Service Manuals, User Guides, Schematic Diagrams or docs for : . Car Manuals Subaru Legacy 2000-2003 Approved Subaru Legacy 2000 2000 Service Manual MECHANISM AND FUNCTION SECTION Air Conditioning System MSA5TCD00L18240

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MSA5TCD00L18240


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              LEGACY (W2260BE_SGML Complete)



                               MECHANISM AND FUNCTION                                     [M2A0]    4-7
                                                                                           2. Compressor


2. Compressor
A: GENERAL
The vane rotary type compressor has five vanes fitted in the rotor mounted on the shaft. The centrif-
ugal force produced by rotation of the rotor in the elliptical cylinder causes the vanes to move out
and change the volumes in the areas surrounded by the rotor and cylinder. Suction, compression
and discharge take place 10 times per rotation. A roll type valve is used on the discharge side only.
Shaft seals are provided for the shaft and front head to maintain air tightness in the compressor.
A trigger valve is provided in the side block to apply a back pressure to the vanes. The compressor
is charged with the specified quantity of compressor oil which is forced to all the parts for lubrica-
tion by the discharge pressure of the refrigerant.




                                                                                               S4H0307A


  (1) Front head                    (6) Vane                         (11) Shaft seal
  (2) Side block                    (7) Rotor                        (12) Magnet clutch
  (3) Rear head                     (8) Roll valve                   (13) Trigger valve
  (4) Check valve                   (9) Cylinder
  (5) Rear bearing                 (10) Front bearing




                                                     3
                        LEGACY (W2260BE_SGML Complete)



4-7    [M2B0]                   MECHANISM AND FUNCTION
2. Compressor


B: FUNCTION
Rotation of the shaft changes the volumes in the areas surrounded by the rotor, vanes, cylinder
and side block, thereby accomplishing the functions of suction, compression and discharge.
1) Suction:
The low-pressure gaseous refrigerant forced out from the evaporator by rotation of the compressor
passes from the suction side of the rear head through the check valve and enters the low pressure
chamber in the rear head. The gaseous refrigerant is drawn into the cylinder by rotation of the
vanes from the two suction ports provided in the side block. Air tightness in the cylinder chamber
is maintained by the compressor oil.




                                                                                               B4H0745A

  (1) Rotor                          (4) Rear head                           (7) Vane
  (2) Refrigerant                    (5) Low-pressure chamber                (8) Drive shaft
  (3) Check valve                    (6) Rear side block

2) Compression:
Further rotation after suction makes the cylinder chamber smaller, thus the compression starts.




                                                                                               B4H0746A

      (1) Drive shaft                                      (2) Refrigerant




                                                     4
               LEGACY (W2260BE_SGML Complete)



                                    MECHANISM AND FUNCTION                                       [M2C0]    4-7
                                                                                                  2. Compressor


3) Discharge:
When the refrigerant pressure in the cylinder chamber exceeds the high pressure value, the roll
valve opens to discharge the refrigerant through the pipe portion jointly provided in the front side
block into the high pressure chamber in the front head. The gaseous refrigerant in the high pres-
sure chamber is led through a baffle to separate the compressor oil contained in the gaseous re-
frigerant before it is forced to the high pressure piping.




                                                                                                      B4H0747A

  (1) Front head                      (4) Roll valve                          (7) High-pressure chamber
  (2) Refrigerant (Discharging)       (5) Front side block
  (3) Refrigerant (High-pressure)     (6) Pipe


C: TRIGGER VALVE
This mechanism is designed to maintain proper vane back pressure to allow the vanes to move
out with ease when the compressor starts. The trigger valve is provided in the side block, and a
ditch called the K-ditch is provided in the side block rotor surface. The trigger valve has a ball com-
bined with a spring. When vane chattering readily occurs like when the compressor starts or when
the difference between the high and low pressures is small, spring action causes the valve to open
to provide additional back pressure to the vanes, thereby assuring smooth operation.




                                                                                                          S4H0308A

     (1) K-ditch                                             (3) Front head
     (2) Check ball                                          (4) Spring




                                                       5
                          LEGACY (W2260BE_SGML Complete)



4-7    [M2C0]                     MECHANISM AND FUNCTION
2. Compressor


1) When compressor starts or when load is low:
When the compressor starts or when the load is low (the high pressure value is low), the trigger
valve is opened by spring action to apply the pressure of the high pressure chamber to the back
plane of vane to prevent vane chattering.




                                                                                          B4H0749A


      (1) High-pressure chamber                            (3) Valve
      (2) Trigger valve (Open)                             (4) Rotor

2) When compressor is in regular operation:
When the pressure in the high pressure chamber of the compressor increases, the pressure differ-
ence closes the trigger valve against spring action. The oil port pressure of the side block is ap-
plied to the back plane of vane to maintain proper back pressure.




                                                                                          B4H0750A


      (1) High-pressure chamber                            (3) Valve
      (2) Trigger valve (Shut)                             (4) Rotor




                                                    6
               LEGACY (W2260BE_SGML Complete)



                                 MECHANISM AND FUNCTION                               [M2D0]    4-7
                                                                                       2. Compressor


D: CHECK VALVE
A plate and spring are provided on the suction side of the rear head. When there is a large differ-
ence between the high and low pressures immediately after the compressor has stopped, reverse
rotation of the compressor could cause counter flow to the evaporator, as no suction valve is pro-
vided. For this reason, a check valve is provided to prevent counter flow. Immediately after the
compressor has stopped, the high pressure refrigerant forces the check valve up to close the suc-
tion side piping passage and prevent counter flow from the high to low pressure side.




                                                                                           B4H0751A


  (1) Refrigerant suction port      (3) Spring                      (5) Refrigerant
  (2) Plate                         (4) Check valve




                                                      7
                      LEGACY (W2260BE_SGML Complete)



4-7    [M2E0]                   MECHANISM AND FUNCTION
2. Compressor


E: LUBRICATION
The oil in all the parts is forced up from the bottom of the front side block along the oil passages
by the pressure on the high pressure side to lubricate the rotor front end. The oil passed through
the oil port at the bottom of the cylinder lubricates the rear end of the rotor. The oil that has lubri-
cated each of the ends of the rotor is returned to the low pressure side by the internal pressure
of the compressor.
The oil contained in the gaseous refrigerant returned from the evaporator passes through the low
pressure chamber and lubricates the rear bearing. Furthermore, the oil passes through the guide
hole provided in the drive shaft and lubricates the front bearing and shaft seal before returning
to the suction portion of the cylinder.
Since the pressure in the suction portion of the cylinder is slightly lower than that in the low pressure
side, the oil that has lubricated all the parts is returned to the suction chamber.




                                                                                                B4H0752A

  (1) Front bearing                  (4) Low-pressure chamber           (7) High-pressure chamber
  (2) Vane                           (5) Rotor                          (8) Shaft seal
  (3) Rear bearing                   (6) Oil port




                                                    8



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