In view of the pump product seal leakage and reciprocating diaphragm pump structure is complex, bulky, difficult to debug and other issues, we developed a successful Q = 2m3 / h, 25m3 / h; P ≤ 0.4MPa ring diaphragm pump two products, and in 1994 yuan Month passed ministerial appraisal, and access to national patents, patent number .1. 1, the structural characteristics of the annular diaphragm pump first planar peristaltic rigid ring and the annular diaphragm is different from the general rotor pump and reciprocating diaphragm pump. In addition, the existing diaphragm pumps use a sheet-type diaphragm to separate the conveying medium and the working medium, and uses a reciprocating crank-and-rod mechanism, a three-valve mechanism, and an inlet and outlet valve groups; the annular diaphragm pump absorbs the hose pump and the flexible bushing Pump and other rotor pump characteristics, the rotary drive mechanism and annular diaphragm organic combination of novel structure, with a ring diaphragm to separate the transmission medium and the drive element, the transmission medium can not be leaked to the outside. The annular diaphragm pump is mainly composed of a pump body 1, an isolation mechanism 2, a rigid support ring 3, an annular diaphragm 4, a bearing sleeve 5, a bearing 6, a transmission shaft 7, a floating pressure ring and a pump cover (FIG. 1) The end of the bearing cap by the axial compression, which and the pump cover, rigid support ring, the pump body to form a closed volume, when the drive shaft rotates, with the inlet and outlet isolation mechanism and the rigid support ring, the pump body to form a suction And drainage chamber, to achieve the purpose of the transmission medium without leakage. The main structural features of the annular diaphragm pump are: (1) a flat peristaltic rigid support ring is provided between the diaphragm and the pump body; (2) the annular diaphragm has a built-in floating pressure ring; (3) the annular diaphragm separates the conveying medium from the lubricating medium ; (4) annular diaphragm pump exclusive combination of import and export isolation mechanism; (5) without the end of the valve and the import and export valve group; (6) a unique axial seal structure; (7) rigid support ring and the shaft between the bearing . 2, design points 2.1, flow ring diaphragm pump rigid support ring and isolation components, the pump body will be separated into suction and discharge liquid chamber, with the intake and discharge liquid chamber volume changes, the medium along the import to export continuous flow. As shown in Fig. 2, suction port A and discharge port B are respectively suction and discharge chamber radial seal dead spots. It can be seen that the theoretical flow rate per discharge is: Q; t = 10-n (RZ-r2) BK ] Where B - rigid support ring width, cm R - pump cavity radius, cm r - rigid support ring radius, cm K - theoretical volume factor, the main consideration of invalid seal angle α and structure size R, r, etc. The theoretical flow rate; usually invalid seal angle α were controlled at 20. Within, K value can be accurately obtained, generally take 0.90-0.95 design R = r + e, where e is the eccentric value, cm. The theoretical flow rate of the pump is: Taking into account the pressure drop of the pump, the viscosity of the medium, the size of the gap and the influence of the pump speed on the flow rate, the rated flow rate of the pump is: Qr = KvQth Where Kp-- volumetric coefficient 2.2, Radial and axial clearance determination 2.2.1 Pump speed The relative sliding speed between the pump body, the pump cover and the rigid support ring is related to the pump speed due to the use of a flat peristaltic rigid support ring whose value can be estimated as : V = πne / 30 Shows reasonable control and reduce pump speed, you can reduce the friction and power loss, extend pump life, improve pump efficiency. As a rule of thumb, the pump speed is usually controlled in the n <300 min-1 range. 2.2.2, shaft, radial clearance inhalation and discharge chamber radial seal for the wedge-shaped gap, the axial gap for the parallel gap. Pump performance and radial, axial clearance and related structural parameters and media properties are closely related, of which the radial gap mainly based on differential pressure △ P; viscosity of the transmission medium γ; radius of rigid support ring r; eccentricity e and other factors to determine. That is, the gap T = f (ν, r) / f (ΔP, e). Obviously, when ΔP and e increase, the gap T should be small; when ν and r increase, the gap T can take a large value. The axial seal with a gap seal and elastic seal combination of good results; and the amount of parallel gap leakage can be estimated by the following formula: q = 10-5xT3b △ P / 1.2γL [mL / s] where b-gap width, cm L- Gap length, cm △ P-pressure difference, MPa ν-medium dynamic viscosity, Pa · s T-gap value, cm In general, reasonable control of diameter, axial clearance can improve self-suction performance and discharge pressure, reduce pump leakage , To maintain a high volume factor. Practice has proved that the rigid support ring and the pump body, drive shaft and bearing sleeve and bearing and bearing cap tolerances, radial axis dimension chain calculation is crucial. Through the design analysis and test verification, radial, axial clearance should be controlled in the range of 0.03 ~ 0.20. 2.3, the design of the annular diaphragm ring diaphragm is a circular diaphragm pump away from the transport medium and lubricating medium, the key elements of the transmission medium to achieve non-leakage, the design is different from the sheet-shaped diaphragm, we guarantee from the structure to withstand low-pressure state, through the scheduled Elongation to make work under the state of additional deformation is minimal, follow the following principles in the design: (1) ring-shaped diaphragm on the outer surface without relative sliding friction; (2) control the pressure difference between the inner and outer diaphragm within 0.1MPa; (3) (4) to improve the diaphragm tensile and fatigue resistance; (5) a reasonable choice of diaphragm hardness; (6) to ensure that the diaphragm assembly and disassembly convenient; (7) given pre-membrane elongation △ L. If the size of the annular diaphragm is L, and the installation dimension is L ', then the design length of the annular diaphragm is: L = ΔL + L' where ΔL = e / sin (arctge / L) -L usually ΔL = 0.5-2.Omm, consider the ring diaphragm pressure is lower, but contact with corrosive media and the work of the cycle of flexible with the structural size of the demanding, we and the manufacturers and research institutes developed Ding La rubber, poly Urethane rubber and natural rubber and other septum, the comparative test, urethane diaphragm physical properties and fatigue performance is better. 2.4, rigid support ring design Ring diaphragm pump rigid support ring is different from the ordinary rotor pump and reciprocating diaphragm pump. Its settings not only make axial and radial seal easy to form, but also to protect the diaphragm, to ensure that the pump has high discharge pressure and good self-priming performance. The motion of any mass point on the rigid support ring is the reciprocal motion of the vertical axis cross section and the plane motion of the synthetic motion of the slewing motion. The design of rigid support rings should consider the use of lightweight materials or hollow structures to reduce weight and reduce inertial forces. Under its working condition, the outer surface is subjected to the unbalanced hydraulic pressure, so that the radial force F can be absorbed by the transmission shaft. When the radial sealing point is away from the lowest point of the combination isolation mechanism, it has the following formula: Fmax = 20 · ΔP · B · r Where △ P-pressure difference, MPa B-rigid support ring width, cm r-radius of rigid support ring, cm From the above formula, the rigid support ring to bear a greater radial force, so not only in the design should ensure that it is sufficient Of the stiffness and strength, but also should consider the drive shaft may have deflections, through the structural design to ensure that the pump radial clearance within the design range. 3, the performance characteristics