JP3438449B2 - Swash plate type compressor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an open type swash plate compressor which is driven by receiving a driving force from an external drive source and uses a refrigerant having a high working pressure such as carbon dioxide (CO ₂ ). It is suitable for use in a refrigeration cycle.

[0002]

2. Description of the Related Art As is well known, a swash plate type compressor is one which converts a rotary motion of a rotary shaft into a reciprocating motion through a swash plate diagonally arranged with respect to a rotary shaft to move a piston. is there. At this time, the refrigerant is sucked from the suction port, passes through the swash plate chamber in the housing (cylinder block), is guided to the working chamber including the cylinder and the piston, and is compressed.

The axial load of the rotary shaft is received by a thrust bearing that rotatably holds the rotary shaft.

[0004]

By the way, as a recent countermeasure against CFCs, the inventors have been studying a refrigeration cycle using carbon dioxide (CO ₂ ) as a refrigerant, and found that a thrust bearing of a swash plate type compressor is used. It has been found that the life of is significantly reduced as compared with the conventional refrigeration cycle using Freon as a refrigerant.

Then, the inventors of the present invention have made various investigations into the life reduction of the thrust bearing, and have found the following points. That is, an axial load acts on the rotary shaft connected to the external drive source in the direction of the external drive source due to the pressure difference between the atmospheric pressure and the swash plate chamber pressure (equal to the suction pressure). And in the refrigeration cycle using CO ₂ as a refrigerant,
Since the suction pressure of the swash plate type compressor is about 35 kgf / cm ² which is much higher than the conventional pressure, the pressure difference between the swash plate type internal pressure and the swash plate type compressor external pressure (atmospheric pressure) becomes large, and The directional load is also very large. Therefore, the load acting on the thrust bearing becomes large, which causes a problem of shortening the life of the thrust bearing.

Incidentally, according to the calculation by the inventors, the conventional refrigeration cycle using CFC as a refrigerant (suction pressure 2 kgf / c).
m ² ), the load acting on the thrust bearing is about 10 kg
On the other hand, in the refrigeration cycle using CO ₂ as a refrigerant, about 200 kgf, and in the refrigeration cycle using CO ₂ as a refrigerant, the load acting on the thrust bearing is much larger than in the refrigeration cycle using CFCs as a refrigerant. Become.

In view of the above points, the present invention has an object to suppress the life reduction of the thrust bearing in the swash plate compressor by reducing the load acting on the thrust bearing.

[0008]

The present invention uses the following technical means in order to achieve the above object. In the invention according to claim 1, the axial load (Fo) generated by the pressure difference between the internal pressure of the swash plate chamber (38a) and the external pressure of the housing (1, 2, 3, 4) is the first and second operations. Room (39,
It is characterized in that the fluid in 38) is substantially offset by the acting forces (F ₁ , F ₂ ) exerted on the double-headed piston (8).

According to a second aspect of the invention, in the swash plate type compressor according to the first aspect, the second working chamber (39) is formed on the external drive source side. Then, of the cross-sectional area in the direction perpendicular to the axis of the double-headed piston (8), the second working chamber (3
The cross-sectional area on the 9) side is characterized by being larger than the cross-sectional area on the first working chamber (38) side in the cross-sectional area in the direction perpendicular to the axis of the double-headed piston (8).

Next, the function and effect will be described. According to the invention as set forth in claim 1 or 2, the compression reaction force F ₁ generated in the first working chamber (38) is caused by the compression reaction force (F ₂ ) generated in the second working chamber (39). Since the axial load (Fo) generated by the pressure difference between the internal pressure of the swash plate chamber (38a) and the external pressure of the housing (1, 2, 3, 4) can be substantially offset, the thrust bearing (11, 12). It is possible to reduce the axial load (FB) acting on the. Therefore, the life of the thrust bearings (11, 12) can be prevented from being shortened, and the reliability of the compressor can be improved.

Further, since the axial load (FB) acting on the thrust bearings (11, 12) can be reduced, it is possible to suppress the thrust bearings (11, 12) from increasing in size, and, by extension, It is possible to suppress the increase in size of the compressor. According to the invention of claim 2, the cross-sectional area of the double-headed piston (8) on the second working chamber (39) side is larger than the cross-sectional area of the double-headed piston (8) on the first working chamber (38) side. , The compression reaction force (F ₂ ) generated in the second working chamber (39) is the compression reaction force F generated in the first working chamber (38).
Can be greater than ₁ . Therefore, due to the compression reaction force (F ₂ ) generated in the second working chamber (39), the compression reaction force F ₁ generated in the first working chamber (38), the internal pressure of the swash plate chamber (38a), and the housing (1 2, 3, 4) The axial load (Fo) generated by the pressure difference from the external pressure can be substantially canceled.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention shown in the drawings will be described. (Embodiment) The swash plate compressor according to the present embodiment is used in a refrigeration cycle using a refrigerant having a high working pressure such as carbon dioxide (CO ₂ ), and FIG. An axial cross section of such a swash plate compressor (hereinafter, simply referred to as a compressor) is shown.

Reference numeral 5 denotes a rotary shaft which rotates by receiving a driving force from an external drive source (vehicle running engine or the like) via an electromagnetic clutch (not shown). The rotary shaft 5 is a cylinder block (housing) 2, 3 Radial bearings 1
It is rotatably held by 3, 14 and thrust bearings 11, 12. Here, the radial bearings 13, 14
Is against the vertical load of the rotating shaft 5, and thrust bearing 1
Reference numerals 1 and 12 counter the axial load of the rotary shaft 5.

In the cylinder blocks 2 and 3, a rotary shaft 5 is provided.
And cylindrical cylinders 9a, 9b are formed at positions parallel to and in the circumferential direction about the rotation axis 5, and three cylinders 9a are provided on the cylinder block 2 side, and three cylinders 9a are provided on the cylinder block 3 side. Is formed with three cylinders 9b, six in total. A double-headed piston 8 having cylindrical piston portions 8a and 8b on both front and rear sides in the axial direction is inserted into both cylinders 9a and 9b. The piston portions 8a and 8b of the double-headed piston 8 and both cylinders 9a and 9b are inserted. The working chambers 39 and 38 are formed by.

The cross-sectional area of the piston portion 8a forming the working chamber 39 on the external drive source side and the cylinder 9a in the direction perpendicular to the axes of the piston portion 8b and the piston portion 8b forming the working chamber 38 located on the opposite side to the external drive source side. It is larger than the cross-sectional area in the direction perpendicular to the axis of the cylinder 9b. In other words, the diameter of the piston portion 8a and the cylinder 9a is larger than the diameter of the piston portion 8b and the cylinder 9b.

The double-headed piston 8 is driven by a swash plate 6 which is tilted by a predetermined amount with respect to a rotary shaft connected to the rotary shaft 5, and the swash plate 6 converts the rotary motion of the rotary shaft 5 into a reciprocating motion. Then, the double-headed piston 8 is reciprocated in both cylinders 9a and 9b. A pair of shoes 7 are arranged between the swash plate 6 and the double-headed piston 8 so that they can move smoothly, and the double-headed piston 8 can rotate the rotary shaft 5 as shown in FIGS. Three are arranged around it.

The cylinder block 2 is formed with a suction port 24 for sucking the refrigerant flowing out of an evaporator of a refrigeration cycle (not shown), and the suction port 24 is formed in both cylinder blocks 2 and 3. The swash plate 6 is in communication with the rotating swash plate chamber 38a. Further, on the end faces of both the cylinder blocks 2 and 3, suction valves 21 and 22 for preventing the backflow of the refrigerant sucked into the working chambers 39 and 38 and valve plates 15 and 16 for closing the cylinders 9a and 9b are arranged. Has been done. A suction port 34 and a discharge port 35 that communicate with the cylinder 9a are formed in the valve plate 15, and a discharge valve 17 that prevents the backflow of the refrigerant discharged from the working chamber 39 is formed in the discharge port 35 on the opposite side of the cylinder 9a. And this discharge valve 1
A valve stop plate 18 for controlling the maximum opening degree of the valve 7 is fixed to the valve plate 15 by a bolt (not shown). Similarly, the valve plate 16 is formed with an intake port 25 and a discharge port 26 communicating with the cylinder 9b, and a discharge valve 19 and a valve stop plate 20 are shown in the discharge port 26 on the opposite side of the cylinder 9b. It is fixed to the valve plate 16 by bolts that are not attached.

The valve plate 15 and the intake valve 2
1 is sandwiched between the front housing 1 and the cylinder block 2 and fastened together by bolts 37. Similarly, the valve plate 16 and the intake valve 22 are sandwiched between the rear housing 4 and the cylinder block 3 and fastened together by bolts 36. The front housing 1 is provided with a shaft seal 10 that prevents the refrigerant from leaking to the outside through a gap between the front housing 1 and the rotating shaft 5. The shaft seal 10 is an end surface 10b of a ring 10a press-fitted into the rotating shaft 5. To prevent the refrigerant from leaking.

In the cylinder block 2, a communication passage 33 for communicating the suction chamber 31 formed by the shaft seal 10 and the front housing 1 with the swash plate chamber 38a.
Is formed, and the suction chamber 31 communicates with the suction port 34. In addition, the front housing 1 has a discharge port 3
A discharge chamber 32 communicating with 5 is formed. As shown in FIG. 2, the suction chamber 31 distributes the refrigerant to three suction ports 34 formed in the front housing 1, and the discharge chamber 32 has three discharge ports 35 formed in the front housing 1. The refrigerant discharged from is collected and discharged from the discharge port 23 to the condenser of the refrigeration cycle (not shown) through the communication passage 30 formed in the cylinder block 2.

As shown in FIG. 1, the rear housing 4 is provided with a suction chamber 27 communicating with the suction port 25 and a discharge chamber 28 communicating with the discharge port 26.
7 communicates with the swash plate chamber 38a through a communication passage 29. Further, the discharge chamber 28 communicates with the discharge port 23 via a communication passage 30 formed in the cylinder blocks 2 and 3. As shown in FIG. 3, the suction chamber 27 distributes the refrigerant to three suction ports 25 formed in the rear housing 4, and the discharge chamber 28 has three discharge ports 26 formed in the rear housing 4. The refrigerant discharged from the above is collected and communicated with the communication passage 30.

Next, the operation of the compressor according to this embodiment is illustrated.
It will be described based on 1. Low pressure sucked from the suction port 24
Refrigerant (in this embodiment, approximately 35 kgf / cm ²And
Hereinafter, the suction pressure Ps will be referred to as the suction pressure Ps).
9 and 33, suction chambers 27 and 31, suction ports 25 and 34
Working chamber 38 (first working chamber), working chamber 39 (second working chamber)
Inhaled into. The discharge pressure of the refrigerant is (in this embodiment,
Is about 110 kgf / cm²And the discharge pressure Pd
(Referred to as "), the discharge chambers 28 and 32, the communication passage 3
After passing 0, the gas is discharged from the discharge port 23 to the outside of the compressor.

Next, the features of this embodiment will be described. Figure 4
[Fig. 3] is an explanatory diagram for explaining the axial load acting on the thrust bearings 11 and 12, and the features of the present embodiment will be described based on this explanatory diagram. As mentioned above, the rotating shaft 5
Is applied with an axial load Fo due to the differential pressure between the suction pressure Ps (pressure in the swash plate chamber 38a) and the atmospheric pressure Po, and the acting forces F ₁ , F acting on the double-headed piston 8 by the refrigerant in the working chambers 39, 38. ₂ acts via the swash plate 6. That is,
The axial load FB acting on the thrust bearings 11 and 12 is
It is given as the sum of the axial load Fo due to the differential pressure and the compression reaction forces F ₁ and F ₂ . If this is expressed in an equation, it becomes Equation 1.

[0023]

[Formula 1] FB = Fo + F ₁ + (− F ₂ ) In addition, the axial direction load Fo due to the differential pressure is set to the positive direction. As is clear from Equation 1, the direction of the acting force F ₂ acting on the piston 8a in the working chamber 39, the axial load Fo due to the differential pressure, and the piston 8b in the working chamber 38.
The direction of the acting force F ₁ acting on
The forces of both parties are almost offset. Therefore, the thrust bearing 1
Since the axial load FB acting on the bearings 1 and 12 can be reduced, it is possible to suppress the life reduction of the thrust bearings 11 and 12. In addition, the reliability of the compressor can be improved.

Further, since the axial load FB acting on the thrust bearings 11 and 12 can be reduced, it is possible to prevent the thrust bearings 11 and 12 from increasing in size, which in turn increases the size of the compressor. Can be suppressed. Incidentally, FIG. 5 shows the ratio of the axial load FB based on Formula 1 to the diameter Rb of the piston 8b and the diameter Ra of the piston 8a (hereinafter,
It is called the piston diameter ratio Rb / Ra. ) Is the calculation result showing the relationship with. 6 shows the calculation results when Rb = Ra, and the calculation conditions are shown below.

[0025]

[Formula 2] Fo = So × (Ps−Po)

[0026]

[Formula 3] F ₁ = P ₁ × S ₁

[0027]

F ₂ = P ₂ × S ₂ So: Pressure receiving area where atmospheric pressure acts on the rotary shaft 5 So = 2.9 cm ² P ₁ : Working chamber 38 internal pressure S ₁ : Double-headed piston 8 piston part 8 b Cross-sectional area S ₁ = 7.9 cm ² (diameter 1 cm) P ₂ : Working chamber 39 internal pressure S ₂ : Cross-sectional area of piston portion 8 a of double-headed piston 8 S ₂ = 3.1 cm ² (diameter 2 cm) Note that S ₁ and S ₂ is the piston diameter ratio Rb / Ra = 0.
The value is 5 and the pressure condition is as described above.

As apparent from FIGS. 5 and 6, the maximum value of the axial load FB acting on each of the thrust bearings 11 and 12 of the compressor according to this embodiment is about 100 kgf,
The maximum value of axial load FB when Rb = Ra is about 2
It is 00 kgf. Therefore, according to the compressor of the present embodiment, the axial load FB acting on the thrust bearings 11 and 12 can be reduced to about 1/2.

The positive direction of the axial load FB is that the axial load Fo due to the differential pressure is positive, as described above.
The positive direction axial load FB indicates the load acting on the thrust bearing 11 (hatching portion in the lower right of FIG. 5), and the negative direction axial load FB indicates the load acting on the thrust bearing 12. (The upward hatching portion in FIG. 5).

Further, by appropriately selecting the piston diameter ratio Rb / Ra, the loads acting on the thrust bearings 11 and 12 can be made substantially equal, so that the sizes of the thrust bearings 11 and 12 should be made equal. You can Therefore, when both thrust bearings 11 and 12 have the same size, one of them does not have an excessive quality, so that it is possible to suppress the enlargement of the compressor while selecting an appropriate thrust bearing.

By the way, in the present invention, the double-headed piston 8 has three
The present invention is not limited to books, and the number of books can be changed and implemented. In the above embodiment, the piston diameter ratio R
The compression reaction force F of the working chamber 38 is changed by changing b / Ra.
₁ and the compression reaction force F ₂ of the working chamber 39 and the axial load Fo due to the differential pressure are canceled out.
38 axial load F by the compression reaction force F ₂ and the differential pressure of the compression ratio by changing the compression of the working chamber 38 the reaction force F ₁ and working chamber 39 of the
The present invention can be implemented even when o is offset.

The double-headed piston 8 is not limited to the cylindrical shape, and the present invention can be implemented by using the double-headed piston 8 having other shapes such as an elliptical shape. Furthermore, the use of the compressor according to the present invention is not limited to a refrigeration cycle using carbon dioxide as a refrigerant, and may be used for a cycle in which the working pressure of fluid is high.

[Brief description of drawings]

FIG. 1 is an axial sectional view of a swash plate compressor according to the present embodiment.

FIG. 2 is a front view of the front housing 1 seen from the swash plate chamber 38a side.

FIG. 3 is a front view of the rear housing 4 seen from the swash plate chamber 38a side.

FIG. 4 is an explanatory diagram illustrating a load that acts on the swash plate compressor according to the present embodiment.

FIG. 5 is a maximum axial load FB acting on the thrust bearing of the swash plate compressor according to the present embodiment and a piston diameter ratio Rb / R.
It is a graph which shows the relationship with a.

FIG. 6 is a graph showing the relationship between the axial load Fo and the compression reaction forces F ₁ and F ₂ acting on the swash plate compressor according to the prior art, and the rotation angle of the rotary shaft 5.

[Explanation of symbols]

1 ... Front housing, 2, 3 ... Cylinder block,
4 ... Rear housing, 5 ... Rotating shaft, 6 ... Swash plate, 7 ... Shoe, 8 ... Double-headed piston, 9a, 9b ... Cylinder, 10 ...
Shaft seal, 11, 12 ... Thrust bearing, 13, 14 ... Radial bearing, 15, 16 ... Valve plate, 17 ... Discharge valve, 18 ... Valve stop plate, 19 ... Discharge valve, 20 ... Valve stop plate, 2
1, 22 ... Suction valve, 23 ... Discharge port, 24 ... Suction port, 25
... suction port, 26 ... discharge port, 27 ... suction chamber, 28 ... discharge chamber, 29 ... communication passage, 30 ... communication passage, 31 ... suction chamber, 32
... discharge chamber, 33 ... communication passage, 34 ... suction port, 35 ... discharge port, 36, 37 ... bolts, 38, 39 ... working chamber.

─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kazuhide Uchida 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute, Inc. (72) Inventor Takeshi Sakai 1-1, Showa-cho, Kariya, Aichi Japan Denso Co., Ltd. (56) Reference JP-A-7-301176 (JP, A) JP-A-7-279838 (JP, A) JP-A-4-94470 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) F04B 27/08 F04B 39/00 107

Claims (2)

(57) [Claims] 1. A rotary shaft (5) which rotates by receiving a driving force from an external drive source, and a thrust bearing (11, 12) which opposes an axial load (FB) acting on the rotary shaft (5), While holding the thrust bearings (11, 12),
Housings (1, 2, 3, etc.) for accommodating the rotating shaft (5)
4), a plurality of cylinders (9a, 9b) formed in the housing (2, 3) in parallel with the rotating shaft (5), and reciprocating in the cylinders (9a, 9b), A double-headed piston (8) having pistons (8a, 8b) on both front and rear sides in the direction, and a double-headed piston (8) provided on the rotary shaft (5) to convert the rotary motion of the rotary shaft (5) into reciprocating motion. ) Reciprocating the swash plate (6), the cylinder (9a, 9b) and the double-headed piston (8)
A first working chamber (38) and a second working chamber (39) formed by: a suction port (24) formed in the housing (1, 2, 3, 4) for sucking a fluid; A discharge port (23) formed in (1, 2, 3, 4) for discharging the fluid compressed in the first and second working chambers (39, 38); and the housing (1, 2, 3) 4) having a swash plate chamber (38a) formed inside the swash plate chamber (38a) and communicating with the suction port (24).
2, 3, 4) The axial load (Fo) generated by the pressure difference from the external pressure is applied to the first and second working chambers (39, 3).
A swash plate compressor characterized in that the fluid in 8) is substantially offset by the acting forces (F ₁ , F ₂ ) exerted on the double-headed piston (8). 2. The second working chamber (39) is formed on the side of the external drive source, and the second working chamber (39) of the cross-sectional area perpendicular to the axis of the double-headed piston (8). The swash plate mold according to claim 1, wherein a cross-sectional area on the side is larger than a cross-sectional area on the first working chamber (38) side in a cross-sectional area in a direction perpendicular to the axis of the double-headed piston (8). Compressor.