CN2491628Y - Spiral rotor of vacuum pump - Google Patents

Abstract

The utility model relates to a spiral rotor of a vacuum pump. A screw-thread lead number of arranged in a screw-thread portion of the spiral rotor is set as an integer plus 0.5 to be used to reduce a torque of an unbalanced force of the spiral rotor, thereby reducing the disequilibrium amount of dynamic balancing, and ensuring easy manufacture of hole drilling of the needed screw-thread of the dynamic balancing.

Description

The helical rotor of vacuum pump

Technical field

The utility model relates to a kind of helical rotor of Scroll-type spiral rotor-type vacuum pump.

Background technique

Scroll-type spiral rotor-type pump, be to have the helical rotor of the helical rotor of right-hand screw of most screw threads (pitch number) and left hand screw to be meshing with each other and the pump that rotates in the enclosure, because therefore the pump efficiency height not only in the general pump use of accommodating fluid, also is widely used as vacuum pump.

The shape of the cross section of helical rotor A as shown in Figure 4, constitute like the circular arc d of Archimedian curve C and external diameter by the circular arc b at the bottom of queen bee curve a, the tooth, plan, the center of gravity G of rotor be from the center of rotation O of helical rotor to the position of φ direction off-centre, therefore, can produce mass unbalance during rotation.

On the other hand, in order to make the miniaturization of spiral rotor-type vacuum pump, must use the high speed rotating helical rotor, and that the leakage rate of fluid of supply is considered to the transfer number is irrelevant, keeps certain value, therefore, more therefore high speed rotating, its volumetric efficiency height of can healing wishes its speed up, but, can shake during high speed rotating because of helical rotor has above-mentioned unbalance mass.

Therefore, effectively bring into play the advantage of spiral rotor-type vacuum pump, use, it also can be used in the high speed rotating field, need to improve its balancing rotor for this reason, reduce the vibrations that produce in the high speed rotating field with high efficiency.

Therefore, the claimant once proposed application (the special fair 2-17716 communique of Japan), and the number of threads of helical rotor is an even number, to reach static equilibrium.To transient equiliblium, then set up the cavity separately in the screw section at helical rotor two ends, or establishing the material that empty part is cast into lightweight, therefore with lightweight, to reach balance.

Set up the cavity separately in the screw section at helical rotor two ends, to reach transient equiliblium, the neutron shape that need become the cavity is big, has rigidity.If the neutron shape is little, when being the shape of frangibility, the neutron skew can take place during cast rotor or fracture, can't become correct cavity.

On the other hand, the requirement with the vacuum pump miniaturization is arranged always on the market, shown in Fig. 5 (A), the length L of pitch is dwindled into length L shown in Fig. 5 (B) ' time, screw thread e can become the screw thread e ' of thinner thickness.

It is very difficult to make the cavity at the screw thread e ' of thinner thickness, thereby can only average out by boring processing.

Even use boring processing, also can only obtain very little amount of unbalance to the screw thread e ' of very thin thickness, therefore must reduce amount of unbalance as far as possible.

Change the result that the screw section total length of helical rotor experimentizes through the claimant, show that it is minimum that the unbalance moment of helical rotor can become when the screw section total length reached certain condition.

The utility model is according to this result, and it is minimum helical rotor that unbalance moment is provided.

Summary of the invention

For achieving the above object, the utility model is that the shape of cross section becomes the Scroll-type screw vacuum pump that a pair of helical rotor of right-hand screw, the left hand screw of asymmetry is meshing with each other and forms by queen bee curve, circular arc, plan like the Archimedian curvilinerar figure, set the thread pitch number of the screw section of its helical rotor for unbalance moment that (integer+0.5) is used for reducing helical rotor, be its feature.

Description of drawings

Fig. 1 illustrates the front elevation that the utility model helical rotor size is used.

Fig. 2 (A)～(C) be used for illustrating unbalanced force the generation state helical rotor front elevation and about side view.

Fig. 3 is the helical rotor of equalizing orifice is established in expression in order to reach transient equiliblium a side view.

Fig. 4 is the cross-sectional view of the screw section of helical rotor.

Fig. 5 is the shaft section figure that is used for illustrating the screw thread that screw thread form changes because of the pitch length of spiral.

Fig. 6 is the front elevation with the utility model traditional helical rotor A relatively.

Embodiment

Helical rotor A of the present utility model ₁The same with traditional helical rotor A, constitute by screw section 2 and the axial region 1 that is located at 2 both sides, screw section, the shape of the cross section of screw section 2 is identical.

Axial region 2 then becomes rotary shape to be supported in the bearing of the shell that is located at vacuum pump, and also the helical rotor A with traditional is identical, but is located at helical rotor A of the present utility model ₁The number of threads and the traditional helical rotor A of screw section 2 inequality.

The length of supposing a screw thread is L ₂The time, of the present utility model being characterised in that: the total length L that makes screw thread ₀For

L ₀=(n+0.5) L ₂(n: integer)

At this moment unbalanced force F _rShown in Fig. 2 (A), become power corner effect, about uneven F _rThe balance M of moment _oLength at a side's (left side) axial region 1 is L ₁The time, shown in following (1) formula.

M _o＝F _r·L ₁-F _r(L ₁+N1 ₂+0.5L ₂)

=-F _r(n+0.5) L ₂(1) formula

Fig. 2 (B), (C) are the side views when seeing Fig. 2 (A) from the left and right sides, and expression is to the position of centre of gravity G of center of rotation O.

If the total length L of the screw section 2 of traditional helical rotor A _TBe L _T=nL ₂The time, unbalanced force F _rBe same direction, therefore, about unbalanced force F _rThe balance M of moment _TIt is following (2) formula.

M _T＝F _r·L ₁+F _r(L ₁+nL ₂)

=F _r(2L ₁+ nL ₂) ... (2) formula

(1) formula with the difference of the unbalance moment of (2) formula is

|M _T|-|M _o|＝2F _r·L ₁+F _r·nL ₂

-F _r·rL ₂-0.5?F _rL ₂

=(2L ₁-0.5L ₂) _F(3) formula

Can prove that the utility model makes unbalance moment reduce the deal of (3) formula.

As mentioned above, the utility model can reduce unbalance moment.Therefore, if in the screw section when 2 screw thread e ' (with reference to Fig. 5 (B)) sets the cavity and has any problem,, be easy to the equalizing orifice 3 that end face between the bottom surface 2a of the outside of axial region 1 and screw section 2 is drilled with the end then as Fig. 2, shown in Figure 3.

In sum, according to the utility model since with the total length of the screw section of helical rotor set become screw thread (integer+0.5) doubly, therefore can reduce the unbalance moment of helical rotor, make the boring processing of the equalizing orifice that transient equiliblium is required be easy to.

Claims (1)

1. the helical rotor of a vacuum pump, being cross section becomes the vortex shape screw vacuum pump that a pair of helical rotor of left hand screw, the right-hand screw of asymmetry is meshing with each other and forms by queen bee (Queen Bee) curve, circular arc, plan Archimedian curvilinerar figure, and it is characterized in that: the thread pitch number of the screw section of helical rotor is set at (integer+0.5).

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