JP2008175121A - Piston for compressor unit, and production method of piston for compressor unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability and quality by alleviating stress concentration at a joint of a main body part and an interlocking part. <P>SOLUTION: The piston comprises a welding part 29c formed by welding along the circumference of the front end part of the main body part 29a and the projecting end part 29d of an interlocking part 29b fitted with each other for integrally jointing the main body part 29a and the interlocking part 29b. The welding part 29c is formed by welding at a position shifted to the side of the fitting region with the projecting end part 29d with respect to the position of the front end part of the main body part 29a provided as the reference. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a compressor piston reciprocated in a cylinder bore and a method for manufacturing the same.

  Conventionally, a compressor used in a refrigeration cycle such as a vehicle air conditioner is known. This compressor compresses the refrigerant gas sucked from the suction chamber by reciprocating the piston in a cylinder bore formed in the cylinder block, and discharges the compressed refrigerant gas to the discharge chamber.

As a piston for a compressor used in a compressor, a cylindrical main body portion accommodated in a cylinder bore and a connecting portion connected to a driving mechanism are fitted to each other, and both are integrally joined by electron beam welding. By doing this, the structure provided with a hollow part inside is known (for example, refer patent documents 1-3). By the way, since electron beam welding is performed under vacuum, the hollow portion inside the piston also needs to be in a vacuum state. Therefore, in this type of compressor piston, a fitting clearance is provided between the inner peripheral surface of the main body portion and the outer peripheral surface of the connecting portion, and these are fitted to perform electron beam welding.
JP 2001-159391 A JP 2001-153046 A JP 2000-38987 A

  However, when welding is performed after the main body portion and the connecting portion are fitted, the main body portion and the connecting portion overlap in the fitting region, so that welding is not performed over the entire fitting clearance. There is a possibility that only a part thereof is included in the welding region, and the welding end portion looks like the fitting clearance. Since a composite force such as bending and tension acts on the piston for the compressor, there is a possibility that stress is concentrated on the weld end due to deflection or twisting and the piston is damaged. .

  The present invention has been made in view of such circumstances, and its purpose is to improve the durability and quality of a compressor piston by reducing the stress concentration at the joint between the main body and the connecting portion. It is to plan.

  In order to solve this problem, a first invention provides a piston for a compressor that reciprocates in a cylinder bore. The compression piston has a hollow cylindrical shape with a front end opened and a rear end bottomed, and a projecting end whose outer peripheral shape corresponds to the inner peripheral shape of the main body. A connecting portion connected to the drive mechanism, and a front end portion of the main body portion and a protruding end portion of the connecting portion are fitted together and welded along the circumferential direction to be connected to the main body portion. A welded portion that integrally joins the welded portion, and the welded portion is welded based on a position shifted from the position of the front end portion of the main body portion toward the fitting region side with the protruding end portion. Formed by.

  In the first invention, the welded portion includes a fitting clearance between the inner peripheral surface of the main body portion and the outer peripheral surface of the protruding end portion, and the welded end portion includes an end surface corner portion of the protruding end portion. Is formed.

  In the first aspect of the invention, the connecting portion has a chamfered end surface corner portion of the protruding end portion, and the weld portion is fitted between the inner peripheral surface of the main body portion and the outer peripheral surface of the protruding end portion. The welded end portion is formed so as to include a part of the tapered surface of the projecting end portion.

  The second invention provides a method of manufacturing a compressor piston that reciprocates in a cylinder bore. In this compressor piston manufacturing method, the front end is open and the rear end has a hollow cylindrical shape with a bottom, the main body accommodated in the cylinder bore, and the outer peripheral shape is the inner peripheral shape of the main body. A first step of performing temporary assembly by fitting a connecting portion connected to the drive mechanism with a corresponding protruding end portion between the front end portion of the main body portion and the protruding end portion of the connecting portion; and the main body portion And a second step of performing welding along the circumferential direction with reference to the position shifted from the position of the front end portion toward the fitting region side with the protruding end portion.

  According to the present invention, welding is performed on the basis of the position shifted from the front end portion of the main body portion toward the fitting region side with the protruding end portion of the connecting portion. For this reason, the curvature of the weld end portion is increased, and the notch coefficient at the portion tends to be reduced, so that stress concentration can be reduced. As a result, it is possible to suppress a situation in which the compressor piston is damaged due to deflection or twist caused by a force acting on the compressor piston. As a result, the durability and quality of the compressor piston can be improved.

  Drawing 1 is a mimetic diagram showing the whole compressor 1 composition concerning an embodiment of the present invention. The compressor 1 is a swash plate type variable capacity compressor, and is used, for example, in a cooling cycle of a vehicle air conditioner and adiabatically compresses refrigerant gas evaporated in a refrigeration cycle. The compressor 1 includes a cylinder block 2 having a plurality of cylinder bores 3, a front housing 4, and a rear housing 6. The front housing 4 is provided on the front end surface of the cylinder block 2, and a crank chamber 5 is formed between the front housing 4 and the cylinder block 2. The rear housing 6 is provided on the rear end surface of the cylinder block 2 via a valve plate 9 and forms a suction chamber 7 and a discharge chamber 8. The cylinder block 2, the front housing 4 and the rear housing 6 are fastened and fixed by a through bolt B through a through hole provided in the cylinder block 2.

  The valve plate 9 includes a suction hole (not shown) that allows the cylinder bore 3 and the suction chamber 7 to communicate with each other, and a discharge hole 12 that allows the cylinder bore 3 and the discharge chamber 8 to communicate with each other. A suction valve 13 for opening and closing the suction hole is provided on the cylinder block 2 side of the valve plate 9. On the other hand, on the rear housing 6 side of the valve plate 9, a discharge valve (not shown) that opens and closes the discharge hole 12 and a retainer 15 that holds the discharge valve are provided. The valve plate 9, the discharge valve 14, and the retainer 15 are integrally fixed by a rivet R. A gasket (not shown) is interposed between the valve plate 9 and the rear housing 6 to keep the suction chamber 7 and the discharge chamber 8 sealed. Further, an O-ring is interposed on the periphery of the valve plate 9 to suppress the leakage of the refrigerant gas to the outside of the compressor 1.

  A shaft support hole 19 is provided at the center of the cylinder block 2, and bearings 17 and 37 are provided in the shaft support hole 19. A shaft support hole 20 is provided at the center of the front housing 4, and a bearing 18 is provided in the shaft support hole 19. A drive shaft 10 is inserted into the shaft support hole 19 on the cylinder block 2 side and the shaft support hole 20 on the front housing 4 side. The drive shaft 10 is rotatably supported by individual bearings 17, 18, and 37. Has been.

  In the crank chamber 5, there are a drive plate 21 fixed to the drive shaft 10, a sleeve 22 slidably attached to the drive shaft 10, and a journal 24 slidably connected to the sleeve 22 by pins 23. A swash plate 26 fixed to the boss 25 of the journal 24 is provided. The hinge arm 21h on the drive plate side 21 and the hinge arm 24h on the journal 24 side are connected to each other by a ring member 27 having a track-shaped long hole and a pin 28, and regulate the swing of the swash plate 26. ing.

  Each cylinder bore 3 accommodates a piston 29. Each piston 29 is connected to the swash plate 26 via a pair of shoes 30 sandwiching the swash plate 26, and reciprocates in the cylinder bore 3 using the rotational movement of the drive shaft 10 as a driving force.

  Such a compressor 1 sucks the refrigerant gas from the suction chamber 7 into the cylinder bore 3 through the suction hole of the valve plate 9 by the reciprocating motion of the piston 29 and compresses the refrigerant gas. The compressor 1 discharges the compressed refrigerant gas from the cylinder bore 3 to the discharge chamber 8 through the discharge hole 12 of the valve plate 9.

  The compressor 1 includes a pressure control mechanism including an extraction passage 31, an air supply passage 32, and a pressure control means 33 in order to make the discharge capacity variable. As shown by the arrows in the drawing, the extraction passage 31 always communicates the crank chamber 5 and the suction chamber 7, and the refrigerant gas in the crank chamber 5 is drawn in accordance with the refrigerant gas pressure in the crank chamber 5. Return to Specifically, the extraction passage 31 includes an extraction hole 10 s provided in the drive shaft 10, a shaft support hole 19 provided in the cylinder block 2, an extraction hole 9 s provided in the valve plate 9, and the shaft support. It is comprised from the extraction groove | channel (not shown) provided in the rear-end surface of the cylinder block 2 which connects the hole 19 and the extraction hole 9s. Here, the bleed hole 10s provided in the drive shaft 10 includes an axial passage 35 extending along the axis of the drive shaft 10 from the rear end 10b of the drive shaft 10 toward the front end 10a, and a shaft A radial passage 36 that communicates with the directional passage 35 and opens directly to the crank chamber 5 and constitutes the inlet portion of the extraction passage 31. The radial passage 36 constituting the inlet portion of the extraction passage 31 is formed outside the moving range of the sleeve 22, so that it is always open to the crank chamber 5.

  The air supply passage 32 communicates with the crank chamber 5 and the discharge chamber 8 as indicated by arrows in the figure, and the passage is opened and closed by the pressure control means 33. The pressure control means 33 adjusts the pressure of the crank chamber 5 by opening and closing the air supply passage 32 and controlling the amount of refrigerant gas flowing from the discharge chamber 8 toward the crank chamber 5. By changing the inclination angle of the swash plate 26 by this pressure adjustment, the piston stroke changes and the discharge capacity of the compressor 1 can be changed. Specifically, the pressure control means 33 sucks the refrigerant returning to the compressor 1 so that the suction pressure of the refrigerant returning to the compressor 1 is kept constant in order to avoid freezing of the evaporator at low load. The discharge amount of the compressor 1 is changed according to the pressure.

  FIG. 2 is a cross-sectional view schematically showing the piston 29 according to the present embodiment. Here, FIG. 4A is an overall sectional view of the piston 29, and FIG. 4B is an enlarged sectional view of a region A indicated by a broken line in FIG. Each piston 29 is mainly composed of a main body portion 29a and a connecting portion 29b.

  The main body portion 29 a has a hollow cylindrical shape and is accommodated in the cylinder bore 3. The main body portion 29a has a front end portion 29f opened and a rear end portion having a bottom, and a connecting portion 29b is fitted to the front end portion 29f.

  The connecting portion 29 b is connected to a swash plate 26 that is a part of the drive mechanism of the piston 29. The connecting portion 29b includes a protruding end portion 29d having an outer diameter smaller than the outer diameter of the connecting portion main body on the rear end side. The protruding end portion 29d has an outer peripheral shape corresponding to an inner peripheral shape of the main body portion 29a, and has a function of fitting with the front end portion 29f of the main body portion 29a. In the present embodiment, the protruding end 29d has an outer diameter set to a value slightly smaller than the inner diameter of the main body 29a. Therefore, when the front end portion 29f of the main body portion 29a and the protruding end portion 29d of the connecting portion 29b are fitted, the fitting is performed between the inner peripheral surface of the main body portion 29a and the outer peripheral surface of the protruding end portion 29d. Clearance will occur (see the two-dot chain line in the figure). Further, a substantially conical concave portion with the top portion cut off is formed on the end face of the protruding end portion 29d (see FIG. 2), and this concave portion constitutes a hollow portion inside the piston 29 together with the main body portion 29a. .

  As one of the features of this embodiment, the piston 29 is formed by fitting the protruding end portion 29d of the connecting portion 29b to the front end portion 29f of the main body portion 29a and performing welding along the circumferential direction. A welded portion 29c is further provided, and the main body portion 29a and the connecting portion 29b are integrally joined by the welded portion 29c. The welded portion 29c includes a fitting clearance between the inner peripheral surface of the main body portion 29a and the outer peripheral surface of the projecting end portion 29d, and the welded end portion 29e is formed to include an end surface corner of the projecting end portion 29d. ing.

  FIG. 3 is an explanatory diagram for explaining a method of manufacturing the piston 29 according to the present embodiment. The piston 29 according to the first embodiment is created from the following steps. First, as a first step, the projecting end portion 29d of the connecting portion 29b and the front end portion 29f of the main body portion 29a are fitted to perform temporary assembly of the main body portion 29a and the connecting portion 29b. Then, as a second step, electron beam welding is performed along the circumferential direction for this fitting region. Specifically, the electron beam is irradiated on the basis of the position shifted from the position of the front end portion 29f of the main body portion 29a that abuts the outer peripheral edge portion of the connecting portion 29b toward the fitting region side with the protruding end portion 29d. Then, welding is performed in the region B shown in FIG. Thereby, after welding, it includes a fitting clearance between the inner peripheral surface of the main body portion 29a and the outer peripheral surface of the protruding end portion 29d of the connecting portion 29b, and the welded end portion 29e is an end surface corner portion of the protruding end portion 29d. The weld 29c is formed to include

  Note that these first to second steps are performed under vacuum. When joining the main body 29a and the connecting portion 29b under such a vacuum, the hollow portion of the piston 29 also needs to be in a vacuum state. Therefore, the hollow portion of the piston 29 is evacuated by providing a fitting clearance between the inner peripheral surface of the main body portion 29a and the outer peripheral surface of the protruding end portion 29d.

  FIG. 4 is a conceptual diagram showing a piston 39 as a comparative example to the piston 29 in the present embodiment. Similar to the piston 29 described above, the piston 39 shown in the figure is welded along the circumferential direction by fitting the protruding end 39d of the connecting portion 39b and the inner peripheral surface of the main body 39a. It has a weld 39c to be formed. In the example shown in the figure, the welded portion 39c irradiates an electron beam with reference to the position of the front end portion 39f of the main body 39a that abuts the outer peripheral edge of the connecting portion 29b, and the main body is larger than the region B shown in FIG. Welding is performed in a region C that is shifted to the 39f side of the portion 39a.

  By the way, the fitting region between the main body 39 a and the connecting portion 39 b overlaps in the axial direction of the piston 39. Therefore, when welding is performed on the basis of the front end 39f of the main body 39a, only a part of the fitting clearance is included in the welding region, and the welded end 39e is an end face corner of the protruding end 39d. It does not include, but it will look like fitting clearance. In this case, the curvature of the weld end 39e in the fitting clearance is small, in other words, the angle formed by the weld end 39e and the outer peripheral surface of the projecting end 39d of the connecting portion 39b tends to be an acute angle. . Therefore, the notch coefficient in the said part becomes high and causes stress concentration. Since a complex force such as bending or pulling acts on the piston 39, the piston 39 may be damaged due to bending or twisting.

  In this regard, according to the present embodiment, welding is performed on the basis of a position shifted from 29f of the main body portion 29a to the fitting region side with the protruding end portion 29d of the connecting portion 29b. Therefore, the welded portion 29c formed by this welding includes a fitting clearance between the inner peripheral surface of the main body portion 29a and the outer peripheral surface of the protruding end portion 29d, and the welded end portion 29e is an end surface of the protruding end portion 29d. Formed to include corners. For this reason, the weld end 29e is applied to the end face of the projecting end 29d, and the curvature thereof is large. In other words, the angle formed by the weld end 29e and the end face of the projecting end 29d tends to be an obtuse angle. Therefore, since the notch coefficient tends to be low at the part, stress concentration can be relaxed. As a result, it is possible to suppress a situation in which the piston 29 is damaged due to deflection or twist caused by a force acting on the piston 29. As a result, the durability and quality of the piston 29 can be improved.

(Second Embodiment)
FIG. 5 is a cross-sectional view schematically showing a piston 29 according to the second embodiment. Here, FIG. 4A is an overall cross-sectional view of the piston 29, and FIG. 4B is an enlarged cross-sectional view of a region A indicated by a broken line in FIG. The piston 29 according to the second embodiment is different from that of the first embodiment in the shape of the protruding end portion 29d. In the present embodiment, the description will be focused on differences from the first embodiment, and the detailed description will be omitted by quoting the reference numerals for the overlapping configurations.

  Similarly to the first embodiment, the piston 29 according to the present embodiment can be applied to the compressor 1 and is accommodated in each cylinder bore 3. Each piston 29 is connected to the swash plate 26 via a pair of shoes 30 sandwiching the swash plate 26, and reciprocates using the rotational motion of the drive shaft 10 as a driving force. Each piston 29 is mainly composed of a main body portion 29a and a connecting portion 29b.

  As one of the features of this embodiment, a protruding end 29d is formed on the rear end side of the connecting portion 29b, and this protruding end 29d is aligned when the main body 29a and the connecting portion 29b are fitted. In order to facilitate this, a tapered surface 29g having a chamfered end surface corner portion along the circumferential direction is provided.

  Further, the piston 29 of the present embodiment has a welded portion 29c formed by fitting the protruding end portion 29d of the connecting portion 29b to the front end portion 29f of the main body portion 29a and performing welding along the circumferential direction. Furthermore, the main body 29a and the connecting portion 29b are integrally joined by the welded portion 29c. The welded portion 29c includes a fitting clearance between the inner peripheral surface of the main body portion 29a and the outer peripheral surface of the protruding end portion 29d of the connecting portion 29b, and the welded end portion 29e is a part of the tapered surface 29g of the protruding end portion 29d. It is formed so that a part may be included.

  FIG. 6 is an explanatory diagram illustrating a method for manufacturing the piston 29 according to the present embodiment. The piston 29 according to the second embodiment is created from the following processes. First, as a first step, the projecting end portion 29d of the connecting portion 29b and the front end portion 29f of the main body portion 29a are fitted to perform temporary assembly of the main body portion 29a and the connecting portion 29b. Then, as a second step, electron beam welding is performed along the circumferential direction for this fitting region. Specifically, the electron beam is irradiated with reference to the position shifted from the front end portion 29f of the main body portion 29a that faces the outer peripheral edge portion of the connecting portion 29b toward the fitting region side with the protruding end portion 29d, Welding is performed in the region B shown in FIG. Thereby, after welding, it includes a fitting clearance between the inner peripheral surface of the main body portion 29a and the outer peripheral surface of the protruding end portion 29d of the connecting portion 29b, and the welded end portion 29e is a tapered surface 29g of the protruding end portion 29d. The welded portion 29c is formed so as to include a part thereof.

  FIG. 7 is a conceptual diagram showing a piston 39 as a comparative example with the piston 29 in the present embodiment. Similar to the piston 29 described above, the piston 39 shown in the figure is welded along the circumferential direction by fitting the protruding end 39d of the connecting portion 39b and the inner peripheral surface of the main body 39a. It has a weld 39c to be formed. In the example shown in the figure, the welded portion 39c irradiates the electron beam with reference to the front end portion 39f of the main body 39a that abuts the outer peripheral edge of the connecting portion 29b, and the main body 39a is irradiated more than the region B shown in FIG. Welding is performed in a region C shifted to the front end 39f side. Even in this case, the welded end 39e does not include the tapered surface 39g, and the fitting clearance is applied, and the piston 39 may be damaged.

  In this regard, according to the present embodiment, welding is performed with reference to a position shifted from the front end portion 29f of the main body portion 29a toward the fitting region side with the protruding end portion 29d of the connecting portion 29b. Therefore, the welded portion 29c formed by this welding includes a fitting clearance between the inner peripheral surface of the main body portion 29a and the outer peripheral surface of the protruding end portion 29d, and the welded end portion 29e is a taper of the protruding end portion 29d. Welded portion 29c is formed so as to include a part of surface 29g. For this reason, the weld end 29e is applied to the tapered surface 29g of the protruding end 29d, and the curvature thereof is large. In other words, the angle formed by the welded end 29e and the tapered surface 29g of the protruding end 29d becomes an obtuse angle. Cheap. Therefore, the notch coefficient in the said part becomes low and stress concentration can be relieved. As a result, it is possible to suppress a situation in which the piston 29 is damaged due to deflection or twist caused by a force acting on the piston 39. As a result, the durability and quality of the piston 29 can be improved.

The schematic diagram which shows the whole structure of the compressor 1 concerning embodiment of this invention. Sectional drawing which shows typically the piston 29 concerning 1st Embodiment Explanatory drawing explaining the manufacturing method of piston 29 concerning 1st Embodiment. The conceptual diagram which shows piston 39 as a comparative example with piston 29 in 1st Embodiment. Sectional drawing which shows typically the piston 29 concerning 2nd Embodiment Explanatory drawing explaining the manufacturing method of piston 29 concerning 2nd Embodiment. The conceptual diagram which shows piston 39 as a comparative example with piston 29 in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Cylinder block 3 Cylinder bore 4 Front housing 5 Crank chamber 6 Rear housing 7 Suction chamber 8 Discharge chamber 10 Drive shaft 29 Piston 29a Main body portion 29b Connection portion 29c Welding portion 29d Protruding end portion 29e Welding end portion 29f Front end portion 29g Taper surface

Claims (4)

In the compressor piston (29) that reciprocates in the cylinder bore (3),
A main body (29a) having a hollow cylindrical shape with a front end (29f) open and a rear end having a bottom, and being accommodated in the cylinder bore (3);
A connecting portion (29b) having a protruding end portion (29d) having an outer peripheral shape corresponding to the inner peripheral shape of the main body portion (29a) and connected to a drive mechanism;
The main body part (29a) and the connecting part are formed by fitting the front end part (29f) of the main body part and the protruding end part (29d) of the connecting part and performing welding along the circumferential direction. (29b) and a welded portion (29c) that integrally joins,
The welded portion (29c) is formed by performing welding with reference to a position shifted from the position of the front end portion (29f) of the main body portion toward the fitting region side with the protruding end portion (29d). A piston for a compressor.   The welded portion (29c) includes a fitting clearance between the inner peripheral surface of the main body portion (29a) and the outer peripheral surface of the protruding end portion (29d), and the welded end portion (29e) is the protruding end. The piston for a compressor according to claim 1, wherein the piston is formed so as to include an end face corner portion of the portion. The connecting portion (29d) has a tapered surface (29g) in which an end surface corner portion of the protruding end portion (29d) is chamfered in a tapered shape,
The welded portion (29c) includes a fitting clearance between the inner peripheral surface of the main body portion (29a) and the outer peripheral surface of the protruding end portion (29d), and the welded end portion (29e) is the protruding end. The piston for a compressor according to claim 1, wherein the piston is formed so as to include a part of a tapered surface (29g) of the portion. In the manufacturing method of the piston (29) for the compressor that reciprocates in the cylinder bore (3),
The front end portion (29f) is open and the rear end portion has a hollow cylindrical shape with a bottom, and the main body portion (29a) accommodated in the cylinder bore (3), and the outer peripheral shape is the inside of the main body portion (29a). A connecting portion (29b) having a protruding end portion (29d) corresponding to the circumferential shape and connected to the drive mechanism is formed by a front end portion (29f) of the main body portion and a protruding end portion (29d) of the connecting portion. A first step of performing temporary assembly by fitting;
A second step of performing welding along the circumferential direction with reference to a position shifted from the position of the front end portion (29f) of the main body portion toward the fitting region side with the protruding end portion (29d); The manufacturing method of the piston for compressors which has this.

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