JPH0218438B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a rotary compressor that is used as a mechanical supercharger for intake supercharging in an engine, for example, and has a rotating sleeve that rotates synchronously with a rotor. In particular, the invention relates to an air-bearing rotary sleeve.

(Prior Art) Rotary compressors having a rotating sleeve have been known (for example, "displacement compressor" (1973)).
Figure 15.1 (a) published by Sangyo Tosho Co., Ltd. on April 5, 2017)
reference). That is, a rotary sleeve is rotatably fitted into a casing formed by a cylindrical center housing and side housings arranged on both sides of the casing, and a rotor driven from the outside is centered at the rotation center of the rotary sleeve. The rotor is arranged eccentrically with respect to the rotor, and a plurality of plate-shaped vanes whose tips are in contact with the inner circumferential surface of the rotating sleeve are removably fitted into the rotor. The rotating sleeve is rotated along with the rotor. and,
This rotary compressor is advantageous in terms of durability because the rotating sleeve rotates together with the vane, which prevents heat generation and wear caused by the sliding of the vane tips. Recently, it has been attracting attention as an optimal supercharger for engines, etc. that are operated in the rotation range.

(Problem to be solved by the invention) However, in the case where the sleeve is rotated in this way, the high pressure side (discharge port side) and the low pressure side of the compression chamber, which are partitioned by the inner peripheral surface of the rotating sleeve and the outer peripheral surface of the rotor The rotating sleeve is pushed toward the discharge port side of the inner circumferential surface of the center housing and comes into contact with the inner circumferential surface of the center housing due to the internal acting force of the rotating sleeve caused by the differential pressure between the inner circumferential surface of the center housing and the inner circumferential surface of the center housing. This not only causes local wear but also limits the rotation of the rotary sleeve, making it impossible for the rotary sleeve to fully perform its original function. In order to solve these problems, the conventional rotary compressor mentioned above supplies oil between the rotating sleeve and the center housing to give it the effect of an oil bearing, but this oil supply causes wear and tear. However, the space between the rotating sleeve and the center housing, which is only a few tens of microns thick, is filled with oil, and its high viscosity becomes a source of resistance that suppresses the rotation of the rotating sleeve, resulting in compressor drive torque loss. This inevitably leads to an increase in the number of revolutions, and although it may be used in 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.

For this reason, the above-mentioned rotating sleeve is an air bearing type, and compression grooves (or dimples) are carved on the outer circumferential surface of the rotating sleeve to compress the air trapped in the compression grooves (or dimples) and reduce its viscous shear. It is conceivable to prevent the rotary sleeve from coming into contact with the center housing by generating a so-called viscosity pump action that increases the pressure. However, in this case, a sufficient pressure increase may not be obtained in the compression groove in the contact area between the rotating sleeve and the center housing simply by the viscostay pump action in the compression groove (or dimple).
There is a problem in that the intended contact prevention effect cannot be sufficiently exerted.

An object of the present invention is to improve the cross-sectional shape of compression grooves or dimples provided on the outer peripheral surface of the rotary sleeve in order to put into practical use a rotary compressor having an air bearing type rotary sleeve which is advantageous in terms of durability as described above. By creating a shape that maximizes the viscous shearing action of the air within the groove or dimple, even with a simple structure, it reliably prevents the rotating sleeve from coming into contact with the center housing, eliminating local wear. Moreover, the object is to reduce driving torque loss.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention is a rotary compressor having a rotating sleeve as described above, in which the rotating sleeve has an outer circumferential surface and an inner circumferential surface of the center housing. A communication hole is formed for supplying air between the inner circumferential surface of the rotary sleeve and the outer circumferential surface of the rotor by making the gap formed between the two communicate with the compression chamber formed between the inner circumferential surface of the rotating sleeve and the outer circumferential surface of the rotor. Compression grooves or dimples for performing the viscostay pump action are provided on the outer circumferential surface of the rotating sleeve that was in local contact with the contact area of the inner circumferential surface of the center housing, that is, the portion corresponding to the vicinity of the discharge port, and The dimples are characterized by being tapered so that the depth of the dimples is deep at the front and shallow at the rear in the direction of rotation so as to form a Rayleigh step.

(Function) Accordingly, in the present invention, the air that is supplied between the rotating sleeve and the center housing through the communication hole and flowing therebetween is arranged so that the depth within the compression groove or dimple increases in the direction of rotation as the rotating sleeve rotates. Because it has a so-called infinitely small Rayleigh step that is deeper at the front and gradually shallower at the rear, smooth compression is performed without producing counter-rotational force due to air turbulence, etc. A high pressure is generated due to sufficient compressive force. Furthermore, when the rotating sleeve approaches the contact area of the inner circumferential surface of the center housing due to its internal acting force, the air in the compression groove or dimple performs the above-mentioned viscostay pump action and is further compressed, so that the pressure is reduced. As a result, the adjacent rotary sleeve receives the repulsive force and moves to a position where it can maintain an equilibrium state, thereby preventing contact between the two.

(Effects of the Invention) Therefore, according to the present invention, in a rotary compressor having a rotary sleeve, air is supplied between the rotary sleeve and the center housing, and compression grooves or dimples provided on the outer peripheral surface of the rotary sleeve are provided. is tapered so that its depth is deeper at the front and shallower at the rear with respect to the rotation direction, and the Viscostay pump action is synergized with the infinitesimal Rayleigh step action. By forming a sufficiently high-pressure air bearing layer, contact between the rotating sleeve and the center housing can be prevented, localized wear unlike conventional systems can be prevented, and the rotating sleeve can rotate smoothly. Therefore, it is possible to put into practical use a rotary compressor having a rotary sleeve that can reduce driving torque loss and has excellent durability, thereby making it possible to provide and realize an optimal supercharger for an engine.

(Example) Hereinafter, an example as a specific example of the technical means of the present invention will be described based on the drawings.

1 to 4 show one embodiment of the present invention. In FIGS. 1 and 2, 1 is a casing, and the casing 1 includes a cylindrical center housing 2 and a plurality of side housings 3, 3 (four in the figure) arranged on both the left and right sides of the cylindrical center housing 2. It is configured by being fastened by fastening bolts 4, 4, . . . . A cylindrical rotating sleeve 5 whose outer diameter is slightly smaller than the inner diameter of the center housing 2 is fitted into the casing 1 so as to be rotatable and concentric with the axis of the center housing 2. The space between the outer peripheral surface 5a of the center housing 2 and the inner peripheral surface 2a of the center housing 2 (e.g., 30 to 50μ) creates an air bearing chamber 6 as an air bearing section using only air.
is formed. Furthermore, the rotating sleeve 5
Inside, a cylindrical rotor 7 having shaft portions 7a, 7a at both ends is eccentric to the rotation center of the rotating sleeve 5 (the axis of the center housing 2) and is attached to the rotating sleeve 5 at a tangential seal point P. A substantially crescent-shaped space 8 is formed between the inner circumferential surface 5b of the rotary sleeve 5 and the outer circumferential surface 7b of the rotor 7.

One of the side housings 3 (the left side housing in FIG. 2) has a suction port 9 on the trailing side (left side in FIG. 1) of the space 8, facing the space 8, and a space Discharge ports 10 are opened on the leading side (right side in FIG. 1) of the portion 8, respectively. Furthermore, annular seal grooves 1 are formed in inner wall surfaces 3a, 3a of both side housings 3, 3 corresponding to both end surfaces 5c, 5c of the rotating sleeve 5.
1 and 11 are formed, and a side seal 12 is installed in each of the seal grooves 11 in sliding contact with the rotary sleeve end surface 5c for gas sealing.

Further, the rotor 7 is rotatably supported at its shaft portions 7a, 7a via bearings 14, 14 in support holes 13, 13 provided in both side housings 3, 3, respectively.
(the shaft portion on the right side in FIG. 2) is extended outside the casing 1, and a pulley 15 connected to a rotary drive device (not shown) such as an engine by a Verna drive is attached to the extended portion of the shaft portion 7a. The rotor 7 is rotatably driven via a pulley 15 by an external rotary drive device.

Further, on the outer circumferential surface 7b of the rotor 7, a plurality of (four in the figure) vane grooves 16, 16, . A plate-shaped vane 17 is fitted into each of the vanes 16 so as to be slidable and retractable in the radial direction of the rotor 7. The vanes 17, 17... are subjected to centrifugal force when the rotor 7 rotates, and their tips are brought into airtight pressure contact with the inner circumferential surface 5b of the rotating sleeve 5, thereby forming a connection between the inner circumferential surface 5b of the rotating sleeve and the outer circumferential surface 7b of the rotor. The space 8 is divided into four compression chambers 18, 18, . . . , and the rotating sleeve 5 is rotated synchronously with the rotor 7 in this state.

As a feature of the present invention, as shown in FIGS. 3 and 4, the rotating sleeve 5 has a large number of V-shaped compression grooves 19, 19 on its outer peripheral surface 5a.
... are carved at equal intervals in the circumferential direction. Each compression groove 19 is formed such that both groove ends 19a, 19a of the V-shaped groove are located forward with respect to the rotation direction X, and the groove center portion 19b is located at the center in the axial direction. The groove is tapered so that the groove depth is deep in the rotation direction X at the groove front part 19c and gradually becomes shallower toward the groove rear part 19d.

Furthermore, the rotary sleeve 5 has a large number of communication holes 20, 20, .
is provided, and the air in the compression chamber 18 is injected and supplied to the air bearing chamber 6 to form an air bearing layer between the rotating sleeve 5 and the center housing 2.

Note that a portion of the inner circumferential surface 2a of the center housing 2 corresponding to the vicinity of the discharge port 10, that is, a contact area θ, with which the rotating sleeve 5 has conventionally been in local contact is a tangential seal between the rotating sleeve 5 and the rotor 7. Diameter line perpendicular to diameter line l ₁ passing through point P
70° on the trailing side with respect to l ₂ , and the maximum from the angle θo passing through the center of the discharge port 10 on the leading side
It has been experimentally determined that the range is up to 70°, that is, θo+70°≦θ≦140°.

Next, to explain the operation of the above embodiment,
The rotor 7 is rotated by an external rotary drive device such as an engine.
When the rotor 7 is rotated in the X direction in FIG.
The vanes 17 fitted in the respective vane grooves 16 are subjected to centrifugal force and their tips are brought into airtight pressure contact with the inner circumferential surface 5b of the rotating sleeve 5, so that the inner circumferential surface 5b of the rotating sleeve and the outer circumference of the rotor Surface 7b
The space 8 between them is divided into four compression chambers 18, 18..., and while this state is maintained, the rotational force of the rotor 7 is transmitted to the rotating sleeve 5 via the vanes 17, 17... The rotating sleeve 5 rotates synchronously with the rotor 7. and,
With the synchronous rotation of the rotor 7 and the rotating sleeve 5, the volume of the compression chamber 18 changes synchronously,
The compression chamber 18 is connected from the suction port 9 side to the discharge port 10
The volume gradually increases as you move to the side, reaches the maximum volume, and then gradually decreases. As a result, the air sucked into the compression chamber 18 from the suction port 9 is compressed and pressurized within the compression chamber 18, and then the air is sent to the discharge port 10.
It will be discharged from the casing 1.

At this time, a part of the high-pressure air in the compression chamber 18 located near the discharge port 10 is transferred to the communication hole 2 of the rotating sleeve 5 near the contact area θ due to the pressure difference between the compression chamber 18 and the air bearing chamber 6. , 20 . . . into the air bearing chamber 6. This ejected compressed air performs an air bearing action in the air bearing chamber 6, and then is guided into the compression groove 19. The air introduced into the compression groove 19 is arranged so that the groove depth of the compression groove 19 is deep in the front part and gradually becomes shallower towards the rear part with respect to the rotation direction X. Since it forms an infinitely small Rayleigh step, the groove front part 19c expands as the rotating sleeve 5 rotates, and then the groove rear part 19c expands.
It is recompressed at 9d to generate a compressive force. At this time, since the compression groove 19 is formed in a tapered shape that is deep at the front and shallow at the rear, the compressed air in the compression groove 19 flows smoothly without turbulence, and the compression is performed smoothly and gradually. The effect can be effectively demonstrated and a sufficiently high compression force can be obtained. Furthermore, since the groove ends 19a, 19a of the V-shaped compression groove 19 are located forward in the direction of rotation, the air in the compression groove 19 is absorbed by the rotation of the rotary sleeve 5 and the inertia of the air. The groove moves from both end portions 19a, 19a toward the groove center portion 19b while being rapidly compressed. As a result, the compressed groove 19 in the contact area θ is filled with air at a sufficiently high pressure.

In this state, the rotating sleeve 5 is inserted into the compression chamber 18.
When the air in the compression groove 19 approaches the contact area θ of the inner circumferential surface 2a of the center housing due to the internal force caused by the pressure difference between the high pressure side (discharge port 10 side) and the low pressure side (suction port 9 side), the air in the compression groove 19 is almost compressed. Since it is a completely confined field, it is compressed by the proximity of the rotating sleeve 5, and its pressure rises rapidly, producing a so-called viscostay pump action. The pressure becomes even higher. The rotating sleeve 5, which is approaching the center housing 2, receives a large repulsive force from this high-pressure air and moves to a position where it maintains an equilibrium state.

Therefore, the rotating sleeve 5, which is about to be pushed against the contact area θ of the center housing inner circumferential surface 2a due to the internal force, is supported by high air pressure to prevent such contact, and the rotating sleeve 5 is smoothed. Therefore, it is possible to prevent local wear as in the conventional case and reduce drive torque loss. In particular, due to the synergistic effect of the Rayleigh step action of the compression groove 19 and the Visco stay pump action, smooth rotation of the rotary sleeve 5 can be ensured even at low rotation speeds.

In the above embodiment, the outer circumferential surface 5 of the rotating sleeve 5
A has been described in which a V-shaped compression groove 19 is provided, but various other shapes such as W-shape, U-shape, etc. can be adopted as the compression groove, and instead of the compression groove, circular, circular, Compression dimples of various shapes such as triangular shapes may be used, and the same effects as in the above embodiments can be achieved.

Next, the synergistic effect of the Rayleigh step action and the Viscostay pump action according to the present invention will be theoretically explained based on FIGS. 5 and 6. Fifth
Figures a and b are schematic diagrams for explaining the Rayleigh step action in a stepped groove, where h is the distance between the outer circumferential surface of the rotating sleeve and the inner circumferential surface of the center housing, and Lg is the deep bottom of the stepped groove. (front) circumferential width,
Similarly, Le is the circumferential width of the shallow bottom (rear part), Lr is the circumferential interval between the grooves, e is the depth of the shallow bottom of the groove, and d is the distance from the inner peripheral surface of the center housing to the bottom of the deep bottom of the groove. be. In addition, FIGS. 6a and 6b are schematic diagrams for explaining the Viscostay pump action in a V-shaped compression groove, where ag is the circumferential width of the compression groove,
ar is the circumferential spacing between compression grooves, f is the depth of compression grooves,
L is the length of the compression groove, and θ is the inclination angle of the compression groove with respect to the axial direction.

First, referring to Fig. 5, assuming that the stepped groove is a Rayleigh step, and finding the peak pressure Pmax at the step (shallow bottom), Pmax=1+[Σ・(-1)/(+1)・(・³ + 1)] Here, =Lr/Le, = (h+e)/h Σ=6μ・(Lr+Le)・U/h ²・Po μ: Air viscosity coefficient, Po: Groove inlet pressure, U: Sleeve rotation It becomes speed. When this pressure value Pmax is converted into the expression _R of pressure increase in the groove in order to compare it with the Viscostay pump action in the compression groove, it becomes _R = Pmax/Po...().

Next, from Fig. 6, find the rate of pressure increase _B due to the action of the Viscostay pump in a compression groove without steps: _B = C K K Λ + 1 ... () Where, C: proportionality constant, Λ = 6 μ U・L/P・h ² K=(H ³ −1)・(H−1)・sin2θ/ {(H ³ +1) ² +2H ³・(A+A ⁻¹ ) +(H ³ −1) ²・cos2θ } ...() A=ag/ar, H=(f+h)/h.

Therefore, if the compression groove shown in Fig. 6 above is a stepped groove as shown in Fig. 5, the effective depth (i) of the compression groove is
is = (Lg・d+Le・e)/(Lg+Le).In the end, the rate of pressure increase due to the action of the Viscostay pump in the stepped compression groove is obtained by substituting H=(+h) into the above equation (), and further calculating this ( ) is the value obtained by substituting the () expression into the () expression.

Therefore, the overall pressure increase rate, that is, the pressure increase rate m due to the Rayleigh step action and the Viscostay pump action, was determined above ()
The product of the pressure increase rate _B in the formula and the pressure increase rate P _R in the formula (), _n = _R・_B.

As an example, FIG. 7 shows the calculated value of the pressure increase rate when h is plotted on the horizontal axis using numerical values corresponding to a rotary compressor. In FIG. 7, the solid line shows the pressure rise rate characteristic in the case of a stepped compression groove, and the broken line shows the pressure rise rate characteristic in the case of a simple compression groove of the same depth. According to the same figure, the rate of pressure increase is larger in the case of stepped compression grooves than in the case of compression grooves of equal depth, especially in the range of 30 to 50μ, which is the range of normal air bearing layer h. It can be seen that the height rises significantly, which shows that the effect of preventing contact between the rotating sleeve and the center housing is excellent. From this, in the case of a tapered compression groove as in the present invention,
Since the taper can be regarded as a collection of infinitely small Rayleigh steps, a higher rate of pressure increase can be expected than the stepped compression groove, and it is extremely effective.

[Brief explanation of drawings]

The drawings illustrate an embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view, FIG. 2 is a sectional view taken along the line -- of FIG.
The figure is a perspective view of the rotating sleeve, and FIG. 4 is an enlarged sectional view of the main part of FIG. 3. Figures 5a and b are schematic plan views and cross-sectional views for explaining the Rayleigh step action, Figures 6 a and b are schematic plan views and cross-sectional views for explaining the Viscostay pump action, and Figure 7 is a schematic plan view and cross-sectional view for explaining the Rayleigh step action. It is a graph showing pressure increase rate characteristics. 1...Casing, 2...Center housing, 3
...Side housing, 5... Rotating sleeve, 7... Rotor, 17... Vane, 19... Compression groove, 19c... Front part, 19d... Rear part, 20... Communication hole.

Claims (1)

[Claims] 1. A casing formed of a cylindrical center housing and side housings arranged on both sides of the casing, a rotating sleeve rotatably fitted into the casing, and eccentrically arranged with respect to the center of rotation of the rotating sleeve. a rotor which is rotatably driven from the outside, and a plurality of plate-shaped plates which are retractably fitted into the rotor and whose tips abut against the inner circumferential surface of the rotating sleeve to divide the space inside the rotating sleeve into a plurality of compression chambers. In a rotary compressor comprising a vane, the rotary sleeve is rotated via the vane by rotation of the rotor, and the rotary sleeve has a gap formed between an outer circumferential surface of the rotary sleeve and an inner circumferential surface of the center housing. 〓 is communicated with the compression chamber, and during the
A communication hole is formed for supplying air to the rotary sleeve, and a compression groove or dimple is carved on the outer circumferential surface of the rotating sleeve, and the depth of the compression groove or dimple is the same as the front part in the direction of rotation. By forming a tapered shape so that it is deep at the rear and shallow at the rear, the air in the void formed between the outer circumferential surface of the rotating sleeve and the inner circumferential surface of the center housing is compressed, and the void is filled with air only. A rotary compressor having a rotary sleeve forming an air bearing part.