Design method of diagonal flow pump intermediate sleeve coupling

Abstract

The invention discloses a design method of a diagonal flow pump intermediate sleeve coupling, which comprises the following steps: designing parameters of the diagonal flow pump sleeve coupling according to the matching power, the rotating speed, the allowable shear stress, the allowable stress, the maximum axial thrust, the allowable extrusion stress and the allowable tensile stress of a given diagonal flow pump, and the parameters comprise the minimum shaft diameter, the key size, the coupling length and the snap ring size. According to the design method of the diagonal flow pump intermediate sleeve coupling, design and calculation of the diagonal flow pump intermediate sleeve coupling are scientific and digitized, and the design is not based on feeling and experience any more; multiple design sizes of sleeve couplings with the same shaft diameter due to the difference of design experiences and habits of design engineers are avoided; the design quality of the diagonal flow pump can be guaranteed, and safe, stable and efficient operation of the diagonal flow pump is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of diagonal flow pump structures, and in particular to a design method for an intermediate sleeve coupling of a diagonal flow pump. Background Art

[0002] Mixed-flow pumps, also known as guide vane mixed-flow pumps, offer advantages such as a small footprint, small outer diameter, easy startup, and high efficiency. Their performance and structure lie somewhere between centrifugal and axial-flow pumps, offsetting the shortcomings of both while offering the advantages of both. With a specific speed range of 290 to 590 rpm, mixed-flow pumps are gradually expanding into other pump categories.

[0003] The diagonal flow pump is a vane pump with a higher specific speed. It is not only widely used in farmland irrigation and drainage, sewage treatment and flood control, but also in cooling systems, power stations and other fields.

[0004] A mixed-flow pump uses a prime mover to rotate its impeller, generating thrust and centrifugal force that acts on the liquid, thereby increasing the liquid's potential, pressure, and kinetic energy. It is often referred to as a mixed-flow pump. Its structure and performance lie somewhere between those of centrifugal and axial-flow pumps. It overcomes the unstable performance of axial-flow pumps at low flow rates and also addresses the centrifugal pump's unsuitability for low-head applications. Therefore, mixed-flow pumps combine the advantages of both centrifugal and axial-flow pumps while overcoming their disadvantages. This has led to their application expanding beyond traditional axial-flow and centrifugal pumps. Under normal operating conditions, mixed-flow pumps offer a wide range of flow and head variations, minimal power variation, and a wide high-efficiency zone. Furthermore, proper design can effectively avoid the phenomenon of saddle points during operation. Therefore, considering various factors, mixed-flow pumps should be preferred wherever practical.

[0005] Intermediate sleeve couplings are widely used in various pump types, including diagonal flow pumps, long-shaft pumps, and condensate pumps, due to their excellent centering properties. However, an effective and systematic calculation method has long been lacking. Typically, designs based on the designer's experience can lead to design flaws, safety hazards, and resource waste, complicating the work of inexperienced design engineers. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: the present invention provides a design method for an intermediate sleeve coupling of a diagonal flow pump, which can ensure the design quality of the diagonal flow pump and ensure the safe, stable and efficient operation of the diagonal flow pump.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0008] A design method for an intermediate sleeve coupling of a diagonal flow pump includes the design of the following parameters:

[0009] Step S1, calculate the minimum shaft diameter:

[0010]

[0011] Where M is the torque transmitted by the pump shaft, [τ] is the allowable shear stress; the minimum shaft diameter at the retaining ring is d>d min ;

[0012] Step S2, stress check at the sleeve coupling retaining ring:

[0013]

[0014] Where F is the maximum axial force, ΔS is the force-bearing area, and [σ] is the allowable stress;

[0015] Step S3, determine the key size:

[0016] (1) The torque of the check key is:

[0017] M <Th,M<Ts

[0018] Where M is the torque transmitted by the pump shaft, Th is the allowable torque on the hub side, and Ts is the allowable torque on the shaft keyway side;

[0019] (2) The extrusion stress on the working surface is:

[0020]

[0021] In the formula, [σ j ] is the allowable extrusion stress, M is the torque transmitted by the pump shaft, D is the diameter of the sleeve, h is the key height, and l is the effective key length;

[0022] Step S4, determine the length of the sleeve coupling:

[0023] L A =2×(l+b+10~20)+10

[0024] Where l is the length of the key, b is the width of the key, 10 to 20 is used to eliminate the influence of the spindle end face chamfer and the verticality of the retaining ring, and 10 is the reserved distance for the spindle not to top the shaft;

[0025] Step S5, calculation of the outer diameter of the sleeve coupling:

[0026] D 2 =1.5*(D 2j -D1)+D

[0027] Where D 2j To calculate the outer diameter; D 2jis an assumed value used for calculation; D1 is the circumscribed circle diameter of the keyway, D is the inner diameter of the shaft hole, and 1.5 is the effective thickness safety factor;

[0028] Step S6, calculation of the sleeve coupling retaining ring: first determine the strength and quantity of the fixing screws; then confirm the maximum tensile force on the screws; and then determine the size of the sleeve coupling retaining ring based on the screw size.

[0029] As a further improvement of the above technical solution:

[0030] Furthermore, after the key size is determined, the tensile stress of the screw is checked:

[0031]

[0032] In the formula, [σ 1p ] is the allowable tensile stress, F0 is the maximum tensile force a single screw can withstand, and d1 is the cross-sectional diameter of the screw.

[0033] Furthermore, in step S1, the torque M transmitted by the pump shaft is:

[0034]

[0035] Where P is the matching power of a given diagonal flow pump and n is the speed.

[0036] Furthermore, in step S3, the allowable torque Th on the hub side is:

[0037]

[0038] Permissible torque Ts on the shaft keyway side:

[0039]

[0040] Where D is the shaft diameter at the sleeve coupling, h is the key height, D is the shaft diameter at the sleeve coupling, L is the effective length of the key, b is the width of the key, t is the depth of the key on the shaft side, and c is the chamfer of the key.

[0041] Furthermore, in step S5, effective thickness = D 2j -D1

[0042]

[0043] Where, k is the working condition coefficient, for the motor k = 1.5 ~ 2.0; ΔS j For the effective calculation of cross-sectional area, τ is the shear stress.

[0044] The design method of the intermediate sleeve coupling of the diagonal flow pump provided by the present invention has the following advantages compared with the prior art:

[0045] The design method for the intermediate sleeve coupling of a diagonal flow pump, presented in this paper, digitizes the design calculations for this purpose, eliminating the need for intuition and experience. This eliminates the possibility of multiple design sizes for the same shaft diameter sleeve coupling due to differences in design experience and habits among design engineers. For example, the outer diameter and screw size of sleeve couplings with an inner diameter of 150 mm and 200 mm are no longer the same. This also avoids strain caused by insufficient coupling design strength, breakage caused by undersized or insufficient screws, and overly conservative designs that waste resources and increase costs. Instead of relying on the design engineer's experience, calculations based on the design method are sufficient, providing an effective calculation basis for the design and verification of intermediate sleeve couplings. Furthermore, this design method allows for standardized, serialized designs and even mass production, saving companies significant time and material costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the assembly structure of the sleeve coupling components of the present invention.

[0047] Figure 2 It is a schematic diagram of a sleeve coupling of the present invention.

[0048] Figure 3 It is a schematic diagram of the sleeve coupling retaining ring of the present invention. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the embodiments described are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this invention.

[0050] Figures 1 to 3 An embodiment of the design method of the intermediate sleeve coupling of the diagonal flow pump of the present invention is shown. The design of the coupling includes the design of the following parameters:

[0051] Step S1, calculate the minimum shaft diameter:

[0052] The calculation formula for the minimum shaft diameter is as follows:

[0053]

[0054] Where M is the torque transmitted by the pump shaft, [τ] is the allowable shear stress; the minimum shaft diameter at the retaining ring is d>d min , ensure that the strength of the shaft can meet the requirements.

[0055] Among them, the torque M transmitted by the pump shaft is:

[0056]

[0057] Where P is the matching power of a given diagonal flow pump and n is the speed.

[0058] Step S2, stress check at the sleeve coupling retaining ring:

[0059] The stress calculation formula is as follows:

[0060]

[0061] Where F is the maximum axial force, ΔS is the load area, and [σ] is the allowable stress.

[0062] Step S3, determine the key size:

[0063] (1) The torque of the check key is:

[0064] M <Th,M<Ts

[0065] Where M is the torque transmitted by the pump shaft, Th is the allowable torque on the hub side, and Ts is the allowable torque on the shaft keyway side.

[0066] The allowable torque Th on the hub side is:

[0067]

[0068] Permissible torque Ts on the shaft keyway side:

[0069]

[0070] Where D is the shaft diameter at the sleeve coupling, h is the key height, D is the shaft diameter at the sleeve coupling, L is the effective length of the key, b is the width of the key, t is the depth of the key on the shaft side, and c is the chamfer of the key.

[0071] (2) The extrusion stress on the working surface is:

[0072]

[0073] In the formula, [σ j ] is the allowable extrusion stress, M is the torque transmitted by the pump shaft, D is the diameter of the sleeve, h is the key height, and l is the effective key length.

[0074] Step S4, screw tensile stress check:

[0075]

[0076] In the formula, [σ 1p ] is the allowable tensile stress, F0 is the maximum tensile force a single screw can withstand, and d1 is the cross-sectional diameter of the screw.

[0077] Step S5, determining the length of the sleeve coupling:

[0078] L A =2×(l+b+10~20)+10

[0079] Where l is the length of the key, b is the width of the key, 10 to 20 is used to eliminate the influence of the spindle end face chamfer and the verticality of the retaining ring, and 10 is the reserved distance for the spindle not to top the shaft.

[0080] Step S6, calculation of the outer diameter of the sleeve coupling:

[0081] D2=1.5*(D 2j -D1)+D

[0082] Where D 2j To calculate the outer diameter; D 2j is an assumed value used for calculation; D1 is the circumscribed circle diameter of the keyway, D is the inner diameter of the shaft hole, and 1.5 is the effective thickness safety factor.

[0083] Effective thickness = D 2j -D1

[0084]

[0085]

[0086] In the formula, k is the working condition coefficient, which is related to the prime mover. For electric motors, k = 1.5 to 2.0 (take k = 1.8). ΔS j For the effective calculation of cross-sectional area, τ is the shear stress.

[0087] Step S7, calculation of sleeve coupling retaining ring:

[0088] (1) Determine the strength and quantity of fixing screws.

[0089] Choose M A For large and small screws, use a 6.8-level guaranteed load Ft, a safety factor of ns = 3, and select countersunk screws in number n.

[0090] The screw force condition meets F 总 =Ft / 3×n>F, F is the maximum axial thrust.

[0091] (2) The maximum tensile force on the screw is F0 = F" + F1.

[0092] F" is the residual preload of the bolt, generally F" = (0.2-0.6) F1, F1 is the axial thrust exerted on a single bolt.

[0093] Select n GB / T70.1 M A For countersunk screws, F1=F / n, take F"=0.5F1, then F0=F"+F1=1.5F1.

[0094] Check the tensile stress of the screws to prove that the specifications and quantity of the selected screws meet the requirements.

[0095] (3) Confirm the size of the sleeve coupling retaining ring according to the screw size.

[0096] Take the pitch circle diameter D1 = D + 4 + a * 2 (or 0 or 5 which is greater than this value, round up), D is the inner diameter of the sleeve, 4 is the shaft shoulder at the neutral position, a is the reserved installation space, M A The corresponding relationship corresponding to the reference minimum a value is shown in Table 1.

[0097] Table 1 Screw size M A Corresponding relationship with a

[0098] <![CDATA[Screw size M A > M6 M8 M10 M12 M16 M20 M24 M30 M36 a(mm) 13 14 15 18 22 25 30 35 42

[0099] (4) Selection of retaining ring thickness.

[0100] According to GB152.3 M A The screw corresponds to the inner hole ΦD3, the countersink ΦD4, the countersink depth h3mm, and GB93 M A Gasket thickness S, GB70.1 M A The screw cap thickness is m, so the countersink depth b1 is the greater of m + S or h3. The outer diameter is equal to that of the sleeve coupling. The total thickness of the retaining ring can be selected according to Table 2.

[0101] Table 2 Comparison table of snap ring thickness b2 and sleeve coupling inner diameter

[0102] Coupling inner diameter D(mm) ≤50 ＞50～≤70 ＞70～≤100 ＞100～≤150 ＞150～≤200 ＞200～≤240 Snap ring thickness (mm) 25 30 40 45 55 60

[0103] Table 2 is the result of serial calculation based on the design method.

[0104] The above examples are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, they are not intended to limit the present invention. Therefore, any simple modifications, equivalent variations, and modifications to the above examples that do not depart from the technical solution of the present invention and are based on the technical essence of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A design method for an intermediate sleeve coupling of a diagonal flow pump, characterized in that: The design includes the following parameters: Step S1, calculate the minimum shaft diameter: Where M is the torque transmitted by the pump shaft, [τ] is the allowable shear stress; the minimum shaft diameter at the retaining ring is d>d min ; Step S2, stress check at the sleeve coupling retaining ring: Where F is the maximum axial force, ΔS is the force-bearing area, and [σ] is the allowable stress; Step S3, determine the key size: (1) The torque of the check key is: M <Th,M<Ts Where M is the torque transmitted by the pump shaft, Th is the allowable torque on the hub side, and Ts is the allowable torque on the shaft keyway side; (2) The extrusion stress on the working surface is: In the formula, [σ j ] is the allowable extrusion stress, M is the torque transmitted by the pump shaft, D is the diameter of the sleeve, h is the key height, l is the effective bond length; Step S4, determine the length of the sleeve coupling: L A =2×(l+b+10~20)+10 Where l is the length of the key, b is the width of the key, 10 to 20 is used to eliminate the influence of the spindle end face chamfer and the verticality of the retaining ring, and 10 is the reserved distance for the spindle not to top the shaft; Step S5, calculation of the outer diameter of the sleeve coupling: D2=1.5*(D 2j -D1)+D Where D 2j To calculate the outer diameter; D 2j is an assumed value used for calculation; D1 is the circumscribed circle diameter of the keyway, D is the inner diameter of the shaft hole, and 1.5 is the effective thickness safety factor; Step S6, calculation of the sleeve coupling retaining ring: first determine the strength and quantity of the fixing screws; then confirm the maximum tensile force on the screws; and then determine the size of the sleeve coupling retaining ring based on the screw size.

2. The design method of the intermediate sleeve coupling of the diagonal flow pump according to claim 1 is characterized in that: After the key size is determined, check the tensile stress of the screw: In the formula, [σ 1p ] is the allowable tensile stress, F0 is the maximum tensile force a single screw can withstand, and d1 is the cross-sectional diameter of the screw.

3. The design method of the intermediate sleeve coupling of the diagonal flow pump according to claim 2 is characterized in that: In step S1, the torque M transmitted by the pump shaft is: Where P is the matching power of a given diagonal flow pump and n is the speed.

4. The design method of the intermediate sleeve coupling of the diagonal flow pump according to claim 3 is characterized in that: In step S3, the allowable torque Th on the hub side is: Permissible torque Ts on the shaft keyway side: Where D is the shaft diameter at the sleeve coupling, h is the key height, D is the shaft diameter at the sleeve coupling, L is the effective length of the key, b is the width of the key, t is the depth of the key on the shaft side, and c is the chamfer of the key.

5. The design method of the intermediate sleeve coupling of the diagonal flow pump according to claim 1 is characterized in that: In step S5, effective thickness = D 2j -D1 Where, k is the working condition coefficient, for the motor k = 1.5 ~ 2.0; ΔS h For the effective calculation of cross-sectional area, τ is the shear stress.

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