Theoretical flowrate characteristics of the conjugated involute internal gear pump

Abstract

The aim of this article is to study the theoretical flowrate characteristics of the conjugated involute internal gear pump. The conjugated involute internal gear pump has a different internal gear, the profile of which is completely conjugated to that of pinion, from the conventional involute internal gear pump. To describe briefly, the former pump is called 'conjugated pump' while the latter pump 'conventional pump'. This structure makes the conjugated pump have smaller volumes of trapped fluid than the conventional pump, which indicates the conjugated pump has a better flowrate performance. Although there have been numerous investigations into gear pumps, none of them have dealt with the conjugated pumps yet. This article presents a systematic study on the theoretical flowrate characteristics of the conjugated pumps. It is expected to obtain some generalized conclusions to guide the design of internal gear pumps. Firstly, a double envelope concept is applied to derive the mathematical models of the conjugated involute internal gear couple. Next, mesh characteristics of the gear couple, which mainly decide the fluid delivery performance of the pumps, are analyzed. Finally, using a control volume approach, the theoretical flowrate characteristics of the pump under different design parameters of gears are investigated. Results show the conjugated pump has a better performance than the conventional one. To design a conjugated pump with good flowrate characteristics, it's feasible to choose a proper shifting coefficient, a larger tooth number of the pinion, a smaller tooth number of the internal gear, a larger pressure angle and a larger fillet radius, under the condition that no tooth interference occurs.

Theoretical Analysis for the Flow Ripple of a Tandem Crescent Pump with Index Angles

“…Regarding the term dV/dt, it denotes the time derivative of the discharge chamber's volume, which can be interpreted as the kinematic flow of the crescent pump derived from the kinematic relations according to the work by Zhou et al [17].…”

“…With respect to the crescent pumps, Ichikawa [16] addressed the mathematical expressions for the ideal delivery from a kinematic aspect, focusing on the variations of the trapped volume. Zhou et al [17] studied the theoretical flow characteristics based on the theory of gearing, and presented a set of conjugated involute gears that enabled better fluid delivery capacity. Additionally, the same research group in Reference [18] extended the study to the trapped volume performances via a discretization approach, with a specific focus on the gears' geometric parameters.…”

Investigation of fluid delivery and trapped volume performances of Truninger gear pump by a discretization approach

“…The control volume approach is often used to derive the instantaneous flowrate formula of gear pumps. [2][3][4][5][21][22][23][24]28,29 Figure 4 shows the two control volumes, V 1 and V 2 , built for the pinion and the internal gear, respectively. With hypotheses of incompressible fluid, no fluid leakage and rigid parts of the pump, the discharge volume of fluid, dV, equals the difference between the input volumes, dV i1 and dV i2 , and the output volumes, dV o1 and dV o2 , as represented by equation (13)…”

Pinyon-Tipi Takımla İmal Edilen Standart Olmayan Dişlilerin Bilgisayar Simülasyonu

“…Nemcek [11], yuvarlatılmış uçlu pinyon-tipi takım için maksimum evolvent noktası ile baş dairesi arasındaki radyal mesafe ile yuvarlatma yarıçapı arasındaki bağıntıyı çeşitli durumlar için incelemiştir. Zhou ve Song [12], iç dişli pompalarda debi karakteristiğini iyileştirmek ve dişli elemanların ömrünü artırmak için eşlenik evolvent profil kullanmışlardır. Ardışık dönüşümün kullanıldığı bu yaklaşımda evolvent yanaklara ilave olarak pinyonun kökü ile eşlenik formda iç dişli yuvarlatılmış baş ucu da devreye girmektedir.…”