Wobble plate compressor

An object of the present invention is to provide a wobble plate compressor equipped with a mechanism for preventing the rotation of the wobble plate which is simply structured, producible at low cost, and does not cause heavy noise or vibration.A wobble plate compressor comprises a main shaft driven by a power source, a wobble plate driven by the main shaft to swing, a piston connected to the wobble plate by a connecting rod, and a cylinder bore extending parallel to the main shaft to accept the piston. The connecting rod is connected to the wobble plate by a ball joint, precession of the connecting rod is allowed when the piston moves reciprocally, and the outer circumferential surface of the piston is forced against the inner circumferential surface of the cylinder bore when the wobble plate is driven by the main shaft to rotate and the connecting rod is driven by the rotating wobble plate to swing beyond the range of the precession. Thus, rotation of the wobble plate is prevented.

CROSS-REFERENCE TO RELATED APPLICATION

This application is the National Stage of International Patent Application No. PCT/JP2006/314547, filed Jul. 24, 2006, which claims the benefit of Japanese Patent Application No. 2005-279453, filed Sep. 27, 2005, the disclosures of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a wobble plate compressor.

BACKGROUND ART

A wobble plate compressor comprising a main shaft driven by a power source, a wobble plate driven by the main shaft to swing, a piston connected to the wobble plate by a connecting rod, and a cylinder bore extending parallel to the main shaft to accept the piston is well known. The wobble plate compressor is equipped with a mechanism for preventing rotation of the wobble plate. Patent document 1 discloses a mechanism for preventing rotation of the wobble plate comprising a guide rod and a clamping member slidably engaging the guide rod. Patent document 2 discloses a mechanism for preventing rotation of the wobble plate comprising a pair of bevel gears engaging each other. Patent document 3 discloses a mechanism for preventing rotation of the wobble plate comprising a ball joint provided with a key and a key groove.

DISCLOSURE OF INVENTION

Problems to be Solved

The mechanisms for preventing wobble plate rotation disclosed in Patent documents 1 to 3 have problems in that vibration is caused by ununiform motion of the wobble plate, noise is caused by engagement of the pair of gears, structure is complicated, manufacturing cost is high, etc.

An object of the present invention is to provide a wobble plate compressor equipped with a mechanism for preventing the rotation of the wobble plate which is simply structured, producible at low cost, and does not cause heavy noise or vibration.

Means for Solving the Problems

In accordance with the present invention, there is provided a wobble plate compressor comprising a main shaft driven by a power source, a wobble plate driven by the main shaft to swing, a piston connected to the wobble plate by a connecting rod, and a cylinder bore extending parallel to the main shaft to accept the piston, wherein the connecting rod is connected to the wobble plate by a ball joint, precession of the connecting rod is allowed when the piston moves reciprocally, and the outer circumferential surface of the piston is forced against the inner circumferential surface of the cylinder bore when the wobble plate is driven by the main shaft to rotate and the connecting rod is driven by the rotating wobble plate to swing beyond the range of the precession, thereby preventing rotation of the wobble plate.

The center of the ball joint connecting the connecting rod to the wobble plate reciprocally moves in the longitudinal direction of the main shaft and orbits with a small radius in the radial direction of the main shaft to cause precession of the connection rod. Therefore, allowance of the precession of the connecting rod enables smooth movement of the piston. When the wobble plate is driven by the main shaft to rotate, the rotation of the wobble plate is transmitted to the connecting rod through the ball joint to cause swing of the connecting rod beyond the range of the precession. When the connecting rod swings beyond the range of the precession, the outer circumferential surface of the piston is forced against the inner circumferential surface of the cylinder bore to prevent the swing of the connecting rod. When the swing of the connecting rod is prevented, the rotation of the wobble plate is prevented.

The mechanism for allowing the precession of the connecting rod and forcing the outer circumferential surface of the piston against the inner circumferential surface of the cylinder bore when the connecting rod swings beyond the range of the precession can be structured simply and produced at low cost. Prevention of rotation of the wobble plate causes no heavy noise or vibration because the rotation of the wobble plate is prevented by forcing the outer circumferential surface of the piston against the inner circumferential surface of the cylinder bore. Therefore, the present invention can provide a wobble plate compressor equipped with a mechanism for preventing the rotation of the wobble plate which is simply structured, producible at low cost, and does not cause heavy noise or vibration.

In accordance with a preferred embodiment of the present invention, the connecting rod is connected to the piston by a ball joint, a radial space is formed between the piston and the connecting rod to allow the precession of the connecting rod when the piston moves reciprocally, and the connecting rod abuts the piston to force it when the connecting rod is driven by the rotating wobble plate to swing beyond the range of the precession, thereby forcing the outer circumferential surface of the piston against the inner circumferential surface of the cylinder bore.

In accordance with a preferred embodiment of the present invention, the connecting rod is connected to the piston by a pin, a radial space is formed between the piston and the connecting rod to allow the precession of the connecting rod when the piston moves reciprocally, and the connecting rod abuts the piston to force it when the connecting rod is driven by the rotating wobble plate to swing beyond the range of the precession, thereby forcing the outer circumferential surface of the piston against the inner circumferential surface of the cylinder bore.

When the connecting rod is connected to the piston by a ball joint or a pin, the connecting rod moves relative to the piston because the connection between the connecting rod and the piston becomes the support point of the precession. Therefore, the connecting rod can precess if only a radial space for allowing the precession of the connecting rod during the reciprocal movement of the piston is formed between the piston and the connecting rod. When the wobble plate is driven by the main shaft to rotate, and the connecting rod is driven by the rotating wobble plate to swing beyond the range of the precession, the connecting rod swings beyond the radial space to abut the piston, thereby forcing the piston to force the outer circumferential surface of the piston against the inner circumferential surface of the cylinder bore. As a result, the swing of the connecting rod is prevented and the rotation of the wobble plate is prevented.

In accordance with a preferred embodiment of the present invention, the connecting rod is connected to the piston by a ball joint or a pin, a cylindrical member is fitted in and fixed to the piston to form a part of the piston, and the radial space for allowing the precession of the connecting rod during the reciprocal movement of the piston is formed between the cylindrical member and the connecting rod.

In accordance with a preferred embodiment of the present invention, the connecting rod is connected to the piston by a ball joint or a pin, the connecting rod is provided with a portion with large diameter, and the radial space for allowing the precession of the connecting rod during the reciprocal movement of the piston is formed between the piston and the portion of the connecting rod with large diameter.

The radial space between the piston and the connecting rod for allowing the precession of the connecting rod during the reciprocal movement of the piston can be formed between a cylindrical member fitted in and fixed to the piston to form a part of the piston and the connecting rod or between a large diameter portion of the connecting rod and the piston.

In accordance with a preferred embodiment of the present invention, the connecting rod is fixed to the piston, a radial space is formed between the outer circumferential surface of the piston and the inner circumferential surface of the cylinder bore to allow the precession of the connecting rod during the reciprocal movement of the piston, and the outer circumferential surface of the piston is forced against the inner circumferential surface of the cylinder bore when the connecting rod is driven by the rotating wobble plate to swing beyond the range of the precession.

When the connecting rod is fixed to the piston, the connecting rod and the piston do not move relatively but unitarily. Therefore, the connecting rod can precess if only a radial space is formed between the outer circumferential surface of the piston and the inner circumferential surface of the cylinder bore to allow the precession of the connecting rod during the reciprocal movement of the piston. When the connecting rod is driven by the rotating wobble plate to swing beyond the range of the precession, the piston moving unitarily with the connecting rod swings beyond the aforementioned radial space, and the outer circumferential surface of the piston is forced against the inner circumferential surface of the cylinder bore. As a result, the swing of the connecting rod is prevented and the rotation of the wobble plate is prevented.

In accordance with a preferred embodiment of the present invention, the connecting rod is fixed to the piston, a radial space is formed between the outer circumferential surface of the piston and the inner circumferential surface of the cylinder bore to allow the precession of the connecting rod during the reciprocal movement of the piston, and the piston is made of flexible material.

When the connecting rod is fixed to the piston and moves unitarily with the piston, the connecting rod can precess smoothly and the piston can reciprocally move smoothly if only the piston is made of flexible material to bend accompanying the precession of the connecting rod.

Effect of the Invention

In the present invention, when the wobble plate is driven by the main shaft to rotate, the rotation of the wobble plate is transmitted to the connecting rod through the ball joint to cause swing of the connecting rod beyond the range of the precession. When the connecting rod swings beyond the range of the precession, the outer circumferential surface of the piston is forced against the inner circumferential surface of the cylinder bore to prevent the swing of the connecting rod. When the swing of the connecting rod is prevented, the rotation of the wobble plate is prevented.

The mechanism for allowing the precession of the connecting rod and forcing the outer circumferential surface of the piston against the inner circumferential surface of the cylinder bore when the connecting rod swings beyond the range of the precession can be structured simply and produced at low cost. Prevention of rotation of the wobble plate causes no heavy noise or vibration because the rotation of the wobble plate is prevented by forcing the outer circumferential surface of the piston against the inner circumferential surface of the cylinder bore. Therefore, the present invention can provide a wobble plate compressor equipped with a mechanism for preventing the rotation of the wobble plate which is simply structured, producible at low cost, and does not cause heavy noise or vibration.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will be described.

As shown inFIG. 1, a variable displacement wobble plate compressor100comprises a main shaft3, a rotor10fixed to the main shaft3, a cam plate1connected to the rotor10to be tiltable relative thereto and a wobble plate2supported by the cam plate1through bearings21and22to be rotatable relative to the cam plate1.

A connecting rod5is provided with a spherical portion4at one end. The wobble plate2is provided with a spherical concave. The connecting rod5is connected at one end to the wobble plate2by a ball joint23formed by the spherical concave of the wobble plate2and the spherical portion4of the connecting rod5slidably fitting in the spherical concave of the wobble plate2.

The connecting rod5is provided with a spherical portion8at the other end. The spherical portion8is inserted in a piston6formed as a cylinder closed at one end. A cylindrical member13is fitted in the piston6. The cylindrical member13is fixed to the piston6as clamped between the caulked open end14of the piston6and the spherical portion8of the connecting rod5. The cylindrical member13forms a part of the piston6. The cylindrical member13is provided with a concave at one end. The concave forms a part of a spherical surface. The piston6is provided with a semispherical concave at the closed end. The concave provided on the cylindrical member13and the semispherical concave provided on the piston6cooperate to form a substantially spherical concave. The connecting rod5is connected at the other end to the piston6by a ball joint24formed by the substantially spherical concave and the spherical portion8slidably fitted in the substantially spherical concave.

A small radial space7is formed between the cylindrical member13and the connecting rod5.

The variable displacement wobble plate compressor100further comprises a cylinder bore9extending parallel to the main shaft3. The piston6is inserted in the cylinder bore9. One end of the cylinder bore9communicates with a crank chamber15for accommodating the main shaft3, the rotor10, the cam plate1, the wobble plate2, the bearings21and22, etc. The other end of the cylinder bore9communicates with a suction chamber11through a suction hole25formed in a valve plate and a discharge chamber12through a discharge hole26formed in the valve plate. A suction valve for closing the suction hole25and a discharge valve for closing the discharge hole26are installed. The suction valve and the discharge valve are not shown inFIG. 1. A retainer27for restricting excessive movement of the discharge valve is installed in the discharge chamber12.

One end of the main shaft3extends out of the crank chamber15to be connected to a power source through a power transmission mechanism, neither of which is shown inFIG. 1.

In the variable displacement wobble plate compressor100, the main shaft3is driven by the power source to rotate, the rotor10and the cam plate1are driven by the main shaft3to rotate, the wobble plate2is driven by the cam plate1to swing, and the piston6connected to the wobble plate2by the connecting rod5is driven by the wobble plate2to move reciprocally in the cylinder bore9. Accompanying the reciprocal movement of the piston6, fluid is sucked into the cylinder bore9from the suction chamber11through the suction hole25and compressed in the cylinder bore9. The compressed fluid is discharged from the cylinder bore9to the discharge chamber12through the discharge hole26.

When the wobble plate2swings and the piston6moves reciprocally, the center of the ball joint23for connecting the connecting rod25to the wobble plate5, more specifically, the center of the spherical portion4, reciprocally moves in the longitudinal direction of the main shaft3and orbits with small radius in the radial direction of the main shaft3. The orbital motion of the center of the spherical portion4causes precession of the connection rod5supported by the ball joint24connecting the connecting rod5to the piston6and motion of the connecting rod5relative to the piston6. The small radial space7formed between the cylindrical member13and the connecting rod5prevents interference between the cylindrical member13and the connecting rod5to allow the precession of the connecting rod5. The allowance of the precession of the connecting rod5leads to smooth movement of the piston6.

When the wobble plate2is driven by the cam plate1to rotate, the rotation of the wobble plate2is transmitted to the connecting rod5through the ball joint23to cause swing of the connecting rod5beyond the range of the precession. As a result, the connecting rod5swings beyond the small radial space7to abut the cylindrical member13forming a part of the piston6, thereby forcing the piston6to force the outer circumferential surface of the piston6against the inner circumferential surface of the cylinder bore9. As a result, the swing of the connecting rod5is prevented and the rotation of the wobble plate2is prevented.

A mechanism for allowing the precession of the connecting rod5and preventing the rotation of the wobble plate2by forcing the outer circumferential surface of the piston6against the inner circumferential surface of the cylinder bore9when the connecting rod5swings beyond the range of the precession can be structured simply and produced at low cost by the cylindrical member13fitted in and fixed to the piston6and the small radial space7disposed between the cylindrical member13and the connecting rod5.

Prevention of rotation of the wobble plate2does not cause heavy noise or vibration because the outer circumferential surface of the piston6is forced against the inner circumferential surface of the cylinder bore9to prevent the rotation of the wobble plate2. The variable displacement wobble plate compressor100is thus equipped with a mechanism for preventing rotation of the wobble plate which is simply structured, producible at low cost, and does not cause heavy noise or vibration.

The cylindrical member13can be structured by a plurality of members or made of flexible material such as resin, etc. The piston6can be provided with a lubrication hole for supplying the ball joint24with lubrication oil. The cylindrical member13can be pressed into, or welded to, or adhered to the piston6. The cylindrical member13can be formed integrally with the piston6. The piston6can be coated with various kinds of lubricant. The piston6can be equipped with adequate number of piston rings.

The present invention can be applied to not only a variable displacement compressor, but also a fixed displacement compressor as shown inFIG. 2or an electric compressor as shown inFIG. 3.

In a fixed displacement compressor200shown inFIG. 2, no cam plate is provided and a wobble plate2is directly driven by a rotor10afixed to a main shaft3ato swing. Similarly to the variable displacement wobble plate compressor100, one end of a connecting rod5ais connected to the wobble plate2by a ball joint23provided with a spherical portion4. However, the other end of the connecting rod5ais fixed to a piston6a. A small radial space7ais formed between the outer circumferential surface of the piston6aand the inner circumferential surface of a cylinder bore9.

The connecting rod5aand the piston6ado not move relatively but unitarily because the connecting rod5ais fixed to the piston6aat the other end. Therefore, the connecting rod5aand the piston6acan precess if only the radial space7ais formed between the outer circumferential surface of the piston6aand the inner circumferential surface of the cylinder bore9to allow the precession of the connecting rod5aduring the reciprocal movement of the piston6a. When the connecting rod5aand the piston6ais driven by the rotating wobble plate2to swing beyond the range of the precession, the piston6aswings beyond the radial space7a, and the outer circumferential surface of the piston6ais forced against the inner circumferential surface of the cylinder bore9. As a result, the swing of the connecting rod5ais prevented and the rotation of the wobble plate2is prevented.

In an electric compressor300shown inFIG. 3, a main shaft3bis driven by a built-in electric motor31. No cam plate is equipped. Displacement of the compressor is fixed. The structures of a piston6, a connecting rod5and ball joints23and24are the same as those of the variable displacement wobble plate compressor100.

Other preferred embodiments are shown inFIGS. 4 to 6.

In a preferred embodiment shown inFIG. 4, a piston6bis provided with a concave formed by a caulking41. The concave forms a part of a spherical surface. The piston6bhas a cylindrical shape closed at one end and is provided with a semispherical concave at the closed end. The concave formed by the caulking41and the semispherical concave provided on the closed end cooperate to form a substantially spherical concave. The other end of the connecting rod5bis connected to the piston6bby a ball joint formed by the substantially spherical concave and a spherical portion8slidably fitted therein.

The connecting rod5bis provided with a large diameter portion42. A small radial space7bis formed between the circumferential sidewall of the piston6band the large diameter portion42of the connecting rod5b. The space7ballows precession of the connecting rod5bduring the reciprocal movement of the piston6b.

When the wobble plate2rotates, the rotation of the wobble plate2is transmitted to the connecting rod5bthrough a ball joint for connecting the connecting rod5bto the wobble plate2and the connecting rod5bswings beyond the range of the precession. As a result, the large diameter portion42of the connecting rod5bswings beyond the small radial space7bto abut the circumferential sidewall of the piston6b, thereby forcing the piston6band forcing the outer circumferential surface of the piston6bagainst the inner circumferential surface of the cylinder bore9. As a result, the swing of the connecting rod5bis prevented and the rotation of the wobble plate2is prevented.

In a preferred embodiment shown inFIG. 5, a semispherical portion8cis provided on the other end of a connecting rod5c. A piston6chas a cylindrical shape closed at one end and is provided with a semispherical concave at the closed end. The semispherical portion8cslidably fits in the semispherical concave. A pin51passes through the piston6cand the semispherical portion8cto be fixed to the piston6c, thereby connecting the other end of the connecting rod5cto the piston6c. A small amount of play is provided between the pin51and the part of the semispherical portion8cthrough which the pin51passes.

The connecting rod5cis provided with a large diameter portion52. A small radial space7cis formed between the circumferential sidewall of the piston6cand the large diameter portion52of the connecting rod5c. The space7callows precession of the connecting rod5cduring the reciprocal movement of the piston6c.

When the wobble plate2rotates, the rotation of the wobble plate2is transmitted to the connecting rod5cthrough a ball joint for connecting the connecting rod5cto the wobble plate2and the connecting rod5cswings beyond the range of the precession. As a result, the large diameter portion52of the connecting rod5cswings beyond the small radial space7cto abut the circumferential side wall of the piston6c, thereby forcing the piston6cand forcing the outer circumferential surface of the piston6cagainst the inner circumferential surface of the cylinder bore9. As a result, the swing of the connecting rod5cis prevented and the rotation of the wobble plate2is prevented.

In a preferred embodiment shown inFIG. 6, the other end of the piston5is fixed to a piston6dand the piston6dis made of flexible material such as resin, etc.

When the connecting rod5is fixed to the piston6dand moves unitarily with the piston6d, the connecting rod5can precess smoothly and the piston6dcan reciprocally move smoothly if only the piston6dis made of flexible material to bend accompanying the precession of the connecting rod5.

INDUSTRIAL APPLICABILITY

The present invention can be widely used in both variable displacement compressors and fixed displacement compressors.

BRIEF EXPLANATION OF DRAWINGS

FIG. 1is a longitudinal sectional view of a variable displacement wobble plate compressor in accordance with a preferred embodiment of the present invention.

FIG. 2is a longitudinal sectional view of a fixed displacement wobble plate compressor in accordance with another preferred embodiment of the present invention.

FIG. 3is a longitudinal sectional view of an electric fixed displacement wobble plate compressor in accordance with another preferred embodiment of the present invention.

FIG. 4is a longitudinal sectional view of a connecting rod and a piston of a wobble plate compressor in accordance with another preferred embodiment of the present invention.

FIG. 5is a longitudinal sectional view of a connecting rod and a piston of a wobble plate compressor in accordance with another preferred embodiment of the present invention.

FIG. 6is a longitudinal sectional view of a connecting rod and a piston of a wobble plate compressor in accordance with another preferred embodiment of the present invention.