High-torque hydraulic motor crankshaft

Abstract

The invention discloses a large torque hydraulic motor crankshaft, which can improve the starting torque and transmission torque of the motor. The invention is realized by the following technical scheme: the eccentric crank neck end of the motor crankshaft and the coaxial connecting rod are connected to the eccentric wheel shaft, which limits the horizontal, up and down, front and back reciprocating freedom of the crankshaft. A pressure ring that bears the hydraulic pressure and a needle roller installed in the pressure ring are installed on the crankshaft between the eccentric crank neck end and the eccentric wheel shaft end, and each pressure ring is arranged at intervals by a spacer ring and distributed in a linear array between the positioning spacer ring and the retaining ring, so as to ensure that the needle roller is always in contact with the pressure ring during the operation of the crankshaft, play an axial positioning role for the needle roller, and form a static pressure balance structure with the crankshaft kinematic pair; the hydraulic pressure applied to the pressure ring generates a torque that rotates the crankshaft through the eccentric distance e of the crankshaft, and the needle roller converts the 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 reliability of transmission efficiency and stable precision is guaranteed.

Description

Technical Field

[0001] The present invention relates to a hydraulic motor mainly used in injection molding machinery, ships, hoists, engineering machinery, construction machinery, coal mining machinery, mining machinery, metallurgical machinery, ship machinery, petrochemical industry, port machinery, etc. Specifically, it relates to the design of the hydraulic motor crankshaft. Background Art

[0002] The hydraulic motor is an actuator of the hydraulic system and a device that converts liquid pressure energy into mechanical energy. It converts the liquid pressure energy provided by the hydraulic pump into the mechanical energy (torque and speed) of its output shaft. Liquid is the medium for transmitting force and motion. The hydraulic motor, also known as the oil motor, requires forward and reverse rotation, and its structure is symmetrical. The function of the hydraulic motor is to convert hydraulic energy into mechanical energy. The crankshaft is the output end of the hydraulic motor, and the output form is torque. When the crankshaft is working, all parts on the crankshaft are moving. The crankshaft is subjected to the mechanical force generated by the hydraulic energy and converts it into torque. In order to ensure the high efficiency of power transmission and high precision of motion transmission during the service life of the crankshaft, the parts assembled on the crankshaft that have relative motion should not be abnormally worn during the working process. However, during the rotational motion of the crankshaft, it is lubricated by the oil hole. Because the kinematic pairs between the parts have a large contact pressure ratio, friction generates heat, and there is a large friction loss during the work. At the same time, the friction of the kinematic pairs between the parts causes the wear of the corresponding parts, which reduces the matching accuracy between the parts, resulting in a reduction in the mechanical efficiency and accuracy of power transmission. Wear reduces the accuracy of crankshaft power transmission, affecting the performance at the end of product life. The heat generated during crankshaft rotation reduces the mechanical efficiency of crankshaft power transmission. At the same time, the heat causes the local temperature of the product to rise, which has an adverse effect on the product. Therefore, the performance of the hydraulic motor requires that the kinematic pair of the hydraulic motor crankshaft must have low friction coefficient and low wear performance. The motor has low mechanical efficiency, and the starting torque efficiency is usually only about 0.8, which seriously affects the low-speed stability of the motor.

[0003] Hydraulic motors can also be divided according to their structural type, which can be divided into gear type, vane type, plunger type and other types. According to the rated speed of hydraulic motors, they are divided into high-speed and low-speed categories. High-speed hydraulic motors have a rated speed higher than 500r / min, and low-speed hydraulic motors have a rated speed lower than 500r / min. The basic types of high-speed hydraulic motors include gear type, screw type, vane type and axial plunger type. Their main features are high speed, small moment of inertia, easy starting and braking, and high sensitivity in adjustment (speed regulation and reversing). Usually, the output torque of high-speed hydraulic motors is not large, so they are also called high-speed low-torque hydraulic motors. The basic type of low-speed hydraulic motor is radial plunger type. In addition, there are also low-speed structural types in axial plunger type, vane type and gear type. The main features of low-speed hydraulic motors are large displacement, large volume and low speed (sometimes up to several revolutions per minute or even zero revolutions), so they can be directly connected to the working mechanism; no reduction device is required, which greatly simplifies the transmission mechanism. Usually, low-speed hydraulic motors have a large output torque, so they are also called low-speed high-torque hydraulic motors. The prior art CLJM series motor is a single-acting or radial piston hydraulic motor with a crankshaft connecting rod structure, which is often called "Staffa" motor abroad. It is the longest-used type of radial piston low-speed and high-torque hydraulic motor. The motor consists of a plunger, a connecting rod, a crankshaft, a star-shaped housing, and a distribution shaft. Five plunger cylinders are evenly distributed radially on the circumference of the star-shaped housing of the motor, and a plunger is installed in each plunger cylinder hole. The ball head of the small end of the connecting rod is installed in the central ball socket of the plunger, and the concave cylindrical surface of the large end of the connecting rod is tightly attached to the eccentric circle of the crankshaft, and the connecting rod is pressed by two pressure rings to prevent it from separating from the eccentric circle. The extended end of the crankshaft is the output shaft of the motor. The other end of the crankshaft drives the distribution shaft to rotate through a cross slider coupling. The distribution shaft is supported on two needle bearings in the valve housing. There are two annular grooves on the left side of the distribution shaft, which are connected to the inlet and outlet oil ports on the valve housing through the radial holes on the distribution sleeve. The annular groove a is connected to the distribution window m on the lower right side by means of the axial oil holes c and d on the distribution shaft, and the annular groove is connected to the distribution window n on the upper right side by the axial oil holes e and f. There is a radial channel on the top of each of the five plunger cylinders, which is connected to the distribution windows m and n on the distribution shaft, and connected to the oil inlet and return port on the housing through the distribution shaft. As the crankshaft rotates, the distribution shaft also rotates, so that the relative position of each plunger cylinder and the distribution windows m and n on the distribution shaft, that is, the distribution state, changes. When the crankshaft rotates within the range of 0 to 90 degrees, the plunger cylinder I is connected to the pressure oil from the transition state, and then the plunger cylinder II is also connected to the pressure oil from the return oil state. On the contrary, the plunger cylinder IV changes from being connected to the pressure oil to being connected to the return oil. At this time, the torque output by the crankshaft becomes the sum of the torques generated by the three plunger cylinders I, II, and V compared to the original position of the piping connection, but the direction of the torque remains unchanged.When the crankshaft rotates from 90° to 180°, cylinder I is in a closed transition state again, while plunger cylinders II and III have been switched to communicate with pressure oil, and plunger cylinders IV and V are switched to communicate with return oil. The torque on the crankshaft becomes the sum of the torques generated by the two plunger cylinders. When the crankshaft rotates 180°, the working chamber of the plunger cylinder is switched with pressure oil and return oil once, and the torque direction remains unchanged. When the crankshaft rotates from 180° to 360°, the plunger cylinders undergo the opposite conversion and return to the piping connection state, repeating the above process. However, the actual working pressure difference of the hydraulic motor depends on the size of the load torque. When the driven load has a large moment of inertia, a high speed, and requires rapid braking or reversal, a higher hydraulic shock will be generated. Since internal leakage is inevitable, when the motor's oil discharge port is closed and braking is performed, there will still be a slow slip. The hydraulic motor drives the pulley through a chain drive. Since the chain drive generates radial force, the oil seal deforms after being subjected to the radial force, resulting in oil leakage. Due to poor sealing performance, large leakage, instability at low speed and low volumetric efficiency.

[0004] Some hydraulic motors are equipped with fixed dampers, and an oil groove or oil chamber is set at the bottom of the connecting rod slider. The high-pressure oil at the bottom of the slider enters the bottom oil chamber through the central damper. The connecting rod crankshaft kinematic pair of the hydraulic motor is designed as a hydrostatic support structure that increases the area of ​​the oil chamber. When the power oil at pressure P is introduced into the connecting rod through the small hole at the end of the plunger, it enters the rectangular oil chamber at the bottom of the connecting rod after the pressure is reduced by the fixed resistor at the center of the connecting rod; then it flows out through the gap hole between the connecting rod bearing and the crankshaft after the secondary pressure reduction. The disadvantage is that the hydraulic motor must have sufficient back pressure at the return oil port to ensure normal operation, and the higher the speed, the greater the back pressure required. The increase in back pressure means that the pressure utilization rate of the oil source is low and the system loss is large. The hydrostatic support structure increases leakage and reduces the volumetric efficiency. When the hydraulic motor works at a low speed, it often cannot maintain a uniform speed and enters an unstable state of intermittent movement. The reasons why the hydraulic motor produces creeping phenomenon at low speed are: (1) The magnitude of friction is unstable. The usual friction force increases with the increase of speed, while the friction resistance inside the motor working in the static and low-speed area does not increase but decreases when the working speed increases, forming the so-called "negative characteristic" resistance. The leakage of the hydraulic motor is not the same at every moment, and it also fluctuates periodically with the phase angle of the rotor rotation. Since the flow entering the motor is small at low speed, the proportion of leakage increases, and the instability of the leakage will obviously affect the flow value involved in the motor work, thereby causing the fluctuation of the speed. When the motor is running at a low speed, the inertia of its rotating parts and the load it carries is small, and the above-mentioned influence is more obvious, so the creeping phenomenon occurs. The maximum operating speed of the hydraulic motor is mainly limited by the service life and mechanical efficiency. When the speed increases, the wear of each moving pair increases and the service life decreases. The higher the speed, the larger the flow required to input by the hydraulic motor. Therefore, the flow rate of each flow-through part increases accordingly, and the pressure loss also increases, thereby reducing the mechanical efficiency.

[0005] Usually, there should be enough back pressure at the oil return port of low-speed motors, especially for inner-curved motors. Otherwise, the roller may break away from the curved surface and cause collision, which may cause noise and reduce the service life, or even break the roller and damage the entire motor. For some hydraulic motors, the increase in speed is also limited by back pressure. For example, for crankshaft connecting rod hydraulic motors, when the speed increases, the oil return back pressure must be significantly increased to ensure that the connecting rod does not hit the crankshaft surface, thereby avoiding the collision phenomenon. As the speed increases, the back pressure value required for the oil return chamber should also increase accordingly. However, excessive increase in back pressure will significantly reduce the efficiency of the hydraulic motor. Summary of the invention

[0006] The purpose of the present invention is to address the shortcomings of the existing hydraulic motor crankshaft kinematic pairs and to provide a high-torque hydraulic motor crankshaft with reduced friction work loss and heat generation, high motor starting torque efficiency, and the ability to improve power transmission efficiency and stable precision during its service life.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a large torque hydraulic motor crankshaft, comprising: a crankshaft 1 sealed in a housing through an end cover 2, the extended end of the crankshaft 1 is the output shaft of the motor, characterized in that: the eccentric crank neck end of the crankshaft 1 is connected to an eccentric wheel shaft of a coaxial connecting rod, the eccentric wheel end is supported on the bearings of the end cover 2 and the rear end cover of the housing through a pair of tapered roller bearings, and rotates around the central axis of rotation of the bearing, limiting the horizontal, up and down, front and back reciprocating motion of the crankshaft 1, and assembling a There are a pressure ring 4 that bears the hydraulic pressure and a needle roller 5 assembled in the pressure ring 4, and each pressure ring 4 is arranged at intervals through a spacer ring 6, and is distributed in a linear array between the positioning spacer ring 3 and the retaining ring 7, to ensure that the needle roller 5 is always in contact with the pressure ring 4 during the operation of the crankshaft 1, to play an axial positioning role for the needle roller 5, and to form a static pressure balance structure with the crankshaft 1 kinematic pair; the hydraulic pressure applied to the pressure ring 4 generates a torque that rotates the crankshaft 1 through the eccentricity e of the crankshaft 1, and the needle roller 5 converts the 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.

[0008] Compared with the prior art, the present invention has the following beneficial effects:

[0009] The present invention adopts a crankshaft 1 between the eccentric crank neck end and the eccentric wheel shaft end, and a pressure ring 4 that bears hydraulic pressure and a needle roller 5 installed in the pressure ring 4 are installed to reduce the contact specific pressure. Each pressure ring 4 is arranged at intervals by a spacer ring 6, and the linear array is distributed between the positioning spacer ring 3 and the retaining ring 7, so as to ensure that the needle roller 5 is always in contact with the pressure ring 4 during the operation of the crankshaft 1. The application structure is simple, the radial force is balanced, the torque pulsation is small, the starting torque is large, and it can operate stably at low speed and work reliably. Through the axial positioning of the needle roller 5, the wear of the contact surface is reduced, the contact specific pressure is reduced, the static pressure balance is achieved, and the friction pair is well lubricated. The static pressure balance structure formed between the moving pair of the crankshaft 1 can make the main engine drive mechanism very compact and the motor structure simpler. Due to the reduction of friction work loss and heat generation, the mechanical efficiency and starting torque efficiency of the motor are improved. It can also be installed in the rope drum to directly drive the drum to work.

[0010] The present invention utilizes a needle roller to convert the sliding friction with a high friction coefficient between the inner surface of the pressure ring and the outer surface of the crankshaft into rolling friction with a low friction coefficient, thereby improving the mechanical efficiency of power transmission, while eliminating the direct friction contact between the inner surface of the pressure ring and the outer surface of the crankshaft, reducing the amount of wear between the inner surface of the pressure ring and the outer surface of the crankshaft, and ensuring the motion transmission accuracy of the crankshaft during its service life. When the hydraulic motor is loaded, the total reaction force generated by the oil chamber is balanced with the clamping force and transmitted to the crankshaft through the oil film. There is no direct contact and friction between the metal materials of the kinematic pairs of the positioning spacer ring 3, the spacer ring 6, and the retaining ring 7, and the hydraulic oil plays a supporting role in the hydrostatic bearing. When the clamping force is greater than the total supporting reaction force, the oil film thickness h of the positioning spacer ring 3, the spacer ring 6, and the retaining ring 7 decreases, and the decrease in h increases the rated pressure Ps, so the total pressure also increases until it reaches a balance with the changed clamping force. The kinematic pairs of the positioning spacer ring 3, the spacer ring 6, and the retaining ring 7 are hydrostatically supported, and the friction power consumption is reduced. The mechanical efficiency and starting mechanical efficiency are improved, thereby also increasing the working pressure (above 20MPa) and speed of the motor, especially the low-speed stability. The motor can run smoothly at a speed less than or equal to 5r / min.

[0011] The present invention uses the hydraulic pressure applied to the pressure ring 4 to generate a torque to rotate the crankshaft 1 through the eccentricity e of the crankshaft 1, and the needle roller 5 converts the sliding friction motion pair between the inner surface of the pressure ring 4 and the outer surface of the crankshaft 1 into a rolling friction motion pair. During the operation of the crankshaft, the rotation directions of the three pressure rings may be different, so a spacer ring is used to separate the pressure rings in the axial direction, and the material is reasonably selected to ensure that the cross section of the pressure ring is not scratched during its service life, avoid the increase of friction caused by the scratch of the parts and the loss of mechanical efficiency, and ensure the stability of the mechanical efficiency transmitted by the crankshaft. When the hydraulic power is transmitted to the crankshaft 1 through the pressure ring 4 and the needle roller 5, the crankshaft 1 begins to rotate around its axis due to the existence of the eccentricity e of the crankshaft 1. During the rotation process, the friction pair between the pressure ring 4 and the crankshaft 1 is converted from sliding friction with a larger friction coefficient to rolling friction with a smaller friction coefficient. The friction pair with a high friction coefficient between the pressure rings is converted into a friction pair with a low friction coefficient with a longer service life and more stable precision through positioning spacer rings 3, spacer rings 6, and retaining rings 7, thereby ensuring the reliability of transmission efficiency and stable precision and improving the ability to transmit torque. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a cross-sectional view of the crankshaft of the high-torque hydraulic motor of the present invention.

[0013] Figure 2 It is a schematic diagram of the external structure of the crankshaft kinematic pair of the present invention.

[0014] In the figure: 1 crankshaft, 2 end cover, 3 spacer ring, 4 pressure ring, 5 needle roller, 6 spacer ring, 7 retaining ring.

[0015] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to the scope of the embodiments described. All these concepts should be regarded as the content disclosed by the present technology and the protection scope of the present invention. DETAILED DESCRIPTION

[0016] See also Figure 1-2 In the preferred embodiment described below, a large torque hydraulic motor crankshaft comprises: a crankshaft 1 sealed in a housing through an end cover 2, and the extended end of the crankshaft 1 is the output shaft of the motor. The eccentric curved neck end of the crankshaft 1 and the eccentric eccentric wheel shaft end of the coaxial connecting rod are supported on the bearings of the end cover 2 and the rear end cover of the housing through a pair of tapered roller bearings, and rotate around the central axis of rotation of the bearings to limit the horizontal, up and down, and forward and backward reciprocating motion freedom of the crankshaft 1. A pressure ring 4 that bears hydraulic pressure and a needle roller 5 installed in the pressure ring 4 are installed on the crankshaft 1 between the eccentric curved neck end and the eccentric wheel shaft end, and each pressure ring 4 is arranged at intervals through a spacer ring 6 and distributed in a linear array between the positioning spacer ring 3 and the retaining ring 7 to ensure that the needle roller 5 is always in contact with the pressure ring 4 during the operation of the crankshaft 1, which plays an axial positioning role for the needle roller 5 and forms a static pressure balance structure with the crankshaft 1 kinematic pair; the hydraulic pressure applied to the pressure ring 4 generates a torque that rotates the crankshaft 1 through the eccentric distance e of the crankshaft 1, and the needle roller 5 converts the 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.

[0017] In order to ensure high efficiency and high precision of power transmission, a pressure ring 4 is installed on the crankshaft 1, and a needle roller 5 is installed between the inner surface of the pressure ring 4 and the outer surface of the crankshaft 1. The sliding friction with a larger friction coefficient between the inner surface of the pressure ring 4 and the outer surface of the crankshaft 1 is converted into rolling friction with a smaller friction coefficient through the needle roller 5.

[0018] In order to ensure that the power generated by the hydraulic pressure is transmitted to the crankshaft 1 through the pressure ring 4 with high efficiency and high precision, the axial position of the pressure ring 4 needs to be ensured. The positioning spacer ring 3, the spacer ring 6, and the retaining ring 7 are all set to ensure the exact axial position of the pressure ring 4. At the same time, because the rotation directions of the three pressure rings 4 may be different during the operation of the crankshaft 1, in order to reduce the friction between the parts and reduce the mechanical efficiency due to the scratches on the end faces of the pressure ring 4 caused by friction, it is necessary to ensure that the materials of the positioning spacer ring 3, the spacer ring 6, and the retaining ring 7 are lower in hardness than the material of the pressure ring 4. In addition, the positioning spacer ring 3, the spacer ring 6, and the retaining ring 7 ensure that the needle roller 5 is always in contact with the pressure ring 4 during the operation of the crankshaft 1, and play an axial positioning role for the needle roller 5.

[0019] The end cover 2 is provided to locate the axial position of the spacer ring 3 .

[0020] When hydraulic power is transmitted to the crankshaft 1 through the pressure ring 4 and the needle roller 5, since the small diameter end and the large diameter end of the crankshaft 1 have only the freedom to rotate around their axis, and the crankshaft 1 has an eccentricity e, the crankshaft 1 begins to rotate around its axis, and the end cover 2, the positioning spacer ring 3, the pressure ring 4, the needle roller 5, the spacer ring 6, and the retaining ring 7 installed on the crankshaft 1 all rotate with the crankshaft 1. When the crankshaft 1 rotates, there is a relative movement between the inner surface of the pressure ring 4 and the needle roller 5, there is a relative movement between the needle roller 5 and the outer surface of the crankshaft 1, there is a relative movement between the end face of the pressure ring 4 and the end faces of the positioning spacer ring 3, the spacer ring 6, and the retaining ring 7, there is a relative movement between the end face of the positioning spacer ring 3 and the end face of the end cover 2, and there is a relative movement between the end face of the retaining ring 7 and the large diameter end face of the crankshaft.

[0021] During the rotation of the crankshaft, the hydraulic power is transmitted to the crankshaft 1 from the pressure ring 4 through the needle roller 5. The friction pairs between the inner surface of the pressure ring 4 and the needle roller 5, and between the needle roller 5 and the outer surface of the crankshaft 1 are rolling frictions with a small friction coefficient. The rolling friction reduces the mechanical energy and wear generated by the relative motion between the inner surface of the pressure ring 1 and the outer surface of the crankshaft 1. The reduction in mechanical energy improves the mechanical efficiency of the crankshaft 1 in transmitting power. The reduction in wear keeps the motion accuracy of the crankshaft 1 in a stable state during its service life, thereby ensuring the motion accuracy during its service life.

[0022] During the rotation of the crankshaft, the long-term friction between the end faces of the pressure rings and between the end face of the pressure ring 4 and the large diameter end face of the crankshaft 1 will scratch the end face of the pressure ring 4, increase the internal friction force when the crankshaft 1 rotates, generate more mechanical energy, and reduce the mechanical efficiency of the crankshaft in transmitting power. By setting the positioning spacer ring 3, the spacer ring 6, and the retaining ring 7 to isolate the direct friction contact between the pressure ring 4 and the end face of the pressure ring 4, and between the end face of the pressure ring 4 and the large diameter end face of the crankshaft 1, the positioning spacer ring 3, the spacer ring 6, and the retaining ring 7 are selected from materials with low hardness and good wear resistance, so as to improve the relative friction motion performance between the pressure ring and the end face of the pressure ring, and between the end face of the pressure ring 4 and the large diameter end face of the crankshaft 1, reduce the friction coefficient, reduce the wear between the end faces of the pressure rings, and ensure the power transmission efficiency of the crankshaft.

[0023] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A high torque hydraulic motor crankshaft, comprising: A crankshaft (1) is sealed in the housing through an end cover (2), and the extended end of the crankshaft (1) is the output shaft of the motor. The crankshaft (1) is characterized in that: the crankshaft (1) includes an eccentric curved neck end and an eccentric wheel shaft end, and the eccentric curved neck end and the eccentric wheel shaft end are supported on the bearings of the end cover (2) and the rear end cover of the housing through a pair of tapered rollers, and rotate around the central axis of the bearing rotation to limit the horizontal, up and down, and forward and backward reciprocating freedom of the crankshaft (1). A A positioning spacer ring (3), three pressure rings (4) bearing hydraulic pressure, a needle roller (5) and a retaining ring (7) mounted in the pressure ring (4), and each pressure ring (4) is arranged in a spaced manner through a spacer ring (6) and distributed in a linear array between the positioning spacer ring (3) and the retaining ring (7), so as to ensure that the needle roller (5) is always in contact with the pressure ring (4) during the operation of the crankshaft (1), play an axial positioning role for the needle roller (5), and form a static pressure balance structure with the kinematic pair of the crankshaft (1); the hydraulic pressure applied to the pressure ring (4) is The eccentricity e of the crankshaft (1) generates a torque that causes the crankshaft (1) to rotate, and the needle roller (5) converts the sliding friction between the inner surface of the pressure ring (4) and the outer surface of the crankshaft (1) into rolling friction; the positioning spacer ring (3), the spacer ring (6), and the retaining ring (7) are all provided to ensure the exact axial position of the pressure ring (4); the rotation directions of the three pressure rings (4) of the crankshaft (1) are different during operation; the positioning spacer ring (3), the spacer ring (6), and the retaining ring (7) ensure that the needle roller (5) is always in the position of the pressure ring (4) during operation of the crankshaft (1). The end cover (2) is provided to locate the axial position of the spacer ring (3); during the rotation of the crankshaft, the hydraulic power is transmitted from the pressure ring (4) to the crankshaft (1) through the needle roller (5); the friction between the inner surface of the pressure ring (4) and the needle roller (5), and between the needle roller (5) and the outer surface of the crankshaft (1) is rolling friction with a relatively small friction coefficient, and the rolling friction reduces the mechanical energy and wear generated by the relative motion between the inner surface of the pressure ring (1) and the outer surface of the crankshaft (1).

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