JPH02264163A - Refrigerant overheating preventive device for variable volume compressor - Google Patents

Abstract

PURPOSE:To reduce overheating of a refrigerant in a suction passage system, to improve volume efficiency, and to reduce the temperature of gas delivered from a compressor by a method wherein a suction passage for communicating a suction chamber and a refrigerant passage independent from the refrigerant passage of a rear cover are formed in the refrigerant passage of a suction chamber with a gap therebetween. CONSTITUTION:A suction union 61 of a cold suction passage in a rear cover 3 is formed with a screw part 64 situated at the one end and connected to a vaporizer and a line part 62 situated at the other end and having a suction passage 65 for a refrigerant and a suction passage 302 of a rear cover which are formed with a space part 63 formed therebetween to prevent suction of heat from the rear cover 3. A refrigerant returned through a freezing cycle flows in a suction port 60 of the union 61 and is controlled to a proper pressure by a control valve 41 after the flow of it through the passage 65. After a pressure is lowered, the refrigerant is introduced in an inflow port 82 of a box body 85 and a refrigerant passage 802 and flows in a cylinder 33 through an outflow port 84 of the box body 85, a suction port 401 to a cylinder head 4, and a suction valve 5 to complete a suction stroke. Since overheating of a suction refrigerant can be reduced within a suction passage, the volume efficiency of a compressor is improved.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a variable capacity compressor used in automobile refrigeration and air conditioning equipment r', etc. The present invention relates to a variable displacement compressor having means for preventing overheating from the passage wall surface during the passage from the suction to the compression chamber such as a cylinder.

[Conventional technology]

For example, as a compressor for automobile air conditioning,
No. 198, JP 58-4195, JP 62-67
4, Japanese Patent Application Laid-open No. 11f (No. 63-41676, etc.), a variable view compressor is used.

[Problem to be solved by the invention]

In the above-described compressor, the refrigerant sucked from the compressor refrigerant suction port is heated from the passage wall or the like while reaching the compression chamber such as the cylinder from the suction port. For this reason, there have been disadvantages in that the volumetric efficiency of the compressor decreases and the temperature of the gas discharged from the compressor increases. For example, the relationship between refrigerant overheating in a two-legged passage and the decrease in volumetric efficiency Δηヮ is as follows: Vl is the specific volume of refrigerant at the compressor refrigerant inlet, v2 is the specific volume of refrigerant at the entrance of the compression chamber of the cylinder, etc. The volumetric efficiency of the compressor is η
9, then ΔηV=ηv(vx/vil) 9For example, to show an actual measurement example at a low rotational speed of the compressor, the temperature and pressure of the refrigerant at the compressor refrigerant inlet are 9°C and 2°C, respectively. When .0kgf/cdG,
The temperature and pressure of the refrigerant in a compression chamber such as a cylinder were 461° C. and 1.98 kgf/IG, respectively, and the volumetric efficiency of the actual 4j11 was 70%. Using the above formula, the decrease in volumetric efficiency in this actual example of Δ1 is approximately 4-3
%. In other words, if the suction refrigerant in the compressor population could be directly sucked into the compression chamber, the volumetric efficiency of the compressor would be 83%.

In addition, in the calculation of ΔηV in the above example, v2 is affected by both the overheating of the refrigerant in the suction passage system and the pressure loss, but Δη9 due to only the pressure loss is the overall Δηv
(=13%), and the decrease in volumetric efficiency due to refrigerant overheating is about 92% of the total Δη9. An object of the present invention is to significantly improve volumetric efficiency by reducing refrigerant overheating in the suction passage system. Furthermore, by reducing refrigerant overheating in the suction passage system, the purpose is to also reduce the temperature of the discharged scum from the compressor.

[Means to solve the problem]

The present invention is characterized by a cylinder block in which a plurality of cylinders are formed around a drive shaft, a plurality of screws 1 to 1 fitted to the cylinders, and a suction port provided at one end of the cylinder block. and a cylinder head in which a plurality of discharge ports are formed corresponding to the cylinders, a suction valve that opens and closes the suction port, a discharge valve that opens and closes the discharge port, and a cylinder head that is sandwiched between the cylinder head and provided at one end of the cylinder block. a fixed rear cover, partitioning the inside of the rear cover into a suction chamber communicating with the suction port and a discharge chamber communicating with the discharge port, a motion conversion mechanism engaged with the drive shaft, and a motion conversion mechanism engaged with the motion conversion mechanism. It is composed of a piston that moves reciprocatingly within the cylinder while holding the cylinder,
In the variable displacement compressor in which the discharge amount of the piston is continuously variable, a suction passage communicating between a suction port provided in the rear cover and the suction chamber, and a refrigerant passage formed in the rear cover within the refrigerant passage of the suction chamber; The above object is achieved by forming independent refrigerant passages with gaps.

[Effect]

According to the present invention, a refrigerant passage that is independent of the refrigerant passage formed in the rear cover is formed in the suction passage that communicates the suction port provided in the rear cover with the suction chamber, and in the refrigerant passage of the suction chamber, with a gap provided between the rear cover and the refrigerant passage. By doing so, it is possible to prevent the refrigerant from overheating in the refrigerant suction passage from the compressor suction port to the suction port, thereby achieving the above object.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the structure of a variable capacity swash plate compressor to which the present invention is applied, and FIG. 2 shows the front view of the rear cover.

FIG. 1 shows a state where the swash plate tilt angle is maximum, that is, the piston stroke is maximum.

The housing consists of a front housing 1 and a cylinder block 2. That is, a cylindrical cylinder block 2
A bowl-shaped front housing 1 is installed and fixed at one end of the housing tb. At the center of these cross sections, there is a main 1lI through a radial needle roller
lll] 3 is rotatably supported. A swash plate chamber in which a swash plate exists is formed within the front housing. Inside the cylinder block 2, a plurality of cylinders 33 are arranged in the circumferential direction parallel to the axis of the main shaft 13 with the main shaft "-3 as the center.

A drive plate 14 is fixed to the main shaft 13 by press fitting, pin 11, or plastic coupling. This one
(The live play 1-14 constitutes a swash plate together with the swash plate main body 12. In other words, by dividing the swash plate into the drive plate 14 and the swash plate main body 12 and adopting the configuration described below, the inclination angle of the swash plate main body 12 (swash plate It is possible to change the stroke of the piston by changing the tilting angle.In other words, the live plate 14 is formed with an ear 14, and this ear 141 is provided with a cam groove 142. In the cam groove 142, a pivot pin 16 on the swash plate side is movably attached.
The lug portion 141 of No. 4 and the swash plate lug shaft 12] have a structure such that their sides are in contact with each other. As a result, when the drive plate 14 rotates due to the rotation of the main shaft 3, rotational force is applied from the lug 141 on the drive plate 14 to the swash plate lug shaft 121, causing the swash plate main body 12 to rotate. The cam grooves 142 formed in the cam grooves 1 to 1-14 have edges made of one closed curve, and even if the pivot pin 16 moves within this cam groove 142, the top dead center position of the piston 31 does not change. It is a curve like this.

A sleeve 15 is incorporated into the main shaft 13 so as to be slidable in the axial direction with respect to the main shaft 13 . The sleeve 15 and the swash plate main body 12 are connected by a sleeve pin 17, and the swash plate main body 12 is fastened to the sleeve 15 so as to be rotatable around the sleeve pin 17. At this time, when the sleeve 15 slides to the right in the figure, the inclination of the swash plate main body 12 becomes smaller. Note that due to the rotation of the main shaft 13, the drive plate 14. Swash plate body 12. Sleeve 15 rotates together.

A piston support 21 is held in contact with the swash plate body 12 via a ball bearing 23. That is, pressurization is applied to the ball bearing 23 by the spacer 221 and retaining ring 22 fixed to the swash plate main body 12,
The hub portion 122 of the swash plate body 12 is configured to prevent the ball bearing 23 from moving relative to the swash plate body 12 in the rotational direction.
Fixed.

Furthermore, the piston sabots 1 to 21 are restricted from moving in the right direction in FIG. Movement to the left in the figure is also restricted. Further, a support bin 26 is fixed at a lower position of the piston support 21 in the radial direction by a method such as press-fitting, screwing, or plastic coupling.

This support bin 26 has a slide ball 27. A slide shoe 29 having a cylindrical outer surface and a spherical surface that comes into contact with the outer peripheral surface of the slide ball 27 is attached, and the support bin 26 can rotate and move relative to the axial groove 28 . In this way, this slice 1 and shoe 2
9 reciprocates in the axial groove 28 provided in the inner circumference of the front housing 1. This allows the screws 1 to 1 to
The movement around the axis is restricted so that the sensors 1 to 21 do not rotate around the main axis 13.

The piston support 21 holds one end of a connecting rod 32. That is, the connecting rod 32 is formed by connecting ball portions 321 and 322 to both ends of one stem portion 323 by welding or the like. One end of this connecting rod 32, ie, a ball; I21, is held by the piston support 21. This holding is performed rotatably between the centers of the ball 321. The other end, that is, the veil 322 also
Similarly, it is rotatably held on the piston 31 by caulking or the like between the centers of the ball 322. A plurality of such connecting rods 32 and pistons 31 exist.

The plurality of pistons 31 are fitted and built into a plurality of cylinders 33 provided in the cylinder block 2 so as to be able to reciprocate. In addition, the piston 31 has screws 1~
ring 34.35 is installed.

On the right side of the cylinder block 2 is a suction valve plate 5. Cylinder head 4. Discharge valve plate 6. The gasket 7 is positioned with a fixing pin 75, and these and the rear cover 3 are arranged.

As you can see, this cylinder block 2 is fixed integrally with the fluorocarbon 1 to the housing 1 with bolts 36 (a) to 36 (f). The airtightness between the front housing and the cylinder block 2 is maintained by an O-ring. Rear cover 3 and cylinder block 2 and ring; 3
9 to keep it airtight.

Next, a structure for regulating the upper and lower limits of the swash plate tilt angle will be described. In the process in which the swash plate tilt angle increases from E to E, the sleeve 15 slides on the main shaft J3 from right to left in the figure. As a result, the swash plate main body 12 is tilted clockwise about the sleeve pin 17.

When the swash plate tilting angle reaches the maximum (the maximum piston stroke), tilting regulating sections (not shown) are installed on the drive plate 14 at two symmetrical positions with respect to the main axis.
Then, a tilting restriction portion (not shown) provided on the swash plate main body 12 symmetrically with respect to the main axis comes into contact.

At this time, since appropriate gaps are provided between the sleeve 15, the drive plate 4, the pivot 1 to the pin 16, and the cam groove 142, collision of each member is avoided. Also, the swash plate tilt angle is minimum (viston stroke is minimum)
Sometimes a stopper 1; 32 and a spring 8 installed on the main shaft 13
The minimum stroke position is regulated by bringing the tip of the sleeve]-5 into contact with the sleeve. Main shaft 13''2,
The spring 81 installed between the live plate 14 and the sleeve 15 and the spring 80 installed between the sleeve 15 and the retaining ring 132 are configured to bias the piston 1 in the minimum direction and the maximum direction, respectively. It has become.

The leftward thrust force (axial force) that acts when compressing the gas is supported by the thrust bearing 42 installed between the Freon l and the housing 1 via the drive plate 14. Furthermore, the radial force (force in the radial direction) acting on the main shaft 13 is applied to the bearing housing 20 of the front housing 1 and the cylinder block 2.
Two radial needle roller bearings 19 and 1 provided in
Supported by 8.

A thrust bearing 201 is fixed to the bearing housing 20 of the cylinder block 2 by a screw member 202 at the rear end of the main shaft 13 . The thrust bearing 4
The top clearance of this compressor (when the piston 31 is at top dead center, the gap between the heads of the screws 1 to 31 and the suction valve 5) is (defined) can be adjusted.

Next, the refrigerant passage formed in the rear cover 3 will be described with reference to FIGS. 1 and 2. Inlet port 60 on rear cover 3
A suction union 61 having a discharge port 57 and a discharge union 58 having a discharge port 57 are installed. ). The suction port 60 is connected to the suction passage 302 and to the suction chamber 8 via the pressure control valve 4. The suction chamber 8 and the discharge chamber 9 are partitioned by a circular partition wall 50 centered on the main shaft 13. The suction chamber 8
The discharge chamber 9 communicates with a suction port 401 and a discharge port 402 via a suction valve 5 and a discharge valve 6, respectively.

These suction ports 401 and discharge ports 402 are provided in the cylinder head 4 in correspondence with the cylinders 33, respectively.

The pressure control valve 41 is composed of a bellows (or diaphragm) and a spring, and the upstream side of the control valve 41 communicates with the swash plate chamber 10 in the front housing to equalize the pressure. In other words, rear cover 3
．． The respective conductive holes 303, 76 and 203 provided in the center of the stop pin 75 and the screw member 202, and the passage 131 provided in the center of the main shaft 13, connected to this passage 131 and connected to the drive plays 1 to 14 in the radial direction. passage 14 opening to
It is connected by 3. On the other hand, the downstream side of the control valve 41 communicates with the suction chamber 8 .

A communication hole 62 (J4) is provided at the end of the suction passage 302, and this communication hole 62 is connected to the gasket 7° cylinder head 4. The suction valve 5 and the cylinder block 2 are connected to a swash plate chamber 10 in the front housing 1 through communication holes (not shown), respectively.

Next, the refrigerant suction passage formed in the rear cover 3 will be described in detail. The suction union 61 has one end connected to a threaded portion 64 that connects to an evaporator (not shown), and the other end separated from the suction passage 302 of the rear cover by a space 63 formed to prevent heat absorption from the rear cover 3. Refrigerant suction passage 6 inside
5 and a conduit section 62 having a diameter of The suction union 61 and the rear cover 3 are sealed with an O-ring 66.

The low pressure chamber 8 is formed by the partition wall 50 and the rear cover outer wall 305, and is provided with reinforcing ribs 801. A box 85 having a refrigerant passage 802 inside is installed in the low pressure chamber 8. The box body 85 has a convex portion 86 with respect to the partition wall 50 and a fourth portion 87 with respect to the rear cover outer wall 305 to restrict movement in the rotational direction in FIG.
Other than the recess 87, gaps 88 and 89 are formed between the outer wall of the partition wall 50 and the inner wall of the rear cover outer wall 305,
Contact with the partition wall 50 and the outer wall of the rear cover is avoided. In addition, the box body 85 has four parts 83 that contact the reinforcing ribs 801 provided on the rear cover 3, and has four parts 83 so as to correspond to the suction bows 1-401 provided on the cylinder head 4. Exit 84 (a) - 84. (f) is provided, and the box body 85 is connected by the four parts 83 and the outlet 84.
The axial distance between the recess 8:3 and the outlet 84 is not in contact with the wall surface of the low pressure chamber 8 and the cylinder 4 except for the recess 8:3 and the outlet 84. That is, in the box body 85, the convex portion 86. Recessed portion 87. Except for the recess 83 and the outlet 84, a space is formed between the wall surface of the rear cover 3 and the cylinder head 4, so that the structure is such that heat absorption from each member can be prevented.

Note that the box body 85 can be easily manufactured by pressing, soldering, or the like. Furthermore, although the refrigerant passage 802 formed inside the box body 85 is rectangular in this embodiment,
The present invention is not limited to this, and the shape may be circular, for example.

With the configuration described above, when driving force is input to the main shaft 13 of this compressor by the engine (not shown), the drive plate 14 and the swash plate main body 12 rotate, and the rotation axis of the main shaft 13 rotates. On the other hand, the piston support 21 swings. This rocking motion is called misosuri motion, and is similar to the motion that occurs when a liquid in a round container is subjected to circular motion. This swinging motion causes the piston 31 to reciprocate within the cylinder 33 (linear motion a parallel to the axial direction of the main shaft 13).

The refrigerant returned from the refrigeration cycle (not shown) flows into the suction port 6o of the suction union 61, passes through the suction passage 65, is controlled to an appropriate pressure by the control valve 41, and is then lowered to the box body 8.
5 is introduced into the refrigerant passage 802 from the outlet 84 of the box body 85 to the suction port 40 of the cylinder head 4.

It flows into the cylinder 33 through the suction valve 5 and completes the suction stroke.

The refrigerant compressed by the piston 31 is delivered to the discharge port 402 of the cylinder head 4. The liquid is then discharged from the discharge chamber 91 formed in the rear cover 3 through the discharge valve 6, and is discharged from a nine discharge outlet 157 provided in the discharge union 58 to a refrigeration cycle (not shown).

FIG. 3 shows the suction pressure of the compressor.

A certain suction port 40 when the discharge pressure and the refrigerant superheat degree at the suction port are constant and the compressor rotation speed Nr is varied.
Difference Δ between the refrigerant temperature on the upstream side of No. 1 and the refrigerant temperature at the suction port 60
1''S and an experimental curve diagram showing the volumetric efficiency at that time, where the solid line is the conventional example and the broken line is the example of the present invention.

As is clear from FIG. 3, in the conventional system, when the rotational speed of the compressor is low, the refrigerant is superheated in the refrigerant suction passage. In the embodiment according to the present invention, refrigerant overheating is significantly reduced, especially in the low speed rotation range. This will also significantly improve the volumetric efficiency. Despite the reduced degree of refrigerant superheating in the high-speed rotation range,
The reason why the increase in volumetric efficiency is small at that time is due to the increase in pressure loss in the suction passage. However, this result is obtained when the compressor capacity is forcibly set to the maximum capacity (that is, the maximum stroke), and in reality, the machine has a variable capacity, so pressure control is required in the high-speed rotation range. As the engine is operated, the flow of refrigerant is reduced, which reduces the pressure loss in the suction passage, and increases the volumetric efficiency even in the high-speed rotation range. Although not shown in the drawings, the temperature of the discharge gas of the compressor can be lowered by reducing the superheating of the refrigerant in the suction passage.

〔Effect of the invention〕

As described above, according to the present invention, the degree of superheating of the suction refrigerant in the suction passage of the compressor can be reduced, so the volumetric efficiency of the compressor can be improved, and the discharge gas temperature of the compressor can be lowered. There is.

[Brief explanation of drawings]

Fig. 1 is a structural diagram of a variable displacement compressor showing an embodiment of the present invention, Fig. 2 is a front view of a rear cover showing an embodiment of the invention, and Fig. 3 is a comparison between the present invention and a conventional example. It is an experimental curve diagram. 2... Cylinder block, 3... Rear cover, 4...
Cylinder head, 8・Suction chamber, 9・Discharge chamber, 3]・
Piston, 33... Cylinder, 60... Suction [], 6
F. Suction union, 65. Suction passage, 82. Sulfur population, 84. Outlet, 85. Box body, 86. Convex part.
87 recess, 802...refrigerant passage.

Claims (3)

[Claims] 1. A cylinder block includes a plurality of cylinders formed on the same circumference around a drive shaft, a plurality of pistons that are fitted into the cylinders and reciprocate, and a suction port and a discharge port provided at one end of the cylinder block. a plurality of cylinder heads formed corresponding to the cylinders, a suction valve for opening and closing the suction port, a discharge valve for opening and closing the discharge port, and a cylinder head fixed to one end of the cylinder block with the cylinder head sandwiched therebetween. a rear cover, the interior of the rear cover is partitioned into a suction chamber communicating with the suction port and a discharge chamber communicating with the discharge port, a motion conversion mechanism is engaged with the drive shaft, and a piston is hooked to the motion conversion mechanism. In a variable capacity compressor configured as follows, in which the discharge amount of the piston is continuously variable, the rear cover includes a suction passage that communicates the suction port provided in the rear cover with the suction chamber, and a refrigerant passage of the suction chamber. A refrigerant overheat prevention device for a variable capacity compressor, characterized in that a refrigerant passage is formed with a gap between the rear cover wall surface and the rear cover wall surface. 2. The refrigerant overheat prevention device for a variable capacity compressor according to claim 1, wherein a suction union installed at the suction port is provided with a pipe portion extending into the suction passage. 3. 2. The variable refrigerant according to claim 1, further comprising a box body provided with an inlet communicating with the suction passage and an outlet communicating with the suction port, the refrigerant passage being formed within the box body, in the refrigerant passage of the suction chamber. Refrigerant overheating prevention device for capacity compressors.