Crankcase and bushing adding method thereof
By adding bushings and setting up a sealing structure in the crankcase, the vibration and friction problems caused by direct contact between the bearing and the housing were solved, achieving low-cost and rapid repair.
Patent Information
- Application Number
- CN202511877588.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-12
- Publication Date
- 2026-03-10
AI Technical Summary
The existing crankcase structure results in direct contact between the bearing and the housing. After long-term operation, the bearing suffers excessive impact, vibration and friction, leading to high maintenance costs, long maintenance cycles, and inconvenient disassembly of parts.
A bushing is installed in the crankcase, with the bushing installed inside the bearing bore of the case. The bearing is installed inside the bushing, and a sealing structure is set between the bushing and the bearing cover to reduce radial movement and friction. The bearing bore diameter is enlarged by boring and an O-ring seal is installed.
This effectively reduces direct contact between the bearing and the housing, lowers vibration and friction, simplifies the maintenance process, and reduces maintenance costs and time.
Smart Images
Figure CN121630876A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of diaphragm pump accessory structure, specifically relating to a crankcase and its bushing installation method. Background Technology
[0002] The diaphragm pump consists of a transmission system (drive motor and reducer), a power end, a hydraulic end assembly, a control system, and an auxiliary system. The transmission method is variable frequency motor-reducer-diaphragm pump. The control system mainly controls the motor and lubrication system through the variable frequency motor.
[0003] The working principle of the diaphragm pump is as follows: Figure 1 The motor ① drives the crankshaft ② and connecting rod ③ through a reducer, converting rotary motion into linear motion, which in turn drives the crosshead ④ and piston ⑥ to reciprocate. The piston ⑥ is in the hydraulic cylinder ⑤. When the piston ⑥ moves to the left, it pulls the rubber diaphragm ⑨ in the diaphragm chamber ⑩ to the left, increasing the volume of the working chamber. Simultaneously, the discharge valve ⑪ closes, and the slurry to be conveyed opens the feed valve ⑫ with the help of feeding pressure, entering and filling the diaphragm chamber ⑩. When the piston ⑥ moves to the right, it closes the feed valve ⑥, and the piston ⑥ pushes the hydraulic oil to push the rubber diaphragm ⑨ in the diaphragm chamber ⑩ to the right, opening the discharge valve ⑪ with pressure and conveying the slurry to the pipeline.
[0004] Because the slurry does not contact moving parts such as the piston, abrasion of these parts is avoided, reducing maintenance frequency and operating costs. Simultaneously, a sensitive and reliable automated detection system ensures a long service life for the rubber diaphragm. These advantages make the reciprocating piston diaphragm pump an ideal device for pipeline slurry transportation. The diaphragm pump has three diaphragm chambers, each with a 120° interval between the initial discharge phases, ensuring uniform slurry delivery.
[0005] Existing crankcase structure such as Figure 2 As shown, the crankshaft consists of a crankshaft, bearing, crankcase, and bearing cover. The bearing is in direct contact with the crankcase. After assembly, there is a gap of 0.4mm between the bearing cover and the bearing. Due to long-term operation, the crankshaft will experience axial and radial movement during operation, causing it to move between the crankcases. The 0.4mm gap will cause the bearing on the crankshaft and the bearing cover to collide back and forth, resulting in excessive impact on the bearing, generating vibration, and affecting normal operation. Furthermore, the outer circle of the bearing on the crankshaft will rub against the crankcase, which over time will cause the bearing to run out of race and the bearing bore of the crankcase to be scratched, resulting in the crankcase not operating normally.
[0006] Existing diaphragm pump parts are inconvenient to disassemble, resulting in high maintenance costs, long cycles, and a wide range of issues. Summary of the Invention
[0007] To overcome the shortcomings of diaphragm pump crankcase parts being inconvenient to disassemble, resulting in high maintenance costs and long cycles, this invention proposes a method for adding crankcase and its bushing.
[0008] The technical solution adopted by this invention to solve its technical problem is: A crankcase includes a crankshaft, bearings, bearing caps, housing, and bushings.
[0009] The bushing is installed in the bearing hole of the housing, and the bearing is installed inside the bushing.
[0010] The inner diameter of the bushing matches the outer diameter of the bearing, and the bushing matches the bearing cover. A seal is provided at the connection between the bushing and the bearing cover to prevent oil leakage.
[0011] The bushing has a sealing groove on its outer circumference, and an O-ring is installed in the sealing groove on the outer circumference of the bushing. The O-ring is used to prevent oil leakage at the junction of the bushing and the bearing hole.
[0012] The bushing has a bushing threaded hole and a bearing cover threaded hole at the end where it connects with the bearing cover. The bushing threaded hole is used to connect and fix the bushing to the housing, and the bearing cover threaded hole is used to connect and fix the bearing cover to the bushing.
[0013] The bushing is used to isolate the bearing from direct contact with the housing, reducing radial movement of the crankshaft during operation.
[0014] A gap is left between the bearing and the bearing cap.
[0015] The crankcase described above has a bearing bore inner diameter of Ø470 and an end face depth of 8mm.
[0016] In the aforementioned crankcase, the gap between the bearing cover and the bearing end face is 1mm.
[0017] A method for installing a crankcase bushing, comprising the following steps, involves adding a bushing to the existing crankcase housing: Step 1, filling the threaded hole The original threaded hole of the housing is enlarged using a boring process. The enlarged hole is matched with a cylindrical pin. The cylindrical pin is then inserted into the enlarged hole of the threaded hole and fixed.
[0018] Step 2, boring the bearing hole The bearing bore is bored using a boring process to match the diameter of the bearing bore with the outer diameter of the bushing.
[0019] Step 3, Machining the bearing hole end face: Mill the bearing hole end face to the required depth according to the form and position tolerance requirements of the bearing hole end face; Step 4: Drill a threaded hole for the bushing on the end face of the housing. The threaded hole is used to fix the bushing. Step 5: Install O-rings on the bushing An O-ring is installed on the outer circumference of the bushing for sealing.
[0020] Step 6, Install the bushing Install the bushing with the O-ring into the bearing hole and fix the bushing in the bearing hole with screws.
[0021] In the above-mentioned crankcase bushing installation method, step 1 uses a cold fitting process to insert the cylindrical pin into the enlarged hole of the threaded hole.
[0022] In the above crankcase bushing installation method, in step 1, threaded pins are used to fix each cylindrical pin on both sides.
[0023] In the above crankcase bushing installation method, in step 2, the bearing hole diameter is bored from Ø420 to Ø470.
[0024] In step 3, the depth of the bearing hole end face is milled from 5.2mm to 8mm.
[0025] The beneficial effects of this invention are: A crankcase with a bushing installed between the bearing and the housing prevents direct contact between the bearing and the housing, thus avoiding direct damage to the housing and effectively reducing radial movement of the crankshaft during operation. A gap is left between the bearing cover and the bearing end face, which facilitates heat dissipation of moving parts, facilitates installation, improves lubrication of moving parts, and effectively reduces the number of collisions between the bearing and the bearing cover, thereby reducing vibration.
[0026] A crankcase with a bushing installed between the bearing and the housing, which facilitates disassembly, reduces maintenance time, and lowers costs. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the working principle of a diaphragm pump; Figure 2 This is a schematic diagram of the existing crankcase structure; Figure 3 This is a schematic diagram of the bushing structure according to Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the housing mounting bushing structure according to Embodiment 1 of the present invention; Figure 5 This is a drawing showing the pitch circle dimensions of the bearing bore and thread in existing technology. Figure 6 This is a diagram showing the threaded hole enlargement dimensions of Embodiment 1 of the present invention; Figure 7 (a) Dimensional diagram of the cylindrical pin in Embodiment 1 of the present invention; Figure 7 (b) is a schematic diagram of the cylindrical pin fixing position according to Embodiment 1 of the present invention; Figure 8 This is a schematic diagram of the enlarged bearing hole in the housing according to Embodiment 1 of the present invention; Figure 9 This is a structural diagram of the bushing dimensions in Embodiment 1 of the present invention; Figure 10 This is an installation diagram of the housing bushing according to Embodiment 1 of the present invention.
[0028] The attached figures are labeled as follows: 1. Motor, 2. Crankshaft, 3. Connecting rod, 4. Crosshead, 5. Hydraulic cylinder, 6. Piston, 7. Guide rod, 8. Probe, 9. Rubber diaphragm, 10. Diaphragm chamber, 11. Discharge valve, 12. Feed valve, 13. Support bearing, 14. Crankshaft housing, 15. Bushing, 16. Bearing cover. Detailed Implementation
[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0030] Example 1 This invention provides a crankcase, the structure of which is as follows: Figure 4 As shown, it consists of a crankshaft, bearings, bushings, and housing. The bushing structure is as follows: Figure 3 As shown, the bushing is first connected to the housing, and then the bearing is connected to the bushing. The gap between the bearing cover and the bearing end face is 1mm. There are two bearing holes, located on both sides of the housing and arranged coaxially.
[0031] Advantages: Because the crankshaft undergoes axial and radial movement during operation, a large clearance (standard clearance) is left between the bearing cap and the bearing, effectively reducing the number of collisions between the bearing and the bearing cap, reducing vibration. Furthermore, the existing structure ensures that the bearing does not directly contact the crankshaft housing, thus preventing direct damage to the crankshaft housing. In addition, the bushing is connected to the crankshaft housing. Dimension A ensures proper installation of the crankshaft housing and bushing, while dimension B ensures proper installation of the bearing and bushing. Due to the addition of the bushing structure, the radial movement caused by the crankshaft can be effectively reduced.
[0032] The measures to change the existing crankcase structure to a crankcase structure with bushings are as follows: Measurements showed the original bearing bore size was Ø420, and the pitch circle of the threaded holes on both sides was Ø480. Since the bearing bore needed to be enlarged, interference with the pitch circle of the original bearing cap's threaded holes was inevitable. Therefore, the original threaded holes needed to be filled before boring the bearing bore. Due to the less-than-ideal welding performance of cast iron, a bushing method was used for repair. The original bearing bore and threaded hole pitch circle dimensions are as follows: Figure 5 As shown.
[0033] The threaded holes are enlarged, and cylindrical pins are used to fill the gaps. Dimensional tolerances and a cold-fitting process ensure a tight fit between the cylindrical pins and the enlarged holes. After installation, threaded pins are used on both sides of each cylindrical pin to secure it, preventing rolling during processing and ensuring that this structure will not cause vibration of the housing during equipment operation. The enlarged hole dimensions are as follows... Figure 6 As shown, the dimensions of the cylindrical pin are as follows: Figure 7 As shown in (a), the cylindrical pin is fixed as follows: Figure 7 As shown in (b).
[0034] After the above work is completed, the bearing hole end face is machined to ensure the form and position tolerances between the end face and the bearing hole. The design incorporates overall assembly to ensure sufficient installation space and secure fastening. The original bearing hole Ø420 is enlarged to Ø470 using a boring machine to ensure the required form and position tolerances and dimensions. The end face depth is milled from 5.2mm to 8mm. A threaded hole is drilled on the crankcase end face for connection and fixation with the bushing. The bearing hole enlargement dimensions are as follows: Figure 8 As shown.
[0035] The machining of the bushing primarily ensures that its outer diameter mates with the bearing bore in the crankcase, and its inner bore mates with the supporting bearing. Key considerations include ensuring the dimensional and positional tolerances of the inner and outer diameters, preventing interference with the crankcase and bearing cap bores during installation, and maintaining a reasonable layout. The thickness of the inner and outer diameters must be close to the final assembly position of the bearing; too short a length will cause bearing vibration during operation, while too long a length will cause interference with the crankshaft's angled rotation. An O-ring is installed on the outer diameter of the bushing to prevent oil leakage. The bushing's dimensions and structure are as follows... Figure 9 As shown.
[0036] The machining of the bearing cover (bearing through cover) primarily ensures no interference with the bushing's hole installation, and the forced lubrication point is positioned directly above. This area cannot be directly reused with the previous oil pipe because the structural change shifts the forced lubrication point backward, requiring on-site modification of the oil pipe. Furthermore, during the design of the bearing cover (bearing through cover), a 1mm gap must be maintained between the final assembled bearing cover (bearing through cover) and the bearing end face. A seal is placed at the connection between the bushing and the bearing cover (bearing through cover) to prevent oil leakage. The bushing installation position is as follows... Figure 10 As shown.
[0037] Example 2 A crankcase includes a crankshaft, bearings, bearing caps, housing, and bushings.
[0038] The bushing is installed inside the bearing hole of the housing, and the bearing is installed inside the bushing.
[0039] The inner diameter of the bushing matches the outer diameter of the bearing, and the bushing matches the bearing cap. A seal is provided at the connection between the bushing and the bearing cap to prevent oil leakage. The inner diameter of the bearing bore is Ø470, and the end face depth is 8mm.
[0040] A sealing groove is provided on the outer circle of the bushing, and an O-ring is installed in the sealing groove on the outer circle of the bushing. The O-ring is used to prevent oil leakage at the junction of the bushing and the bearing hole.
[0041] The bushing has threaded holes at the end where it connects with the bearing cover. The bushing threaded holes are used to connect and fix the bushing to the housing, and the bearing cover threaded holes are used to connect and fix the bearing cover to the bushing.
[0042] Bushings are used to isolate the bearing from direct contact with the housing, reducing radial movement of the crankshaft during operation.
[0043] The gap between the bearing cap and the bearing is 1mm.
[0044] A method for installing a crankcase bushing, comprising the following steps, involves adding a bushing to the existing crankcase housing: Step 1, filling the threaded hole The original threaded hole of the housing is enlarged using a boring process. The enlarged hole is matched with the cylindrical pin. The cylindrical pin is installed into the enlarged hole of the threaded hole using a cold fitting process. Threaded pins are fixed on both sides of each cylindrical pin.
[0045] Step 2, boring the bearing hole The bearing bore is bored using a boring process to match its diameter to the bushing's outer diameter. For example, the bearing bore diameter can be bored from Ø420 to Ø470.
[0046] Step 3, Machining the bearing hole end face Mill the bearing hole end face to the required depth according to the form and position tolerance requirements.
[0047] Step 4: Drill a bushing threaded hole on the end face of the housing. The bushing threaded hole is used to fix the bushing. For example, the bearing hole end face depth is milled from 5.2mm to 8mm.
[0048] Step 5: Install O-rings on the bushing An O-ring is installed on the outer circumference of the bushing for sealing.
[0049] Step 6, Install the bushing Install the bushing with the O-ring into the bearing hole and fix the bushing in the bearing hole with screws.
Claims
1. A crankcase comprising a crankshaft, a bearing, a bearing cap, a case, characterized in that, Also include the bushing; The bushing is installed in the bearing hole of the box body, and the bearing is installed in the bushing; The inner diameter size of the bushing matches the outer diameter size of the bearing, the bushing matches the bearing cover, and the connection between the bushing and the bearing cover is provided with a seal to prevent oil leakage; The outer circle of the bushing is provided with a sealing groove, and an O-shaped ring is installed in the sealing groove of the outer circle of the bushing, which is used to prevent oil leakage at the joint of the bushing and the bearing hole; The bushing is provided with a bushing threaded hole and a bearing cover threaded hole at the joint end with the bearing cover, the bushing threaded hole is used for connecting and fixing the bushing with the box body, and the bearing cover threaded hole is used for connecting and fixing the bearing cover with the bushing; The bushing is used to isolate the bearing from direct contact with the box body, and reduce the radial movement of the crankshaft during operation; The bearing and the bearing cover are left with a gap.
2. The crankcase according to claim 1, characterized in that The bearing hole is provided with two, which are coaxially arranged on both sides of the box body.
3. The crankcase according to claim 1, characterized in that The inner diameter of the bearing hole is 470, and the end face depth is 8mm.
4. The crankcase according to claim 1, characterized in that The gap between the bearing cover and the bearing end face is 1mm.
5. A method for manufacturing a crankcase liner according to any one of claims 1 to 4, characterized in that, On the basis of the original box body, the bushing is installed, including the following steps: Step 1, thread hole filling: Using boring process, the original box body threaded hole is reamed, the reaming hole is matched with the cylindrical pin, the cylindrical pin is installed in the reaming hole of the threaded hole, and the cylindrical pin is fixed; Step 2, bearing hole boring: Using boring process, the bearing hole is bored to match the outer diameter of the bushing; Step 3, bearing hole end face processing: According to the shape and position tolerance requirements of the bearing hole end face, the bearing hole end face is milled to the required depth; Step 4, drill bushing threaded hole on the end face of the box body, the bushing threaded hole is used to fix the bushing: Step 5, install O-shaped ring on the bushing: Install the O-shaped ring for sealing on the outer circle of the bushing; Step 6, install the bushing: Install the bushing with O-shaped ring to the bearing hole, and fix the bushing in the bearing hole with screws.
6. The method of crankcase liner retrofitting according to claim 5, characterized in that In step 1, the cylindrical pin is installed in the reaming hole of the threaded hole by cold mounting process.
7. The method according to claim 5, characterized in that In step 1, thread is punched on both sides of each cylindrical pin.
8. The method of crankcase liner retrofitting according to claim 5, characterized in that, In step 2, the bearing hole diameter is bored from 420 to 470; In step 3, the bearing hole end face depth is milled from 5.2mm to 8mm.