WO1995013475A1

WO1995013475A1 - Fluid compressor

Info

Publication number: WO1995013475A1
Application number: PCT/KR1994/000159
Authority: WO
Inventors: Young Jae Shin
Original assignee: Young Jae Shin
Priority date: 1993-11-11
Filing date: 1994-11-09
Publication date: 1995-05-18
Also published as: KR950014601A; KR960014087B1

Abstract

A fluid compressor according to the present invention comprises an inner conical rotating body (1) being mounted in the interior conical hollow of an outer conical rotating body (2) eccentrically, a spiral type blade (13) having pitches being narrowed gradually and sliding between the inner and the outer conical rotating bodies, and a drive pin (3) being fixed on the inner conical rotating body (1) such that its outer end is fitted in an engaging groove (4) of the outer conical rotating body (2) so as to be movable. The present invention takes advantage of higher compression efficiency and capacity, because of the volume reduction of compression chamber caused both by the spiral type blade having gradually narrowing pitch and by the conical shapes of the inner and outer rotating bodies.

Description

FLUID COMPRESSOR

Technical Field

The present invention relates to an axial flow type fluid compressor, and more particularly to a fluid compressor comprising an inner body which is rotating within an outer rotating body and a spiral type blade which is sliding between the inner and the outer rotating bodies.

Background Art As shown in Fig. 5, a conventional fluid compressor comprises a rotating cylinder 101 having a suction side and a discharge side; a columnar rotating body 102 being located in the cylinder 101 eccentrically such that a portion of the peripheral surface of the rotating body 102 is in contact with a portion of the inner peripheral surface of the cylinder 101: a spiral groove 104 having pitches narrowed gradually on the outer peripheral surface of the rotating body 102: a spiral blade 105 being fitted in the groove 104 such that the spiral blade 105 slides in the radial direction of the rotation body 102 and outer peripheral surface of the blade is closely in contact with the inner peripheral surface of the cylinder, and a plurality of compression chambers being formed between the inner peripheral surface of the cylinder 101 and the outer peripheral surface of the rotating body 102 by the spiral blade 105 such that volume of each compression chamber is gradually decreasing with the distance from the suction side of the cylinder 101, thereby introducing fluid from the suction side of the cylinder 101 and transporting fluid toward the discharge side of the cylinder 101.

However, since the volume of each compression chamber of the above-mentioned fluid compressor is reduced gradually only by narrowing pitch of the spiral blade, it is difficult to obtain high compression ratio and capacity.

Disclosure of Invention

Therefore, the present invention is provided to solve the above-described problems of the conventional fluid compressor.

It is an object of the present invention to provide a fluid compressor of which the inner and the outer rotating bodies are shaped into the conical ones, thereby obtaining the high compression efficiency and capacity of the fluid compressor.

It is another object of the present invention of which the drive pin is fixed to the inner rotating body and the drive pin groove is formed on the outer rotating body, therby reducing the contact force and the wear and fracture of the drive pin and the engaging groove. To achieve the above objects, the present invention provides a fluid compressor comprising: an outer rotating body being formed into conical shape such that the sectional area of its interior hollow is reduced gradually from the suction side to the discharge side: an inner rotating body being formed into conical shape and contained in the interior conical hollow of the outer rotating body eccentrically such that a portion of its peripheral surface comes in contact with the inner peripheral surface of the outer rotating body: a cone-shaped spiral groove being formed on the perpheral surface of the inner rotating body such that its pitches gradually become narrower with distance from the suction side of the inner rotating body; a spiral blade being formed of an elastic material, and fitted freely into the cone-shaped spiral groove; an engaging groove being formed on the inner peripheral surface of the outer rotating body: and a drive pin being fixed on the peripheral surface of the inner rotating body, and fitted in the engaging groove such that the drive pin is movable in the radial direction of the outer rotating body. Brief Description of Drawings

The present invention will be more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus, are not limitative of the present invention, and wherein: Fig. 1 is a sectional view of a fluid compressor according to an embodiment of the present invention

Fig. 2A and 2B are views for simplified models of the compression chamber presented in a cylindrical coordinates to obtain the compression ratio of the fluid compressor

Fig. 2C and 2D are views of compression chamber of the fluid compressor projected on the Z-plane

Fig. 3A is a sectional view showing drive means of the present invention

Fig. 3B is a sectional view showing drive means of the conventional compressor

Fig. 4 is a sectional view of an embodiment of a cone-shaped blade groove of the present invention

Fig. 5 is a sectional view of the conventional compressor

Mode For Carrying Out the Invention

Embodiments of the present invention will be described in detail with reference to the accompanying drawings hereinafter.

Fig. 1 shows an embodiment according to which the present invention is applied to a fluid compressor. The inner rotating body 1 and the outer rotating body 2 are formed into conical shape such that their sectional areas are reduced gradually from the suction side to the discharge side for higher compression efficiency and capacity. They are supported by bearings 6 having suction hole 10 or discharge hole 11. The inner rotating body 1 is mounted in the interior conical hollow of the outer rotating body 2, extending along the axis 7 which is placed eccentrically in the interior conical hollow of the outer rotating body 2. One side of the peripheral surface of the inner rotating body 1 is in contact with the inner peripheral surface of the outer rotating body 2.

Drive pin 3 is fixed on the peripheral surface of the inner rotating body 1 and engaging groove 4 is formed on the inner peripheral surface of the outer rotating body 2, and drive pin 3 is fitted in the engaging groove 4 so as to be movable in the radial direction of the outer rotating body 2.

The torque of the outer rotating body 2, which is rotated by means of a motor M, is transmitted to the inner rotating body 1 by the drive pin 3.

The inner rotating body 1 rotates within the outer rotating body 2 while the peripheral surface of the inner rotating body 1 is partially in contact with the inner peripheral surface of the outer rotating body 2. The cone-shaped spiral blade groove 5, extending between the suction side and the discharge side of the inner rotating body is formed on the peripheral surface of the inner rotating body 1.

As shown in Fig. 1, the balde groove 5, within which cone-shaped spiral blade 13 is fitted, is formed such that its pitch gradually become narrower with distance from the suction side of the inner rotating body and each portion of the blade is movable in the radial direction of the inner rotating body 1 within the blade groove 5.

The outer peripheral surface of the cone-shaped spiral blade 13 slides on the inside peripheral surface of the outer rotating body 2 with close contact.

Spiral blade 13 is formed of an elastic material and can be fitted into the blade groove 5.

In Fig. 1, unexplained symbol 30 is the case of the compressor, symbol 31 is oil passage, symbol 32 is lubricating oil and symbol 33 is the cavity of discharge.

As stated above, the fluid in the compression chamber moves from the suction side to the discharge side when the inner and the outer rotating bodies are rotating. When the fluid in the compression chamber is forced into the next compression chamber by gradually reducing spiral blade pitch and sectional area of the compression chamber from the suction side to the discharge side, it can be compressed because the volume of the following compression chamber is less than that of the preceding one. As the rotating bodies rotates further, the fluid is driven into the next compression chamber and compressed to a higher pressure level. Fig. 2 shows a simplified model of the compression chamber presented in a cylindrical coordinates to obtain the compression ratio of the present invention. The Z-plane is the plane which contains the starting point of the cone-shaped spiral blade 13 and is perpendicular to the Z-axis, the axis of the inner rotating body 1.

Fig. 2A shows the configuration of the model at an instant when the first compression chamber begins and Fig. 2B shows the projection on the Z-plane. The configuration at the instant when the inner rotating body 1 rotates an angle a from the position shown in Fig. 2A is displayed in Fig. 2B. In these figures, the thickness of the cone-shaped spiral blade is ignored. The position z of a point on the blade corresponding to that have same angle θ Fig. 2A, is defined by the function h which indicate the distance between the Z-plane and point. z = h( θ + 2i π ) ( i = 0. 1 , 2 ... .. ) where, θ is a phase angle measured from the contacting point of the inner rotating body 1 and the outer rotating body 2 on the Z-plane, and i means the position that has same phase angle with θ.

H(θ), a pitch of the cone-shaped spiral blade of the first compression chamber, is represented as follows. H( θ ) = h( θ + 2π ) - h( θ )

As shown in Fig. 2C, S_LO and S_UO are the areas projected on the Z-plane surrounded by the inner rotating body 1 and the outer rotating body 2 at h(θ) and h(θ+2π) in Fig. 2B, respectively.

where, R_o is the maximum inner radius of the outer rotating body, R_i is the maximum outer radius of the outer rotating body, e = R_o - R_i,

and 2δ is the vertical angle of each conical rotating body.

An infinitesimal volume dV(θ) of the compression chamber at an angle θ can be written as follows.

As shown in Fig. 2C, dS_LO and dS_UO are the infinitesimal increments of S_LO and S_UO, respectively. Since the volume of the first compression chamber is the total sum of the infinitesimal volume, the displacement volume Vs that is the volume of the first compression chamber, is given by

Fig. 2D shows the configuration at the instant when the inner rotating body rotates an angle α.

The distance from the Z-plane of a point on the cone-shaped spiral blade is defined as follows. z = h(θ + α + 2iπ), (i = 0, 1, 2 ...... )

And a pitch of cone-shaped spiral blade at an angle θ is H(θ + α) = h(θ + α + 2π) - h(θ + α).

As shown in Fig. 2D, S_LF and S_UF are projected areas surrounded by the inner rotating body and outer rotating body at h(θ+α) and h(θ+α+2π), respectively. These areas SLF and SUF are

where,

In Fig. 2D, an infinitesimal volume dV_a(θ, α) of the compression chamber at an angle θ is given by

As shown in Fig. 2D, dS_LF and dS_UF are the infinitesimal increments of S_LF and S_UF, respectively.

The volume V(α) of the compression chamber at the instant when the inner rotating body rotates an angle α can be obtained by

If polytropic compression is assumed to take place in the compression chamber, the pressure P(α) in the compression chamber is given by

P(α) = Ps(Vs / V(α))ⁿ where, Ps is the suction pressure and n is the polytropic coefficient.

The pressure difference, ΔP, between two adjacent compression chambers, can be written as

ΔP = P(α + 2π) - P(α) Suppose that the fluid starts to discharge when the inner rotating body ratates an angle a_d, then the compression ratio ε can be obtained by ε = (Vs / V(α_d))ⁿ

Fig. 3A shows the sectional view of drive means of the present invention and Fig. 3B shows that of the conventional compressor.

In these figures, the moment T that is transmitted to the outer rotating body is

T = a₁ · F₁ = a₂ . F₂ then,

Since

Where, F₁ and F₂ are forces acting between the drive pin and the engaging groove of the present invention and the conventional compressor, respectively, and a₁ and a₂ are moment arms.

The contacting force becomes less, compared with that of the conventional compressor, and less wear and fracture of the drive pin and the engaging groove take place in the present invention. Fig. 4 is a sectional view of another embodiment of the blade groove 5 formed on the inner rotating body 1. the cone-shaped spiral blade 13 can slide freely in the direction of groove depth of the inner rotating body 1. The blade groove 5 is formed at an angle a' less than 90° to the axis of the inner rotating body. The outer peripheral surface of the blade 13 can be contacted closely to the inside peripheral surface of the outer rotating body.

Unbalancing force owing to pressure diference between two adjacent compression chambers of the present invention becomes small, because sectional area of higher pressure compression chamber is bigger than that of lower pressure compression chamber by the structural characteristics of the conical rotating bodies. Therefore, unbalancing force acting on the blade can be made small.

As apparent from the above description, the compressor of the present invention takes advantages of higher compression efficiency and capacity, because of the gradual volume reduction of compression chamber caused both by cone-shaped spiral blade having gradually narrowing pitch and by the conical shapes of the inner rotating body and the outer rotating body.

And fixing the drive pin to the inner conical rotating body enlarges the moment arm and reduces the contact force, therefore, the present invention has another feature of reducing the wear and fracture of the drive pin and the engaging groove.

Claims

1. A fluid compressor comprising: an outer rotating body being formed into conical shape such that the sectional area of its interior hollow is reduced gradually from the suction side to the discharge side; an inner rotating body being formed into conical shape such that its sectional area is reduced gradually from the suction side to the discharge side, and contained in the interior conical hollow of the outer rotating body eccentrically such that a portion of its peripheral surface comes in contact with the inner peripheral surface of the outer rotating body; a cone-shaped spiral blade groove being formed on the peripheral surface of the inner rotating body such that its pitches gradually become narrower with distance from the suction side of the inner rotating body; a spiral blade being formed of an elastic material, and fitted freely into the cone-shaped spiral groove by utilizing its elasticity; and drive means for relatively rotating the inner rotating body and the outer rotating body to successively transport a fluid introduced from the suction side toward the discharge side through the compression chambers:

2. A fluid compressor in accordance with claim 1, wherein the drive means comprises a engaging groove being formed on the inner peripheral surface of the outer rotating body: and a drive pin being fixed on the peripheral surface of the inner rotating body, and fitted in the engaging pin groove such that the drive pin is movable in the radial direction of the outer rotating body.

3. A fluid compressor in accordance with claim 1, wherein the cone-shaped spiral blade groove of the inner rotating body is formed at an acute angle to the axis of the inner rotating body.