CN1082149C

CN1082149C - Roots pump returning cold air back at multiplied speed

Info

Publication number: CN1082149C
Application number: CN98110987A
Authority: CN
Inventors: 凌岗
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-07-30
Filing date: 1998-07-30
Publication date: 2002-04-03
Anticipated expiration: 2018-07-30
Also published as: CN1243918A

Abstract

The present invention relates to a multiplied-speed cold air return type Roots pump which comprises a casing and two rotors arranged in the casing, wherein the two rotors rotate through a pair of gears with high precision, the speed ratio of the two rotors is 1: 2, the rotor with the low rotation speed is a slow rotor, the rotor with the high rotation speed is a fast rotor, the two rotors are symmetrically arranged, and the molded lines of the two rotors are different. The slow rotor side in the casing is provided with a returned cold air reinjection opening, so that the whole pump is cooled. The present invention can enhance the volumetric efficiency of the cold air return type Roots pump, can reduce the leakage and can enhance the operation efficiency.

Description

Roots pump returning cold air back at multiplied speed

The present invention relates to the rotating machinery pump, particularly a kind of roots pump returning cold air back at multiplied speed.

The molded lines of rotor kind of existing various roots pumps is a lot, but its rotor is always done that is to say that the rotating speed of two rotors is identical, so the molded lines of rotor to have certain narrow limitation with rotating relatively.

The rotor majority of roots pump is the double leaf direct tooth type at present, usually the molded lines that adopts has circular arc flute profile, involute tooth type and cycloid flute profile etc., and wherein the volumetric efficiency of involute tooth type is bigger, reaches as high as 0.57, the roots pump efficient of these molded lines is higher, and cooling is quite difficult.Another kind of roots pump returning cold air back has solved the cooling problem preferably by the re-injection of cold air, but its volumetric efficiency is low excessively, and maximum is not more than 0.27.In addition, the leakage of existing various roots pumps is comparatively serious, has limited their boost pressure, has reduced working efficiency, and in every leakage, the leakage between the rotor has accounted for sizable part of total leakage rate.

In order to overcome the shortcoming of above-mentioned two class roots pumps, the purpose of this invention is to provide a kind of roots pump returning cold air back at multiplied speed of new velocity ratio, it can allow to design the high roots pump returning cold air back molded lines of rotor of volumetric coefficient, makes the leakage way lengthening, leak resistance increases, and leakage rate reduces.

Technical solution of the present invention is as follows:

A kind of roots pump returning cold air back at multiplied speed, it comprises housing and two rotors that are provided with in housing, described two rotors are by a pair of high-precision gear transmission, the rotating ratio of two rotors is 1: 2, the low rotor of rotating speed is rotor at a slow speed, and the rotor that rotating speed is high is quick rotor, two rotor symmetric arrangement, its molded lines has nothing in common with each other, and near the curve during two rotor engaged the contact points is similar; Described molded lines of rotor at a slow speed is divided into four sections of A, B, C, D, the smooth connection of each section; Described quick molded lines of rotor is divided into four sections of a, b, c, d, the smooth connection of each section equally.

Adopt design of the present invention can improve the volumetric efficiency of roots pump returning cold air back, reduce and leak, increase work efficiency, roots pump can be used under big compression ratio, elevated pressures, be particularly useful for the operational site of discharging directly into atmosphere such as paper industry.

Below in conjunction with accompanying drawing the present invention is elaborated.

Fig. 1 is a kind of fundamental diagram of roots pump returning cold air back at multiplied speed.

Fig. 2 is the schematic representation of molded lines of rotor at a slow speed in the above-mentioned roots pump.

Fig. 3 is the quick molded lines of rotor schematic representation in the above-mentioned roots pump.

Referring to Fig. 1, two rotors that a kind of roots pump returning cold air back at multiplied speed comprises housing 1 and is provided with in housing 1.Two rotors remained the rotating ratio of two rotors 1: 2 by a pair of high-precision gear transmission.The low rotor of rotating speed is rotor 2 at a slow speed, and the rotor that rotating speed is high is a high speed rotor 3.For example two centre of rotor distances are 90, and symmetric arrangement has the higher degree of balance separately, can run up.

Because the rotating speed difference of two rotors, so their molded lines has nothing in common with each other, and having eliminated present roots pump molded lines of rotor must identical narrow limitation.

Referring to Fig. 2, rotor 2 has four leaves at a slow speed, is four leaf direct tooth types.Rotor 2 molded lines are divided into four sections of A, B, C, D at a slow speed, the smooth connection of each section, and wherein A, D section are circular curve, B, C section are involute curve.For example the coordinate of tie point can for:

X-axis-curve A (27,0), curve A-B (27.5017,5.7307), curve B-C (44.3414,38.2914), curve C-D (45.4264,42.4264), curve D-straight line Y=-X (44.5478,44.5478).

Referring to Fig. 3, rotor 3 has two leaves fast, is the double leaf direct tooth type.Fast rotor 3 molded lines are divided into four sections of a, b, c, d, the smooth connection of each section equally, wherein a, d section are and the A of rotor 2 at a slow speed, the circular curve that the D section is identical, b, c section respectively with the B of rotor 2 at a slow speed, C section conjugate curve each other.For example the coordinate of tie point can for:

X-axis-curve a (63,0), curve a-b (62.4987,5.7304), curve b-c (6.0474,32.8401), curve c-d (2.1213,27.8787), curve d-Y (0,27).

The molded lines of above-mentioned rotor is the molded lines more complicated of rotor 3 especially fast, but they have bigger volumetric efficiency, for example meet the molded lines of above-mentioned tie point coordinate, and the volumetric efficiency of its quick rotor 3 is 0.3445, and the volumetric efficiency of rotor 2 is up to 0.651 at a slow speed.Be not difficult to find out that from figure near the curve during two rotor engaged the contact points is similar, that is to say that leakage way length is bigger, and leakage has been played inhibition, thereby has reduced leakage rate.In addition,, therefore improved volumetric efficiency, just reduced relative leakage rate owing to there is no direct relation between leakage rate and the volumetric efficiency.

Cold air re-injection mouth 4 is returned in the 2 side settings of rotor at a slow speed in roots pump housing 1, and this returns cold air re-injection mouth 4 deflections and is close to relief opening 5 one sides, and its cooling principle is similar to existing four leaf roots pump returning cold air backs.

Cooling situation of the present invention as shown in Figure 1, the cooling principle of rotor 2 is identical with four leaf roots pump returning cold air backs at a slow speed, so the temperature of relief opening 5 sides can be controlled effectively, fast rotor 3 compressions the temperature rise that produces also just obtained restriction.Though the temperature of rotor 3 is higher than rotor 2 at a slow speed fast, because the temperature of relief opening 5 is relatively stable, according to the contraction principle of roots pump, the temperature of rotor 3 also should obtain control fast.So though the cold air inlet only is arranged in rotor 2 one sides at a slow speed, in fact entire pump can both obtain cooling.Certainly, its cooling effect outline is worse than existing roots pump returning cold air back, but these cooling effects can satisfy in the use of many places, to bring into play its efficient, low premium properties that leaks.

Complicated molded lines processing problems of the present invention, along with science and technology is constantly progressive, the development of numerical control electric spark cutting especially in recent years (being the line cutting) technology, accurate die casting technology constantly perfect makes this processing problems obtain comparatively satisfied solution, both can adopt the numerical control electric spark cutting technique, its precision is generally 0.01～0.1mm, also can adopt accurate die casting technology, its machining accuracy can reach 0.05mm, all required far above general roots pump required precision.

Claims

1. roots pump returning cold air back at multiplied speed, it comprises housing and two rotors that are provided with in housing, it is characterized in that, described two rotors are by a pair of high-precision gear transmission, and the rotating ratio of two rotors is 1: 2, and the low rotor of rotating speed is rotor at a slow speed, the rotor that rotating speed is high is quick rotor, two rotor symmetric arrangement, its molded lines has nothing in common with each other, and near the curve during two rotor engaged the contact points is similar; Described molded lines of rotor at a slow speed is divided into four sections of A, B, C, D, the smooth connection of each section; Described quick molded lines of rotor is divided into four sections of a, b, c, d, the smooth connection of each section equally, and the rotor-side at a slow speed in the described housing is provided with returns cold air re-injection mouth.

2. roots pump returning cold air back at multiplied speed according to claim 1 is characterized in that, described rotor A at a slow speed, D section are circular curve, and rotor B, C section are involute curve at a slow speed.

3. roots pump returning cold air back at multiplied speed according to claim 1 is characterized in that, described quick rotor a, d section be and rotor A at a slow speed, circular curve that the D section is identical, fast rotor b, c section respectively with the conjugate curve each other of rotor B, C section at a slow speed.

4. roots pump returning cold air back at multiplied speed according to claim 1 is characterized in that, described rotor at a slow speed has four leaves.

5. roots pump returning cold air back at multiplied speed according to claim 1 is characterized in that, described quick rotor has two leaves.

6. roots pump returning cold air back at multiplied speed according to claim 1 is characterized in that, the described cold air re-injection mouth deflection of returning is close to relief opening one side.