Double-sided face flow distribution multi-stage variable displacement radial piston hydraulic motor

Abstract

A double-end face flow distribution multi-stage variable displacement radial piston hydraulic motor relates to the technical field of hydraulic motor. The stator is provided with an inner curve guide rail, the rotor is centrally mounted with an output shaft and arranged inside the stator, the housing is fixed on both sides of the stator and mounted with a first end cover and a last end cover at both ends, two flow distribution bodies are annular structures with stepped outer walls and symmetrically positioned and mounted inside the housing at both sides of the first and last ends, the two flow distribution bodies are machined with different numbers of flow guide channels, three annular oil channels are machined at corresponding positions of the inner wall of the housing and the two flow distribution bodies, two displacement switching valves are symmetrically arranged at both sides of the first and last ends inside the housing in a two-position four-way structure, an inner valve core is arranged, and the form of the hydraulic oil entering the oil channel is switched through the position of the valve core. By arranging the displacement switching valve and the flow distribution body with two different flow guide channels on both sides of the rotor, four displacement specifications can be switched, and the displacement adjustment range of the radial piston hydraulic motor is widened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic motor, in particular to a double-end-face flow distribution multi-stage variable displacement radial piston hydraulic motor. BACKGROUND

[0002] Multi-acting inner curve radial piston hydraulic motor is a typical volumetric hydraulic actuator, which relies on hydraulic pressure to push the rotor to contact with the inner curve guide rail of the stator through the piston, to generate tangential reaction force to form torque to drive the output shaft to rotate mechanically, has the advantages of low output speed (ω≤400r / min), large torque, stable operation and high starting efficiency, can be directly connected with the load without intermediate speed change mechanism, thereby improving the transmission efficiency of the hydraulic system, and the motor has a variable displacement function to adapt to different working conditions.

[0003] However, the existing radial piston hydraulic motor is mostly a two-stage variable displacement motor, and the displacement adjustment range is limited, so the displacement adjustment range needs to be further improved. SUMMARY

[0004] To solve the problems in the background art, the present application provides a double-end-face flow distribution multi-stage variable displacement radial piston hydraulic motor, which can realize the switching of four displacement specifications by arranging displacement switching valves and two kinds of flow distribution bodies with different flow channels on both sides of the rotor, thereby widening the displacement adjustment range of the radial piston hydraulic motor.

[0005] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a double-end face distribution multi-stage variable displacement radial piston hydraulic motor, comprising a stator, a rotor, a housing, two distribution bodies and two displacement switching valves, the stator is provided with an inner curved guide rail, the output shaft is installed in the center of the rotor and is coaxially arranged inside the stator, the rotor is evenly provided with a plurality of rotor oil channels and plungers, the housing is fixed on both sides of the stator and a head end cover and an end cover are installed at both ends, the two distribution bodies are annular structures with stepped outer walls and are symmetrically positioned and installed on both sides of the head and end of the housing, the large end faces of the two distribution bodies are arranged corresponding to the rotors and a plurality of flow guide channels are uniformly machined respectively, three annular oil channels are machined at the corresponding positions of the inner wall of the housing and the small end faces of the two distribution bodies and the large diameter section and small diameter section of the outer wall, and in the annular oil channels corresponding to the small end faces of the two distribution bodies, one is provided with an oil discharge port and the other is provided with a back pressure oil port, and the large diameter sections of the two distribution bodies correspond to The annular oil passages are respectively provided with oil inlets, the multiple flow guide passages are divided into three types and are respectively connected to the corresponding three annular oil passages. The difference between the two distribution bodies is that the number of the flow guide passages is different, the two displacement switching valves are respectively provided with control oil ports, and the two displacement switching valves adopt a two-position four-way structure and are symmetrically arranged on both sides of the head and end of the shell, so that the two annular oil passages corresponding to the outer wall of the distribution body on the same side are connected with the oil inlet and the control oil port. A valve core is provided in the middle of the displacement switching valve and is supported and positioned by springs at both ends. The valve core has a throttle hole and is divided into an initial position and a switching position before and after the hydraulic oil is injected into the control oil port. In the initial position of the valve core, the hydraulic oil injected through the oil inlet enters the two annular oil passages corresponding to the outer wall of the distribution body at the same time. In the switching position of the valve core, the annular oil passage corresponding to the small-diameter section of the distribution body is cut off from the oil inlet, and the hydraulic oil injected from the control oil port is replenished into the annular oil passage after passing through the throttle hole.

[0006] Furthermore, a braking mechanism is provided in the end cover, and the braking mechanism includes a disc spring, a brake piston and a friction plate. The disc spring is abutted against the inner end surface of the end cover, and the friction plate is fixedly provided at the inner end of the output shaft. The brake piston is in close contact with the friction plate through the preload force provided by the disc spring. A brake oil channel is provided through the end cover, and the hydraulic oil passing through the brake oil channel can enable the brake piston to overcome the preload force provided by the disc spring and separate from the friction plate.

[0007] Furthermore, distribution plates are positioned between the two distribution bodies and the rotor respectively. The distribution plates are annular plates adapted to the large end faces of the distribution bodies, and the surfaces of the distribution plates are uniformly processed with distribution holes that are the same in number and communicate with the flow guide channels of the corresponding distribution bodies.

[0008] Furthermore, compression springs are provided in the annular oil passages corresponding to the two small end faces of the ballast bodies inside the housing, supported between the small end faces of the ballast bodies and the end of the housing, respectively providing preload forces toward the rotor for the two ballast bodies.

[0009] Furthermore, a sealing support belt and an auxiliary support belt are provided on the end surface of the distribution plate.

[0010] Furthermore, the distribution plate and the corresponding distribution body are positioned along the circumferential direction through a pin shaft and a shell.

[0011] Furthermore, sealing rings are respectively provided at the inner circle positions of the large end surfaces of the two distribution bodies and at both ends and the middle positions of the outer walls.

[0012] Furthermore, the output shaft adopts a stepped shaft, the output shaft is rotatably connected to the center hole of the head end cover through a bearing, and the inner end of the output shaft is inserted into the inner ring of the corresponding ballast body for axial positioning.

[0013] Furthermore, rollers are provided at the outer ends of the plungers of the rotor and are in contact with the inner curved guide rails of the stator.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The present invention is equipped with a displacement switching valve and a distribution body with different flow guides on both sides of the rotor, which can enable the motor to operate under different action numbers, thereby changing the motor's displacement. The use of a double-end surface distribution method can achieve switching between four displacement specifications, broadening the applicable working conditions of the motor;

[0016] 2. To broaden the motor displacement switching range, the present invention improves the housing head end structure by adding an independent oil passage inside the housing that is mirror-symmetrical to the housing tail end, without increasing the axial and radial dimensions of the motor.

[0017] 3. The present invention provides a throttle hole in the valve core, and inputs the control hydraulic oil as back pressure oil into the internal oil channel, so that the control oil port and the back pressure oil port are integrated, which helps to reduce the axial size of the motor;

[0018] 4. The present invention effectively positions and seals the valve body, valve plate and housing, which helps to ensure that the internal parts of the motor are not prone to vibration and noise, while also having a higher volumetric efficiency;

[0019] 5. The main structures of the two distribution bodies and the two distribution plates of the present invention are similar, and only the number of openings is different, which helps to control the manufacturing cost to a certain extent. Moreover, the installation of the distribution plate avoids the direct wear of the distribution body by the rotor. The processing of the distribution plate is simpler than that of the distribution body, and it is also convenient to replace, which helps to control the maintenance cost to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic cross-sectional view of the hydraulic motor of the present invention;

[0021] Figure 2 1 is a structural diagram of the distribution body 1 in the present invention;

[0022] Figure 3 This is a structural diagram of the distribution body 2 in the present invention;

[0023] Figure 4 It is a structural diagram of the distribution plate in the present invention;

[0024] Figure 5 Schematic diagram of the state change of the displacement switching valve in the present invention;

[0025] Figure 6 It is a structural diagram of the valve core in the present invention.

[0026] In the figure: 1-stator, 2-rotor, 3-housing, 4-output shaft, 5-first end cover, 6-end cover, 7-distribution body 1, 8-distribution body 2, 9-displacement switching valve, 10-distribution plate, 21-rotor oil channel, 22-plunger, 23-roller, 31-first annular oil channel, 32-second annular oil channel, 33-third annular oil channel, 34-fourth annular oil channel, 35-fifth annular oil channel, 36-sixth annular oil channel, 311-first oil inlet, 312-first control oil port, 31 3-Second oil inlet, 314-Second control oil port, 61-Disc spring, 62-Brake piston, 63-Friction plate, 64-Brake oil channel, 71-Flow guide channel one, 711-Large diameter section L-shaped oil channel one, 712-Small diameter section L-shaped oil channel one, 713-Axial through oil channel one, 81-Flow guide channel two, 811-Large diameter section L-shaped oil channel two, 812-Small diameter section L-shaped oil channel two, 813-Axial through oil channel two, 91-Valve core, 92-Spring, 911-Throttle hole, 101-Distribution hole. DETAILED DESCRIPTION

[0027] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] A double-end flow distribution multi-stage variable displacement radial piston hydraulic motor, combined with Figure 1 Shown, including:

[0029] Stator 1, the inner ring of the stator 1 is provided with an inner curved guide rail, which cooperates with the plunger 22 of the rotor 2 to limit its extension and contraction state. Screw holes are evenly distributed on both end surfaces of the stator 1 for bolt connection of the housing 3 on both sides;

[0030] The rotor 2 is coaxially arranged inside the stator 1. The outer ring of the rotor 2 is evenly provided with multiple plunger holes along the radial direction and each of which is equipped with a plunger 22. The outer end of the plunger 22 is provided with a roller 23 that contacts the inner curved guide rail. The end surface of the rotor 2 is evenly penetrated by multiple rotor oil passages 21 along the axial direction to supply oil to the bottom end of the corresponding plunger 22. Under the action of the hydraulic oil, torque is generated to rotate;

[0031] The housing 3 is coaxially fixed to both sides of the stator 1 by bolts. Double nuts are preferably used to prevent loosening to facilitate disassembly and assembly of the housing during later maintenance of internal parts. Together with the head cover 5 and the end cover 6, the housing 3 defines the inner cavity of the motor;

[0032] Output shaft 4, which is coaxially connected to the inner ring of rotor 2 by splines and rotates with rotor 2 to achieve power output. Output shaft 4 is a stepped shaft and is connected to head cover 5 by bearings;

[0033] A first end cover 5, which is sleeved on the outer end of the output shaft 4 and fixed to the housing 3 by bolts. The first end cover 5 has a center hole for the output shaft 4 to extend out, and the two are rotatably connected by a bearing;

[0034] The end cover 6 is sealed on the inner end of the output shaft 4 and fixed to the housing 3 by bolts. A braking mechanism is generally arranged inside the end cover 6, and the braking mechanism includes a disc spring 61, a brake piston 62 and a friction plate 63. The disc spring 61 is abutted against the inner end face of the end cover 6, and the friction plate 63 is fixedly arranged on the inner end of the output shaft 4. When the motor is not working, the brake piston 62 is in close contact with the friction plate 63 through the disc spring 61 to achieve brake locking. The end cover 6 is provided with a brake oil channel 64. When the motor is working, the hydraulic oil entering the brake oil channel 64 can enable the brake piston 62 to overcome the preload force provided by the disc spring 61 and separate from the friction plate 63 to achieve brake unlocking.

[0035] In addition, the present invention adds two distribution bodies and two displacement switching valves 9 in the form of an approximately symmetrical structure inside the housing 3. In order to facilitate the understanding of the overall oil circuit, combined with Figure 1 as well as Figures 2-3 As shown, the two distribution bodies are divided into distribution body 1 7 and distribution body 2 8 for description, specifically:

[0036] Both the ballast body 2 8 and the ballast body 1 7 have annular structures with stepped outer walls, which are sleeved on the outside of the output shaft 4 and symmetrically positioned on both sides of the head and end of the housing 3. The large end faces of the ballast body 1 7 and the ballast body 2 8 are set corresponding to the rotor 2, and the inner end of the output shaft 4 can be inserted into the inner ring of the ballast body 1 7 for axial positioning to avoid axial movement.

[0037] A first annular oil passage 31 and a second annular oil passage 32 are respectively machined at positions corresponding to the large-diameter section and the small-diameter section of the inner wall of the housing 3 and the outer wall of the distribution body 7, and a third annular oil passage 33 is formed between the end of the housing 3 and the small end face of the distribution body 7; a fourth annular oil passage 34 and a fifth annular oil passage 35 are respectively machined at positions corresponding to the large-diameter section and the small-diameter section of the inner wall of the housing 3 and the outer wall of the distribution body 2 8, and a sixth annular oil passage 36 is formed between the head end of the housing 3 and the small end face of the distribution body 2 8.

[0038] The large end surface of the distribution body 7 is uniformly machined with multiple flow guide channels 71 along the circumference of the rotor oil passage 21. The multiple flow guide channels 71 are divided into three types: a large-diameter L-shaped oil passage 711, a small-diameter L-shaped oil passage 712, and an axial through-passing oil passage 713. The large-diameter L-shaped oil passage 711 is connected to the first annular oil passage 31, the small-diameter L-shaped oil passage 712 is connected to the second annular oil passage 32, and the axial through-passing oil passage 713 is connected to the third annular oil passage 33. A first oil inlet 311 is provided through the first annular oil passage 31 and the outer wall of the housing 3, and an oil outlet is provided through the third annular oil passage 33 and the outer wall of the housing 3. The large end surface of the distribution body 8 is uniformly machined with multiple guide channels 81 along the circumference of the rotor oil channel 21. The multiple guide channels 81 are divided into three types: large-diameter L-shaped oil channels 811, small-diameter L-shaped oil channels 812 and axial through-oil channels 813. The large-diameter L-shaped oil channels 811 are all connected to the fourth annular oil channel 34, the small-diameter L-shaped oil channels 812 are all connected to the fifth annular oil channel 35, and the axial through-oil channels 813 are all connected to the sixth annular oil channel 36. The fourth annular oil channel 34 is connected to the outer wall of the shell 3 to provide a second oil inlet 313, and the sixth annular oil channel 36 is connected to the outer wall of the shell 3 to provide a back-pressure oil port.

[0039] Among them, the difference between the distribution body 1 7 and the distribution body 2 8 is that the number of the flow guide channel 1 71 and the flow guide channel 2 81 is different. In addition, in order to enhance the sealing performance of the distribution body 1 7 and the distribution body 2 8, sealing rings can be respectively set at the inner ring position of the large end surface of the two distribution bodies and at both ends and the middle position of the outer wall. Setting the sealing ring at the inner ring position of the large end surface helps to reduce external leakage of the motor, and setting the sealing ring on the outer wall helps to reduce internal leakage caused by pressure difference between different annular oil channels.

[0040] Two displacement switching valves 9 are symmetrically integrated on both sides of the housing 3. Figure 1 and Figures 5 and 6As shown, one displacement switching valve 9 is connected to the outer wall of the housing 3 at the rear end to form a first control oil port 312, while the other displacement switching valve 9 is connected to the outer wall of the housing 3 at the front end to form a second control oil port 314. The displacement switching valve 9 adopts a two-position, four-way structure. The displacement switching valve 9 at the front end connects the fourth annular oil passage 34, the fifth annular oil passage 35, the second oil inlet 313, and the second control oil port 314. The displacement switching valve 9 at the rear end connects the first annular oil passage 31, the second annular oil passage 32, the first oil inlet 311, and the first control oil port 312. A valve core 91 is positioned in the middle of the displacement switching valve 9, supported and positioned at both ends by springs 92 to define an initial position. The inner side of the shoulder of the valve core 91 is hollow to better cooperate with the spring 92 for axial positioning. A throttle hole 911 is opened at the bottom of the shoulder sidewall of the valve core 91 near the control oil port. Hydraulic oil injected through the control oil port is reduced in pressure after passing through the throttle hole 911.

[0041] Taking the displacement switching valve 9 at the head end as an example, the displacement switching valve 9 is divided into two positions, initial and switching, before and after the hydraulic oil is injected into the second control oil port 314. The valve core 91 is in the left position in the initial position, and the hydraulic oil injected through the second oil inlet 313 will enter the fourth annular oil channel 34 and the fifth annular oil channel 35 at the same time. The valve core 91 is in the right position in the switching position, cutting off the fifth annular oil channel 35 from the second oil inlet 313, and the hydraulic oil injected through the second oil inlet 313 only enters the fourth annular oil channel 34. At the same time, the hydraulic oil injected by the second control oil port 314 is reduced in pressure through the throttle hole 911 and then replenished into the fifth annular oil channel 35. The reduced-pressure hydraulic oil is input into the inactive plunger hole as back pressure oil, so that the plunger 22 is always in contact with the inner curved guide rail of the stator 1 in the inactive state, reducing the vibration and noise of the motor. The same is true for the displacement switching valve 9 at the end.

[0042] Since the balancing body 1 7 and the balancing body 2 8 are fixed, and the rotor 2 rotates under the action of the plunger 22, the large end faces of the two balancing bodies will be worn after a long time of work. The design and manufacturing cost of the balancing body is relatively high due to the different flow guide channels. In order to reduce the wear problem of the balancing body and extend its service life, the balancing body is combined with the balancing body. Figure 1 and Figure 4 As shown, a distribution plate 10 can be positioned and added between the two distribution bodies and the rotor 2. The distribution plate 10 adopts an annular sheet adapted to the large end surface of the distribution body. Compared with the distribution body, its manufacturing is simpler. Its surface is evenly processed with distribution holes 101 with the same number and communication with the flow guide channels of the corresponding distribution body, thereby transferring the wear of the distribution body caused by the rotor 2 to the distribution plate 10, which is convenient for maintenance and replacement in the later stage.

[0043] To ensure sealing between the ballast body and rotor 2 after the addition of the distribution plate 10, and to enhance the strength of the distribution plate 10 itself, sealing support bands and auxiliary support bands can be provided on the end faces of the distribution plate 10. The auxiliary support bands are preferably provided on the inner and outer rings of the distribution plate 10. This enhances the support capacity of the ballast pair without increasing the separation force, while also alleviating the unbalanced roll moment of the distribution plate 10 caused by radial unbalanced forces, reducing the contact pressure ratio, and lowering leakage losses. Furthermore, compression springs can be provided within the third annular oil passage 33 and the sixth annular oil passage 36 within the housing 3, respectively, supporting the small end face of the ballast body and the end of the housing 3. These springs provide preload forces toward the rotor 2 for the ballast body 1 7 and the ballast body 2 8, respectively, ensuring more effective contact between the ballast plate 10 and the rotor 2. Since the ballast plate 10 is also fixed, to ensure that the distribution holes 101 are aligned with the corresponding flow guide channels, the ballast plate 10 and the corresponding ballast body can be positioned circumferentially with the housing 3 via pins.

[0044] When the motor is at different displacements, the corresponding plunger action sections are different, which can easily lead to radial unbalanced forces. The position of the plunger action sections needs to be arranged reasonably. Therefore, the arrangement of the plunger action sections should meet the following conditions:

[0045] ① Ensure that the phases of the plungers in the same group are different at any position, otherwise the motor may be locked;

[0046] ②On the premise of meeting condition ①, the radial unbalance force of the motor should be as small as possible.

[0047] According to the requirements, the guide channels of the two distribution bodies are reasonably arranged along the circumferential direction to meet the conditions ① and ②. The rotor 2 is provided with 10 rotor oil passages 21 (i.e., 10 plungers 22), the distribution body 7 is provided with 16 guide channels 71 (divided into 4 large-diameter L-shaped oil passages 711, 4 small-diameter L-shaped oil passages 712, and 8 axial through oil passages 713), the distribution body 8 is provided with 8 guide channels 81 (divided into 3 large-diameter L-shaped oil passages 811, 3 small-diameter L-shaped oil passages 812, and 8 axial through oil passages 713). 812, two axial through oil passages 813) as an example, since each displacement switching valve 9 has two working positions, the left position and the right position, each working position of each displacement switching valve 9 corresponds to a displacement of the motor, so the motor has a total of four displacement specifications. By adjusting the pressure of different control oil ports to change the position of the valve core 91, the hydraulic oil circulation form of the oil passage inside the housing 3 is changed, thereby adjusting the number of actions of the plunger 22 of the rotor 2 to achieve the change of the motor displacement. The specific implementation method of variable displacement is as follows:

[0048] When the motor is working, one end of the housing 3 is always connected to the hydraulic circuit, and the other end is disconnected from the hydraulic circuit. At the same time, hydraulic oil is introduced into the brake oil channel 64, so that the brake piston 62 overcomes the preload force of the disc spring 61 and separates from the friction plate 63 at the inner end of the output shaft 4 to achieve brake unlocking. After that, the hydraulic circuit is connected to the first oil inlet 311 / the second oil inlet 313 and the oil discharge port of the third annular oil channel 33. When the first oil inlet 311 at the end of the housing 3 is connected to the hydraulic circuit, the second oil inlet 313 and the back pressure oil port of the sixth annular oil channel 36 are blocked. When the first control oil port 312 does not flow into the pressure oil, the valve core 91 at the end is in the right position. At this time, the first oil inlet 311 is connected with the first annular oil channel 31 and the second annular oil channel 32. After the high-pressure oil of the hydraulic circuit enters the first annular oil channel 31 and the second annular oil channel 32, it flows out from the large end face through the large-diameter L-shaped oil channel 1711 and the small-diameter L-shaped oil channel 1712 of the distribution body 7, and enters the rotor oil channel 21 under the distribution of the corresponding distribution plate 10 to push the plunger 22, and cooperates with the inner curved guide rail of the stator 1 to generate a contact reaction force. The tangential component force forms a torque to drive the rotor 2 to rotate, thereby driving the output shaft 4 to rotate with load. As the rotor 2 rotates, when the plunger 22 retracts into the plunger hole, the hydraulic oil flows out in the opposite direction, enters the third annular oil channel 33 through the axial through oil channel 1713 of the distribution body 7, and flows back to the hydraulic circuit from the oil discharge port. Under this working condition, the number of motor actions is 8, and the displacement specification is 100%; when the first control oil port 312 is fed with pressure oil, the valve core 91 at the end is in the left position to cut off the second annular oil channel 32 from the first oil inlet 311. At this time, the first oil inlet 311 is only connected to the first annular oil channel 31, and the pressure oil flows into the second annular oil channel 32 as back pressure oil after being reduced in pressure through the throttle hole 911 and flows into the inactive plunger hole. Finally, the hydraulic oil also enters the third annular oil channel 33 and flows back to the hydraulic circuit from the oil discharge port. Under this working condition, the number of motor actions is 4, and the displacement specification is 50%;When the second oil inlet 313 at the head end of the housing 3 is connected to the hydraulic circuit, the first oil inlet 311 is blocked, and the back pressure oil port of the sixth annular oil channel 36 is always connected to the back pressure oil. When the second control oil port 314 does not flow into the pressure oil, the valve core 91 at the head end is in the left position. At this time, the second oil inlet 313 is connected to the fourth annular oil channel 34 and the fifth annular oil channel 35. After the high-pressure oil of the hydraulic circuit enters the fourth annular oil channel 34 and the fifth annular oil channel 35, it flows out from the large end face through the large diameter section L-shaped oil channel 2 811 and the small diameter section L-shaped oil channel 2 812 of the distribution body 2, and enters the rotor oil channel 21 under the distribution of the corresponding distribution plate 10 to push the plunger 22, and cooperates with the inner curved guide rail of the stator 1 to generate a contact reaction force. Its tangential component forms a torque to drive the rotor 2 to rotate, thereby driving the output shaft 4 to rotate with the load. Since the number of motor actions is 6 at this time, it is necessary to go out from the sixth annular oil channel 36 Back-pressure oil is introduced into the back-pressure oil port to ensure that the inactive plunger 22 is in close contact with the inner curved guide rail of the stator 1. As the rotor 2 rotates, when the plunger 22 retracts into the plunger hole, the hydraulic oil flows out in the opposite direction, enters the third annular oil passage 33 through the axial through-passage 1713 of the valve body 7, and flows back into the hydraulic circuit from the oil drain port. Under this operating condition, the number of motor actions is 6, and the displacement specification is 75%. When pressurized oil is introduced into the second control oil port 314, the valve core 91 at the head end is in the right position, cutting off the fifth annular oil passage 35 from the second oil inlet port 313. At this time, the second oil inlet port 313 is connected only to the fourth annular oil passage 34. The pressurized oil is reduced in pressure through the throttle hole 911 and flows into the fifth annular oil passage 35 as back-pressure oil, which flows into the inactive plunger hole. Finally, the hydraulic oil also enters the third annular oil passage 33 and flows back into the hydraulic circuit from the oil drain port. Under this operating condition, the number of motor actions is 3, and the displacement specification is 37.5%.

[0049] The back pressure oil introduced into the motor prevents the inactive plunger 22 from colliding with the inner curved guide rail of the stator 1, thus preventing motor vibration and noise. The third annular oil passage 33 at the end of the housing 3 is an oil drain passage. Regardless of whether the hydraulic circuit is connected to the first oil inlet 311 at the end of the housing 3 or the second oil inlet 313 at the head of the housing 3, the hydraulic oil always drains back into the hydraulic circuit through the third annular oil passage 33.

[0050] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other configurations without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations coming within the meaning and range of equivalents of the claims are intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0051] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A double-end-face flow distribution multi-stage variable displacement radial piston hydraulic motor, comprising a stator (1), a rotor (2) and a housing (3), wherein the stator (1) is provided with an inner curved guide rail, the rotor (2) is centrally mounted with an output shaft (4) and is coaxially arranged inside the stator (1), the rotor (2) is evenly provided with a plurality of rotor oil passages (21) and plungers (22), the housing (3) is fixed to both sides of the stator (1) and a head cover (5) and a tail cover (6) are mounted at both ends thereof, and is characterized in that: It also includes two balancing bodies and two displacement switching valves (9); The two distribution bodies are annular structures with stepped outer walls and are symmetrically positioned and installed on both sides of the front and rear ends of the shell (3). The large end faces of the two distribution bodies are arranged corresponding to the rotor (2) and a plurality of flow guides are uniformly processed respectively. Three annular oil passages are respectively processed at the positions corresponding to the small end faces of the two distribution bodies and the large diameter section and small diameter section of the outer wall of the shell (3). In the annular oil passages corresponding to the small end faces of the two distribution bodies, one is provided with an oil discharge port and the other is provided with a back pressure oil port. The annular oil passages corresponding to the large diameter sections of the two distribution bodies are respectively provided with oil inlets. The multiple flow guides are divided into three types: large diameter section L-shaped oil passages, small diameter section L-shaped oil passages and axial through oil passages and are respectively connected to the corresponding three annular oil passages. The difference between the two distribution bodies is that the number of large diameter section L-shaped oil passages and small diameter section L-shaped oil passages is different. The two displacement switching valves (9) are respectively provided with control oil ports. The two displacement switching valves (9) adopt a two-position four-way structure and are symmetrically arranged on both sides of the inner end of the housing (3). The two annular oil passages corresponding to the outer wall of the balancing body on the same side are connected with the oil inlet and the control oil port. A valve core (91) is provided in the middle of the displacement switching valve (9) and is supported and positioned by springs (92) at both ends. The valve core (91) has a throttle hole (911) and is divided into an initial position and a switching position before and after the hydraulic oil is injected into the control oil port. When the valve core (91) is in the initial position, the hydraulic oil injected through the oil inlet enters the two annular oil passages corresponding to the outer wall of the balancing body at the same time. When the valve core (91) is in the switching position, the annular oil passage corresponding to the small diameter section of the balancing body is cut off from the oil inlet, and the hydraulic oil injected from the control oil port is replenished into the annular oil passage after passing through the throttle hole (911).

2. The double-valve multi-stage variable displacement radial piston hydraulic motor according to claim 1, characterized in that: A brake mechanism is provided in the end cover (6), and the brake mechanism includes a disc spring (61), a brake piston (62) and a friction plate (63). The disc spring (61) is abutted against the inner end surface of the end cover (6), and the friction plate (63) is fixedly provided at the inner end of the output shaft (4). The brake piston (62) is in close contact with the friction plate (63) by providing a preload force through the disc spring (61). A brake oil channel (64) is provided through the end cover (6). When hydraulic oil is introduced into the brake oil channel (64), the brake piston (62) can overcome the preload force provided by the disc spring (61) and separate from the friction plate (63).

3. A double-valve multi-stage variable displacement radial piston hydraulic motor according to claim 1 or 2, characterized in that: A distribution plate (10) is positioned and added between the two distribution bodies and the rotor (2), respectively. The distribution plate (10) is an annular plate adapted to the large end surface of the distribution body, and its surface is uniformly processed with distribution holes (101) having the same number as and communicating with the flow guide channels of the corresponding distribution bodies.

4. The double-valve multi-stage variable displacement radial piston hydraulic motor according to claim 3, characterized in that: Compression springs are provided in the annular oil passages corresponding to the small end faces of the two balancing bodies inside the housing (3) and supported between the small end faces of the balancing bodies and the end of the housing (3), respectively, to provide pre-tightening forces in the direction of the rotor (2) for the two balancing bodies.

5. The double-valve multi-stage variable displacement radial piston hydraulic motor according to claim 4, characterized in that: The end surface of the distribution plate (10) is provided with a sealing support belt and an auxiliary support belt.

6. The double-valve multi-stage variable displacement radial piston hydraulic motor according to claim 3, characterized in that: The distribution disc (10) and the corresponding distribution body are positioned along the circumferential direction via a pin shaft and the housing (3).

7. The double-valve multi-stage variable displacement radial piston hydraulic motor according to claim 1, characterized in that: Sealing rings are respectively arranged at the inner circle positions of the large end surfaces of the two distribution bodies and at both ends and the middle positions of the outer walls.

8. The double-valve multi-stage variable displacement radial piston hydraulic motor according to claim 1, characterized in that: The output shaft (4) is a stepped shaft. The output shaft (4) is rotatably connected to the center hole of the head end cover (5) via a bearing. The inner end of the output shaft (4) is inserted into the inner ring of the corresponding balancing body for axial positioning.

9. The double-valve multi-stage variable displacement radial piston hydraulic motor according to claim 1, characterized in that: Rollers (23) are provided at the outer ends of the plungers (22) of the rotor (2) and are in contact with the inner curved guide rail of the stator (1).

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