JP4506211B2 - Sliding mechanism - Google Patents

Description

  The present invention relates to a sliding mechanism, and more particularly to a sliding mechanism that includes a shoe and a washer that are in sliding contact with each other and is suitable for use in, for example, a hydraulic transmission or a swash plate type pump.

2. Description of the Related Art Conventionally, for example, as a sliding mechanism for a hydraulic transmission, a washer in which one end surface is a sliding contact surface and the other end surface is supported by a support member, and an axial end is in sliding contact with the sliding contact surface of the washer. A thing provided with the shoe which formed 1 sliding contact surface is known (patent documents 1).
Japanese Patent Laid-Open No. 9-14125.

By the way, the washer of the conventional sliding mechanism is formed in an annular shape with an iron-based thin plate, and the entire region has the same thickness. In this way, since the entire area of the washer is set to the same thickness, there is a drawback that the outer peripheral side of the washer is deformed so as to warp toward the shoe due to frictional heat (see FIGS. 8 and 9). ). When the washer is deformed in this manner, as shown in FIG. 8, a radial gap is generated between the sliding contact surface of the washer and the first sliding contact surface of the shoe. As a result, there is a drawback in that the lubricating oil leaks on the sliding contact surface through the radial gap and the life of the sliding mechanism is shortened.
Further, the shoe of the conventional sliding mechanism has a C-chamfered outer peripheral edge of the first sliding contact surface. With such a configuration, the first sliding contact surface of the shoe is intended to smoothly contact the sliding contact surface of the washer. However, the conventional shoe uses high-strength brass as a material and is manufactured by cutting the material, so there is a drawback that the shoe manufacturing cost is high.
Furthermore, as described above, since the first sliding contact surface of the conventional shoe is a flat surface, it is difficult for the lubricating oil to be drawn between the first sliding contact surface of the shoe and the sliding contact surface of the washer. There were drawbacks. As described above, when the pulling property of the lubricating oil is poor, the wear of the shoe and the washer progresses quickly, and thus the conventional sliding mechanism has a drawback that the life is short.

In view of the above-described circumstances, the present invention interlocks a washer whose one end surface is a sliding surface and the other end surface is supported by a swash plate , and a piston fitted to a cylinder at one end in an axial direction so as to be freely movable back and forth. is allowed, Bei a shoe forming the first sliding surface of the other axial end in sliding contact with the sliding contact surface of the washer Eteori, the shoe is adapted to be slid in the circumferential direction of the washer In the sliding mechanism,
An annular groove along the circumferential direction is formed on the other end face of the washer, and the depth of the annular groove is set to a dimension of 40% or less of the thickness of the washer .

According to such a configuration, the rigidity of the washer can be suppressed by forming the annular groove, and therefore the deformation of the washer due to the influence of frictional heat can be reduced. Therefore, the lubricating oil interposed between the first sliding contact surface of the shoe and the sliding contact surface of the washer is difficult to leak in the circumferential direction of the washer.
Therefore, it is possible to provide a sliding mechanism that has a longer life than the conventional one.

The present invention will be described below with reference to the illustrated embodiment. FIG. 1 shows a main part of a hydraulic mission using the sliding mechanism 1 of the present embodiment.
This hydraulic transmission is integrated with a rotating shaft 6 that is rotatably supported by a bearing (not shown), an annular swash plate 5 that passes through the rotating shaft 6, and a tip (left end portion) of the rotating shaft 6. And a cylindrical cylinder block 7 connected to each other. The cylinder block 7 is formed with a plurality of cylinders 7A each having a bottomed hole at equally spaced positions in the circumferential direction, and a round bar-like piston 4 is slidably fitted to each cylinder 7A.
The sliding mechanism 1 is interposed between the spherical portion 4 </ b> A of each piston 4 and the swash plate 5, and this sliding mechanism 1 has an annular shape slidably superposed on the surface of the swash plate 5. The washer 3 is composed of a plurality of shoes 2 that engage with the spherical portion 4A of each piston 4 and are in sliding contact with the washer 3.
The surface of the washer 3 is a sliding contact surface 3A that is in sliding contact with the first sliding contact surface 2A of the shoe 2, and the back surface 3B of the washer 3 is polymerized on the surface of the swash plate 5. As described above, since the back surface 3B of the washer 3 is simply superposed on the surface of the swash plate 5, the washer 3 and the swash plate 5 can slide in the circumferential direction.
The swash plate 5 and the washer 3 supported by the swash plate 5 are held in a state of surrounding the rotating shaft 6 and inclined by a predetermined angle with respect to the axis of the rotating shaft 6. When necessary, the swash plate 5 and the washer 3 supported by the swash plate 5 have a holding position at a position perpendicular to the rotation shaft 6 from the inclined position shown in FIG. Can be switched.

The shoe 2 is formed in a substantially columnar shape, and the outer peripheral portion on the washer 3 side is a large diameter portion 2C. The end surface of the large diameter portion 2C facing the washer 3 is the first sliding contact surface 2A. A circular recess 2D having a shallow bottom is formed on the center side of the end surface facing the washer 3.
Further, a hemispherical recess is formed on the end surface opposite to the first sliding contact surface 2A, and this is used as the second sliding contact surface 2B. The spherical portion 4A of the piston 4 is slidably engaged with the second sliding contact surface 2B.
The central portion of the second sliding contact surface 2B and the central portion of the concave portion 2D are communicated with each other through a stepped through hole 2E. With such a configuration, the first sliding contact surface 2A having an annular shape is formed on the outer side of the recess 2D, and the first sliding contact surface 2A is brought into contact with the sliding contact surface 3A (front surface) of the washer 3. I am letting.

Since the hydraulic pressure is acting in each cylinder 7A of the cylinder block 7, each shoe 2 engaged with each piston 4 and its spherical portion 4A is urged toward the washer 3. Accordingly, the first sliding contact surface 2A of each shoe 2 is lightly pressed against the sliding contact surface 3A of the washer 3, and the first sliding contact surface 2A and the sliding contact surface 3A of the washer 3 slide in this state. It has become. The back surface 3B of the washer 3 is also lightly pressed against the surface of the swash plate 5.
When the rotary shaft 6 and the cylinder block 7 are rotated by a driving source (not shown), the pistons 4 and the shoes 2 are rotated about the axis of the rotary shaft 6 as a rotation center. Then, the first sliding contact surface 2A of each shoe 2 comes into sliding contact with the sliding contact surface 3A of the washer 3 held in the inclined state shown in FIG. It has come to be.
The above configuration is not different from the conventionally known sliding mechanism 1 of a hydraulic mission.

Thus, in this embodiment, the sliding mechanism 1 is improved as follows, thereby reducing the manufacturing cost of the sliding mechanism 1 and extending its life.
That is, in this embodiment, the shoe 2 is manufactured by forging using a round bar of iron-based material (SUJ2) as a material.
Further, as shown in an enlarged cross-sectional view in FIG. 2, the first sliding contact surface 2 </ b> A of the shoe 2 is not a completely flat surface orthogonal to the axis C of the shoe 2, and the center side (axis The region 2a on the center C side) bulges out from the region 2b on the outer side, whereby the cross section of the first sliding contact surface 2A has a smooth arc shape.
In FIG. 2, only the cross section above the axis C of the first sliding contact surface 2A is shown, and the sectional shape of the first sliding contact surface 2A below the axis C is as follows. Since it appears symmetrically with the upper side, the display is omitted in FIG.
In the present embodiment, the outer diameter D of the large-diameter portion 2C in the shoe 2 is 16 mm, and the central region 2a of the first sliding contact surface 2A is the outer peripheral edge 2b ′ of the outer region 2b (that is, the first The bulging amount L that bulges in the axial direction from the outer peripheral edge 2d of the sliding surface 2A is set to 0.5 μm to 30 μm, more preferably 1 μm to 15 μm.

Further, a portion on the outer side adjacent to the outer peripheral edge 2d of the first sliding contact surface 2A is a chamfered portion 2e, and the chamfered portion 2e is 15 with respect to a virtual plane orthogonal to the axis C. It is chamfered to make an inclination of less than 1 degree. The boundary between the chamfered portion 2e and the outer peripheral surface of the large-diameter portion 2C is chamfered in a circular arc shape, and the boundary portion between the chamfered portion 2e and the outer peripheral edge 2d of the first sliding contact surface 2A is a cross-section. Are connected by a smooth arc 14. The radial dimension for providing the chamfered portion 2e is 0.4 mm to 0.7 mm, and the axial dimension for providing the chamfered portion 2e is 50 μm. The angle between the chamfered portion 2e and a virtual flat surface orthogonal to the axis C may be 10 degrees to 14 degrees.
Moreover, the corner | angular part 8 used as the boundary of the recessed part 2D provided in the center of 2 A of 1st sliding surfaces and the 1st sliding contact surface 2A is chamfering in cross-sectional arc shape.
In the shoe 2 of this embodiment having such a structure, after the round bar as the material is formed by forging, gas soft nitriding treatment is finally applied to the entire area of the first sliding contact surface 2A and the chamfered portion 2e. Has been given.

On the other hand, the washer 3 of this embodiment is manufactured using a copper-based material in connection with manufacturing the shoe 2 using an iron-based material. That is, as shown in the front view from the back surface 3B side in FIG. 3, the washer 3 is made of a thin copper sintered bimetal having an annular shape as a whole, and the back surface 3B on the side opposite to the sliding contact surface 3A is arranged in the circumferential direction. The annular groove 3C is formed.
The annular groove 3C is formed at the center position in the radial direction of the back surface 3B. In other words, when the shoe 2 is in sliding contact with the sliding contact surface 3A and moves in the circumferential direction of the washer 3, the annular groove 3C is formed at the position of the back surface 3B corresponding to the movement locus. Further, as shown in FIG. 4, the annular groove 3C has a semicircular cross section.
Here, assuming that the original thickness of the washer 3 is T, the depth d of the annular groove 3C is set to a dimension of T × (0.3 to 0.4). That is, when T is 12 mm , the depth of the annular groove 3C is set to 3.6 mm to 4.8 mm . Further, when the outer diameter of the large-diameter portion 2C of the shoe 2 is D, the width W of the annular groove 3C is set to a dimension of D × (0.2 to 0.3). That is, when the large diameter portion D is 16 mm, the width W of the annular groove 3C is set to 3.2 to 4.8 mm.
As described above, the washer 3 of this embodiment is manufactured by using a copper sintered bimetal as a material, and the annular groove is formed on the back surface 3B (polymerized surface with the swash plate 5) opposite to the sliding contact surface 3A. 3C is formed. With this configuration, when the first slidable contact surface 2A of the shoe 2 made of an iron-based material and the slidable contact surface 3A of the washer 3 made of a copper-based material are in slidable contact with each other, these slidable contact portions are seized. Is less likely to occur. That is, the sliding mechanism 1 of this embodiment has good seizure resistance.

As described above, in the sliding mechanism 1 of the present embodiment, the shoe 2 is manufactured by forging using an iron-based material. Therefore, the processing time when manufacturing the shoe 2 can be significantly shortened compared to the case of conventional cutting. Further, since the shoe 2 is manufactured by forging as compared with the cutting process, the yield of the material is extremely good. Furthermore, since the shoe 2 of the present embodiment uses an iron-based material (SUJ2), the manufacturing cost can be reduced as compared with the conventional case in which high-strength brass is used.
Moreover, the shoe 2 of the present embodiment bulges the central region 2a of the first sliding contact surface 2A by 0.5 μm or more and 30 μm or less, more preferably 1 μm or more and 15 μm or less than the outer peripheral edge 2d.
Therefore, when the first slidable contact surface 2A of the shoe 2 is in slidable contact with the washer 3, a minute annular space having a wedge-shaped cross section by the two members at the radially inner and outer positions of the central region 2a. Will be formed. Thereby, the lubricating oil is easily drawn into the sliding contact portions (the first sliding contact surface 2A and the sliding contact surface 3A) of both members through the space portion. That is, the sliding mechanism 1 according to the present embodiment can provide a sliding mechanism 1 that has a good pull-in property of the lubricating oil and therefore has a longer life than the conventional one.

Further, the washer 3 of this embodiment is made of a copper-sintered bimetal that is a copper-based material, and has one annular groove 3C formed on the back surface 3B. By providing the annular groove 3C, the deformation can be reduced when the washer 3 is heated by frictional heat.
More specifically, by providing the annular groove 3C, the rigidity of the washer 3 can be suppressed as compared with the case where the annular groove 3C is not provided. Therefore, as shown in FIG. 5, the axial pressing force against the washer 3 due to the first sliding contact surface 2A of the shoe 2 slidingly contacting the sliding contact surface 3A, and the sliding contact surface 3A and the first sliding contact surface 2A The hydraulic pressure of the lubricating oil intervening is added together, and the added load acts to press the washer 3 against the swash plate 5. Therefore, it is possible to suppress the outer peripheral portion of the washer 3 from warping due to the influence of heat, and to reduce the deformation of the washer 3 as compared with the conventional case. As described above, since the deformation of the washer 3 can be reduced, the radial gap generated in the sliding contact portion between the shoe and the washer as shown in FIG. 8 can be reduced. Therefore, the oil leakage of the lubricating oil interposed between the first sliding contact surface 2A of the shoe 2 and the sliding contact surface 3A of the washer 3 can be reduced. As a result, seizure hardly occurs in the sliding contact portion between the first sliding contact surface 2A of the shoe 2 and the sliding contact surface 3A of the washer 3. Therefore, according to the present Example, the sliding mechanism 1 with a long lifetime compared with the past can be provided.
In contrast to the present embodiment, as shown in FIGS. 8 and 9, the conventional washer has high rigidity and is deformed so that the outer peripheral portion is greatly warped due to the influence of heat. Therefore, there is a radial gap in the sliding part between the shoe and the washer, which makes it easier for the lubricating oil to leak. is there.

Next, FIG. 6 shows a second embodiment of the present invention relating to the washer 3. In the second embodiment, the cross-sectional shape of the annular groove 3C of the washer 3 is formed in a trapezoidal shape. Other configurations are the same as those in the first embodiment.
Even in the second embodiment having such a configuration, the same operation and effect as the first embodiment can be obtained.

FIG. 7 shows a sliding mechanism 1 according to a third embodiment of the present invention. In the first embodiment, only one annular groove is formed at the center position in the radial direction on the back surface of the washer 3, but in this third embodiment, three concentric positions are formed on the center side of the back surface of the washer 3. The annular groove 3C is formed. The cross-sectional shape of these annular grooves 3C is semicircular, and the width and depth of the annular grooves 3C are the same. These annular grooves 3 </ b> C are arranged at the position of the back surface 3 </ b> B in the movement locus when the shoe 2 slides on the sliding contact surface 3 </ b> A of the washer 3 in the circumferential direction. Other configurations are the same as those in the first embodiment.
Even in the third embodiment having such a configuration, the same operations and effects as those of the above-described embodiments can be obtained.
In the third embodiment, two annular grooves 3C may be provided, or each annular groove 3C may have a trapezoidal cross section as shown in FIG.
In each of the above embodiments, the case where the present invention is applied to a structure in which the washer 3 is integrally attached to the rotating swash plate 5 has been described. However, the washer 3 is superposed on the inclined surface of the housing on the fixed side. The present invention can also be applied to a configuration in which the above-described shoe 2 is slid with respect to the washer 3 in a state.
Moreover, in the said Example, although the copper sintered bimetal is used as a material of the washer 3, high strength brass may be used instead.

Sectional drawing which shows one Example of this invention. FIG. 2 is an enlarged cross-sectional view exaggerating the main part of FIG. 1. The front view which looked at the washer shown in FIG. 1 from the back surface side. FIG. 4 is an enlarged sectional view taken along line IV-IV in FIG. 3. The figure which shows the state by which the washer shown in FIG. 2 was heated. Sectional drawing which shows 2nd Example of the washer in this invention. Sectional drawing which shows 3rd Example of this invention. Sectional drawing which shows the state by which the conventional sliding mechanism was heated. Sectional drawing which shows the washer of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sliding mechanism 2 ... Shoe 3 ... Washer 3A ... Sliding contact surface 3B ... Back surface 3C ... Annular groove 5 ... Swash plate

Claims (12)

A washer to one end face with a sliding surface and the other end face is supported by the swash plate, in conjunction with a piston fitted in a freely advancing and retreating in a cylinder in the axial direction of the end, the washer in the axial direction of the other end the sliding contact surface in sliding contact first sliding contact surface formed was shoe and the Bei Eteori, in the sliding mechanism the shoe which is adapted to be slid in the circumferential direction of the washer,
A sliding mechanism characterized in that an annular groove is formed along the circumferential direction on the other end face of the washer, and the depth of the annular groove is set to a dimension of 40% or less of the thickness of the washer. .   2. The sliding mechanism according to claim 1, wherein only one annular groove is formed on a radial center side of the other end face.   2. The sliding mechanism according to claim 1, wherein a plurality of the annular grooves are concentrically formed at a location on the other end face on the central portion side in the radial direction.   The annular groove has a semicircular cross section, and the width of the annular groove is a dimension corresponding to 20% to 30% of the outer diameter of the end portion where the first sliding contact surface of the shoe is formed. The slide according to claim 1 or 2, wherein the depth of the annular groove is set to a size corresponding to 30 to 40% of the thickness of the washer. Moving mechanism.   The sliding mechanism according to any one of claims 1 to 3, wherein a cross-sectional shape of the annular groove is substantially trapezoidal.   2. The shoe according to claim 1, wherein the shoe is manufactured using an iron-based material, and a central region of the first sliding contact surface of the shoe is bulged from an outer region. The sliding mechanism according to any one of 5.   The sliding mechanism according to claim 6, wherein a bulging amount of a central region on the first sliding contact surface of the shoe is set to 0.5 μm or more and 30 μm or less.   A chamfered portion is formed at an outer position adjacent to the outer peripheral edge of the first sliding contact surface, and the chamfered portion forms an angle of about 15 degrees with respect to a virtual plane orthogonal to the axial center of the shoe. The first sliding contact surface and the outer peripheral surface of the shoe are connected via the chamfered portion, and the outer peripheral edge of the first sliding contact surface and the chamfered portion are connected to each other. The sliding mechanism according to claim 6 or 7, wherein the boundary portion is formed in an arc shape in cross section.   The sliding mechanism according to any one of claims 6 to 8, wherein a circular recess is formed in the center of the first sliding contact surface.   10. The sliding according to claim 9, wherein a corner portion serving as a boundary between an outer peripheral edge of the circular recess and a central end portion of the first sliding contact surface is chamfered in a circular arc shape in cross section. mechanism.   The sliding mechanism according to any one of claims 1 to 10, wherein the washer is manufactured using a copper-based material. The sliding mechanism according to any one of claims 1 to 11, wherein nitriding treatment is performed on the entire area of the first sliding contact surface.

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