Plunger assembly with needle bearing for reducing stress concentration and hydraulic motor

Abstract

The utility model discloses a plunger assembly with a needle roller bearing and capable of reducing stress concentration and a hydraulic motor, the plunger assembly comprises a plunger, a spring pin and the needle roller bearing, the needle roller bearing comprises an outer ring and a needle roller, and the plunger is provided with a needle roller bearing cavity for the needle roller bearing to be installed in. A first arc-shaped chamfer, a second arc-shaped chamfer, a first logarithmic curve and a second logarithmic curve are arranged on the surface of the outer ring, the first logarithmic curve and the second logarithmic curve are connected to form a logarithmic curve main surface, and the logarithmic curve main surface is arranged in the center of the outer ring. The first arc-shaped chamfer and the second arc-shaped chamfer are arranged on the two sides of the logarithmic curve main surface respectively, and the hydraulic motor has the advantages that due to uniform stress distribution, the local stress peak value of the outer ring is greatly reduced, the risk of fatigue damage caused by stress concentration is greatly reduced, and the stability and reliability of operation of the hydraulic motor are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of hydraulic motor especially to a plunger assembly with stress concentration reducing and needle bearing and hydraulic motor. BACKGROUND

[0002] In various hydraulic systems, hydraulic motor as a key executive component plays an irreplaceable important role. Its working principle is based on energy conversion mechanism, that is, accurately and efficiently converting hydraulic energy into mechanical energy, so as to drive the output shaft to complete continuous and stable rotary motion. Taking a common type of hydraulic motor as an example, its structure is mainly composed of stator, rotor assembly, motor front cover and motor rear cover. Among them, the rotor assembly is closely connected with the output shaft, and in the whole power transmission chain, it bears the core power transmission task, is the key link to realize energy conversion and output effective power. The internal structure of the rotor assembly is relatively complex, including the rotor and the plunger assembly composed of rollers, plungers, spring pins, piston rings and plunger baffles.

[0003] In the operation process of the hydraulic motor, hydraulic oil as a power transmission medium plays a crucial driving role. When high-pressure oil is injected into the plunger cavity, the strong pressure will push the plunger to do linear motion in the cavity. This linear motion drives the roller to do a unique wave motion along the inner wall of the stator with a specific curve shape. Due to the special curve profile design of the inner wall of the stator, the wave motion of the roller can cleverly make the rotor drive the output shaft to rotate, thereby successfully completing the complete conversion process from hydraulic energy to mechanical energy.

[0004] However, in-depth analysis of the prior art shows that there is a significant technical defect in the connection part of the roller and the plunger. At present, the oil-free bearing is generally used as the connecting part between the roller and the plunger, and the roller rotates relative to the oil-free bearing during work. However, the sliding friction characteristics between the oil-free bearing and the roller result in a large friction coefficient. According to the basic principle of mechanical motion, this large friction coefficient makes the hydraulic motor need to overcome a large friction torque at the moment of starting. The larger the friction torque needs to be overcome at the start, the more energy the motor consumes during the starting process, and the starting time will also be prolonged accordingly, which directly leads to a serious decline in the starting efficiency of the hydraulic motor.

[0005] To solve the above problems, the prior art attempts to replace the traditional roller with a needle bearing. However, the outer ring surface of the traditional needle bearing is designed as a straight line, and in actual operation, stress concentration phenomenon inevitably occurs at both ends, which is called "edge effect". With the long-term uninterrupted operation of the hydraulic motor, this stress concentration will continuously aggravate the fatigue damage of the motor, resulting in a significant reduction in the fatigue life of the motor, which seriously restricts the improvement of the performance of the hydraulic motor and the stability and reliability of the operation, and innovative technical solutions are urgently needed to overcome this technical problem. Utility Model Content

[0006] The technical problem to be solved by this utility model is to provide a plunger assembly with needle roller bearing and a hydraulic motor that reduces stress concentration. This utility model can evenly distribute the stress of the needle roller bearing, including the outer ring, on the surface, thereby greatly improving the service life of the motor.

[0007] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: a plunger assembly with needle roller bearing to reduce stress concentration, characterized in that it includes a plunger, a spring pin and a needle roller bearing, the needle roller bearing includes an outer ring and needle rollers, a core is provided in the center of the needle roller bearing, the needle rollers are provided between the core and the outer ring, fixing grooves are provided on both sides of the plunger, the two sides of the core are inserted into the fixing grooves, a spring pin is also provided at one end of the core, a needle roller bearing cavity is provided on the plunger for the needle roller bearing to be installed, the surface of the outer ring is provided with a first arc chamfer, a second arc chamfer, a first logarithmic curve and a second logarithmic curve, the first logarithmic curve and the second logarithmic curve are connected to form a logarithmic curve main surface, the logarithmic curve main surface is provided in the center of the outer ring, and the first arc chamfer and the second arc chamfer are respectively provided on both sides of the logarithmic curve main surface.

[0008] A further preferred embodiment of this utility model is: a first step is provided at the connection between the first arc-shaped chamfer and the main surface of the logarithmic curve, and a second step is provided at the connection between the second arc-shaped chamfer and the main surface of the logarithmic curve.

[0009] A further preferred embodiment of this utility model is that at the connection between the first step and the second step, the position of the main surface of the logarithmic curve is higher than the first arc-shaped chamfer and the second arc-shaped chamfer.

[0010] A further preferred embodiment of this utility model is that the radii of the first and second arc-shaped chamfers are 5.8% to 6.4% of the width of the outer ring.

[0011] A further preferred embodiment of this utility model is that the radii of the first and second arc-shaped chamfers are 6.09% of the width of the outer ring.

[0012] This utility model focuses on the innovative design of the outer ring of a needle roller bearing. By setting a first arc-shaped chamfer, a second arc-shaped chamfer, a first logarithmic curve, and a second logarithmic curve on the surface of the outer ring, the stress distribution of the outer ring is optimized, which significantly improves the overall performance of the hydraulic motor.

[0013] In traditional linear outer ring designs, stress tends to concentrate at both ends, significantly reducing the fatigue life of the needle roller bearing and even the entire hydraulic motor. This design cleverly connects the first and second logarithmic curves to form the main logarithmic surface located in the center of the outer ring, with the first and second arc-shaped chamfers positioned on either side of this main surface. As a result, when the needle roller bearing is operating, the forces from the needle rollers and external loads are no longer concentrated at the ends of the outer ring. The stress gradually transitions along the arc-shaped chamfers to the main logarithmic surface, and is then evenly distributed across the entire outer ring surface.

[0014] This unique design brings significant technical advantages. On the one hand, the uniform stress distribution greatly reduces local stress peaks in the outer ring, significantly reducing the risk of fatigue damage caused by stress concentration. On the other hand, the extended service life of the needle roller bearing directly improves the stability and reliability of the hydraulic motor. Whether under continuous high-load operation or complex conditions of frequent start-stop, the improved needle roller bearing can more effectively resist fatigue damage, ensuring the long-term stable operation of the hydraulic motor, reducing the probability of equipment failure, reducing maintenance costs, and providing solid support for the efficient operation of related mechanical equipment. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of this utility model;

[0016] Figure 2 A 3D view of the plunger assembly;

[0017] Figure 3 This is a schematic diagram of a needle roller bearing;

[0018] Figure 4 for Figure 3 The large image at point A in the middle;

[0019] Figure 5 This is a cross-sectional view of the plunger assembly. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0021] like Figures 1-5As shown, a plunger assembly with needle roller bearings to reduce stress concentration includes a plunger 1, a spring pin 2, and a needle roller bearing 3. The needle roller bearing 3 includes an outer ring 4 and needle rollers 5. A shaft core 6 is provided in the center of the needle roller bearing 3. The needle rollers 5 are disposed between the shaft core 6 and the outer ring 4. Fixing grooves 7 are provided on both sides of the plunger 1. The two sides of the shaft core 6 are inserted into the fixing grooves 7. A spring pin 2 is also provided at one end of the shaft core 6. A needle roller bearing cavity 8 is provided on the plunger 1 for the needle roller bearing 3 to be installed. The surface of the outer ring 4 is provided with a first arc chamfer 9, a second arc chamfer 10, a first logarithmic curve 11, and a second logarithmic curve 12. The first logarithmic curve 11 and the second logarithmic curve 12 are connected to form a logarithmic curve main surface. The logarithmic curve main surface is located in the center of the outer ring 4. The first arc chamfer 9 and the second arc chamfer 10 are symmetrically arranged on both sides of the logarithmic curve main surface. By setting the surface of the outer ring 4 of the needle roller bearing 3 into a special shape including a first arc-shaped chamfer 9, a second arc-shaped chamfer 10, a first logarithmic curve 11, and a second logarithmic curve 12, where the first and second logarithmic curves are connected to form the main surface of the logarithmic curve located in the center of the outer ring 4, and the first and second arc-shaped chamfers are placed on both sides of the main surface of the logarithmic curve, this unique design allows the stress on the outer ring 4 to be evenly distributed along the arc and logarithmic curves when subjected to the forces from the needle rollers 5 and external loads. This avoids the stress concentration phenomenon (edge ​​effect) that easily occurs at the ends of traditional straight outer rings. The uniform stress distribution effectively reduces the local stress peaks on the outer ring 4, greatly reducing the probability of fatigue damage, thereby significantly improving the service life of the needle roller bearing 3 in the hydraulic motor, and ultimately improving the durability and reliability of the entire hydraulic motor.

[0022] A first step 14 is provided at the connection between the first arc-shaped chamfer 9 and the logarithmic curve main surface, and a second step 15 is provided at the connection between the second arc-shaped chamfer 10 and the logarithmic curve main surface. The presence of these steps further optimizes stress transition. When the outer ring 4 is subjected to loads of different directions or variations, the step structure can change the stress transmission path, preventing abrupt stress changes at the connection point. This allows the stress to transition more smoothly from the arc-shaped chamfer region to the logarithmic curve main surface region, further enhancing the outer ring 4's resistance to stress concentration and ensuring the stable operation of the needle roller bearing 3 under complex working conditions.

[0023] At the junction of the first step 14 and the second step 15, the position of the main surface of the logarithmic curve is higher than that of the first arc-shaped chamfer 9 and the second arc-shaped chamfer 10. Because of this height difference design, during the operation of the needle roller bearing 3, the force distribution of the needle rollers 5 is guided, ensuring that when the needle rollers 5 contact the outer ring 4, the load is preferentially applied to the main surface area of ​​the logarithmic curve. Utilizing the excellent stress dispersion characteristics of the main surface of the logarithmic curve, the concentrated force on the needle rollers 5 at the arc-shaped chamfer is reduced, thereby further reducing wear in the arc-shaped chamfer area and extending the overall service life of the needle roller bearing 3.

[0024] The radii of the first arc-shaped chamfer 9 and the second arc-shaped chamfer 10 are 5.8% to 6.4% of the width of the outer ring 4. This specific range of radii has been determined through extensive experimentation and engineering practice. Within this range, the arc-shaped chamfers achieve optimal stress dispersion while ensuring the structural strength of the outer ring 4. If the radius is too small, stress cannot be sufficiently dispersed; if the radius is too large, the structural strength of the outer ring 4 may be weakened. This range ensures a balance between optimizing stress distribution and maintaining the structural stability of the outer ring 4, effectively improving the overall performance of the needle roller bearing 3 and the hydraulic motor.

[0025] The radii of the first arc-shaped chamfer 9 and the second arc-shaped chamfer 10 are 6.09% of the width of the outer ring 4. This specific ratio of 6.09% has been proven in practical applications to more accurately balance the relationship between stress dispersion and structural strength. Using this radius value allows the outer ring 4 of the needle roller bearing 3 to achieve optimal stress dispersion under various operating loads, while maximizing the structural integrity of the outer ring 4, further improving the reliability and durability of the needle roller bearing 3 in the hydraulic motor. The hydraulic motor includes the aforementioned plunger assembly with needle roller bearings to reduce stress concentration.

[0026] like Figure 2 As shown, the plunger 1 is cylindrical, the outer wall of the plunger 1 is arc-shaped, the two ends of the shaft core 6 are arc-shaped, and the two ends of the shaft core 6 and the outer wall of the plunger 1 are on the same plane.

[0027] After analyzing different logarithmic curve equations, This is the optimal logarithmic curve equation. Taking the midpoint of the principal surface of the logarithmic curve as the origin, the points on the first and second logarithmic curves are arranged according to... The equations are arranged such that the coordinates of the first logarithmic curve are (x, y) and the coordinates of the second logarithmic curve are (-x, y), L is the width of the outer circle, and R is the radius of the first and second arc chamfers.

[0028] The following are experimental data under different logarithmic curve equations: Equation 1 is: Equation 2 is: Equation 3 is: Equation 4 is: Equation 5 is:

[0029]

[0030]

[0031] The above provides a detailed description of a plunger assembly with needle roller bearings and a hydraulic motor for reducing stress concentration, as provided by this utility model. Specific examples have been used to illustrate the principle and implementation of this utility model. The descriptions of the embodiments are merely for the purpose of helping to understand this utility model and its core ideas. It should be noted that those skilled in the art can make various improvements and modifications to this utility model without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. A stress concentration reducing roller pin bearing plunger assembly characterized by The plunger assembly comprises a plunger, a spring pin and a needle bearing, the needle bearing comprises an outer ring and needles, a shaft core is arranged in the center of the needle bearing, the needles are arranged between the shaft core and the outer ring, both sides of the plunger are provided with fixed grooves, both sides of the shaft core are inserted into the fixed grooves, one end of the shaft core is further provided with a spring pin, the plunger is provided with a needle bearing cavity for accommodating the needle bearing, the surface of the outer ring is provided with a first arc chamfer, a second arc chamfer, a first logarithmic curve and a second logarithmic curve, the first logarithmic curve and the second logarithmic curve are connected to form a logarithmic curve main surface, the logarithmic curve main surface is arranged in the center of the outer ring, and the first arc chamfer and the second arc chamfer are arranged on both sides of the logarithmic curve main surface respectively.

2. A stress concentration reducing roller pin bearing plunger assembly according to claim 1, wherein The connecting part of the first arc chamfer and the logarithmic curve main surface is provided with a first step, and the connecting part of the second arc chamfer and the logarithmic curve main surface is provided with a second step.

3. A stress concentration reducing roller pin bearing plunger assembly according to claim 2, wherein The connecting part of the first step and the second step is higher than the first arc chamfer and the second arc chamfer in position.

4. A stress concentration reducing roller pin bearing plunger assembly as set forth in claim 1 wherein The radius of the first arc chamfer and the second arc chamfer is 5.8% to 6.4% of the width of the outer ring.

5. A stress concentration reducing roller pin bearing plunger assembly as set forth in claim 1 wherein The radius of the first arc chamfer and the second arc chamfer is 6.09% of the width of the outer ring.

6. A stress concentration reducing roller pin bearing plunger assembly as set forth in claim 1 wherein The logarithmic curve main surface has an origin in the middle, and points on the first logarithmic curve and the second logarithmic curve are arranged according to the equation , where the coordinates of the first logarithmic curve are (x, y), the coordinates of the second logarithmic curve are (-x, y), L is the width of the outer ring, and R is the radius of the first arc-shaped chamfer and the second arc-shaped chamfer.

7. A stress concentration reducing roller pin bearing plunger assembly as set forth in claim 1 wherein The plunger is in a cylindrical shape, the outer wall of the plunger is arc-shaped, both ends of the shaft core are arc-shaped, and both ends of the shaft core and the outer wall of the plunger are in the same plane.

8. Hydraulic motor, characterized in that The plunger assembly comprises a plunger assembly with a needle bearing for reducing stress concentration.

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