VARIABLE DISPLACEMENT COMPRESSOR HAVING REFRIGERANT FLOWING FUNCTION IN DRIVING SHAFT

Abstract

Provided is a variable displacement compressor comprising a cylinder block having a plurality of cylinder bores, housing, a drive shaft rotatably supported by the cylinder block, a lug plate, a swash plate being rotated by the lug plate to vary a tilt angle thereof, a sleeve reciprocally moving along the drive shaft, an addition discharge passage for fluid communication between the swash plate chamber and the suction chamber, characterized in that the variable displacement compressor comprises: a communication hole being a part of the addition discharge passage and formed in the drive shaft in its longitudinal direction; and a lateral communication passage formed at the lateral side of the drive shaft to be connected to the communication hole such that the lateral communication passage is opened and closed by reciprocal movement of the sleeve. Therefore, even though the swash plate is at position of the maximum tilt angle, the temperature of the swash plate chamber is prevented from rising by making a smooth refrigerant flow from the swash plate chamber to the suction chamber, thereby maintaining higher lubrication ability.

Description

TECHNICAL FIELD

This present invention relates to a variable displacement compressor having a refrigerant flow function in a drive shaft, more particularly to a variable displacement compressor capable of maintaining higher lubrication ability by making the smooth flow of refrigerant from a swash plate chamber to a suction chamber, at about maximum tilt angle of a swash plate, to prevent a temperature of the swash plate chamber from rising excessively.

BACKGROUND ART

Recently, a lot of research with respect to a swash plate type variable displacement compressor that is used to air conditioning systems for vehicles has been developed. It changes the tilt angle of the swash plate by a control valve depending on a change of thermal load, and controls strokes of pistons to accomplish precise temperature control. At the same time, the tilt angle is continuously varied to reduce abrupt torque fluctuation of an engine caused by the compressor, thereby improving ride comfort of a vehicle.

A swash plate type variable compressor of the prior art includes a special oil separator for separating gas refrigerant and oil from remaining refrigerant in a swash plate chamber such that the separated gas refrigerant is moved to a suction chamber and the separated oil is returned to the swash plate chamber for lubrication.

However, in Korean Registration Patent No. 606641 (hereinafter, referred to as prior art), a structure that can function as separating the oil without the oil separator is disclosed. Hereinafter, constitution of the structure will be described roughly according to FIGS. 1 and 2.

As shown in FIGS. 1 and 2, when a partial high-pressure refrigerant of a discharge chamber 133 is supplied to a swash plate chamber 120a by the operation of control valve 138, the pressure inside the swash plate chamber 120a is changed and oil is separated while mist type refrigerant of the inside of the swash plate chamber 120a passes through an addition discharge passage 145, and then refrigerant gas is returned to the suction chamber 132.

In the concrete, the refrigerant of the inside of the swash plate chamber 120a passes through a first separation hole 185a and a second separation hole 185b formed in a lug plate 180, which are parts of the addition discharge passage 145. In this case, the oil and the refrigerant are separated by an action of centrifugal force due to rotation of the lug plate 180, the separated oil is slidably contacted with an inner periphery of the first separation hole 185a to be supplied to the swash plate chamber 120a, and the separated gas refrigerant is discharged to the suction chamber 132 of lower pressure through the second separation hole 185b. As a result; oil amount of the inside of the swash plate chamber 120a becomes more plentiful, and thereby it is possible to smoothly lubricate. As this, oil separation can be accomplished by the separation holes formed in the lug plate, without using oil separator.

DISCLOSURE

Technical Problem

However, according to the above prior art, when the swash plate reaches at the maximum tilt angle, since the pressure of the inside of the swash plate chamber is lowered, the refrigerant can t smoothly flow in the suction chamber through a communication hole 142 formed in the driving shaft. Thus, according to the prior art, when the swash plate is at the maximum tilt angle, the lubrication ability is lowered due to excessive rise of temperature of the inside of the swash plate chamber, so that durability of the compressor is significantly decreased.

An object of the present invention is to provide a variable compressor capable of maintaining higher lubrication ability by preventing temperature of the swash plate chamber from rising while making a smooth refrigerant flow from a swash plate chamber to a suction chamber, even though the swash plate is at the maximum tilt angle.

Technical Solution

An aspect of the present invention provides a variable displacement compressor comprising a cylinder block having a plurality of cylinder bores, a front housing disposed at a front end of the cylinder block to form a swash plate chamber, a drive shaft rotatably supported by the cylinder block, a lug plate fixedly installed at the drive shaft in the swash plate chamber of the front housing, a rear housing having a suction chamber and discharge chamber and being disposed at a rear end of the cylinder block, a swash plate being rotated by the lug plate to vary a tilt angle thereof, pistons coupled to the swash plate to be reciprocally accommodated in the cylinder bores, a sleeve reciprocally moving along the drive shaft, a spring elastically supporting the sleeve around the drive shaft, an addition discharge passage connect the swash plate chamber and the suction chamber, characterized in that the variable displacement compressor comprises: a communication hole 142 being a part of the addition discharge passage and formed in the drive shaft in its longitudinal direction; and a lateral communication passage formed at the lateral side of the drive shaft to be connected to the communication hole such that the lateral communication passage is opened and closed by reciprocal movement of the sleeve.

Here, the sleeve may be moved at more than a predetermined angle of the swash plate to open the communication passage.

In addition, the addition discharge passage may includes a first separation hole formed through the lug plate, a second separation hole formed in the lug plate to connect the first separation hole and the communication hole, and a connection hole formed in the drive shaft to be connected to the separation hole.

DESCRIPTION OF DRAWINGS

The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a longitudinal cross-sectional view of a variable displacement compressor according to a prior art;

FIG. 2 is a cross-sectional view of refrigerant flow structure of FIG. 1;

FIG. 3A is a detailed sectional view of swash plate of a minimum tilt angle and its peripheral components in a variable displacement compressor according to an exemplary embodiment of the present invention; and

FIG. 3B is a detailed sectional view of swash plate of a maximum tilt angle and its peripheral components in a variable displacement compressor according to an exemplary embodiment of the present invention.

BEST MODE

Hereinafter, exemplary embodiments of the present invention will be described according to the accompanying drawings. The components that may be embodied in the above prior art are denoted by the same reference numerals as the prior art.

As shown in FIGS. 1, 3A and 3B, a swash plate type variable displacement compressor 1000 includes a cylinder block 110 having a plurality of cylinder bores 110a extended along a longitudinal direction of the compressor, a front housing 120 disposed at a front end of the cylinder block 110, a drive shaft 140 rotatably supported by the cylinder block 110 and the front housing 120, a lug plate 180 fixedly installed at the drive shaft 140 in a swash plate chamber 120a of the front housing 120, a rear housing 130 having a suction chamber 132 and discharge chamber 133 and being disposed at a rear end of the cylinder block 110, a swash plate 150 having a disc shape and being rotated by the lug plate 180 to vary a tilt angle thereof, a spring 170 supported between the lug plate 180 and the swash plate 150, and pistons 200 coupled to the swash plate 150 to be reciprocally accommodated in the cylinder bores 110a.

Although the pistons 200 are slidably coupled to the swash plate 150 via shoes 201, a connection constitution including a long connection rod and a guiding groove formed at an end thereof may be allowed in stead of the shoes 201.

The suction chamber 132 and the discharge chamber 133 are respectively formed in the rear housing 130, and a suction port 131a and a discharge port (not shown) are respectively formed in the valve plate 131 to connect the cylinder bore 110a and the suction chamber 132, and between the cylinder bore 110a and the discharge chamber 133 respectively. Further, a suction valve and a discharge valve are respectively provided in the suction port 131a and the discharge port formed in the valve plate 131 to open and close the suction port 131a and the discharge port by a pressure change due to reciprocal movement of the pistons 200.

In addition, an addition discharge passage 145 is provided to connect the swash plate chamber 120a and the suction chamber 132, and a control valve 138 is installed on the way of a suction passage 137.

The addition discharge passage 145 comprises a first separation hole 185a and a second separation hole 185b formed in the lug plate 180, and a connection hole 147 and a communication hole 142 formed in drive shaft 140.

The communication hole 142 as a part of the addition discharge passage 145 is formed in the drive shaft 140 in a longitudinal direction to connect the swash plate chamber 120a and the suction chamber 132.

The first separation hole 185a penetrates the lug plate 180d from the front side to the rear side to be in communication with the swash plate chamber 120a. The second separation hole 185b is formed in the Jug plate 180 to connect the first separation hole 185a and the communication hole 142.

The connection hole 147 is formed in the drive shaft 140 to connect the second separation hole 185b and the communication hole 142.

The first separation hole 185a and the second separation hole 185b separate an oil from mist phase refrigerant including the oil, and the separated gas refrigerant flows toward the suction chamber 132 via the connection hole 147 and the communication hole 142 of the drive shaft 140.

A lateral communication passage 143 which is connected to the communication hole 142 is formed at lateral side of the drive shaft 140 such that the lateral communication passage 143 is opened and closed by reciprocal movement of the sleeve 148 due to tilt movement of the swash plate 150.

In particular, it is preferable that the sleeve 148 closes the lateral communication passage 143 at a minimum tilt angle of the swash plate 150, and opens the lateral communication passage 143 at a maximum tilt angle of the swash plate 150 while moving along the drive shaft 140.

That is, when the swash plate 150 reaches at the maximum tilt angle, since the communication passage 143 is opened, the refrigerant in the swash plate chamber 120a enters the suction chamber 132 through the lateral communication passage 143 and the communication hole 142, thereby, it is possible that the refrigerant flows more smoothly.

The lateral communication passage 143 may be opened prior to the maximum tilt angle of the swash plate 150.

Hereinafter, operation of the variable displacement compressor having a refrigerant flow function in a drive shaft according to an exemplary embodiment of the present invention will be described.

As shown in FIG. 3B, when the high pressure refrigerant of the discharge chamber 133 is supplied to the inside of the swash plate chamber 120a in accordance with the operation of the control valve 138, the refrigerant in the swash plate chamber 120a enters the suction chamber 132 via the addition discharge passage 145 while the pressure of the inside of the swash plate chamber 120a is changed.

In the concrete, first, the refrigerant passes through the first separation hole 185a and the second separation hole 185b, which are parts of the addition discharge passage 145 and formed in the lug plate 180. In this case, the oil and the refrigerant are separated from each other by an action of centrifugal force due to rotation of the lug plate 180. The separated oil is supplied to the swash plate chamber 120a while sliding in contact with a inner periphery of the first separation hole 185a, and the separated gas refrigerant is discharged to the suction chamber 132 of lower pressure through the second separation hole 185b. As a result, oil amount of the inside of the swash plate chamber 120a becomes more plentiful, and thereby, smooth lubrication is possible.

As shown in FIG. 3B, when the swash plate 150 is reached at the maximum tilt angle, the sleeve 148 is moved forward to open the lateral communication passage 143 covered with the sleeve 148 such that the refrigerant of the inside of the swash plate chamber 120a is discharged to the suction chamber 132 through the lateral communication passage 143 and the communication hole 142.

As this, when the swash plate 150 is at the maximum tilt angle, the refrigerant is discharged through the lateral passage 143 and the communication hole 142 of the drive shaft 149, as well as the first separate hole 185a, the second separate hole 185b, and the communication hole 142, and thereby the refrigerant is further smoothly discharged.

According to the exemplary embodiment of the present invention, when the swash plate 150 is at the maximum tilt angle, the refrigerant flows smoothly from the swash plate chamber 120a to the suction chamber 132, thereby preventing the temperature of the inside of the swash plate chamber 120a from rising and maintaining the higher lubrication ability.

A point of time when the lateral communication passage 143 is opened by the sleeve 148 is not necessarily limited to a point of time when the swash plate 150 reaches to about the maximum tilt angle, and a predetermined point of time just prior to the maximum tilt angle of the swash plate 150 can be allowed.

INDUSTRIAL APPLICABILITY

According to the exemplary embodiment of the present invention, even though the swash plate is at the position of the maximum tilt angle, the temperature of the swash plate chamber is prevented from rising by making the smooth refrigerant flow from the swash plate chamber to the suction chamber, thereby maintaining higher lubrication ability.

While this invention has been described with reference to exemplary embodiment thereof, it will be clear to those of ordinary skill in the art to which the invention pertains that various modification may be made to the described embodiments without departing from the spirit and scope of the invention as defined in the appended claims and their equivalents.

Claims

1. A variable displacement compressor comprising a cylinder block having a plurality of cylinder bores, a front housing disposed at a front end of the cylinder block to form a swash plate chamber, a drive shaft rotatably supported by the cylinder block, a lug plate fixedly installed at the drive shaft in the swash plate chamber of the front housing, a rear housing having a suction chamber and discharge chamber and being disposed at a rear end of the cylinder block, a swash plate being rotated by the lug plate to vary a tilt angle thereof, pistons coupled to the swash plate to be reciprocally accommodated in the cylinder bores, a sleeve reciprocally moving along the drive shaft, a spring elastically supporting the sleeve around the drive shaft, an addition discharge passage for fluid communication between the swash plate chamber and the suction chamber, characterized in that the variable displacement compressor comprises: a communication hole being a part of the addition discharge passage and formed in the drive shaft in its longitudinal direction; and a lateral communication passage formed at the lateral side of the drive shaft to be connected to the communication hole such that the lateral communication passage is opened and closed by reciprocal movement of the sleeve.

2. The variable displacement compressor according to claim 1, wherein the sleeve is moved at more than a predetermined angle of the swash plate to open the communication passage.

3. The variable displacement compressor according to claim 1, wherein the addition discharge passage includes a first separation hole formed through the lug plate, a second separation hole formed in the lug plate to connect the first separation hole and the communication hole and a connection hole formed in the drive shaft to be connected to the separation hole.

4. The variable displacement compressor according to claim 2, wherein the addition discharge passage includes a first separation hole formed through the lug plate, a second separation hole formed in the lug plate to connect the first separation hole and the communication hole, and a connection hole formed in the drive shaft to be connected to the separation hole.