JPS6321755Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a rotary sleeve for a vane-type rotary compressor used in an engine supercharger or the like.

(Prior Art) This type of rotary compressor includes a rotary sleeve that rotates within a housing having a cylindrical inner circumferential surface while producing an oil bearing action between the housing and the rotary sleeve, and a rotary sleeve that is eccentrically arranged within the rotary sleeve. [For example, "displacement compressor" (published by Sangyo Tosho Co., Ltd. on April 5, 1971)
Reference] There is something.

However, with a rotating sleeve, the pressure difference between the high pressure side (discharge port side) and low pressure side (suction port side) of the compression chamber defined by the inner circumferential surface of the rotating sleeve and the outer circumferential surface of the rotor The resulting internal force of the rotating sleeve pushes the rotating sleeve toward the discharge port side of the inner circumferential surface of the center housing, causing local wear as it comes into contact with the inner circumferential surface of the center housing, as well as rotation of the sleeve. As a result, the rotary sleeve cannot fully demonstrate its original function. In order to solve these problems, the conventional rotary compressor mentioned above supplies oil between the sleeve and center housing to provide an oil bearing effect, but this oil supply is insufficient to reduce wear. Although it is effective, oil fills between the rotating sleeve and the center housing, which has a gap of only a few tens of microns, and its high viscosity becomes a source of resistance that suppresses the rotation of the sleeve, increasing the drive torque loss of the compressor. Unavoidably, although it is a compressor that rotates at a low speed, it cannot be used practically as a supercharger for an engine that requires high speed rotation of several thousand revolutions per minute.

We are currently developing and researching an air bearing type rotary compressor to solve the above conventional problems, but it is important for this rotary compressor to have a good air bearing effect between the housing and the rotating sleeve. However, if this air bearing action is insufficient, the housing and rotating sleeve will come into contact, resulting in seizure, and will also lead to an increase in drive torque loss.

(Purpose of the invention) In view of the above-mentioned problems, the present invention is an air bearing type rotary compressor, by forming a large number of communication holes that satisfy specific setting conditions in the center of the rotary sleeve. Rotary compression that forms a fluid film between the rotating sleeve and the housing to maximize air bearing action, eliminates seizure caused by contact between the rotating sleeve and the housing, and reduces drive torque loss. The purpose is to seize the opportunity.

(Structure of the invention) The present invention has a central part of a rotating sleeve that rotates in a housing having a cylindrical inner circumferential surface and generates an air bearing action between the housing and the inner circumferential surface thereof, and the inner and outer circumferences thereof are in communication with each other during the compression stroke. A large number of communication holes are formed for blowing air from the working chamber into the gap between the rotating sleeve and the housing, and each communication hole has a hole area S (mm ² ) and a circumferential distance between the communication holes. H (mm) is determined to be in the range of 0.7≦3.0, 10≦H≦20, which allows the rotating sleeve to approach the inner circumferential surface of the housing due to internal force. At this time, a fluid film is formed between the two, and the reaction force of the fluid film moves the rotating sleeve to a position where it can maintain an equilibrium state, thereby preventing contact between the two.

(Embodiment) A rotary sleeve for a rotary compressor according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

This rotary compressor includes a housing 1 having a cylindrical inner circumferential surface 10, a rotary sleeve 4 that rotates within the housing 1 with an air bearing action between the housing 1 and the rotary sleeve 4, and an eccentric arrangement within the rotary sleeve 4. The rotor 5 has a vaned rotor 5.

The housing 1 includes disk-shaped side housings 3, 3 on both sides of a cylindrical center housing 2.
are fixed with bolts 18, 18, . . . .

The outer diameter of the rotating sleeve 4 is slightly smaller than the inner diameter of the center housing 2, and an air bearing chamber 15 of 30 to 50 microns is formed between the two.

The rotor 5 is rotatable by having rotary shafts 6, 6 protruding from both sides supported by bearings 7, 7 provided in the side housings 3, 3.

Further, the rotor 5 has four vane grooves 8, 8, . It is loosely fitted so that it can be protruded. That is, the vane 9 is urged in the direction of protruding from the vane groove 8 by the centrifugal force caused by the rotation of the rotor 5, and its outer end surface is brought into pressure contact with the inner circumferential surface 19 of the rotating sleeve 4, and due to this pressure contact,
The space between the rotating sleeve 4 and the rotor 5 is divided into four working chambers 11a, 11b, 11c, and 11d. And the rotating sleeve 4 is
It is designed to be rotated synchronously with the rotor 5 by the pressure contact force of the vanes 9, 9, . . .

Furthermore, as shown in FIG. 4, the rotary sleeve 4 has a large number of communication holes 13, 13, . It is formed. The communication holes 13, 13, . It has the effect of blowing out air.

In the drawings, reference numeral 12 is a side seal, 16 is an inlet, and 17 is an outlet.

This rotary compressor works as follows.

The fluid sucked into the working chamber (working chambers 11a and 11b in the illustrated example) in the expansion stroke from the intake port 16 is compressed by the vanes 9 as the rotor 5 rotates,
It is discharged from the discharge port 17 .

At this time, due to the rotation of the rotor 5, the pressure in the working chamber ((working chamber 11c in the illustrated example) which has entered the compression stroke becomes larger, but the pressure in the working chamber 11c is higher than the pressure in the air bearing chamber 15 outside the rotating sleeve 4. At the point when the pressure becomes large, part of the air in the working chamber 11c is discharged into the air bearing chamber 15 through the communication hole 13 (angle θ = 20 to 30 degrees since the center of the working chamber 11c is at the top dead center). Discharge begins at the rotated position).Since this discharged air is ejected from the rotating working chamber, it also has momentum in the tangential direction and tends to move in the rotational direction due to inertia.
The center of the area where the rotating sleeve 4 and the center housing 2 come into contact (the discharge side area located within a range of about 70 degrees on the trailing side and the leading side, respectively, from the point X shown in FIG. 1) (as shown in FIG. 1) X
There will be sufficient air supply near point). In this state, the rotating sleeve 4 receives an internal force (vane centrifugal force, an internal acting force due to the pressure difference between the high pressure side (discharge port side) and the low pressure side (suction port side) of the working chamber) and moves toward the center housing 2 side. When pressed, the flowing air is locally trapped in the flat area between the outer circumferential surface 14 of the rotating sleeve and the inner circumferential surface 10 of the housing, and a fluid film is formed there. This fluid film has spring rigidity, and this reaction force pushes back the rotating sleeve 4 to maintain balance within the housing 1.
The rotating sleeve 4 is thus rotated together with the rotor 5.

Based on the above principle, the following three points are necessary and sufficient conditions for fluid film formation.

(1) Sufficient air exists for fluid film formation.

(2) The shape does not obstruct fluid film formation.

(3) A certain amount of clearance must be provided for the air bearing chamber.

In order to satisfy such conditions, the hole area S (mm ² ) of the communication holes 13 and the circumferential distance H (mm) between the communication holes must be set appropriately.

Therefore, when the air flow through the communication hole 13 is modeled as an adiabatic flow as shown in FIG. 5, when the center of the working chamber 11c in the compression stroke rotates by an angle θ from the top dead center (see FIG. 1) ) in 1
Mass flow rate Go of air ejected from communication holes 13
teeth, It is expressed as

Here, P ₁ , P ₂ : Pressure inside and outside the communication hole, T ₁ : Absolute temperature, K : Specific heat ratio, R : Gas constant, a ₀ : Minimum nozzle cross-sectional area, g : Gravitational acceleration, X ₁ : Effect of initial velocity (X ₁ ≒O may be used).

When the number of communication holes 13 in the working chamber 11c is n, the amount G of air jetted from the working chamber 11c to the air bearing chamber 15 is expressed as G=nG ₀ (Equation (2)).

Therefore, the air flow rate Q in the air bearing chamber 15, which is dominant in the formation of a fluid film, is expressed by the following equation (3): Q∝・a ₀ (n ₁ : total number of communicating holes) The stiffness is (n ₁・
The conclusion is that it depends on the value of a ₀ ).

On the other hand, the present inventors conducted an experiment under the following conditions and obtained the results shown in FIGS. 6 and 7.

Experimental conditions: Capacity: 400/rev, Operating condition: Rotary compressor no load, Rotating sleeve: Made of cast iron with outer diameter of 107 mm, Rotating sleeve outer circumferential surface: No sliding material coating, Rotating sleeve inner circumferential surface untreated, Center housing Inner surface: Chrome plated, Vane: Carbon vane, Communication hole position: 1 row in the center of the rotating sleeve.

Figure 6 shows the average relative rotation ratio N _s / _N (where N: rotor rotation speed, N _s : sleeve rotation Figure 7 shows the pore diameter d of the communicating holes when the number of communicating holes n ₁ = 24.
The characteristics of N _s /N are shown.

According to this, when the hole diameter d is constant, 18≦n ₁ ≦
The average relative rotation ratio shows a good value at 30, and when the number _n1 is constant, the average relative rotation ratio shows a good value at 1.0≦d≦2.0. i.e. 18
It can be inferred that a fluid film is formed in the air bearing chamber 15 in the range of ≦n ₁ ≦30 and 1.0≦d≦2.0.

In Fig. 6, when n ₁ <18, this is because condition (1) for fluid film formation is not satisfied due to insufficient air volume, and when n ₁ > 30, there are too many communicating holes and the fluid film is not formed. Because the place for the formation of is lost,
This is because condition (2) above is not met. In addition, in Fig. 7, when d<1.0, condition (1) is insufficient, and when d<2.0, although the rotating sleeve rotates satisfactorily, the volumetric efficiency of the compressor may decrease and the vanes may be damaged. be.

Based on the above results, the pore diameter d can be calculated as the pore area S (mm ² ).
When the number of holes _n1 was converted into the circumferential distance H (mm) between communicating holes, the set values of 0.7≦S≦3.0 and 10≦H≦20 were obtained.

Although the above description describes the case where the communication hole 13 is formed only in the center of the rotating sleeve 4,
FIG. 8 shows experimental data when the rotary sleeve 4 shown in the figure has a plurality of rows (that is, a center row a and left and right rows b and c). FIG. 8 shows a case where 24 communication holes are formed in the center row a, and the number n ₁ of communication holes 13 in the left and right rows b and c is changed (shown by a solid line), and a case where communication holes are formed in the center row a. Without doing so, both left and right rows b,
A case where the number n ₁ of communicating holes 13 in c is changed (shown by dotted lines) is shown in comparison.

According to this, it can be seen that the formation of a fluid film is dominated by the communication holes 13 in the center row a, and is not greatly affected by the number n ₁ of communication holes 13 in the left and right rows b and c. Also, with only left and right rows b and c,
It can also be seen that the formation of a fluid film is insufficient.

Next, we will consider whether the formation of a fluid film is affected by the number of vanes.

When the center of the working chamber 11c in the compression stroke is rotated by an angle θ from the top dead center (see Figure 1), the volume V(θ) of the working chamber 11c is approximately as follows: V(θ)=Dl It is expressed as (1+cosθ)2π/ZL.

Here, D: inner diameter of the rotating sleeve, l: rotor eccentricity, Z: number of vanes, L: length of the rotating sleeve. Therefore, as the rotor 5 rotates, the working chamber 11c
If polytropic compression occurs within the angle θ
The pressure P(θ) in the working chamber 11c at is P(θ)=P ₀ (2/1+cosθ) ^m , and the pressure P(θ) in the working chamber does not depend on the number of vanes.

Here, P ₀ : Suction pressure, m : Polytropic index Therefore, in the above formula (1), the mass flow rate G ₀ does not change even if the number of vanes is changed,
There is no need to change the setting value of the communication hole depending on the number of vanes.

As is clear from the above description, the communication hole 13 formed in the center of the rotating sleeve 4 is determined so as to satisfy the following conditions regardless of the diameter of the sleeve.

0.7≦S≦3.0 10≦H≦20 (Effects of the invention) According to the invention, in the housing having a cylindrical inner circumferential surface, an air bearing action is generated between the housing and the rotating sleeve at the center of the rotating sleeve. , a large number of communication holes are formed that communicate the inner and outer peripheries, and the hole area S (mm ² ) of each communication hole and the circumferential distance H (mm) between the communication holes are 0.7≦S≦3.0, 10
≦H≦20 is determined so that a fluid film is formed between the outer circumferential surface of the rotating sleeve and the inner circumferential surface of the housing, so the rotating sleeve exists in a floating state within the housing, and the rotation The rotor and rotating sleeve can be rotated integrally regardless of the sleeve diameter and the number of vanes. Therefore, wear of the vanes, seizure of the rotating sleeve, increase in drive torque loss, etc. can be suppressed, and there is a practical effect that durability and reliability are significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a rotary compressor according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG.
The figure is a sectional view taken along line B-B in Figure 1, Figure 4 is a perspective view of the rotating sleeve, Figure 5 is a modeled schematic diagram for explaining the air flow in the communication hole of the rotating sleeve, and Figure 6 is a communication diagram. Average relative rotation ratio with respect to the number of communicating holes n ₁ when the hole diameter d is constant
A diagram showing the characteristics of N _s /N, Figure 7 shows the number of communicating holes.
Figure 8 showing the characteristics of the average relative rotation ratio N _s /N with respect to the hole diameter d of the communicating hole when n ₁ is constant.
The figure shows the average relative rotation ratio N _s /N for the number of communicating holes n ₁ in the left and right columns when multiple rows of communicating holes are provided.
(Solid line: center column present, dotted line: center column absent). 1...Housing, 4...Rotating sleeve, 5...
...Rotor, 13...Communication hole.

Claims (1)

[Utility Model Claims] In a volumetric rotary compressor having a rotating sleeve that rotates within a housing having a cylindrical inner peripheral surface while generating an air bearing action between the rotating sleeve and the housing, and a vaned rotor that is eccentrically disposed within the rotating sleeve, a number of communication holes that communicate the inner and outer peripheries of the rotating sleeve are formed in the center of the rotating sleeve, and the hole area S of each of the communication holes is
1. A rotating sleeve for a rotary compressor, wherein the diameter S ( ^{mm 2} ) and the circumferential distance H (mm) between the communicating holes are determined to be within the ranges of 0.7≦S≦3.0 and 10≦H≦20.