A bushing with axial and circumferential positioning functions and a water pump impeller

Abstract

This utility model discloses a bushing with axial and circumferential positioning functions and a water pump impeller. It includes a bushing body with an axially penetrating inner hole. The inner hole includes a grooveless section and a grooved section continuously arranged axially. The inner wall of the grooveless section is a smooth cylindrical surface. The inner wall of the grooved section has several axially extending, non-penetrating grooves evenly distributed circumferentially. The edges of the groove walls form radially inward protrusions due to plastic deformation, making the effective diameter of the inner hole of the grooved section smaller than the inner diameter of the grooveless section. An interference fit is formed between the grooved section and the drive shaft. This structure simultaneously achieves axial and circumferential fixation of the drive shaft, ensuring concentricity after assembly and avoiding scratching and jamming after assembly. It eliminates the need for traditional dotting processes, completing assembly in a single press-in, improving assembly efficiency and yield rate, and does not disrupt the impeller's dynamic balance, resulting in better long-term reliability.

Description

Technical Field

[0001] This utility model relates to the field of water pump impeller technology, specifically a bushing with axial and circumferential positioning functions and a water pump impeller. Background Technology

[0002] In the field of mechanical transmission technology, the interference fit between the bushing and the drive shaft is a common connection method, widely used in the assembly of rotating components such as pump impellers, motor fan blades, gears, and cams with drive shafts. Taking the water pump field as an example, the bushing, usually formed by powder metallurgy, has an interference fit between its inner hole and the drive shaft to transmit torque and prevent axial movement.

[0003] However, in actual production, the machining tolerances of the outer diameter of the drive shaft and the inner hole of the bushing overlap, resulting in unstable fit accuracy and often causing the fit to be too loose or too tight.

[0004] When the fit is too loose, relative sliding or radial movement can easily occur between the impeller and the drive shaft, leading to abnormal noise during impeller rotation and even ineffective torque transmission. Traditional solutions typically employ an axial perforation process: after assembling the impeller onto the shaft, multiple indentations are punched into the shaft's end face, causing plastic deformation of the inner edge of the bushing end, thus tightening the impeller onto the shaft. However, this solution only addresses situations with an excessively loose fit and cannot solve the problem of an excessively tight fit.

[0005] When the fit is too tight, the impeller is difficult to install properly. Forcing it in not only makes assembly difficult, but also damages the concentricity of the impeller and the shaft. This causes the outer circle of the impeller to scrape against the pump body (grinding the outer circle) or to rub violently against the pump head sealing structure when the impeller rotates. In severe cases, this can cause the pump to jam, resulting in decreased pump performance, increased noise, or even damage to the entire machine.

[0006] In addition, the above-mentioned traditional dotting method has the following drawbacks: First, the dotting operation itself cannot guarantee the perpendicularity of the impeller and the shaft. After dotting, it is often necessary to use a hammer to tap the pump head to "align" it, which heavily relies on the experience and feel of the installers. Second, if it still does not meet the requirements after alignment, it must be disassembled and reworked, which seriously affects production efficiency. Third, dotting will produce uneven local deformation on the impeller end face, which will destroy the dynamic balance of the impeller. Fourth, the protrusions produced by dotting are prone to wear during long-term operation, and the clamping force gradually decreases, resulting in poor long-term reliability.

[0007] Therefore, the existing technology lacks a bushing structure that can simultaneously achieve axial and circumferential fixation of the drive shaft while ensuring smooth assembly and concentricity between the impeller and the drive shaft. Utility Model Content

[0008] To address the shortcomings of the prior art, this utility model provides a bushing with axial and circumferential positioning functions and a water pump impeller.

[0009] The technical solution adopted by this utility model is: a bushing with axial and circumferential positioning functions, including a bushing body, the bushing body having an axially penetrating bushing inner hole, the bushing inner hole including a grooveless section and a grooved section continuously arranged along the axial direction; the inner wall of the grooveless section is a smooth cylindrical surface. The grooved section has several grooves evenly distributed circumferentially along its inner wall, extending axially. The grooves are not continuous along the axial direction. The edge of the groove wall forms a bulge that rises radially inward due to plastic deformation, making the effective diameter of the inner hole of the grooved section smaller than the inner diameter of the ungrooved section. The grooved section and the drive shaft form an interference fit.

[0010] Furthermore, the number of grooves is 2 to 6.

[0011] Furthermore, the grooveless section is located at the initial insertion end of the drive shaft.

[0012] Furthermore, the length of the groove is less than the total axial length of the inner hole of the bushing.

[0013] Furthermore, the length of the groove is one-half to one-third of the total axial length of the inner hole of the bushing.

[0014] Furthermore, the cross-sectional shape of the groove is rectangular.

[0015] Furthermore, the cross-sectional shape of the groove is U-shaped.

[0016] Furthermore, the height of the protrusion is 0.05-0.5mm.

[0017] Furthermore, the width 'a' of the groove is 0.1-0.5 mm.

[0018] This application also provides a water pump impeller, including a bracket and blades arranged around the outer ring of the bracket, wherein the aforementioned bushing is disposed inside the bracket.

[0019] The beneficial effects of this utility model are: 1. Simultaneously solves the problems of excessive looseness and excessive tightness: Traditional dotting methods can only address excessively loose fits, not excessively tight fits. This invention, by setting a groove in the grooved section of the bushing's inner hole, utilizes the radially inward bulges formed by plastic deformation at the groove wall edge to reduce the effective diameter of the grooved section's inner hole, forming a stable interference fit with the drive shaft. Regardless of whether the shaft diameter is slightly smaller or larger than the tolerance range, a stable clamping force can be generated through the elastic / plastic deformation of the material, adaptively compensating for machining errors and ensuring smooth and jam-free assembly.

[0020] 2. Achieving a "guided alignment followed by tightening" assembly effect: The inner hole of the bushing is divided into a grooveless section and a grooved section along the axial direction. The inner wall of the grooveless section is a smooth cylindrical surface. When the drive shaft is installed, it first enters the grooveless section, where it is easily guided and automatically aligned using a clearance fit. After being pushed in further, it enters the grooved section, where the reduced bore diameter is firmly tightened. This segmented structure makes the assembly process smooth, ensuring the concentricity and perpendicularity of the impeller and shaft without the need for hammering for alignment.

[0021] 3. Combines axial and circumferential fixation: The interference fit between the grooved section and the drive shaft generates a radial clamping force, which is simultaneously converted into axial and circumferential friction forces. This prevents the drive shaft from shifting or coming off in the axial direction, and also prevents it from slipping in the circumferential direction, achieving double locking. In particular, the raised part at the edge of the groove forms a local high-stress contact area with the drive shaft surface, further increasing the clamping force and the coefficient of friction, making the axial and circumferential fixing effect superior to the interference fit of a smooth hole wall.

[0022] 4. No need for hammering for alignment, reducing reliance on manual labor: Since the grooveless section can automatically align itself in the early stages of assembly and the clamping section can be directly locked, the concentricity and perpendicularity of the impeller and shaft naturally meet the requirements after assembly. There is no need to use a hammer to correct the perpendicularity of the pump head as in the traditional dotting process, which reduces the reliance on the skills of the installers and reduces quality fluctuations.

[0023] 5. Improve assembly efficiency and pass rate: No need for marking, no need for hammering for alignment, no need for disassembly and rework, assembly can be completed in one press, which significantly improves assembly efficiency and first-time assembly pass rate.

[0024] 6. Does not disrupt impeller dynamic balance: The deformation of this invention occurs on the inner wall of the bushing, without changing the external shape and dynamic balance characteristics of the impeller body, thus avoiding the problem of uneven deformation and disruption of dynamic balance caused by traditional dotting process on the impeller end face.

[0025] 7. Better long-term reliability: The bumps produced by traditional dotting are prone to wear, and the clamping force gradually decreases; this utility model uses radial contraction formed by the plastic flow of the inner hole wall material, which has a more stable geometry, and the non-through groove design avoids stress concentration. After long-term operation, the clamping force decreases less and the connection reliability is higher.

[0026] 8. Simple structure and easy to process: It can be achieved by only processing a non-through axial groove in a local area of ​​the inner hole of the bushing. No additional locking elements or complex assembly tools are required, resulting in low processing costs and easy mass production.

[0027] In addition to the objectives, features, and advantages described above, this utility model has other objectives, features, and advantages. The present utility model will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of this utility model.

[0029] Figure 2 for Figure 1 Enlarged diagram of point A in the middle.

[0030] Figure 3 This is a cross-sectional schematic diagram of the present invention.

[0031] Figure 1-3 In the middle: 1. Bushing body; 2. Bushing inner hole; 3. Ungrooved section; 4. Grooved section; 5. Groove; 6. Protrusion; 7. Support; 8. Blade. Detailed Implementation

[0032] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0033] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0034] This utility model provides a bushing with axial and circumferential positioning functions.

[0035] In this embodiment, refer to Figure 1-3 The bushing with axial and circumferential positioning functions includes a bushing body 1, the bushing body 1 having an axially penetrating bushing inner hole 2, the bushing inner hole 2 including a grooveless section 3 and a grooved section 4 continuously arranged along the axial direction; the inner wall of the grooveless section is a smooth cylindrical surface. The inner wall of the grooved section has several grooves 5 that extend axially and are evenly distributed along the circumferential direction. The grooves 5 are not continuous along the axial direction. The edge of the groove wall of the groove 5 forms a protrusion 6 that bulges radially inward due to plastic deformation, so that the effective diameter of the inner hole of the grooved section is smaller than the inner diameter of the ungrooved section. An interference fit is formed between the grooved section and the drive shaft.

[0036] In the above technical solution, by setting grooveless and grooved sections continuously arranged along the axial direction in the inner hole of the bushing, the smooth cylindrical surface of the grooveless section provides clearance guidance, and the radial inner bulge formed by the plastic deformation of the groove wall edge of the grooved section reduces the effective diameter of the inner hole, so that the grooved section and the drive shaft form an interference fit; the radial clamping force generated by the interference fit is simultaneously converted into axial friction force and circumferential friction force.

[0037] While ensuring smooth assembly of the drive shaft, the drive shaft is simultaneously fixed axially (to prevent it from coming off) and circumferentially (to prevent slippage), and the concentricity after assembly is ensured to avoid scratching and jamming after assembly.

[0038] Specifically, the number of grooves is 2 to 6.

[0039] In this embodiment, 2 to 6 grooves are evenly arranged circumferentially in the inner hole of the bushing. This ensures that the plastic deformation and radial shrinkage generated by broaching are evenly distributed circumferentially, avoiding uneven distribution of clamping force due to too few grooves or excessive weakening of the bushing structure due to too many grooves. This ensures that the radial clamping force is evenly distributed circumferentially, preventing unilateral stress on the drive shaft, improving the stability and reliability of the connection, while also maintaining the structural strength of the bushing.

[0040] Specifically, the grooveless section is located at the initial insertion end of the drive shaft.

[0041] In this embodiment, the grooveless section is placed at the initial insertion end of the drive shaft, so that during assembly, the drive shaft first enters the grooveless section (clearance fit section), where the smooth hole wall achieves automatic guidance and alignment, and then continues to be pushed into the grooved section (interference fit section). This achieves the assembly sequence of "guiding first, then clamping," avoiding direct scraping of the groove protrusion of the grooved section by the end of the drive shaft, protecting the groove structure, and reducing assembly resistance.

[0042] Specifically, the length of the groove is less than the total axial length of the inner hole of the bushing.

[0043] In this embodiment, the groove length is set to be less than the total axial length of the bushing's inner hole, meaning the groove does not penetrate the entire inner hole, leaving a complete smooth hole as a grooveless guide section. This ensures the grooveless section has sufficient axial length to achieve reliable guidance and automatic alignment, while the grooved section provides sufficient clamping length to avoid excessive assembly resistance or insufficient guidance caused by a full-length groove.

[0044] Specifically, the length of the groove is one-half to one-third of the total axial length of the inner hole of the bushing.

[0045] In this embodiment, the guide section is long enough to ensure that the drive shaft is fully aligned before it enters the clamping section; the clamping section is of moderate length to provide reliable axial and circumferential fixing force, while avoiding excessive assembly resistance caused by an excessively long clamping section.

[0046] In this embodiment, the groove is formed on the inner wall of the bushing using a broaching process. During broaching, the broach cuts into the inner wall of the bushing from the radially inward side, applying a radially inward cutting force to the material. Since the outer surface of the bushing is a solid constraint, the material cannot flow outward from the bushing and can only undergo plastic flow along both sides of the groove towards the radially inward side (i.e., towards the center of the shaft hole), thus forming protrusions towards the center of the shaft hole at the edges of the groove walls on both sides. After broaching, the effective diameter of the inner hole in the area where the groove is located (i.e., the diameter between the apexes of the two protrusions) is smaller than the original diameter of the smooth hole, resulting in an interference fit between the grooved section and the drive shaft. The mechanism by which the inner hole broaching causes the material to flow inward plastically, leading to a local reduction in hole diameter, is similar to the known principle of inner hole rolling reducing hole diameter. The difference is that this embodiment achieves localized and controllable hole diameter reduction by broaching a non-through axial groove.

[0047] Specifically, the cross-sectional shape of the groove is rectangular.

[0048] In this embodiment, broaching is convenient for forming, the groove wall bulge is uniform and controllable, and a stable local high-stress contact is formed with the drive shaft, which increases the friction coefficient and clamping force, and improves the axial and circumferential fixing reliability.

[0049] Specifically, the cross-sectional shape of the groove is "U".

[0050] In this embodiment, stress concentration at the root of the groove is reduced, improving the fatigue strength and service life of the bushing under alternating loads, while maintaining good clamping performance and guiding function.

[0051] Specifically, the height of the protrusion is 0.05-0.5mm.

[0052] In this embodiment, the interference fit is controlled within a reasonable range, which can provide sufficient radial clamping force to ensure axial and circumferential fixation, while avoiding excessive tightness that could cause assembly jamming or damage to the bushing and drive shaft surfaces.

[0053] Specifically, the width 'a' of the groove is 0.1-0.5 mm.

[0054] In this embodiment, the width of the groove directly affects the plastic flow space of the material and the stress state of the broach during broaching. When the width is too small (less than 0.1 mm), the broach cutting edge is too thin and lacks strength, making it prone to chipping or breakage during machining. Furthermore, the material flow space is limited, making it difficult to form an effective radial inner bulge. When the width is too large (greater than 0.5 mm), the cutting amount in a single broaching operation is too large, the extrusion effect is relatively weakened, and the bulge height at the groove edge is insufficient, resulting in a reduced interference fit. Simultaneously, it excessively weakens the bushing wall thickness, reducing its structural strength. Limiting the groove width to 0.1-0.5 mm achieves a balance between broach strength, material plastic flow, and bushing structural strength, generating controllable and uniform radial extrusion force during broaching and ensuring the formation of a moderately high bulge at the groove edge.

[0055] This application also provides a water pump impeller, including a bracket 7 and blades 8 arranged around the outer ring of the bracket 7, wherein the aforementioned bushing is disposed inside the bracket.

[0056] This design eliminates the need for traditional marking and hammering during pump impeller assembly; assembly can be completed in a single press. It also ensures the concentricity and perpendicularity of the impeller and drive shaft, preventing wear on the outer circumference or jamming during impeller rotation. This improves the pump's operational stability, reduces noise, and extends its service life.

[0057] Attention all technical personnel: Although this utility model has been described according to the specific embodiments above, the concept of this utility model is not limited to this utility model. Any modification that utilizes the concept of this utility model will be included within the scope of protection of this patent right.

Claims

1. A bushing with axial and circumferential positioning functions, comprising a bushing body having an axially penetrating inner hole, characterized in that: The bushing inner hole includes a grooveless section and a grooved section arranged continuously along the axial direction; the inner wall of the grooveless section is a smooth cylindrical surface. The grooved section has several grooves evenly distributed circumferentially along its inner wall, extending axially. The grooves are not continuous along the axial direction. The edge of the groove wall forms a bulge that rises radially inward due to plastic deformation, making the effective diameter of the inner hole of the grooved section smaller than the inner diameter of the ungrooved section. The grooved section and the drive shaft form an interference fit.

2. The bushing with axial and circumferential positioning functions according to claim 1, characterized in that: The number of grooves is 2 to 6.

3. The bushing with axial and circumferential positioning functions according to claim 1, characterized in that: The grooveless section is located at the initial insertion end of the drive shaft.

4. The bushing with axial and circumferential positioning functions according to claim 1, characterized in that: The length of the groove is less than the total axial length of the inner hole of the bushing.

5. The bushing with axial and circumferential positioning functions according to claim 1, characterized in that: The length of the groove is one-half to one-third of the total axial length of the inner hole of the bushing.

6. The bushing with axial and circumferential positioning functions according to claim 1, characterized in that: The groove has a rectangular cross-sectional shape.

7. The bushing with axial and circumferential positioning functions according to claim 1, characterized in that: The groove has a U-shaped cross-section.

8. The bushing with axial and circumferential positioning functions according to claim 1, characterized in that: The height of the protrusion is 0.05-0.5mm.

9. The bushing with axial and circumferential positioning functions according to claim 1, characterized in that: The width 'a' of the groove is 0.1-0.5 mm.

10. A water pump impeller, comprising a support and blades arranged around the outer ring of the support, characterized in that: The bracket is provided with a bushing as described in any one of claims 1 to 9.

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