Crankshaft
The crankshaft design with undercut fillets addresses the reliability issues of existing piston compressors by distributing load and reducing stress concentrations, enhancing fatigue strength and reliability.
Patent Information
- Authority / Receiving Office
- RU · RU
- Patent Type
- Utility models
- Current Assignee / Owner
- NOT PUBLISHED
- Filing Date
- 2026-02-19
- Publication Date
- 2026-07-07
AI Technical Summary
Existing crankshafts in piston compressors suffer from reduced reliability due to the presence of flanges and large radii between cheeks and journals, which decrease the working length and increase stress concentrations, leading to potential cracks and breaks.
The crankshaft design incorporates main and connecting rod journals with fillets featuring an undercut, a recess with a rounding radius ranging from 0.1 to 0.2 times the journal diameter, ensuring smooth transitions and distributing load over a larger area.
This design enhances the fatigue strength and reliability of the crankshaft by reducing stress concentrations and promoting uniform wear, thereby increasing the bearing's load-bearing capacity and preventing cracks.
Smart Images

Figure 00000001_ABST
Abstract
Description
[0001] Technical field
[0002] The utility model relates to the field of mechanical engineering and can be used in piston machines, in particular in a piston compressor.
[0003] Technology Level
[0004] A compressor crankshaft is known in the prior art (see
[0005] https: / / novotex_moscow.ru / upload / iblock / 4a9 / gt7jz8k11vr51c89j3c12qngk04vqoh9 / Kompressory-tekhnologicheskogo-gaza.pdf, page 12), containing main and connecting rod journals with cheeks and fillets located between them.
[0006] A crankshaft for a piston compressor is known in the prior art
[0007] (see https: / / amcor.ru / ge-nuovo-pignone?ysclid=mlf9dq3g7o598052395), containing main and connecting rod journals with cheeks and fillets located between them.
[0008] The prior art contains a technical solution adopted as the closest analogue, a crankshaft containing main and connecting rod journals with fillets (see SU 1796781).
[0009] Fillets in crankshaft design play a crucial role in strength, fatigue resistance, and durability. They smooth the transition from the connecting rod and main journals to the crankshaft webs, thereby reducing stress concentrations at critical points on the crankshaft. By smoothly rounding the fillets, they distribute the load over a larger area, preventing cracks and breaks at the journal-web junction.
[0010] In known technical solutions, the working length of the crankshaft journals is reduced due to the presence of a flange on the crankshaft cheeks, as well as a large radius of rounding between the cheeks and the crankshaft journals, which reduces the reliability of the crankshaft in a piston compressor.
[0011] Technical result - increased reliability of the crankshaft.
[0012] This technical result is achieved by a crankshaft comprising main and connecting rod journals with webs located between them, and fillets that ensure smooth transitions between the journals and webs. The fillets are designed with an undercut, i.e., a recess of the fillet into the web body with a rounding radius R, with the rounding radius R ranging from 0.1 dH to 0.2 dH, where dH is the journal diameter.
[0013] Brief description of drawings.
[0014] The claimed utility model is illustrated by the following illustrations:
[0015] Fig. 1 - shows a general view of the crankshaft;
[0016] Fig. 2 shows a view of a part of the crankshaft with places where the recesses of the fillets transition;
[0017] Fig. 3 shows the shape of the fillet with undercut cheek and journal of the crankshaft.
[0018] Where: 1 - main journal; 2 - crank pin; 3 - cheek; 4 - fillet.
[0019] Implementation of a utility model.
[0020] The crankshaft comprises main journals 1 and connecting rod journals 2 with cheeks 3 and fillets 4 located between them. Fillets 4 provide smooth transitions between journals 1 and 2 and cheeks 3. Fillets 4 are designed with an undercut into cheek 3 with a rounding radius R, while the rounding radius R is in the range from 0.1 dН to 0.2 dН, where dН is the diameter of the shaft journals. Due to the absence of annular flanges on the crankshaft cheeks, the reduction in the length of the working portion of the journal is reduced, thereby increasing the contact area between the journal and the bearing, distributing the load over a larger area, thereby reducing the specific pressure on the bearing, which increases the bearing load-bearing capacity and results in more uniform wear of the bearing with the crankshaft journal.
[0021] Preferably, the rounding radius R is in the range of 0.1 dН to 0.2 dН, where dН is the diameter of the shaft journals.
[0022] If a fillet radius less than 0.1 dН, where dН is the journal diameter, is used, the undercut will be minimal and the stress will not be evenly distributed, increasing the risk of fatigue failure in the fillet area. If a fillet radius greater than 0.2 dН, where dН is the journal diameter, is used, the undercut in the cheek will be excessive, reducing its rigidity and increasing the occurrence of secondary stress concentrators at the edges of the undercut.
[0023] Therefore, it is preferable to use a rounding radius R in the range of 0.1 dН to 0.2 dН, where dН is the journal diameter, to a greater extent, reducing stress concentration, preventing cracks at the journal-web junction. This increases the fatigue strength of the crankshaft, thereby enhancing the reliability of the crankshaft as a whole.
Claims
The utility model relates to mechanical engineering and can be used in piston machines, in particular, in a piston compressor. A crankshaft comprising main and connecting rod journals with webs located between them, and fillets providing smooth transitions between the journals and webs, characterized in that the fillets are formed with an undercut into the web with a rounding radius R, wherein the rounding radius R is in the range from 0.1 dН to 0.2 dН, where dН is the journal diameter. The technical result is increased crankshaft reliability. 3 fig.