FR2791401A1 - Compressor for air conditioning has flap valve with limit stop mounted in inlet valve plate between cylinder block and head - Google Patents

Abstract

The compressor for air conditioning has a cylinder block with a cylinder head defining a suction chamber. A valve carrying plate between the block and head has an inlet opening for a coolant gas. An aspiration valve flap on the plate controls the inlet opening. A stop groove limits movement of the aspiration valve.

Description

i 2791401 Fluid displacement device with valve stop

  suction. The present invention relates to a fluid displacement apparatus, such as a piston type compressor suitable for use in an air conditioning unit, said compressor being provided with a stop for a suction valve in the form of blade, and it relates more particularly to a piston type compressor provided with a stop for a blade-shaped suction valve, said stop stop the movement of the suction valve during each stroke of suction of the pistons while allowing an adequate degree of opening of the valve to allow the suction of fluid

  refrigeration and the suppression of noisy vibrations of the valve.

  Figure 6 shows a refrigerant compressor according to

  the known technique represented by US Patent 4,664,604.

  This compressor comprises a cylindrical casing 1 closed by a front housing 3 and by a cylindrical cylinder head 26. The casing 1 contains a cylinder block 2 on the side of the cylinder head and a hollow part or shaft chamber 1a. The front housing 3 is mounted on the front opening of the cylindrical casing 1 in order to close the opening of the chamber 1a and it

  is fixed to the casing 1 by means of several bolts, not shown.

  The cylinder head 26 and a valve plate 24 are fixed to the other end of the casing 1 by means of a plurality of bolts, not shown, to close off the end part of the cylinder block 2. An opening 3a is formed in the front housing 3 for receiving a drive shaft 4 via a first radial bearing 5 and a mechanical seal 7. An annular sleeve 3b projects from the front end surface of the front housing 3 and surrounds the drive shaft 4 to define a shaft seal cavity 6. The mechanical seal 7 is mounted on the drive shaft 4 inside the seal cavity d 'shaft seal 6. The drive shaft 4 is rotatably mounted in the front housing 3 via the radial bearing 5, which is disposed inside the opening 3a. The outer end of the drive shaft 4 is provided with a rotor 8. A needle bearing 14 is placed between the inner end surface of the front housing 3 and the adjacent axial end surface of the rotor 8 by via a bearing cage 13. This bearing receives the axial thrust which acts on rotor 8

2 2791401

  and guarantees a smooth movement. The drive shaft 4 is rotatably mounted in a second radial bearing 15 and is supported by an adjustment screw 18 which is screwed into a threaded part of the cylinder block 2, by means of a needle bearing 16 and spring devices 17. The needle bearing 16 is placed between the drive shaft 4 and the spring device 17 in order to allow a regular rotation of the shaft

training 4.

  A sleeve 9 which is placed between the rotor 8 and the inner end of the cylinder block 2, is slidably mounted on the drive shaft 4. The sleeve 9 supports a swash plate 10 capable of producing a nutation movement (unbalanced rotation ) and rotary. A helical spring 12 surrounds the drive shaft 4 and is placed between the end surface of the rotor 8 and an axial end surface of the sleeve 9 in order to push the latter towards the block

cylinders 2.

  The swash plate 10 is connected to the rotor 8 by an articulated coupling mechanism so as to produce a rotation synchronized with the rotor 8. For this purpose, the rotor has a first arm 8a which projects axially outward from 'one of its side surfaces. The swash plate 10 also has a second arm 10a projecting towards the first arm 8a of the rotor 8 from one of its lateral surfaces. In this embodiment, as shown in Figure 6, the second arm 10a is formed separately from the swash plate 10 and is fixed on a lateral surface thereof. The arms 8a, 10a overlap each other and are connected to each other by means of a pin 11 which extends into a rectangular hole 8b formed through the arm 8a of the rotor 8 and a pin hole 10b formed through the second arm 10a of the swash plate 10. In this way, the rotor 8 and the swash plate 10 are hinged to each other. In this construction, the pin 11 is slidably disposed in the rectangular hole 8b, and its sliding movement inside the rectangular hole 8b changes the angle of inclination of the inclined surface of the swash plate 10. The cylinder block 2 has a plurality of cylinders 2a arranged

  annularly, inside which pistons 20 slide.

3 2791401

  A typical arrangement includes five cylinders, but the device

  can be fitted with a lower or higher number of cylinders.

  Each piston 20 comprises a head part 21 slidingly mounted inside the cylinder 2a. Hemispherical pads 19 are arranged on the two lateral faces of the swash plate 10 and are turned towards the interior surface of the pistons 20 in order to slide along the lateral surface of the swash plate 10. The rotation of the drive shaft 4 makes turn the swash plate 10 between the pads 19 and move the inclined surface axially to the right and to the left,

  thus making the pistons 20 come and go in the cylinders 2a.

  The cylinder head 26 is formed so as to define a chamber

  27 and a discharge chamber 28. The holder plate

  valves 24, which is fixed with the cylinder head 26 to the end of the cylinder block 2 by bolts, has a plurality of valve suction ports 22 connecting the suction chamber 27 and the respective cylinders 2a, and a plurality valve discharge ports 23 connecting the discharge chamber 28 and the respective cylinders 2a. Static seals 25, 29 are placed between the cylinder block 2 and the valve plate 24 and between it and the cylinder head 26, in order to seal the coupling surfaces of the

  cylinder block, valve plate and cylinder head.

  The shaft chamber 1a and the suction chamber 27 are connected by a passage 30 which includes an orifice 30a formed through the valve plate 24 and through the static seals 25, 29 and which extends into the bore 2a formed in the cylinder block 2. In the bore b of the passage 30 is mounted, on the side of the opening which faces the shaft chamber la, a coupling element 31 having a small orifice 31a. On the other side of the bore 30b is mounted a bellows element 34 containing gas and provided with a needle 34a. The axial position of the bellows element 34 is determined by a frame element 33 disposed in the bore 30b. The opening and closing of the small orifice 31a which connects the motor shaft chamber la and the bore 30b are controlled by the needle 34a. At least one orifice 33a is formed through the frame 33 to establish communication between the opening

30a and bore 30b.

  In operation, the drive shaft 4 is rotated by the engine of a vehicle by means of a system with

4 2791401

  pulley, not shown, and the rotor 8 rotates with the drive shaft 4. The rotation of the rotor 8 is transmitted to the swash plate 10 by the articulated coupling mechanism so that, relative to the rotor 8, the inclined surface of the swash plate 10 moves axially to the right and to the left. Due to the fact that the pistons 20 are functionally connected to the swash plate 10 and that the latter slides between the pads 19, the pistons reciprocate inside the cylinders 2a. During this movement, the refrigerant gas which enters the suction chamber 27 from the fluid inlet orifice 27a is brought into each cylinder 2a to be compressed there. The compressed refrigerant gas is discharged through the discharge port 23 to the discharge chamber 28 of each cylinder 2a and from there it is discharged through the fluid outlet port 28a into

  an external fluid circuit, for example, a cooling circuit.

  As shown in Figures 7 and 8, blade-shaped suction valves 36, made of a metallic elastic material, such as a stainless steel plate, are mounted resiliently movable between a closed position in which they are contact with the valve plate 24 and close the suction ports 22 and an open position in which they are separated from the valve plate 24 and open the ports

suction 22.

  When the suction valves are moved to the open position, their ends bear against a stop constituted by a recess 2b formed in the axial end face of the cylinder block 2. The amplitude of movement of the valve d suction 36 is therefore determined by the depth of the recess 2b relative to

  the axial end face of the cylinder block 2.

  However, it has been discovered that this conventional construction of the suction valve stopper 2b gives rise to the problem that, with each movement of the suction valve 36 from the closed position in contact with the valve plate 24 at the open position in abutment against the bottom of the recess 2b, the suction valve 36 is subjected to a self-induced vibration caused by the flow of refrigerant gas sucked into the cylinders due to the stroke

piston suction.

2791401

  The vibration causes a sound or noise produced in the evaporator of the air conditioning circuit. In particular, when the compressor is in an operating condition such that the amount of circulating flow of refrigerant gas in the air conditioning circuit is low, that is to say either in idle mode of the compressor , or in operation at a low speed of rotation, the end of each suction valve 36 is not sufficiently displaced towards the open position in which it rests stably and is stopped by the bottom of the recess 2b. The suction valve 36 is then subjected to an irregular vibration under the influence of a modification of the flow of refrigerated gas sucked

  in cylinder 2a, which produces a clicking or clicking noise.

  On the other hand, if the depth of each recess 2b is reduced, the above-mentioned vibration can be suppressed, but, since the amplitude of movement of the flexible suction valve 36 from the closed position to the open position is then reduced, a sufficient quantity of refrigerant cannot enter the cylinder 2a during the suction stroke of the piston and therefore the refrigerant gas in the cylinder 2a is subjected to excessive compression and the temperature of the discharged refrigerant gas rises by unfavorable way. The object of the present invention is to eliminate the abovementioned shortcomings presented by conventional piston compressors

  fitted with blade-shaped suction valves.

  Another object of the present invention is to provide a fluid displacement apparatus, such as a piston type compressor whose construction around the stopper is improved in order to suppress the vibration of the suction valves and to allow a sufficient amount of refrigerant gas to flow into the chambers of

  compression during the suction stroke of the pistons.

  A further object of the present invention is to provide a compressor of the piston type which can be used to form a system of

silent air conditioning.

  The fluid displacement apparatus according to the invention comprises a cylinder block in which several cylinders are mounted, a cylinder head closing an axial end of the cylinder block to form a suction chamber, a valve plate disposed between the block

6 2791401

  cylinders and the cylinder head and having an inlet for introducing a refrigerating gas to be compressed into said suction chamber, at least one blade-shaped suction valve disposed on one side of said valve plate, said valve suction having one end fixed on the valve plate and a free end for closing and opening said inlet orifice, at least one limiting recess formed in an adjacent interior wall being at an open end of the cylinder block to limit the displacement of the free end of the suction valve, said recess of concave shape and having a predetermined depth and expansion means formed around the recess, in fluid communication with the recess, in order to allow the

  expansion of the refrigerating gas introduced.

  An embodiment of the invention will now be described with reference to the accompanying drawings in which: FIG. 1 is a partial front view of a swash plate compressor without its cylinder head and provided with a valve stop according to a first embodiment of the invention; Figure 2 is a cross-sectional view along line A-A of Figure 1; Figure 3 is an enlarged partial front view of the rear face of the cylinder block of the swash plate compressor of Figure 1 and showing a valve stop according to an embodiment of the invention; Figure 4 is a view similar to Figure 3 and showing a second embodiment of the valve stop according to the invention; Figure 5 is a view similar to Figure 3 and showing a third embodiment of the valve stop according to the invention; Figure 6 is a longitudinal sectional view of a conventional swash plate compressor; Figure 7 is a view similar to Figure 1 and show a conventional valve stop; and Figure 8 is a cross-sectional view along line A-A of

Figure 7.

  The swash plate compressor according to the present invention will now be described with reference to the figures. However, the embodiments described below are applicable to the plate compressor

7 2791401

  classic oscillating shown in Figures 6, 7 and 8. Description

  which follows therefore relates to embodiments of structures

  different applying to the classic swash plate compressor.

  Figure 1 shows a partial view of an embodiment of compressor according to the invention without its cylinder head, and shows a construction of a valve plate according to the present invention and Figure 2 shows a view in cross section along the line AA of figure 1. The swash plate compressor is identical to that

  described above, as appears from the description which follows.

  The compressor comprises a cylinder block 2 having inside a plurality of axial cylinders 2a forming compression chambers in order to allow pistons 20 mounted therein to move back and forth to compress a refrigerant gas. . A cylinder head 26 closes an axial end of the cylinder block 2, thus forming a suction chamber 27 for receiving a refrigerating gas to be compressed and a discharge chamber 28 for receiving the compressed refrigerating gas. The cylinder head 26 has an inlet port 27a for introducing into the suction chamber 27 the refrigerant gas which must be compressed from an external air conditioning circuit (not shown), and an outlet port 28a for discharge the compressed refrigerant gas from the discharge chamber 28 to the

  outdoor air conditioning system.

  A valve plate 24 is fixed between the cylinder head 28 and the cylinder block 2. In the valve plate are formed a suction port 22 for establishing fluid communication between the suction chamber 27 and the compression and a discharge port 23 allowing fluid communication between the discharge chamber 28 and the compression chambers. On the other face of the valve plate 24 are fixed several suction valves 36 in the form of a blade, capable of moving between a

  closed position where they are in contact with the carrier plate

  valves 24 to close the suction port 22 and an open position where they are separated from the valve plate 24 to open the suction port 22. Each suction valve 36 extends substantially in the diametrical direction of the corresponding cylinder 2a and has a free end. The compressor also includes movement limitation devices formed by several recesses

8 2791401

  concaves 2b formed in the axial end face of the cylinder block 2 to stop the movement of the free end of each valve

  when it moves to the open position.

  Each concave recess 2b is formed in an inner wall which is adjacent to an open end of the cylinder block 2 in order to limit the movement of the free end of the suction valve 36 when the latter opens. A concave recess 2c is formed around the concave recess 2b in order to be in fluid communication with the latter and to allow the flow of suction gas introduced from the suction orifice 22 to expand. The expansion recess 2c has a

  depth different from that of the limiting recess 2b.

  Thus, even if the refrigerant gas is sucked into the cylinder 2a immediately while the free end of the suction valve 36 comes into contact with the limiting recess 2b, the expansion recess 2c expands the gas flow suction introduced from

the suction port 22.

  Since the refrigerating gas does not generate a turbulent flow phenomenon because the suction gas reduces its pressure and its speed, the suction does not cause a self-induced vibration of the

valve.

  In addition, since the suction valves 36 open and close gradually, the suction gas flows in the

  cylinders 2a stably and efficiently.

  Thus, the expansion recess 2c is designed to be in fluid communication with the limitation recess 2b. The depth of the concave expansion recess 2c is different from that of the limiting recess 2b. The expansion recess 2c can have different configurations and the number of these recesses

  may vary and be for example single or multiple.

  FIG. 3 shows an end face of cylinder block 2 on which concave recesses are formed. In this figure, the recess 2c extends towards the cylinder 2a so that a fraction of this concave recess covers two ends of the limiting recess 2b. The expansion recess 2c comprises a first concave part 2ci and a second concave part 2c2 connected to an edge part of the first concave part 2ci. The first concave part 2ci and the second concave part 2c2 are similar to

9 2791401

  the recess 2b, which is in the shape of an arc, and they respectively have a radius of curvature greater than that of the recess 2b. The first concave part 2ci and the second concave part 2c2 preferably have a depth greater than that of the recess 2b, but they may as well have a depth less than that of the recess 2b.

  Figure 4 shows another embodiment of the recesses.

  A concave part 2c3 extends towards the cylinder 2a so that a fraction of this concave part covers a central part of the recess 2b. Preferably, the concave part 2c3 has a depth greater than that of the recess 2b, but it can also

  well have a depth less than that of the recess 2b.

  Figure 5 shows yet another embodiment of the recesses. A concave part 2c4 extends towards the cylinder 2a so that a fraction of this concave part completely covers the recess 2b. The concave part 2c4 has the same shape as the recess 2b, which is in the shape of an arc but has a radius of curvature greater than that of the recess 2b. The concave part 2c4 preferably has a depth greater than that of the recess 2b but it can also

  well have a depth less than that of the recess 2b.

  In construction according to these embodiments, it is possible to obtain substantially the same advantage as with those which have

  have been described in connection with the embodiments described above.

  Although the present invention has been described in connection with preferred embodiments, the invention is not limited thereto. Those skilled in the art will readily understand that variations and modifications can easily be made within the scope of this invention. Although the present invention has thus been widely described with the conventional compressors presented above, it will be possible for those skilled in the art to practice this invention in various other compressors. For example, these embodiments can be applied in

  flat cam or fixed displacement compressors.

t0 2791401

Claims (6)

  1. A fluid displacement apparatus, such as a compressor, characterized in that it comprises: a cylinder block (2) in which are mounted several cylinders (2a); a cylinder head (26) closing an axial end of said cylinder block (2) to form a suction chamber (27); a valve plate (24) disposed between said cylinder block (2) and said cylinder head and having an inlet port (22) for introducing refrigerant gas to be compressed into said suction chamber (27); at least one blade-shaped suction valve (36) disposed on an end face of said valve plate (24) and having one end fixed to said valve plate (24) and a free end for closing and opening said inlet (22); at least one limiting recess (2b) formed in an adjacent inner wall located at an open end of the cylinder block (2), said recess serving to limit the opening movement of the free end of said suction valve ( 36), said recess (2b) being of concave shape and having a predetermined depth; and expansion means (2c) formed around said recess (2b), in fluid communication with said recess to expand said gas refrigerator introduced.   2. Fluid displacement apparatus according to claim 1, characterized in that said expansion means consist of a recess (2c) having a depth different from that of said limitation recess (2b).   3. Fluid displacement apparatus according to claim 2, characterized in that the depth of said expansion recess (2c)   is greater than that of the limiting recess (2b).   4. Fluid displacement apparatus according to claim 2, characterized in that the depth of said expansion recess (2c)   is less than that of said limiting recess (2b).   5. Fluid displacement apparatus according to claim 2, characterized in that said expansion recess (2c) extends towards said cylinder (2a) so that part of said recess is placed in   fluid communication with said limiting recess (2b). 1 1 2791401   6. Fluid displacement apparatus according to claim 2, characterized in that said recess (2c) comprises several recess parts (2ci, 2c2; 2c3; 2c4) placed in fluid communication   with two sides of said limiting recess (2b).