealing assembly 6 as an example, mainly includes a first circumferential combined sealing ring 601, a first oil storage groove 602, a first oil storage hole 603, and a first sealing groove 604 disposed on the inner ring 1, and a contact part on the outer ring 2 that contacts the first circumferential combined sealing ring 601, the contact part being reinforced.

[0046] In this embodiment, taking the first circumferential combined sealing assembly 6 as an example, the first oil reservoir 602 and the first oil reservoir 603 are provided to store a certain amount of working medium, so as to improve the self-lubrication and self-adaptive performance of the first circumferential combined sealing ring 601, so as to be suitable for operating conditions such as when there is no working medium. The first circumferential combined sealing ring 601 is installed in the first sealing groove 604; the first oil reservoir 602 is provided on the side of the first circumferential combined sealing ring 601 adjacent to the sealing interface; a plurality of first oil reservoirs 603 are provided on the surface of the first sealing groove 604 near the first circumferential combined sealing ring 601, and the first oil reservoirs 603 are connected to the first oil reservoir 602.

[0047] In this embodiment, the first oil storage hole 603 is a countersunk hole structure to facilitate smoother release of the medium. It is evenly distributed circumferentially along the first oil storage groove 602 to store and release the lubricating medium to reduce dry friction.

[0048] In this embodiment, the first circumferential combined sealing ring 601 includes a toothed sealing ring with a self-compensating elastomer and a self-lubricating material, so as to further enhance the adaptive self-lubricating ability of the first circumferential combined sealing ring 601.

[0049] In this embodiment, bearing 4 is a thin-walled single-row crossed cylindrical roller bearing with an axial thickness less than 1 / 7 of the radial inner diameter of bearing 4, in order to reduce the axial dimension of the joint.

[0050] In this embodiment, the inner ring 1 of the disc hydraulic rotary joint is generally connected to the stationary ring. The upper fork 103 at the top of the inner ring 1 and the lower fork 104 at the bottom of the inner ring 1 are arranged perpendicularly in the axial direction and do not contact each other, which are used to transmit torque or limit the relative rotation angle. The outer ring 2 of the disc hydraulic rotary joint is generally connected to the moving ring. Its external interface is set on the bearing end cover 3. The bearing end cover 3 is provided with a certain number of mounting holes 14 evenly distributed along the circumference for external connection.

[0051] It should be noted that when the inner ring 1 is connected to the stationary ring, the outer ring 2 is connected to the moving ring; when the inner ring 1 is connected to the moving ring, the outer ring 2 is connected to the stationary ring.

[0052] In this embodiment, the outer ring 2 has a self-heating structure integrated on its shell. The self-heating structure includes: a coolant channel 205 disposed within the shell; a fin structure 206 disposed within the coolant channel 205; and a coolant inlet 203 and a coolant outlet 204 disposed on the shell. The coolant channel 205 is an annular spiral channel, and the fin structure 206 is a plate-shaped fin integrally formed with the shell.

[0053] In this embodiment, the coolant flow channel 205 and the hydraulic flow channel (oil supply channel and oil return channel) are arranged radially in space and are located at the outermost circle of the radial space without increasing the radial envelope size and axial size of the joint. The first oil storage hole 603 is set near the sealing interface to maintain the lubrication state, forming a dual thermal management mechanism of "local oil storage lubrication + overall circulation heat dissipation".

[0054] In this embodiment, the ratio of the axial profile height to the radial diameter of the disc-type hydraulic rotary joint is less than 1:3, demonstrating its low-profile characteristics. The disc-type hydraulic rotary joint is suitable for use with one or more of the following as working media: hydraulic oil, water-glycol antifreeze, or emulsion, with a working pressure range of 0-30 MPa. The disc-type hydraulic rotary joint of this invention can be applied to hydraulic systems for electronic device antenna mounts, rotary systems for engineering machinery, rotary guide systems for oil drilling, rotary table systems for semiconductor processing equipment, and rotary drive systems for medical equipment, all requiring low-profile installation (axial space smaller than radial space) and demanding conditions such as frequent high-pressure start-stop or long-term continuous operation. For example, the disc-type hydraulic rotary joint reduces the axial dimension by more than 35% compared to traditional bushing structures, allowing it to be directly embedded in low-profile antenna mounts to meet the extreme low-profile requirements of modern radar.

[0055] In addition, the inner ring 1 has a central hole 13 in the middle, which is used for the routing of fiber optic cables, signal cables and power cables between the upper and lower parts of the disc-type hydraulic rotary joint.

[0056] Taking the hydraulic system of an electronic device antenna mount as an example, when the disc-type hydraulic rotary joint is working, the hydraulic oil supplied from the ground equipment hydraulic system flows through the oil supply channel to the antenna array hydraulic system, and the hydraulic oil flowing back then returns to the ground equipment hydraulic system through the oil return channel. The flow diagram is shown below. Figure 10 .

[0057] In summary, the disc-type hydraulic rotary joint described above adopts an innovative integrated architecture of disc structure, multi-seal, and self-heating system. It is suitable for scenarios with extreme requirements for installation space thickness (such as low-profile antenna mounts), effectively suppressing the problem of sealing thermal failure during long-term operation of electronic equipment. It significantly improves the reliability and lifespan of dynamic seals under harsh operating conditions (especially dry running and frequent start-stop). At the same time, it ensures that the joint has sufficient rigidity, load-bearing capacity, and rotational accuracy. Furthermore, the radially arranged flow channels are expandable to accommodate three or more multi-channel hydraulic rotary joints.

[0058] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A disc-type hydraulic rotary joint, characterized in that, The device includes an inner ring, an outer ring, a bearing, a circumferential combined sealing assembly, and a self-heating structure. The inner and outer rings are coaxially arranged and can rotate relative to each other. A radially arranged hydraulic flow channel is provided between the inner and outer rings, including an oil supply channel and an oil return channel. The bearing is located between the inner and outer rings as a rotational support. The circumferential combined sealing assembly is located between the inner and outer rings as a dynamic seal. The self-heating structure is located on the shell of the outer ring. The circumferential combined sealing assembly includes a circumferential combined sealing ring, an oil reservoir, an oil reservoir hole, a sealing groove, and a contact portion on the outer ring that contacts the circumferential combined sealing ring. The circumferential combined sealing ring is disposed in the sealing groove, which is located on the inner ring. The oil reservoir is disposed on the side of the circumferential combined sealing ring adjacent to the sealing interface. The oil reservoir hole is located on the surface of the oil reservoir near the circumferential combined sealing ring and communicates with the oil reservoir. The oil reservoir holes are evenly distributed along the circumference of the oil reservoir. The self-heating structure includes a coolant flow channel, a fin structure, a coolant inlet, and a coolant outlet. The coolant flow channel is located inside the outer ring shell, and the fin structure is located inside the coolant flow channel. The coolant inlet and coolant outlet are located on the outer ring shell and communicate with the coolant flow channel. The coolant flow channel is an annular spiral flow channel, and the fin structure is a plate-shaped fin, integrally formed with the outer ring shell.

2. A disc-type hydraulic rotary joint according to claim 1, characterized in that, The circumferential combined sealing assembly consists of three sets, arranged radially in sequence, and respectively located on both sides of the oil supply channel and the inner side of the oil return channel.

3. A disc-type hydraulic rotary joint according to claim 2, characterized in that, The inner ring, outer ring, and three sets of circumferential sealing components form two annular cavities, namely the oil supply cavity and the oil return cavity. The oil supply cavity and the oil return cavity are arranged parallel and spaced apart in the radial direction. The high-pressure inlet of the oil supply cavity is located on the inner ring, and the high-pressure outlet is located on the outer ring. The low-pressure inlet of the oil return cavity is located on the outer ring, and the low-pressure outlet is located on the inner ring.

4. A disc-type hydraulic rotary joint according to claim 3, characterized in that, The disc-type hydraulic rotary joint also includes a first overflow chamber, a second overflow chamber, a first overflow pipe, and a second overflow pipe. The first overflow pipe is connected to the circumferential combined sealing assembly on the outside of the oil supply channel and the first overflow chamber, and the second overflow pipe is connected to the circumferential combined sealing assembly on the inside of the oil return channel and the second overflow chamber.

5. A disc-type hydraulic rotary joint according to claim 4, characterized in that, The inner ring has an upper fork at the top and a lower fork at the bottom. The upper fork and the lower fork are perpendicular to each other in the axial direction and do not contact each other.

6. A disc-type hydraulic rotary joint according to claim 5, characterized in that, The coolant flow channel and the hydraulic flow channel are arranged radially in space, and the coolant flow channel is located at the outermost circle of the radial space but does not increase the radial envelope dimension and axial dimension of the disc hydraulic rotary joint.

7. A disc-type hydraulic rotary joint according to claim 1, characterized in that, The ratio of the axial section height to the radial diameter of the disc-type hydraulic rotary joint is less than 1:

3.

8. A disc-type hydraulic rotary joint according to claim 1, characterized in that, The bearing is a thin-walled single-row crossed cylindrical roller bearing with an axial thickness less than 1 / 7 of the bearing's radial inner diameter.

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