CN214092124U

CN214092124U - Hydraulic motor crankshaft

Info

Publication number: CN214092124U
Application number: CN202022948972.7U
Authority: CN
Inventors: 杨宁都; 苟辽; 王力
Original assignee: SICHUAN LINGFENG AVIATION HYDRAULIC MACHINERY CO Ltd
Current assignee: SICHUAN LINGFENG AVIATION HYDRAULIC MACHINERY CO Ltd
Priority date: 2020-12-08
Filing date: 2020-12-08
Publication date: 2021-08-31
Anticipated expiration: 2030-12-08

Abstract

The utility model discloses a hydraulic motor bent axle, mechanical efficiency, starting torque is big. The utility model discloses a following technical scheme realizes: the eccentric crank end of the motor crankshaft is connected with an eccentric wheel shaft through a coaxial connecting rod, the freedom degree of the horizontal, vertical and back-and-forth reciprocating motion of the crankshaft is limited, compression rings bearing hydraulic pressure and roller pins assembled in the compression rings are assembled on the crankshaft between the eccentric crank end and the shaft end of the eccentric wheel, each compression ring is arranged at intervals through a spacer ring and distributed between a positioning spacer ring and a baffle ring according to linear arrays, the roller pins are ensured to be always in contact with the compression rings in the working process of the crankshaft, the axial positioning effect is realized on the roller pins, and a static pressure balance structure is formed between the roller pins and a crankshaft moving pair; the hydraulic pressure applied on the pressure ring generates torque for rotating the crankshaft through the eccentricity e of the crankshaft, and the rolling needle converts a sliding friction kinematic pair between the inner surface of the pressure ring and the outer surface of the crankshaft into a rolling friction kinematic pair. The transmission efficiency and the reliability of stable precision are ensured.

Description

Hydraulic motor crankshaft

Technical Field

The utility model relates to a mainly be applied to the hydraulic motor of moulding plastics machinery, boats and ships, machine of raising, engineering machine tool, construction machinery, coal mine machinery, mining machinery, metallurgical machinery, ship machinery, petrochemical, harbour machinery etc.. And more particularly to the design of hydraulic motor crankshafts.

Background

The hydraulic motor is an actuating element of a hydraulic system and is a device for converting hydraulic pressure energy into mechanical energy. It converts the hydraulic pressure energy provided by the hydraulic pump into the mechanical energy (torque and rotational speed) of its output shaft. Liquids are media that transmit forces and motions. Hydraulic motors, also known as oil motors, require positive and negative rotation and are symmetrical in their structure. The hydraulic motor is used for converting hydraulic energy into mechanical energy, the crankshaft is the output end of the hydraulic motor, and the output form is torque. When the crankshaft works, all parts on the crankshaft move, and the crankshaft bears mechanical force generated by hydraulic energy and converts the mechanical force into torque. In order to ensure the high efficiency of power transmission and the high precision of motion transmission of the crankshaft in the service life, every two parts which are assembled on the crankshaft and have relative motion are not abnormally abraded in the working process. However, during the rotation of the crankshaft, the crankshaft is lubricated by the oil hole, heat is generated due to friction of a kinematic pair between parts because of large contact specific pressure, and large friction loss exists during the operation. The generation of abrasion causes the reduction of the precision of the power transmission of the crankshaft and influences the performance of the end of the service life of the product. The heat generated in the rotation process of the crankshaft causes the reduction of the mechanical efficiency of the power transmitted by the crankshaft, and meanwhile, the generation of the heat causes the local temperature rise of the product, thereby causing adverse effects on the product. Therefore, the performance of the hydraulic motor requires that the kinematic pair of the crankshaft of the hydraulic motor have low friction coefficient and low wear loss performance. The motor is mechanically inefficient, typically only about 0.8 starting torque efficiency, and severely affects the low speed stability of the motor.

The hydraulic motor can be divided into gear type, vane type, plunger type and other types according to the structural types. The hydraulic motor is classified into a high speed type and a low speed type according to a rated rotation speed of the hydraulic motor. The hydraulic motor with the rated rotating speed higher than 500r/min belongs to a high-speed hydraulic motor, and the hydraulic motor with the rated rotating speed lower than 500r/min belongs to a low-speed hydraulic motor. Basic types of high-speed hydraulic motors include gear type, screw type, vane type, and axial plunger type. They are mainly characterized by high rotating speed, small moment of inertia, convenient starting and braking, and high sensitivity of adjustment (speed regulation and commutation). The high-speed hydraulic motor generally outputs a small torque and is therefore also called a high-speed low-torque hydraulic motor. The low-speed hydraulic motor is mainly characterized by large displacement, large volume and low rotating speed (sometimes reaching a few revolutions per minute or even a few tenths of revolutions per minute), so the low-speed hydraulic motor can be directly connected with a working mechanism; the transmission mechanism is greatly simplified without a speed reducing device, and the low-speed hydraulic motor is also called as a low-speed high-torque hydraulic motor because the output torque of the low-speed hydraulic motor is larger. The CLJM series of motors of the prior art are single-acting or radial piston hydraulic motors of crankshaft-link construction, which are mostly called "Staffa" motors abroad. The hydraulic motor is the one with the longest service time in the radial plunger type low-speed large-torque hydraulic motor. The motor comprises a plunger, a connecting rod, a crankshaft, a star-shaped shell, a valve shaft and the like. Five plunger cylinders are uniformly distributed in the star-shaped shell of the motor along the radial direction on the circumference, and a plunger is arranged in each plunger cylinder hole. A ball head at the small end of a connecting rod is arranged in a central ball socket of the plunger, a concave cylindrical surface at the large end of the connecting rod is tightly attached to an eccentric circle of the crankshaft, and the connecting rod is pressed by two pressing rings to prevent the connecting rod from being separated from the eccentric circle. The outward extending end of the crankshaft is an output shaft of the motor. The other end of the crankshaft drives the valve shaft to rotate through the crosshead shoe coupling. The distributing shaft is supported on two needle roller bearings in the valve casing. The left side of the valve shaft is provided with two annular grooves which are respectively communicated with an inlet and an outlet oil port on the valve shell through radial holes on the valve sleeve, the annular groove a is communicated with a valve window m on the lower right side through axial oil holes c and d on the valve shaft, the annular groove is communicated with a valve window n on the upper right side through axial oil holes e and f, the tops of the five plunger cylinders are respectively provided with a radial pore passage which is communicated with the valve windows m and n on the valve shaft, and the oil inlet and the oil return port on the shell are communicated through the valve shaft. Along with the rotation of the crankshaft, the port shaft also rotates, so that the relative positions of the plunger cylinders and the port windows m and n on the port shaft, namely the port state, are changed. When the crankshaft rotates within the range of 0-90 degrees, the plunger cylinder I is communicated with pressure oil from a transition state, and then the plunger cylinder II is also communicated with the pressure oil from an oil return state. On the contrary, the plunger cylinder IV is changed from pressure oil connection to return oil connection. At this time, the torque output from the crankshaft is the sum of the torques generated by the three plunger cylinders I, II, and V, but the torque direction is not changed yet, compared with the original position of the pipe connection. When the crankshaft rotates from 90 deg. to 180 deg., the cylinder I is in closed transition state again, the plunger cylinders II and III are communicated with pressure oil, the plunger cylinders IV and V are communicated with return oil, and the torque on the crankshaft becomes the sum of the torques produced by the two plunger cylinders. When the crankshaft rotates 180 deg., the working cavity of plunger cylinder is exchanged with pressure oil and return oil once, and the direction of torque is not changed. When the crankshaft rotates from 180 degrees to 360 degrees, each plunger cylinder is reversely switched and returns to the pipe connection state, and the process is repeated. However, the actual working pressure difference of the hydraulic motor depends on the magnitude of the load moment, and when the moment of inertia of the driven load is large, the rotating speed is high, and sudden braking or reverse rotation is required, high hydraulic impact is generated. Since internal leakage is unavoidable, even when braking is performed by closing the oil drain of the motor, the motor can slip slowly. The hydraulic motor drives the belt pulley through chain transmission, and the oil seal deforms after bearing radial force due to the fact that the chain transmission can generate the radial force, so that oil leakage is caused. The sealing performance is poor, the leakage is large, the stability is not enough at low speed, and the volume efficiency is low.

A fixed damper is arranged in a hydraulic motor, an oil groove or an oil cavity is arranged at the bottom of a connecting rod sliding block, and high-pressure oil at the bottom of the sliding block enters the oil cavity at the bottom through a central damper. A static pressure supporting structure for increasing the area of an oil cavity is designed between the connecting rod crankshaft kinematic pairs of the hydraulic motor. When the pressure is P, the power oil is introduced into the small hole in the end of the plunger, and after being reduced in pressure by the fixed resistance device in the center of the connecting rod, the power oil enters the rectangular oil cavity in the bottom of the connecting rod, and then flows out after being reduced in pressure for the second time by the clearance hole between the connecting rod bearing bush and the crankshaft. The hydraulic motor has the disadvantages that the hydraulic motor has enough back pressure at an oil return port to ensure normal operation, the higher the rotating speed is, the higher the required back pressure is, the higher the back pressure is, the lower the pressure utilization rate of an oil source is, and the large loss of the system is caused. Hydrostatic bearings increase leakage and reduce volumetric efficiency. When the working rotating speed of the hydraulic motor is too low, the uniform speed is often not maintained, and the hydraulic motor enters an unstable state of stopping when in motion. The reasons why the hydraulic motor generates the creep phenomenon at a low speed are as follows: (1) the magnitude of the frictional force is unstable. While the normal frictional force increases with increasing speed, the frictional resistance within the motor, which operates in the stationary and low speed regions, does not increase but decreases as the operating speed increases, creating a resistance of the so-called "negative character". The leakage of the hydraulic motor is not the same at every instant, but it also fluctuates periodically with the phase angle change of the rotor rotation. The flow entering the motor at low speed is small, the proportion occupied by leakage is increased, and the instability of the leakage quantity can obviously influence the flow value participating in the work of the motor, thereby causing the fluctuation of the rotating speed. When the motor is operated at a low speed, the inertia of the rotating part and the load is small, and the above-mentioned influence is obvious, so that the creeping phenomenon occurs. The maximum use rotating speed of the hydraulic motor is mainly limited by the service life and the mechanical efficiency, after the rotating speed is increased, the abrasion of each kinematic pair is aggravated, the service life is reduced, and the flow required to be input by the hydraulic motor is large when the rotating speed is high, so that the flow speed of each overflowing part is correspondingly increased, the pressure loss is increased, and the mechanical efficiency is reduced.

Generally, the oil return port of the low-speed motor should have enough back pressure, which is more so for the inner curve motor, otherwise the roller may be separated from the curved surface to generate impact, noise is generated slightly, the service life is reduced, and the roller is broken if the roller is heavy, so that the whole motor is damaged. For some hydraulic motors, the increase in rotational speed is also limited by back pressure. For example, when the rotating speed of a crankshaft connecting rod type hydraulic motor is increased, the oil return back pressure must be obviously increased to ensure that the connecting rod cannot impact the surface of the crankshaft, so that the impact phenomenon is avoided. With the increase of the rotating speed, the back pressure value required by the oil return cavity is increased. However, excessive increase in back pressure significantly reduces the efficiency of the hydraulic motor.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a friction work loss and generating heat and reducing to the weak point that current hydraulic motor bent axle motion pair exists, motor starting torque is high, can improve the hydraulic motor bent axle that power transmission efficiency and precision are stable in the life-span.

The utility model provides a technical scheme that its technical problem adopted is: a hydraulic motor crankshaft comprising: the crankshaft 1 sealed in the shell through the end cover 2, the extending end of the crankshaft 1 is the output shaft of the motor, and the motor is characterized in that: the eccentric crank end of the crankshaft 1 is supported on bearings of an end cover 2 and a shell rear end cover through a pair of tapered roller bearings and rotates around the rotating central axis of the bearings to limit the freedom degree of horizontal, up-down and front-back reciprocating motion of the crankshaft 1, a press ring 4 bearing hydraulic pressure and a needle roller 5 assembled in the press ring 4 are assembled on the crankshaft 1 between the eccentric crank end and the shaft end of the eccentric wheel, and each press ring 4 is arranged at intervals through a spacer ring 6 and distributed between a positioning spacer ring 3 and a baffle ring 7 according to linear arrays, so that the needle roller 5 is always in contact with the press ring 4 in the working process of the crankshaft 1, the needle roller 5 is axially positioned, and a static pressure balance structure is formed between the needle roller 5 and a crankshaft 1 kinematic pair; the hydraulic pressure applied to the pressure ring 4 generates a moment for rotating the crankshaft 1 through the eccentricity e of the crankshaft 1, and the rolling needle 5 converts a sliding friction kinematic pair between the inner surface of the pressure ring 4 and the outer surface of the crankshaft 1 into a rolling friction kinematic pair.

The utility model discloses compare and have following beneficial effect in prior art:

the utility model discloses an on bent axle 1 between eccentric crank neck end and the eccentric wheel axle head, the assembly bears hydraulic pressure force's clamping ring 4 and assembly are in 5 reduction contact specific pressures of kingpin in the clamping ring 4, every clamping ring 4 passes through 6 interval arrangements of spacer ring, and the linear array distributes between location spacer ring 3 and fender ring 7, guarantees kingpin 5 and is in all the time in 1 course of working of bent axle and contacts with clamping ring 4, uses simple structure, and radial force is balanced, and torque pulsation is little, and starting torque is big, can operate under the low-speed stability, reliable operation. Through the axial positioning of the roller pins 5, the abrasion of a contact surface is reduced, the contact specific pressure is reduced, the static pressure balance is realized, and the friction pair is well lubricated. The static pressure balance structure formed between the crankshaft 1 and the kinematic pair can make the main machine driving mechanism very compact and the motor structure more simplified. The loss of work due to friction and heat generation are reduced. The mechanical efficiency and starting torque efficiency of the motor are improved. It can also be installed in rope roller to directly drive roller.

The utility model discloses utilize the kingpin to turn into the higher sliding friction of coefficient of friction between clamping ring internal surface and the bent axle surface into the lower rolling friction of coefficient of friction, improved power transmission's mechanical efficiency, eliminated the direct friction contact of clamping ring internal surface and bent axle surface simultaneously, reduced the wearing and tearing volume between clamping ring internal surface and the bent axle surface, guaranteed the motion transmission precision of bent axle in its life-span. When the hydraulic motor is loaded, the total counter force and the pressing force generated by the oil cavity are balanced and are transmitted to the crankshaft through an oil film, the positioning spacer ring 3, the second spacer ring 6 and the baffle ring 7 are not directly contacted and rubbed with the kinematic pair metal materials, and the hydraulic oil plays a supporting role of the hydrostatic bearing. When the pressing force is larger than the total supporting counter force, the oil film thickness h of the positioning spacer ring 3, the second spacer ring 6 and the baffle ring 7 is reduced, and the rated pressure Ps is increased due to the reduction of h, so that the total pressure is increased until the pressing force is balanced with the changed pressing force. The positioning spacer ring 3, the second spacer ring 6 and the baffle ring 7 are statically supported by a kinematic pair, so that the friction power consumption is reduced. The mechanical efficiency and the starting mechanical efficiency are improved, so that the working pressure ((more than 20 MPa) and the rotating speed of the motor are also improved, particularly the low-speed stability is improved, and the motor can stably run under the working condition of less than or equal to 5 r/min.

The utility model discloses a hydraulic pressure force exerted on clamping ring 4 produces through 1 eccentric distance e of bent axle and makes 1 pivoted moment of bent axle, and bearing pin 5 turns into the rolling friction motion pair with sliding friction motion pair between 4 internal surfaces of clamping ring and the 1 surface of bent axle. The bent axle is at the working process, and the rotation direction between 3 clamping rings is probably different, consequently adopts the spacer ring to keep apart each clamping ring in axial direction to material is selected for use in principle, guarantees that the section of clamping ring is not by the fish tail in its life-span, avoids causing the frictional force increase and loses mechanical efficiency because of the part fish tail, guarantees bent axle transmission mechanical efficiency's stability. When hydraulic power is transmitted to the crankshaft 1 through the pressure ring 4 and the needle rollers 5, the crankshaft 1 starts to rotate about its axis due to the eccentricity e of the crankshaft 1. In the rotating process, the friction pair between the compression ring 4 and the crankshaft 1 is converted into rolling friction with a smaller friction coefficient from sliding friction with a larger friction coefficient, and the friction pair with a high friction coefficient between the compression ring and the compression ring is converted into a friction pair with a lower friction coefficient, which has a longer service life and more stable precision, through the positioning spacer ring 3, the second spacer ring 6 and the baffle ring 7. The transmission efficiency and the reliability of stable precision are ensured.

Drawings

Fig. 1 is a sectional view of a hydraulic motor crankshaft of the present invention.

Fig. 2 is a schematic diagram of the appearance structure of the crankshaft kinematic pair of the present invention.

In the figure: 1 crankshaft, 2 end covers, 3 positioning spacer rings, 4 compression rings, 5 roller pins, 6 second spacer rings and 7 retaining rings.

The present invention is further described with reference to the following figures and examples, but the invention is not limited thereby within the scope of the described embodiments. All of these concepts should be considered as within the scope of the present disclosure and the present invention.

Detailed Description

See fig. 1-2. In a preferred embodiment described below, a hydraulic motor crankshaft comprises: the crankshaft 1 sealed in the housing by the end cover 2, the protruding end of the crankshaft 1 is the output shaft of the motor. The eccentric crank neck end of the crankshaft 1 and the eccentric wheel shaft end of the coaxial connecting rod are supported on bearings of an end cover 2 and a shell rear end cover through a pair of tapered roller bearings and rotate around the rotating central axis of the bearings to limit the freedom degree of horizontal, up-down and front-back reciprocating motion of the crankshaft 1, a press ring 4 bearing hydraulic pressure and a roller pin 5 assembled in the press ring 4 are assembled on the crankshaft 1 between the eccentric crank neck end and the eccentric wheel shaft end, and each press ring 4 is arranged at intervals through a spacer ring 6 and distributed between a positioning spacer ring 3 and a baffle ring 7 according to linear arrays, so that the roller pin 5 is always in contact with the press ring 4 in the working process of the crankshaft 1, the axial positioning effect is realized on the roller pin 5, and a static pressure balance structure is formed between the roller pin 5 and a motion pair of the crankshaft 1; the hydraulic pressure applied to the pressure ring 4 generates a moment for rotating the crankshaft 1 through the eccentricity e of the crankshaft 1, and the rolling needle 5 converts a sliding friction kinematic pair between the inner surface of the pressure ring 4 and the outer surface of the crankshaft 1 into a rolling friction kinematic pair.

In order to ensure high efficiency and high precision of power transmission, a compression ring 4 is arranged on a crankshaft 1, a roller pin 5 is arranged between the inner surface of the compression ring 4 and the outer surface of the crankshaft 1, and sliding friction with a large friction coefficient between the inner surface of the compression ring 4 and the outer surface of the crankshaft 1 is converted into rolling friction with a small friction coefficient through the roller pin 5.

In order to ensure that the power generated by the hydraulic pressure is transmitted to the crankshaft 1 through the compression ring 4 with high efficiency and high precision, the axial position of the compression ring 4 needs to be ensured. The positioning spacer ring 3, the second spacer ring 6 and the retaining ring 7 are all arranged at the exact axial positions of the pressure ring 4, and meanwhile, the rotation directions of the 3 pressure rings 4 in the working process of the crankshaft 1 are possibly different, so that the friction force between parts is increased to reduce the mechanical efficiency due to the fact that the end faces of the pressure rings 4 are scratched mutually due to friction, and the hardness of materials of the positioning spacer ring 3, the second spacer ring 6 and the retaining ring 7 relative to the material of the pressure ring 4 is required to be lower. In addition, the positioning spacer ring 3, the second spacer ring 6 and the retaining ring 7 ensure that the roller pin 5 is always in contact with the compression ring 4 in the working process of the crankshaft 1, and the axial positioning effect is realized on the roller pin 5.

The end cap 2 is provided for positioning the axial position of the spacer ring 3.

When hydraulic power is transmitted to the crankshaft 1 through the compression ring 4 and the roller pins 5, because the small-diameter end and the large-diameter end of the crankshaft 1 only have the freedom degree of rotation around the axis thereof and the crankshaft 1 has the eccentricity e, the crankshaft 1 starts to rotate around the axis thereof, and the end cover 2, the positioning spacer ring 3, the compression ring 4, the roller pins 5, the second spacer ring 6 and the retainer ring 7 which are mounted on the crankshaft 1 all rotate with the crankshaft 1. When the crankshaft 1 rotates, relative motion exists between the inner surface of the compression ring 4 and the roller pin 5, relative motion exists between the roller pin 5 and the outer surface of the crankshaft 1, relative motion exists between the end surface of the compression ring 4 and the end surfaces of the positioning spacer ring 3, the second spacer ring 6 and the baffle ring 7, relative motion exists between the end surface of the positioning spacer ring 3 and the end surface of the end cover 2, and relative motion exists between the end surface of the baffle ring 7 and the end surface of the large diameter of the crankshaft.

In the rotation process of the crankshaft, hydraulic power is transmitted to the crankshaft 1 through the compression ring 4 through the roller pins 5, friction pairs between the inner surface of the compression ring 4 and the roller pins 5 and between the roller pins 5 and the outer surface of the crankshaft 1 are rolling friction with a small friction coefficient, mechanical energy and abrasion loss generated by relative motion between the inner surface of the compression ring 4 and the outer surface of the crankshaft 1 are reduced through the rolling friction, the mechanical efficiency of the power transmission of the crankshaft 1 is improved through the reduction of the mechanical energy, the motion precision of the crankshaft 1 is in a stable state in the service life through the reduction of the abrasion loss, and the motion precision in the service life is guaranteed.

During the rotation of the crankshaft, long-time friction between the end faces of the compression ring and between the end face of the compression ring 4 and the end face of the crankshaft 1 with the large diameter can scratch the end face of the compression ring 4, increase the internal friction force when the crankshaft 1 rotates, generate more mechanical energy and reduce the mechanical efficiency of the crankshaft for transmitting power. Through setting up location spacer ring 3, second spacer ring 6, keep off ring 7 and keep apart between clamping ring 4 and the 4 terminal surfaces of clamping ring, direct frictional contact between 4 terminal surfaces of clamping ring and the 1 big footpath terminal surface of bent axle, location spacer ring 3, second spacer ring 6, keep off ring 7 and choose the material that hardness is lower and have good wearability for use, improve between clamping ring and the clamping ring terminal surface, the relative friction motion performance between 4 terminal surfaces of clamping ring and the 1 big footpath terminal surface of bent axle, reduce coefficient of friction, reduce the wearing and tearing volume between the clamping ring terminal surface, guarantee the power transmission efficiency of bent axle.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A hydraulic motor crankshaft comprising: through bent axle (1), the overhanging end of bent axle (1) of end cover (2) sealed in the casing be the output shaft of motor, its characterized in that: the eccentric crank end of the crankshaft (1) is connected with an eccentric wheel shaft connected with a coaxial connecting rod, the eccentric wheel end is supported on the end cover (2) and a bearing of the rear end cover of the shell through a pair of tapered roller bearings, and rotates around the bearing rotation central axis to limit the freedom degree of the horizontal, up-down and front-back reciprocating motion of the crankshaft (1), a compression ring (4) bearing hydraulic pressure and a roller pin (5) assembled in the compression ring (4) are assembled on the crankshaft (1) between the eccentric crank end and the eccentric shaft end, and each compression ring (4) is arranged at intervals through a second spacing ring (6) and distributed between the positioning spacing ring (3) and the baffle ring (7) according to linear arrays, so that the rolling needles (5) are always in contact with the compression rings (4) in the working process of the crankshaft (1), the needle roller (5) is axially positioned, and forms a static pressure balance structure with a crankshaft (1) kinematic pair; the hydraulic pressure exerted on the pressure ring (4) generates moment for rotating the crankshaft (1) through the eccentricity e of the crankshaft (1), and the rolling needle (5) converts a sliding friction kinematic pair between the inner surface of the pressure ring (4) and the outer surface of the crankshaft (1) into a rolling friction kinematic pair.

2. A hydraulic motor crankshaft as claimed in claim 1 wherein: a compression ring (4) is mounted on a crankshaft (1), a roller pin (5) is mounted between the inner surface of the compression ring (4) and the outer surface of the crankshaft (1), sliding friction is generated between the inner surface of the compression ring (4) and the outer surface of the crankshaft (1), and the rolling friction is converted through the roller pin (5).

3. A hydraulic motor crankshaft as claimed in claim 1 wherein: the positioning spacer ring (3), the second spacer ring (6) and the baffle ring (7) are all arranged at the axial positions which ensure the exact positioning of the pressure ring (4).

4. A hydraulic motor crankshaft as claimed in claim 1 wherein: the crankshaft (1) has 3 compression rings (4) with different rotation directions in the working process.

5. A hydraulic motor crankshaft as claimed in claim 1 wherein: the positioning spacer ring (3), the second spacer ring (6) and the retaining ring (7) ensure that the roller pin (5) is always in contact with the compression ring (4) in the working process of the crankshaft (1), and the axial positioning effect is realized on the roller pin (5).

6. A hydraulic motor crankshaft as claimed in claim 1 wherein: the end cover (2) is arranged for positioning the axial position of the spacer ring (3).

7. A hydraulic motor crankshaft as claimed in claim 1 wherein: in the rotation process of the crankshaft, hydraulic power is transmitted to the crankshaft (1) through the compression ring (4) through the roller pins (5), the friction pairs between the inner surface of the compression ring (4) and the roller pins (5) and between the roller pins (5) and the outer surface of the crankshaft (1) are rolling friction with a small friction coefficient, and mechanical energy and abrasion loss caused by relative motion between the inner surface of the compression ring (4) and the outer surface of the crankshaft (1) are reduced due to the rolling friction.