JP2003286979A - Helical blade compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such problems with a helical blade compressor that a piston is pressed to the center side of a cylinder by a gas compressive load acting on the piston to increase a minimum longitudinal clearance part between a columnar piston outer peripheral surface part and a cylindrical cylinder inner peripheral surface part holding air-tightness in an operating chamber and thus an internal leakage increases to lower an efficiency and that abnormal vibration and noise as well as a damage to a bearing occur due to an abnormal contact between the piston and the cylinder caused by the deformation of a member by heat and gas pressure. <P>SOLUTION: In this helical blade compressor, a piston eccentric amount variable mechanism as a means for minimizing a longitudinal operating chamber seal clearance formed between the piston and the cylinder is installed, between a shaft and the piston, in an operating chamber formed of the cylindrical cylinder inner peripheral surface, the columnar piston outer peripheral surface, and a blade fitted into a spiral groove of the piston. The piston eccentric amount variable mechanism is formed of a slide bush having a flat slide surface linearly movable in one direction and an elastic member. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive displacement compressor or pump for compressing a gas such as a refrigerant gas or a gas such as air in a refrigeration cycle as a working fluid, and more particularly to a helical blade type compression. Regarding the machine.

[0002]

2. Description of the Related Art A compressor part of a helical blade type compressor is provided with a cylindrical cylinder part and a spiral groove eccentrically arranged in the cylinder part and having a gradually changing pitch on the outer peripheral surface. Cylindrical piston, a blade mounted with a minute gap in the spiral groove, a shaft for transmitting power of an electric motor rotatably inserted in a bearing in the piston, and a piston rotating with respect to a cylinder The Oldham mechanism as a means for moving is mechanically connected.

Further, a main frame is fixed to an upper end of a cylinder having a cylindrical cylinder portion space formed therein, and a sub-frame is fixed to a lower end of the cylinder so as to close the space. The main frame is placed in the cylindrical space formed by
A shaft provided with two balancers supported by a bearing provided in the central portion of the frame and the sub-frame, and a cylindrical piston attached to the shaft portion of the shaft are provided.

In the working chamber for compressing gas, the volume of the space formed by the cylinder cylinder portion, the outer wall surface of the piston and the side wall surface of the blade mounted on the piston gradually changes along the longitudinal direction. Divided into multiple rooms.

The airtightness of the working chamber is the minimum clearance in the longitudinal direction, which occurs when the cylinder portion of the piston outer wall surface smaller than that is inserted inside the cylinder cylinder portion with their axes parallel to each other and eccentric. It is held by the seal gap δc of the working chamber, the blade tip contacting the inside of the cylinder cylinder portion, and the contact surface with the blade end surface housed in the spiral groove of the piston.

One end of a cylinder constituting such a compressor unit and a motor constituting an electric motor connected to the compressor unit via a shaft are fixed in a hermetic case to constitute a hermetic compressor. Japanese Patent Laid-Open No. 11-324
955 publication is mentioned.

A mass corresponding to the rotary inertia mass of the piston with blade and the eccentric part of the shaft supporting the piston, which constitutes the compression mechanism, is fixed to the shaft as a balancer.

Therefore, the centrifugal force of the piston acts on the shaft when the seal clearance δc is opened during operation and the cylinder cylinder portion and the outer wall surface of the piston are not in contact with each other. Centrifugal force acts on the cylinder cylinder part.

[0009]

The airtightness of each working chamber is determined by the cylinder cylinder portion and the blade tip, between the spiral groove side wall surface of the piston and the blade end surface, and between the cylinder inner wall surface and the piston outer surface. It is held by a seal clearance δc which is the minimum clearance formed between the wall surfaces.

Of these, the surface sealed by the blade is made airtight by closely contacting the sealing surface by applying tension, which is the elastic force of the blade itself, or gas pressure to the back surface of the blade. Can be held.

However, the size of the seal gap δc, which is determined by the relative positional relationship between the cylinder cylinder portion and the outer wall surface of the piston, depends on the processing accuracy and assembly accuracy of each pump component and the heat and gas pressure applied during operation. It is greatly affected by the movement and deformation of the members.

In particular, a phenomenon in which a part of the gas pressure which is compressed and increased during operation acts in a direction of expanding the seal gap δc by pushing the piston toward the cylinder cylinder central axis will be described in more detail.

When the electric motor is driven to start the operation of the compressor, the gas that has flowed into the working chamber and is trapped therein is gradually revolved without rotation of the piston, that is, the volume of the working chamber is gradually reduced with the swirling motion. Then the pressure rises.

The gas compressive load due to the gas pressure is about a tangential force acting as an axial torque perpendicular to an axial plane including the axial centerline of the cylinder cylinder portion and the axial centerline of the piston outer wall cylinder, and about the axial plane. It can be decomposed into a normal force that is parallel and close to the axis of the piston and the axis of the cylinder.

This normal force acts to separate the piston and the cylinder / cylinder portion from each other in the minimum gap portion in the longitudinal direction which maintains the airtightness of the working chamber to expand the seal gap δc. The centrifugal force caused by the eccentricity of the shaft center acts in the direction opposite to the normal force in proportion to the square of the rotation speed.

Therefore, in a region where the rotational speed of the shaft is low and the centrifugal force of the piston is smaller than the normal force, the seal clearance δ
There is a problem that c is enlarged, the airtightness of the working chamber is lowered, internal leakage is increased, and the efficiency is lowered.

This tendency tends to increase as the differential pressure between the high pressure side and the low pressure side increases and the normal force for expanding the seal gap δc increases, resulting in a greater decrease in efficiency and a higher discharge high pressure. It made it difficult to use.

On the other hand, in a high-speed operation region where the centrifugal force of the piston becomes larger than the normal force, the seal clearance δc becomes smaller and the airtightness of the working chamber is improved, but the increasing centrifugal force of the piston increases the centrifugal force of the cylinder cylinder. There is a problem that it acts on the parts to increase vibration noise and that it acts on the bearings and damages the bearings.

Further, when the outer wall surface of the piston is brought closer to the cylinder cylinder portion in order to reduce the seal clearance δc,
There has been a problem that abnormal contact occurs due to deformation of members due to heat and gas pressure during operation, abnormal vibration and noise, and the above load is applied to the bearing, resulting in bearing damage.

[0020]

As a means for solving the above-mentioned conventional problems, in a working chamber composed of a cylinder cylinder portion 11a, a piston outer wall surface 12a and a blade 14 mounted in a spiral groove 12b of the piston, An eccentricity varying mechanism for varying the eccentricity of the piston central axis as a means for minimizing the longitudinal seal gap δc formed between the piston outer wall surface and the cylinder cylinder portion transmits power to the piston. It is provided between the shaft and the slide portion 8b.

The eccentricity variable mechanism has a slide portion 8b provided with at least one flat surface integrated with the shaft.
In addition, a slide bush 15 having a rectangular fitting hole 15b provided inside thereof is mounted, and at the same time, an elastic member 17 formed of a spring or rubber is mounted in the fitting hole.

The slide bush is assembled so that the slide surface 15e of the fitting hole is in close contact with the flat surface of the slide portion 8b, and the elastic member 17 is provided in the fitting hole 15b of the slide bush and between the slide portion 8b of the shaft. Provide in between. When utilizing the compression load of the elastic member, an elastic member having a certain elastic force is provided so that the minimum gap formed between the cylinder cylinder portion and the piston outer wall surface is minimized.

That is, as a mechanism for applying a seal load against the normal force associated with the gas compressive load, a tangential force or an elastic member associated with the gas compressive load showing a value several times larger than the normal force is generated. The elastic force acts in a direction to expand the eccentricity of the piston shaft center and reduce the seal clearance δc.

The seal clearance δc of the working chamber is calculated by using the tangential force.
When reducing the gas compression load, the tangential force on one side is Ft, the normal force on the other side is Fv, and when the seal load is Fs, Fs> Fv. Should be used.

More specifically, the slide surface 15e for restricting the moving direction of the slide bush 15 is provided so as to be inclined with respect to the direction of the surface including the cylinder cylinder portion axis and the piston axis, which is the normal force direction. As a result, a tangential force component that opposes the normal force is generated.

Since the magnitude of the component force is calculated by Ft × sin θ when the tilt angle is set to θ, the value of θ may be set so that this value becomes Fv or more.

When the elastic member 17 made of spring, rubber or the like is used, the elastic force acts in the direction of sliding the slide surface 15e of the slide bush between the slide bush and the slide portion of the shaft. Attach to.

The magnitude of the elastic force may be set to be equal to or more than the normal force Fv when the inclination angle θ of the slide bush attachment is set to 0, but when θ has a certain value Can be set to a value not less than the remaining value by subtracting Ft × sin θ from Fv.

At this time, the inclination angle θ is set to an optimum value depending on the magnitudes of the tangential force, the normal force and the elastic force, but in consideration of the driving characteristics and the assembling property of the elastic member, the θ is between 5 and 15 degrees. It is good to provide.

On the other hand, a balancer corresponding to a rotary inertia mass or a rotary inertia mass equal to or less than the rotary inertia mass including the bladed piston constituting the compression mechanism and the eccentric portion of the shaft on which the piston is mounted is added. The end face of a cylindrical slide bush is fixed to one or two places.

As a result, the rotational inertial force generated in the compression mechanism portion is almost entirely canceled out, and does not act on the cylinder cylinder portion or the bearing of the piston.

In the helical blade type pump constructed as described above, when the power is turned on and the operation is started, the piston 12 expands the eccentric amount of the axial center by the elastic force of the elastic member 17 at the initial stage of startup. The seal gap δ of the working chamber, which is the minimum gap with the cylinder cylinder portion 11a pushed in the direction.
Since c becomes the smallest and the compressed gas in the working chamber can be prevented from leaking to the low pressure side, the outflow amount of the gas is secured.

Further, in the steady state operation in which the pressure on the discharge side becomes high, the elastic member is added to the component force of the tangential force generated from the inclination angle θ of the slide surface 15e of the slide bush, which is larger than the normal force and acts in the opposite direction. The piston is pushed in a direction to increase the eccentricity of the shaft center by the force of the elastic force applied to the seal clearance δc, which minimizes the flow of high-pressure gas from the high-pressure side including the discharge chamber to the working chamber. Since it is possible to prevent the gas from flowing out of the chamber to the low pressure side, it is possible to secure the amount of gas flowing out and at the same time reduce the gas compression power.

During high-speed operation, the centrifugal force of the slide bush, the piston, and the balancer increases in proportion to the square of the number of revolutions. However, since the balancer is fixed to the slide bush and rotates integrally, the centrifugal forces are the same. Since they cancel each other out, they do not affect the seal clearance δc or the contact load between the cylinder and the piston.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a vertical sectional view of a helical blade type compressor showing an embodiment of the present invention. FIG. 2 shows a sectional view taken along the line AA of FIG. 3 to 6 are external views of components.

As shown in FIG. 1, the compressor section of the present invention has a shaft 8 directly connected to the electric motor section 2 and a slide section 8b.
A cylindrical slide bush 15 having a rectangular fitting hole 15b fitted in the cylindrical groove 15b, and a spiral groove 12 having a pitch gradually changing on the cylindrical outer diameter surface mounted on the cylindrical shaft portion 15a.
a piston 12 provided with b, and an elongated blade 1 having a rectangular cross section mounted with a minute gap in the spiral groove.
4. An Oldham mechanism mechanically connected to the end of the cylinder and the cylinder portion of the cylindrical cylinder that accommodates these inside.

In addition, at the upper end of the cylinder / cylinder portion 11a, a main frame 9 is provided with a bearing in the center so as to close the internal space.
Is fixed to the piston 12 with blade 14 and both end faces of a cylinder in a cylindrical inner space formed by fixing a sub-frame 10 having a bearing at the center so as to close the inner space at the lower end. The slide bush having the balancer A18 and the balancer B19 fixed thereto and the shaft supporting the slide bush are housed therein.

The airtightness of the plurality of working chambers formed by being divided by the blade in the space formed between the cylinder cylinder portion and the outer wall surface of the piston is determined by the cylinder cylinder portion 11
The piston outer wall surface 12a smaller than that is inserted into the cylinder of a with the cylinder axes parallel to each other to cause eccentricity and the seal gap δc of the working chamber in the longitudinal direction and the blur contacting the cylinder portion of the cylinder. It is held by the contact surface with the blade end face housed in the spiral tip of the piston and the spiral groove of the piston.

That is, as shown in FIG. 2 which is a sectional view taken along the line AA of FIG. 1, a mechanism for varying the eccentric amount of the axial center of the piston outer wall surface 12a with respect to the axial center of the cylinder portion 11a and the seal clearance. An eccentricity variable mechanism composed of means for applying to the piston a load in excess of the normal force due to gas compression, which is a factor for expanding δc, is provided with the piston 12 and a rectangular slider portion of the shaft as shown in FIG. It is provided between 8b.

In this eccentricity variable mechanism, a slide portion 8b having at least one flat surface integrated with a shaft is provided with a fitting hole 15b having a cylindrical inner shape for accommodating the slide portion as shown in FIG. The slide bush 15 is provided, and the elastic member 17 made of spring, rubber or the like is mounted in the fitting hole. The elastic member 17 shown in FIG. 5 is composed of a leaf spring formed by forming a steel plate into a mountain shape.

The rotation direction of the shaft 8 having a square cross section shown in the center of FIG. 2 is configured to be clockwise, and the slide surface 15e of the slide bush closely contacting the slide portion 8b of the shaft is downward. Provided on the side of the cylinder cylinder portion 11a and the piston outer wall surface 1
The slide surface 15e with respect to the plane including the centering axis of 2a
Is formed so as to slope upward to the right. The inclination angle is preferably set in the upper range of 5 to 15 ° in order to improve the driving characteristics.

This slide bush is incorporated so that the sliding surface 15e of the fitting hole 15b is in close contact with the flat surface of the sliding portion 8b of the shaft, and the elastic member 17 is provided between the sliding portion of the shaft and the sliding portion of the shaft. Mounting.

The slide bush cylindrical shaft portion 15 shown in FIG.
A balancer-A 18 shown in FIG. 6 and a balancer-B 19 provided on the opposite side to the balancer-A 18 shown in FIG. 6 are mounted so as to sandwich the slide bush 15 by utilizing screw holes 15d provided on both end faces of a.

The operation of the helical blade type compressor constructed as described above will be described below. Prior to operation, the piston 12 is indirectly pushed by the elastic force of the elastic member 17 or leaf spring through the slide bush 15 which supports the piston 12 in a cylindrical portion, and is almost in contact with the cylinder portion of the cylinder.
The gap δc is the smallest.

When the operation is started from this state, the slide bush fitted in the slide portion has the slide surface 15
Although it is pushed by e and rotates in synchronization with the shaft 8, the piston 12 rotatably mounted on the slide bush makes an orbital motion with respect to the cylinder 11 whose rotation is blocked by the Oldham mechanism.

At the same time, the blade mounted on the piston 11 and the working chamber kept airtight by the seal gap δc also rotate, and the working gas is sucked from the suction passage and compressed, and then discharged from the discharge passage. It

At this time, the gas compression load, which increases with the compressed gas as the pressure of the discharged gas rises, is applied from the piston 12 through the bearing to the slide surface 1 of the slide bush.
Acts on 5e.

The movement of the slide bush is determined by three factors, namely, the gas compression load acting on the bearing, the spring force of the elastic member, and the frictional force in close contact with the slide portion of the shaft.

This gas compression load is applied to the cylinder cylinder portion 11
a tangential force perpendicular to the axial plane including the axial centerline of a and the axial centerline of the piston outer wall surface 12a and acting as axial torque, and a direction parallel to the axial plane to bring the piston axis and the cylinder axis closer to each other. Can be decomposed into normal forces that act on.

This normal force acts in the direction of increasing the seal clearance δc by separating the piston and the cylinder from each other in the longitudinal minimum clearance maintaining the airtightness of the working chamber, but the elastic member 17 is used. And the tangential force component generated by the inclination angle of the slide surface 15e of the slide bush is greater than the normal force, the piston outer wall surface comes into contact with the inner surface of the cylinder portion of the cylinder to seal the working chamber. The nature is enhanced.

That is, the normal force is Fr, the spring force is Fk,
When the tangential force is Fd, the inclination angle of the slide surface 15e of the slide bush is θ, and the frictional force of the slide surface is Ff, Fk and the inclination angle θ are set so that the following equation is satisfied. Fr + Ff <Fk + Fd × sin θ

As is clear from this equation, when the inclination of the slide surface of the slide bush is eliminated and θ = 0, the object can be achieved by increasing Fk in accordance with the above equation.

As described above, the airtightness in the working chamber is maintained regardless of the number of rotations of the shaft 8, and the leakage of the working gas from the high pressure side to the low pressure side is greatly reduced, and the outflow amount of the working gas is reduced. That is, the gas compression power can be reduced at the same time.

Piston 1 including slide bush 15
Since the centrifugal force of No. 2 and the centrifugal forces of the balancer-A 18 and the balancer-B 19 cancel each other out, the centrifugal force hardly acts on the cylinder cylinder portion 11a.

[0055]

In the helical blade type compressor constructed as described above, the slide bush 15 and the elastic member 1 are provided.
The seal gap δc formed between the cylinder cylinder portion and the outer wall surface of the piston can be greatly reduced by the eccentricity amount variable mechanism configured by mounting 7 between the shaft and the piston. The space formed between the piston and the outer wall surface of the piston is partitioned in the longitudinal direction by a blade attached to the piston, and the airtightness of the working chamber formed from multiple chambers is greatly increased, and the amount of gas discharged Is increased, and at the same time, the gas compression power is reduced, resulting in high efficiency.

Further, when the processing accuracy or the assembly accuracy of the compressor part is lowered, or due to pressure or thermal deformation during operation,
Even if an abnormally high contact force is expected to occur due to the collision of the piston outer wall surface with the cylinder / cylinder part, the gas that is obtained from the elastic force of the elastic member and the inclination angle of the sliding surface by avoiding the abnormal load due to the slide bush escape Since the load more than the component force of the compressive load does not act, there is an effect that abnormal vibration noise does not occur, and the bearing and members are not damaged, and the reliability is improved.

[0057]

[Brief description of drawings]

FIG. 1 is a sectional view of a helical blade type pump of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

[Figure 3] Shaft part external view

[Fig. 4] External view of slide bush

FIG. 5 is an external view of an elastic member.

FIG. 6 is an external view of the balancer-A.

[Explanation of symbols]

3 Compressor section 8 shafts 8b slide part 8d slide receiving surface 11 cylinders 11a cylinder part 12 pistons 12a outer wall surface 12b spiral groove 12c bearing 14 blades 15 Slide bush 15a cylindrical shaft 15b Mating hole 15d screw hole 15e Sliding surface 17 Elastic member 18 Balancer-A 19 Balancer-B

Claims (4)

[Claims] 1. A cylinder having a cylindrical shape, a piston eccentrically arranged in the cylinder cylinder portion and having a spiral groove on the outer wall surface of the cylinder, the pitch of which gradually changes, and a piston provided with a minute gap in the spiral groove. A blade, a shaft for transmitting power of an electric motor to a piston, and an Oldham mechanism as a means for rotating the piston with respect to a cylinder are mechanically connected to each other. In the compressor, a slide bush 15 having a slidable flat slide surface on one surface of which a rectangular fitting hole is provided inside a cylinder provided inside the cylinder of the piston 12 is used as a bearing for the shaft 8. It is mounted so as to be in close contact with the slide receiving surface formed by the flat surface of the slide part provided between the supporting main frame and the sub-frame, and the cylinder cylinder part and the piston outer wall surface. The longitudinal direction of the working chamber formed between sheet - as Le gaps δc is minimized, Herikarubure characterized by being configured the eccentricity variable mechanism of the piston - de compressor. 2. A flat surface of the slide portion 8b is formed with respect to a plane including a shaft center of a shaft that coincides with a shaft center of a cylinder portion of a cylinder of a cylindrical cylinder and a shaft center of a cylindrical piston eccentrically mounted inside the cylinder portion. 2. The helical blade type compressor according to claim 1, wherein the slanted shaft is mounted so that the slide surface 15e of the slide bush is in close contact with the slanted shaft to constitute a variable mechanism of the eccentricity of the piston. 3. An elastic member 17 composed of a spring, rubber or the like is used as a shaft so that the slide bush is pushed and moved in the direction of the surface where the slide receiving surface 8d of the shaft slide portion and the slide surface 15e of the slide bush are brought together. 3. The helical blade type compressor according to claim 1, wherein the helical blade type compressor is mounted between the slide bush and the sliding bush. 4. A balancer corresponding to a rotary inertia mass equal to or less than a rotary inertia mass including an eccentric portion of a shaft on which the piston is mounted and a piston 12 with a blade forming a compression mechanism. 4. The helical blade type compressor according to claim 1, wherein the cylindrical slide bush 15 is fixed to one or two end faces of the cylindrical slide bush 15.