JP2008038987A - Thrust needle bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thrust needle bearing capable of restraining getting-in abrasion of a retainer formed by bending a plate. <P>SOLUTION: A cutout 16hc is formed on a radial outer end of respective pockets 16hp, and thereby, the cutout 16hc works as a passage permitting passing of lubricating oil even when a bearing radial outer end of a roller 16e is pushed and adhered to the radial outer end of the confronting pocket 16hp by centrifugal force F. When the lubricating oil is supplied from either one side of the axial direction of the retainer 16h, the lubricating oil passes the cutout 16hc and flows to the other side, the lubricating state is sufficient, and abrasion of the radial outer end of the pocket 16hp is restrained even when the roller 16e is rotated in a high speed. Thus, getting-in of the roller 16e can be effectively restrained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thrust needle bearing suitable for use in a compressor of a car air conditioner, a planetary gear mechanism for an automatic transmission, office equipment, and the like.

For example, a variable capacity compressor is known as one type of compressor for a car air conditioner (also called a car cooler compressor). Generally, a variable displacement compressor supports a drive shaft rotatably with respect to a housing by a radial bearing, and a swash plate is connected to the drive shaft in a variable inclination angle, and swings with respect to the swash plate. A plate is slidably attached. A thrust bearing is disposed between the swash plate and the swing plate. One end of a plurality of piston rods is attached to the swing plate at equal intervals in the circumferential direction, and the other ends of the piston rods are connected to the piston. The piston is provided so as to slide inside a cylinder provided in the housing, and compresses and discharges the refrigerant gas flowing into the bore of the cylinder. That is, when the swash plate rotates, the swinging plate performs a so-called razor-like operation, reciprocates the piston in the axial direction via the piston rod, and compresses and discharges the refrigerant gas (Patent Document). 1).
JP 2002-266754 A JP 2006-22846 A

  By the way, a thrust needle bearing may be used for a car air conditioner compressor or the like (see Patent Document 2). When the thrust needle bearing rotates, the roller rolls while being pressed outward by a centrifugal force, so that sliding friction occurs between the roller outer end surface and the pocket outer edge end surface of the cage. If the thrust needle bearing rotates at a low speed, the sliding friction is small, but the sliding friction increases as it rotates at a high speed. Arise. Such inconvenience particularly occurs in a cage formed by bending a single plate. When such digging wear occurs, problems such as a decrease in cage strength, an increase in rotational torque, and an increase in bearing temperature occur, which causes flaking and seizure of the thrust needle bearing. In recent years, the rotational speed required for thrust needle bearings has been increased due to the improvement of automobile performance, and therefore, it is one of the problems to solve the above-mentioned scoring wear.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a thrust needle bearing that can suppress the scuffing of a cage formed by bending a single plate material.

The thrust needle bearing of the present invention is a thrust needle bearing comprising a roller and a cage for holding the roller.
The retainer is formed by bending a single plate material, and has a notch formed in a radially outer edge of a pocket that accommodates the roller.

  During operation of the thrust needle bearing, the roller is pressed against the radially outer edge of the cage pocket by centrifugal force, so that the gap between the radially outer edge of the cage pocket and the end face becomes small or zero. Therefore, it becomes difficult to supply the lubricating oil to the radially outer edge of the pocket of the cage and the sliding portion of the end surface, which causes wear and seizure. On the other hand, according to the thrust needle bearing of the present invention, since the retainer forms a notch in the radially outer edge of the pocket that accommodates the roller, the notch serves as a lubricating oil path, That is, since the lubricant easily flows from one side of the cage to the other side through the notch, the outer edge in the radial direction of the pocket in the single-plate cage where the surface pressure tends to be high is well lubricated. By doing so, the digging-in wear is effectively suppressed.

  If the said notch is provided in the center of the radial direction outer edge of the said pocket and the said radial direction outer edge contacts the end part plane of the said roller, it can suppress a dent wear more effectively.

More specifically, the notch width W is preferably W <2 × D × (m−m ² ) ^0.5 . However,
W: width of the notch D: roller end plane diameter z: contact height of the roller end face (the height of the roller end plane and the pocket lower edge when the cage is at its lowest position and there is no notch Difference)
m: z / D
It is.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a compressor of a car air conditioner in which a thrust needle bearing according to the present embodiment is incorporated, and FIG. 2 is a view of the configuration of FIG. 1 viewed in the direction of arrow II.

  In FIG. 1, a housing 6 constituting the compressor 1 includes a central short cylindrical body 7 sandwiched between a head case 8 and a swash plate case 9 from both sides in the axial direction (left-right direction in FIG. 1). It is united by coupling bolts (not shown). Inside the head case 8, low-pressure chambers 10 and 10 and a high-pressure chamber 11 are provided. Note that not only the inside of the high pressure chamber 11 but also the inside of the low pressure chambers 10 and 10 are positive. A flat partition plate 12 is sandwiched between the main body 7 and the head case 8. The low-pressure chambers 10 and 10 represented as being divided into a plurality of parts in FIG. 1 communicate with each other and communicate with a single suction port 13 (FIG. 2) provided on the outer surface of the head case 8. . The high pressure chamber 11 communicates with a discharge port (not shown) provided in the head case 8. The suction port 13 communicates with the outlet of an evaporator (not shown), and the discharge port (not shown) communicates with the inlet of a condenser (not shown).

  A shaft 14 is rotatably supported in the housing 6 in a state of being spanned between the main body 7 and the swash plate case 9. More specifically, both ends of the shaft 14 are rotatably supported with respect to the main body 7 and the swash plate case 9 by a pair of radial needle bearings 15A and 15B, and a pair of thrust needle bearings 16A and 16B. Thus, the thrust load applied to the shaft 14 can be supported freely.

  The thrust needle bearing 16A has a plurality of rollers 16a, raceways 16b and 16c that clamp the rollers 16a in the axial direction (left and right in FIG. 1), and a cage 16d that holds the rollers 16a. The thrust needle bearing 16B according to the present embodiment includes a plurality of rollers 16e, raceways 16f and 16g that sandwich the rollers 16e in the axial direction (left and right in FIG. 1), and a cage 16h that holds the rollers 16e. is doing.

  The radial needle bearing 15A has a plurality of rollers 15a, a shell-type outer ring 15b, and a cage 15c that holds the rollers 15a. The radial needle bearing 15B includes a plurality of rollers 15d, an outer ring (track ring) 15e, and a cage 15f that holds the rollers 15d.

  The thrust needle bearing 16A is provided via a disc spring 18 between a part of the main body 7 and a step portion 17 formed at one end portion (right end side in FIG. 1) of the shaft 14. The thrust needle bearing 16 </ b> B is disposed between the disc portion 19 and the swash plate case 9 that are fitted and fixed to the outer peripheral surface of the intermediate portion of the shaft 14. A plurality of (for example, six in the example shown in the figure in the circumferential direction) cylinder holes 20, 20 are formed in the periphery of the shaft 14 inside the main body 7 constituting the housing 6. Sliding portions 22, 22 provided in the front half (right half in FIG. 1) of the pistons 21, 21 are respectively provided inside the plurality of cylinder holes 20, 20 formed in the main body 7 in this manner. It is fitted so that it can be displaced in the direction.

  Here, a space provided between the bottom surfaces of the cylinder holes 20 and 20 and the tip surfaces (right end surfaces in FIG. 1) of the pistons 21 and 21 is referred to as a compression chamber 23. The space existing inside the swash plate case 9 is a swash plate chamber 24. A swash plate 25 is fixed at a predetermined inclination angle with respect to the shaft 14 at a portion located in the swash plate chamber 24 on the outer peripheral surface of the intermediate portion of the shaft 14, and the swash plate 25 rotates together with the shaft 14. I try to do it. A plurality of locations in the circumferential direction of the swash plate 25 and the pistons 21 and 21 are connected by a pair of sliding shoes 26 and 26, respectively. For this reason, the inner side surfaces (surfaces facing each other) of these sliding shoes 26 and 26 are flat surfaces so as to be in sliding contact with portions on both side surfaces of the swash plate 25 that are also flat surfaces. Further, the outer side surfaces of these sliding shoes 26, 26 (side surfaces opposite to the mating sliding shoe 26) are spherical convex surfaces. Further, the outer surfaces of the sliding shoes 26 and 26 are positioned on a single spherical surface with the inner surface thereof being in contact with both side surfaces of the swash plate 25. On the other hand, a driving force transmission mechanism is constructed with sliding shoes 26 and 26 and a swash plate 25 at the base end of each piston 21 and 21 (the end far from the partition plate 12 and the left end in FIG. 1). The connecting portions 27 and 27 are formed integrally with the pistons 21 and 21, respectively. The connecting portions 27 and 27 are formed with holding portions 28 and 28 for holding the pair of sliding shoes 26 and 26. The holding portions 28 and 28 are formed with spherical concave surfaces that are in close sliding contact with the outer surfaces of the sliding shoes 26 and 26 so as to face each other.

  Further, a pair of guide surfaces (not shown) for each piston 21, 21 is provided on the part of the inner peripheral surface of the main body 7 that is aligned with the outer end of each connecting portion 27, 27. They are spaced apart in the circumferential direction. The outer end portions of the connecting portions 27 and 27 are guided by the guide surfaces, and can only be displaced in the axial direction of the pistons 21 and 21 (left and right direction in FIG. 1). Therefore, the pistons 21 and 21 are also prevented from rotating around the central axis of the pistons 21 and 21 in the cylinder holes 20 and 20 due to the rotation of the swash plate 25, and can only be displaced in the axial direction (non-rotatable). ). As a result, the connecting portions 27 and 27 push and pull the pistons 21 and 21 in the axial direction as the swash plate 25 is oscillated and displaced by the rotation of the shaft 14. , 20 to reciprocate in the axial direction.

  On the other hand, in order to partition the low-pressure chamber 10 and the high-pressure chamber 11 from the cylinder holes 20, 20, the partition plate 12 sandwiched between the abutting portions of the main body 7 and the head case 8 includes the low-pressure chamber 10 and the cylinder holes 20. , 20 and the discharge holes 30, 30 communicating with the high-pressure chamber 11 and the cylinder holes 20, 20 are formed in a state of penetrating in the axial direction. Accordingly, the opening on the cylinder hole 20, 20 side at one end (the left end in FIG. 1) of each suction hole 29, 29 and each discharge hole 30, 30 is opposed to the tip surface of each piston 21, 21. In addition, a reed valve type suction that allows refrigerant gas to flow only from the low-pressure chamber 10 toward each cylinder hole 20, 20 in a part of each cylinder hole 20, 20 facing one end of each suction hole 29, 29. Valves 31 are provided. Further, in the high-pressure chamber 11, the refrigerant gas is allowed to flow only from the cylinder holes 20, 20 toward the high-pressure chamber 11 in the portion facing the other end (right end in FIG. 1) opening of each discharge hole 30, 30. A reed valve type discharge valve 32 is provided. The discharge valve 32 is provided with a stopper 33 that restricts displacement in a direction away from the discharge holes 30.

  The shaft 14 of the compressor 1 configured as described above is rotationally driven via an endless belt 42 by a vehicle engine (not shown). For this reason, in the case of the illustrated example, the driven pulley 35 around the support cylinder portion 34 provided in the center of the outer surface (left side surface in FIG. 1) of the swash plate case 9 constituting the housing 6 is connected to a double row radial ball. The bearing 36 is rotatably supported. The driven pulley 35 has a U-shaped cross section and is formed in an annular shape as a whole. A solenoid 37 fixed to the outer surface of the swash plate case 9 is disposed in the internal space of the driven pulley 35. On the other hand, a mounting bracket 38 is fixed to a portion protruding from the support cylinder portion 34 at the end of the shaft 14, and an annular plate 39 made of a magnetic material is supported around the mounting bracket 38 via a plate spring 40. is doing. When the solenoid 37 is not energized, the annular plate 39 is separated from the driven pulley 35 by the elastic force of the leaf spring 40 as shown in the figure. However, when the solenoid 37 is energized, the annular plate 39 is attracted toward the driven pulley 35. The rotational force from the driven pulley 35 to the shaft 14 can be freely transmitted. That is, the solenoid 37, the annular plate 39, and the leaf spring 40 constitute an electromagnetic clutch 41 for engaging and disengaging the driven pulley 35 and the shaft 14. Further, an endless belt 42 is stretched between a driving pulley and a driven pulley 35 fixed to an end of a crankshaft (not shown) of a vehicle engine.

  The operation of the compressor of the car air conditioner according to the present embodiment will be described. When the car air conditioner is operated to cool or dehumidify the passenger compartment, the electromagnetic clutch 41 is operated to engage the driven pulley 35 and the shaft 14, thereby causing the vehicle to pass through the endless belt 42. The power of the engine is transmitted to the shaft 14 and is driven to rotate. As a result, the swash plate 25 rotates to reciprocate the sliding portions 22 and 22 constituting the plurality of pistons 21 and 21 in the cylinder holes 20 and 20, respectively. As the sliding portions 22 and 22 reciprocate, the refrigerant gas sucked from the suction port 13 is sucked into the compression chamber 23 from the low pressure chambers 10 and 10 through the suction holes 29 and 29. . The refrigerant gas is compressed in each of the compression chambers 23 and then sent to the high-pressure chamber 11 through the discharge holes 30 and 30 and is discharged from the discharge port. After that, the high-temperature and high-pressure refrigerant gas is cooled by a condenser to become a liquid refrigerant, and then rapidly expanded to flow into the evaporator as a low-temperature and low-pressure mist refrigerant, where the air supplied to the passenger compartment After cooling, the refrigerant gas is sucked into the compressor.

  FIG. 3 is a front view of the thrust needle bearing 16B shown with the raceway removed. FIG. 4 is a view of the configuration of FIG. 3 taken along the line IV-IV and viewed in the direction of the arrow. FIG. 5 is an enlarged view of an arrow V portion of the configuration of FIG. 6 (a) is a partial perspective view of the cage 16h of the present embodiment, and FIG. 6 (b) is a perspective view showing a state in which the rollers 16e are incorporated in the cage 16h. It is shown from the lower surface side.

  In FIG. 5, a cage 16 h that is integrally formed by bending a single donut-shaped plate material so that the cross-section is M-shaped is doubled on the radially inner wall cylinder 16 hi and on the radially outer side. The outer wall cylinder 16ho is bent, and the center portion 16hm is bent in a U shape at the center. Between the inner wall cylinder 16hi and the outer wall cylinder 16ho, rectangular hole-shaped pockets 16hp for accommodating the rollers 16e are formed at equal intervals in the circumferential direction. A notch 16hc is formed in the center of the radially outer edge of each pocket 16hp. As shown in FIG. 6B, the central portion 16hm has a function of holding the rollers 16e disposed on both sides in the circumferential direction and preventing the rollers 16e from coming out upward in FIG.

  FIG. 7 is a cross-sectional view similar to FIG. 5 of the cage 16h 'according to the comparative example. FIG. 8A is a partial perspective view of a cage 16h ′ of a comparative example, and FIG. 8B is a perspective view showing a state in which the roller 16e is incorporated in the cage 16h ′. It is shown from the lower surface side. The cage 16h 'according to the comparative example has the same configuration as the cage 16h, except that a notch is not formed in the radially outer edge of each pocket 16hp. With reference to a comparative example, the effect of this Embodiment is demonstrated.

  First, in the comparative example shown in FIGS. 7 and 8, since the centrifugal force F acts on the roller 16e during the operation of the thrust needle bearing, the outer end in the bearing radial direction of the roller 16e has a pocket facing it as shown by an arrow. Pressed against the radially outer edge of 16 hp, the gap between them is minute or zero. In such a state, even when lubricating oil is supplied from either one of the axial directions of the cage 16h ′, it passes between the bearing radial outer end of the roller 16e and the radial outer edge of the pocket 16hp. In this case, since the flow to the other side is suppressed and the lubrication state becomes poor, the roller 16e that rotates at a high speed wears the radially outer edge of the pocket 16hp, and it gets into the radially outer edge like a drill. May occur.

  On the other hand, according to the present embodiment, as shown in FIG. 5, the notch 16hc is formed in the radially outer edge of each pocket 16hp, so that the bearing radial outer end of the roller 16e is moved by the centrifugal force F. Even when pressed against the radially outer edge of the pocket 16hp facing it, the notch 16hc becomes a passage allowing the passage of the lubricating oil. Therefore, when lubricating oil is supplied from one side of the cage 16h in the axial direction, the lubricating oil flows through the notch 16hc and flows to the other side. Even in the case of high-speed rotation, it is possible to suppress wear of the outer edge in the radial direction of the pocket 16hp and to effectively suppress the rolling-in of the roller 16e.

  Hereinafter, the size of the notch 16hc will be considered. As shown in FIG. 9, generally, the end surface of the roller 16e is formed with a plane portion (also referred to as an end portion plane) 16ep orthogonal to the axis and a chamfered portion 16ec around it. Therefore, the dimensional relationship between the chamfered portion 16ec and the notch 16hc of the pocket 16hp becomes a problem. Here, as shown in FIG. 9, the outer diameter of the flat surface portion 16 ep is D, and the width of the chamfered portion 16 ec in the direction perpendicular to the axis is a chamfering amount C. Also, as shown in FIG. 10, in the state where the cage 16h is instructed, the difference between the upper end of the roller 16e and the upper end of the cage 16h in the state where the roller 16e that has received gravity is lowered most (when the roller 16e is high) Is a positive value, and negative is when the cage 16h is high).

  FIG. 11 is a view of the roller 16e and the cage 16h as seen through in the axial direction. Here, the contact height z of the end face of the roller 16e is defined as “the flat portion 16ep of the roller 16e in the state where the cage 16h is lowest with respect to the roller 16e and no notch 16hc, and the lower edge of the pocket 16hp. If it is defined as “the difference in height of”, it can be expressed by z = t−Q−C (where t is the thickness of the cage). Further, the value represented by z / D is m, and the width of the notch 16hc in the direction perpendicular to the axis is W.

The state shown in FIG. 11A shows a state where the edge of the pocket 16hp interferes with the chamfered portion 16ec of the roller 16e. At this time, the width W of the notch 16hc is
W> 2 × D × (m−m ² ) ^0.5 (1)
It becomes.

The state shown in FIG. 11B shows a state where the edge of the pocket 16hp is located at the boundary between the chamfered portion 16ec and the flat portion 16ep of the roller 16e. At this time, the width W of the notch 16hc is
W = 2 × D × (m−m ² ) ^0.5 (2)
It becomes.

The state shown in FIG. 11C shows a state in which the edge of the pocket 16hp is in contact with the flat portion 16ep of the roller 16e. At this time, the width W of the notch 16hc is
W <2 × D × (m−m ² ) ^0.5 (3)
It becomes.

Considering the above, if the edge of the pocket 16hp interferes with the chamfered portion 16ec of the roller 16e, the cage 16h may be worn by prolonged use even if the lubrication state is good. On the other hand, it can be seen that it is desirable to satisfy the expression (3) in order to always bring the edge of the pocket 16hp into contact with the flat portion 16ep of the roller 16e. Furthermore, in order to reliably suppress interference with the chamfered portion 16ec,
W <1.5 × D × (m−m ² ) ^0.5 (4)
It is desirable to satisfy.

FIG. 12 is a diagram illustrating a dimensional relationship between the roller 16e and the cage 16h according to the embodiment. When the chamfering amount C = 0.4 mm in the roller 16e having an outer diameter of 3 mm, the outer diameter D of the flat portion 16ep is 2.2 mm. On the other hand, when the plate thickness t of the cage 16h is 0.5 mm and the roller drop amount Q is −0.2 mm, the contact height z of the end face of the roller 16e is 0.3 mm. Therefore, since the value m = z / D = 0.136, 2 × D × (m−m ² ) ^0.5 = 1.51. Therefore, if the width W of the notch 16hc is set to 1 mm, a thrust needle bearing with suppressed wear can be provided.

  The present invention has been described above with reference to the embodiments. However, the present invention is not limited to the above-described embodiments, and can of course be changed or improved within the scope of the invention. For example, the thrust needle bearing can be applied not only to a car cooler compressor but also to various machines such as a transmission for an automobile and office equipment.

It is sectional drawing of the compressor of the car air conditioner in which the needle bearing concerning this Embodiment was integrated. It is the figure which looked at the structure of FIG. 1 in the arrow II direction. It is a front view of thrust needle bearing 16B shown in the state where a bearing ring was removed. It is the figure which cut | disconnected the structure of FIG. 3 by the arrow IV-IV line, and looked at the arrow direction. It is a figure which expands and shows the arrow V part of the structure of FIG. FIG. 6A is a partial perspective view of the cage 16h of the present embodiment, and FIG. 6B is a perspective view showing a state in which the rollers 16e are incorporated in the cage 16h. It is sectional drawing similar to FIG. 5 of the holder | retainer 16h 'concerning a comparative example. FIG. 8A is a partial perspective view of a cage 16h ′ of a comparative example, and FIG. 8B is a perspective view showing a state in which the rollers 16e are incorporated in the cage 16h ′. It is a side view of a roller. It is a side view of the roller illustrated with a holder | retainer. It is the figure which saw the roller 16e and the holder | retainer 16h seeing through in the axial direction. It is a figure which shows the dimensional relationship of the roller 16e concerning an Example, and the holder | retainer 16h.

Explanation of symbols

1 Compressor for car air conditioner 6 Housing 14 Shaft 15A, 15B Radial needle bearing 16A, 16B Thrust needle bearing

Claims (2)

In a thrust needle bearing comprising a roller and a cage for holding the roller,
The thrust needle bearing according to claim 1, wherein the retainer is formed by bending a single plate material, and a notch is formed in a radially outer edge of a pocket accommodating the roller. The thrust needle bearing according to claim 1, wherein the notch is provided at a center of a radially outer edge of the pocket, and the radially outer edge contacts an end plane of the roller.

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