JP6672199B2 - Oblique axis type hydraulic rotary machine - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a diagonal axis type hydraulic rotary machine suitably used for a hydraulic pump, a motor, and the like mounted on a construction machine such as a hydraulic shovel.

  2. Description of the Related Art In general, as a hydraulic rotary machine used as a hydraulic pump or a hydraulic motor in a construction machine such as a hydraulic shovel or a general machine, for example, a fixed-capacity or variable-capacity oblique-axis hydraulic rotary machine is known.

  This type of oblique-type hydraulic rotating machine includes a cylindrical casing, a rotating shaft located on one side of the casing and rotatably provided via a bearing, and a rotating shaft located in the casing. And a plurality of cylinder holes provided in the casing so as to rotate integrally with the rotating shaft and extending in the circumferential direction and spaced apart in the circumferential direction. One end in the axial direction forms a spherical surface with the cylinder block, and the joint portion is swingably supported by the concave spherical surface of the drive disk. The other end in the axial direction is reciprocally fitted into each cylinder hole of the cylinder block. And a plurality of pistons serving as piston body portions.

  The piston is provided with an oil hole penetrating in the axial direction of the piston, from which lubricating oil is supplied between the concave spherical surface of the drive disk and the joint portion of the piston. Thus, lubrication is performed between the concave spherical surface of the drive disk and the joint portion of the piston (for example, see Patent Documents 1 and 2).

Japanese Utility Model Publication No. Sho 60-134878 JP 2013-227879 A

  By the way, in the above-described conventional oblique-axis hydraulic rotating machine, if the spherical diameter difference between the joint portion of the piston and the concave spherical surface of the drive disk is too small, the floating of the piston due to pressurization of the lubricating oil occurs, There is a possibility that the leakage amount of the lubricating oil becomes excessive. On the other hand, if the spherical diameter difference between the joint portion of the piston and the concave spherical surface of the drive disk is large, the surface pressure between the joint portion and the concave spherical surface increases, and the output power relative to the input power of the oblique-axis hydraulic rotary machine increases. The efficiency (mechanical efficiency) may be reduced.

  The present invention has been made in view of the above-described problems of the related art, and an object of the present invention is to reduce a surface pressure between a joint portion of a piston and a concave spherical surface of a drive disk and to adjust a leakage amount of a lubricating oil appropriately. Accordingly, it is an object of the present invention to provide an oblique-axis hydraulic rotating machine having improved mechanical efficiency.

In order to solve the above-described problem, the present invention provides a cylindrical casing, a rotating shaft located on one side of the casing and rotatably provided via a bearing, and a rotating shaft located in the casing. And a plurality of cylinder holes provided in the casing so as to rotate integrally with the rotating shaft and extending in the circumferential direction and spaced apart in the circumferential direction. One end in the axial direction forms a spherical surface with the cylinder block, and the joint portion is swingably supported by the concave spherical surface of the drive disk. The other end in the axial direction is reciprocally fitted into each cylinder hole of the cylinder block. In the oblique-axis type hydraulic rotary machine provided with a plurality of pistons serving as a separated piston main body, the piston includes an oil hole formed in the piston in an axial direction and through which lubricating oil flows. Wherein the joint portion of the piston is located on one side of the piston in the axial direction and is formed perpendicular to a piston axis serving as a central axis of the piston, and the flat surface of the piston A first curved surface formed into a spherical surface from the flat surface toward the other side in the axial direction; and a second curved surface formed from the first curved surface of the piston toward the other side in the axial direction with a smaller diameter than the first curved surface. The first curved surface is a curved surface having a radius Ra having a spherical center on the piston axis, and the first curved surface and the curved surface are arranged from the distal end side to the proximal end side of the joint portion. The second curved surface constitutes a range up to a first end point, and has an angle θ between the first end point and the piston axis passing through the center of the spherical surface, and the second curved surface is , The center of the spherical surface of the first curved surface and the The joint portion as a curved surface formed by rotating an arc of a radius Rb having a center on an imaginary line connecting the first end point and having a radius smaller than the radius Ra of the first curved surface around the piston axis. Are formed toward the other side in the axial direction from the first end point, and at the first end point, the tangent to the first curved surface and the tangent to the second curved surface become a common common tangent and are connected. And extending the second curved surface and the first curved surface at a position of a second end point where an intersection line orthogonal to the piston axis passes through the center of the spherical surface of the first curved surface and intersects the second curved surface. The dimensional difference from the imaginary line in this case is set to not less than 12.5 μm and not more than 30 μm, and the first curved surface has an arc shape with the center of the spherical surface and the radius Ra equivalent to the concave spherical surface of the drive disk. Is a part that slides with the concave spherical surface The second curved surface is characterized in that the dimensional difference is set so that lubricating oil flows between the second curved surface and the concave spherical surface of the drive disk.

According to the present invention, it is possible to secure the contact pressure between the joint portion and the concave spherical surface of the drive disc, it is possible to properly secure the amount leaked Jun Namerayu, to improve the mechanical efficiency Can be.

FIG. 1 is a longitudinal sectional view showing a diagonal axis type hydraulic motor according to a first embodiment of the present invention. It is an expanded sectional view which shows the taper piston in FIG. 1 by itself. FIG. 3 is a cross-sectional view of a first curved surface and a second curved surface constituting a joint portion of the tapered piston in FIG. FIG. 4 is a sectional view similar to FIG. 3 showing a joint portion of a tapered piston according to a second embodiment of the present invention. FIG. 13 is an enlarged front view of a main part showing a joint part of a tapered piston according to a third embodiment of the present invention.

  Hereinafter, an example in which the oblique-axis hydraulic rotating machine according to an embodiment of the present invention is applied to a fixed displacement-type oblique-axis hydraulic motor will be described in detail with reference to the accompanying drawings.

  Here, FIGS. 1 to 3 show a first embodiment of the present invention. In FIG. 1, a fixed displacement type oblique-axis hydraulic motor 1 (hereinafter, referred to as a hydraulic motor 1) as an oblique-axis hydraulic rotating machine is supplied with pressure oil from a hydraulic source (not shown) such as a hydraulic pump. Thus, the rotating shaft 5 described later is driven to rotate.

  The casing 2 forms an outer shell of the hydraulic motor 1, and the casing 2 includes a casing main body 3 having a tubular shape with an intermediate portion bent, and a head casing 4 described later.

  As shown in FIG. 1, the casing body 3 is composed of one side cylindrical portion 3A located on one side in the axial direction and another side cylindrical portion 3B on the other side in the axial direction. An intermediate portion with the cylindrical portion 3B is bent. Further, a shaft insertion hole 3C is formed at one end of the one side cylindrical portion 3A of the casing body 3 on one side in the axial direction.

  The head casing 4 is fixed to a head-side end surface located on the other cylindrical portion 3B side of the casing main body 3. The head casing 4 has a pair of supply / discharge passages (both not shown). Of these supply / discharge passages, the supply / discharge passages on the high pressure side supply the pressure oil discharged from a hydraulic pump (not shown) to the respective cylinder holes 9 through supply / discharge ports (not shown) of a valve plate 10 described later. Supply within. The supply / discharge passage on the low pressure side discharges return oil from a supply / discharge port side of the valve plate 10 described later toward a tank (not shown).

  The rotation shaft 5 is provided in one side cylindrical portion 3A of the casing main body 3. The rotary shaft 5 constitutes an output shaft of the hydraulic motor 1 and is rotatably provided in one cylindrical portion 3A of the casing body 3 via a bearing or the like. One end of the rotating shaft 5 projects outside the casing body 3 through the shaft insertion hole 3C, and is connected to devices (not shown) driven by a hydraulic motor such as a planetary gear reduction device.

  On the other hand, a drive disk 6 that rotates integrally with the rotary shaft 5 is integrally formed on the base end side (the other end side) of the rotary shaft 5 extending inside the one side cylindrical portion 3A of the casing body 3 toward the other side cylindrical portion 3B. Is provided. The drive disk 6 is arranged at a position near the boundary between the one side cylindrical portion 3A and the other side cylindrical portion 3B of the casing body 3.

  The drive disk 6 is slidably connected to a spherical portion 11A of a center shaft 11 which is located at the center of the other end face facing the cylinder block 7 which will be described later. A plurality of rotation-transmitting tapers, which are radially outside the spherical surface 6A and the concave spherical surface 6A for the center shaft and are spaced apart from each other in the circumferential direction so that joint portions 17 of the respective tapered pistons 13 described later are swingably connected. A concave spherical surface for piston 6B is provided. The concave spherical surface 6B for a taper piston is formed as a concave spherical surface having a spherical center O1 and a radius Ra. The concave spherical surface for taper piston 6B constitutes the concave spherical surface of the present invention.

  The cylinder block 7 is rotatably provided in the casing 2. The cylinder block 7 is connected to the drive disk 6 via a later-described center shaft 11, tapered pistons 13, and the like, and rotates integrally with the rotating shaft 5. Here, the cylinder block 7 is formed in a thick cylindrical shape, and a center hole 8 into which a center shaft 11 to be described later is slidably inserted is formed in the center of the cylinder block 7 along a rotation center axis. ing. The cylinder block 7 has a plurality of cylinder holes 9 (usually an odd number such as five, seven, or nine) that are spaced apart from each other at a fixed interval in the circumferential direction around the center hole 8 and extend in the axial direction. (Only one is shown).

  The end surface of the cylinder block 7 on the head casing 4 side is a sliding surface 7A having a concave curved surface shape that slides on a valve plate 10 described later. A plurality of cylinder ports 9A (only one is shown) are formed between the sliding surface 7A of the cylinder block 7 and each of the cylinder holes 9 so as to communicate with and block the valve plate 10 on the sliding surface 7A side. .

  The valve plate 10 is provided between the head casing 4 of the casing 2 and the cylinder block 7. This valve plate 10 is fixed to the head casing 4 with one side facing the cylinder block 7 being a convexly curved switching surface 10A and the other side being a flat surface. The cylinder block 7 rotates while its sliding surface 7 </ b> A slides on the switching surface 10 </ b> A of the valve plate 10, so that pressure oil is supplied to and discharged from each cylinder hole 9.

  That is, a pair of supply / discharge ports (not shown) having an eyebrow shape are formed in the valve plate 10 so as to extend in the circumferential direction, and these supply / discharge ports are connected to a pair of supply / discharge passages formed in the head casing 4. (Not shown). The supply / discharge port intermittently communicates with the cylinder port 9A of each cylinder hole 9 as the cylinder block 7 rotates.

  In this case, one supply / discharge port on the high pressure side is connected to the supply / discharge passage on the high pressure side of the pair of supply / discharge passages, and pressurized oil discharged from a hydraulic pump (not shown) is provided in each cylinder hole 9. To supply. The other low pressure side supply / discharge port is connected to the low pressure side supply / discharge passage of the pair of supply / discharge passages, and directs return oil discharged from each cylinder hole 9 to a tank (not shown) side. To discharge.

  The center shaft 11 is provided by being inserted into the center hole 8 for centering the cylinder block 7. The center shaft 11 has a spherical portion 11A at one end and a bottomed spring receiving hole 11B at the other end. The spherical portion 11A of the center shaft 11 is slidably fitted on a center shaft concave spherical surface 6A formed on the center side of the drive disk 6.

  The spring 12 is provided between the center shaft 11 and the cylinder block 7. The spring 12 is disposed in the spring receiving hole 11B of the center shaft 11, and constantly biases the cylinder block 7 toward the switching surface 10A of the valve plate 10. As a result, the cylinder block 7 rotates relative to the valve plate 10 in the forward or reverse direction with the sliding surface 7A being in close contact with the switching surface 10A of the valve plate 10.

  A plurality of taper pistons 13 (only one is shown) are reciprocally inserted into respective cylinder holes 9 of the cylinder block 7. As shown in FIG. 2, these tapered pistons 13 are formed integrally with a piston main body portion 14 formed by tapering from one end side to the other end side, and formed on one end side of the piston main body portion 14. And a lubricating oil hole 26 through which the lubricating oil flows through the tapered piston 13 in the axial direction of the piston from the end face on the other end side of the piston body 14 toward the joint 17. ing.

  That is, these taper pistons 13 form a joint portion 17 which is formed so that one side in the axial direction is spherical and is swingably supported by the concave spherical surface 6B for the taper piston of the drive disk 6, and the other side in the axial direction is the cylinder block 7. A piston body 14 is inserted into each cylinder hole 9 so as to be reciprocally movable.

  The piston body 14 is located on one end side and integrally connected to the joint 17 and the other end is integrally connected to the connection 14A and slides into the cylinder hole 9. And a tapered portion 14B which is inserted as much as possible. A cylinder inner surface contact portion 14C that is in contact with the cylinder hole 9 is formed in the tapered portion 14B, and a portion between the cylinder hole 9 and the cylinder inner surface contact portion 14C is provided on the outer peripheral side of the tapered portion 14B. Seal members 15, 16 made of a piston ring or the like for ensuring sealing performance are mounted. The diameter of the cylinder inner surface contact portion 14 </ b> C is configured to be slightly smaller than the inner diameter of the cylinder hole 9. The tapered piston 13 constitutes the piston of the present invention.

  Next, the joint 17 of the tapered piston 13 will be described.

  The joint portion 17 of the tapered piston 13 has a spherical surface and is swingably (slidably) connected to the concave spherical surface 6B for the tapered piston of the drive disk 6. Between the joint portion 17 and the concave spherical surface 6B for the taper piston, a part of the oil liquid supplied into the cylinder hole 9 becomes lubricating oil and is supplied from the oil hole 26 side. The joint portion 17 is located on one side (tip side) in the piston axial direction and orthogonal to the piston axis A-A, and the other side of the piston axial direction from the flat surface 18 (the piston body portion 14 side). ) As a large-diameter portion extending as a spherical surface and a small-diameter portion extending from the first curved surface 19 toward the other side in the axial direction of the piston and having a smaller diameter than the first curved surface 19. The second curved surface 21 is included.

  As shown in FIG. 3, the first curved surface 19 is formed as a curved surface (arc shape) having a spherical center O1 and a radius Ra. In this case, the spherical center O1 is located on the piston axis AA which is also the center axis of the piston body 14. The first curved surface 19 forms one side (tip side) of the spherical surface of the joint portion 17 in the piston axial direction. Specifically, the first curved surface 19 constitutes a range from the distal end side to the proximal end side of the joint portion 17 to an end point 20. In this case, the end point 20 is located in a range where the angle θ formed between the taper piston 13 and the piston axis AA (dashed-dotted line AA in FIG. 3) passing through the spherical center O1 is represented by the following equation 1. . The position (angle θ) of the end point 20 is set by an experiment or the like based on wear resistance and mechanical efficiency calculated from a relationship with a dimensional difference ΔD described later.

  The radius of the concave spherical surface 6 </ b> B for the taper piston is slightly larger than the radius Ra of the first curved surface 19 in order to ensure assemblability and the like. The first curved surface 19 is a portion that slides (contacts) with the concave spherical surface 6B for the taper piston of the drive disk 6, and is a region where a thin oil film of lubricating oil is formed between the first curved surface 19 and the concave spherical surface 6B for the taper piston.

  On the other hand, the second curved surface 21 constitutes the other side (base end side) of the spherical surface of the joint portion 17 in the piston axial direction. The second curved surface 21 is formed as a curved surface (arc shape) having a center O2 of an arc forming the second curved surface 21 and a radius Rb (Rb <Ra), and the other side in the piston axial direction from the end point 20 (the piston body portion 14 side). ). The second curved surface 21 is a curved surface formed by rotating an arc having a radius Rb around O2 around the piston axis AA. The center O2 of the arc forming the second curved surface 21 is located on a dotted line 22 connecting the spherical center O1 of the first curved surface 19 and the end point 20.

  Thus, at the end point 20 where the first curved surface 19 and the second curved surface 21 are connected, the tangent of the first curved surface 19 and the tangent of the second curved surface 21 are connected to each other as a common tangent 23. As a result, the first curved surface 19 and the second curved surface 21 at the end point 20 are smoothly connected (connected), so that the lubricating oil flowing through the end point 20 can be efficiently circulated, and an increase in surface pressure is suppressed. be able to.

  Further, the radius Rb of the arc forming the second curved surface 21 is formed smaller than the radius Ra of the first curved surface 19. The radius Rb of the second curved surface 21 is such that an intersecting line BB (dashed line BB in FIG. 3) orthogonal to the piston axis AA through the spherical center O1 of the first curved surface 19 is the spherical surface of the joint portion 17. Is set such that a dimensional difference ΔD between an imaginary line 25 (two-dot chain line 25 in FIG. 3) when the second curved surface 21 and the first curved surface 19 are extended at a position of an end point 24 intersecting with the predetermined value. Have been. In this case, the dimensional difference ΔD between the second curved surface 21 and the imaginary line 25 when the first curved surface 19 is extended at the position of the end point 24 is set in the range shown by the following equation (2). The radius Rb of the second curved surface 21 based on the dimensional difference ΔD is set by an experiment or the like from the relationship with the first curved surface 19.

  The dimensional difference ΔD sets the size of the flow path of the lubricating oil flowing from the distal end side to the proximal end side of the joint portion 17. By setting the dimensional difference ΔD in this way, the lubricating oil can be efficiently circulated, so that pressure build-up can be reduced.

  As described above, the joint portion 17 of the tapered piston 13 is located on the distal end side in the piston axial direction and slidably contacts the concave spherical surface 6B for the tapered piston, and the proximal end side in the piston axial direction (the piston body portion 14 side). ) And is connected to the first curved surface 19, and has a second curved surface 21 having a predetermined dimensional difference ΔD between the end surface 24 and the concave spherical surface 6 </ b> B for the tapered piston. That is, the joint portion 17 of the tapered piston 13 has a dimension Ra from the spherical center O1 from the distal end side of the joint portion 17 in the piston axial direction to the end point 20, and has a spherical center from the end point 20 toward the base end side of the joint portion 17. It is formed so that the dimension from O1 gradually decreases.

  The oil hole 26 extends in the taper piston 13 in the axial direction of the piston. The oil hole 26 has an oil passage 26A extending in the axial direction of the piston main body 14 of the tapered piston 13 and a discharge passage 26B having one end opening to the flat surface 18 of the joint portion 17 and the other end communicating with the oil passage 26A. It is composed of As a result, the lubricating oil guided from the cylinder hole 9 to the oil passage 26A is discharged between the tapered piston concave spherical surface 6B and the joint portion 17 through the fine holes 26B1 of the discharge passage 26B. The discharged lubricating oil passes through gaps formed between the concave spherical surface 6B for taper piston and the first curved surface 19, between the concave spherical surface 6B for taper piston and the second curved surface 21, and furthermore, formed by the dimensional difference ΔD. Out into the space inside the casing 2.

  The oblique-axis hydraulic motor 1 according to the present embodiment has the above-described configuration, and its operation will be described below.

  First, when the rotary shaft 5 of the hydraulic motor 1 is driven, the pressure oil discharged from the hydraulic pump (not shown) is supplied to the high pressure side supply / discharge passage formed in the head casing 4 and the supply / discharge port of the valve plate 10. The taper piston 13 is sequentially extended (projected) from the cylinder hole 9 toward the drive disk 6 side by the hydraulic pressure at this time. Further, the return oil from each cylinder hole 9 is discharged toward the tank side from the low pressure side supply / discharge port and supply / discharge passage as each taper piston 13 is displaced in the direction of contracting into the cylinder hole 9. You.

  At this time, in each of the cylinder holes 9 to which the pressure oil is sequentially supplied, the joint portion 17 which is the protruding end of the tapered piston 13 inserted therein is positioned on the side of the concave spherical surface 6B for the tapered piston of the drive disk 6. It is pressed sequentially. As a result, a rotational force about the rotary shaft 5 is generated in the drive disk 6, and the rotational force is taken out from the distal end side of the rotary shaft 5 as a motor output.

  By the way, in the above-described conventional technology, if the spherical diameter difference between the joint portion of the piston and the concave spherical surface of the drive disk is too small, the piston is lifted due to pressure build-up of the lubricating oil, and the leakage amount of the lubricating oil is excessive. There is a risk of becoming. On the other hand, if the spherical diameter difference between the joint portion of the piston and the concave spherical surface of the drive disk is large, the surface pressure between the joint portion and the concave spherical surface increases, and the mechanical efficiency may be reduced.

  Therefore, in the present embodiment, the first curved surface 19 that slides (contacts) the spherical surface of the joint portion 17 of the tapered piston 13 with the concave spherical surface 6B for the tapered piston of the drive disk 6, and the first curved surface 19 whose diameter is smaller than the first curved surface 19 It has two curved surfaces 21.

  The first curved surface 19 is located on one side (tip side) of the joint portion 17 in the piston axial direction, and the angle θ between the tapered piston 13 and the piston axis AA passing through the spherical center O1 is 40 ° or more and 70 ° or more. ° or less (40 ° ≤ θ ≤ 70 °) to the end point 20. The first curved surface 19 has an arc shape with a spherical center O1 and a radius Ra equivalent to the concave spherical surface 6B for the taper piston of the drive disk 6. That is, the first curved surface 19 is a portion that slides (contacts) with the tapered piston concave spherical surface 6B.

  On the other hand, the second curved surface 21 is located on the other side (base end side) of the joint portion 17 in the piston axial direction, and the dimensional difference ΔD at the position of the end point 24 is a predetermined value (12.5 μm or more and 30 μm or less). Thus, it has an arc shape with a center O2 and a radius Rb (Rb <Ra). That is, the second curved surface 21 is a portion where the lubricating oil flows appropriately (smoothly) between the joint portion 17 and the concave spherical surface 6B for the taper piston.

  Thus, according to the first embodiment, the spherical surface of the joint portion 17 of the tapered piston 13 is located on one side in the axial direction of the joint portion 17 and has the spherical center O1 and passes through the spherical center O1. The first curved surface 19 sliding on the concave spherical surface 6B for the taper piston of the drive disk 6 between the angle θ between the tapered piston 13 and the piston axis AA of 40 ° or more and 70 ° or less; A second curved surface 21 connected to the other side in the axial direction and having a smaller diameter than the first curved surface 19.

  As a result, the first curved surface 19 of the joint portion 17 comes into contact with the concave spherical surface 6B for the tapered piston, and a sufficient contact area can be secured, so that the surface pressure can be reduced. Further, the amount of leakage of the lubricating oil flowing between the joint portion 17 and the concave spherical surface 6B for the tapered piston can be made appropriate by the second curved surface 21. Thereby, the loss of the output power with respect to the input power of the hydraulic motor 1 can be reduced, and the mechanical efficiency can be improved. When the angle θ formed between the piston axis AA and the piston axis A is smaller than 40 °, the contact area decreases and the surface pressure increases. On the other hand, if the angle θ formed with the piston axis AA is larger than 70 °, the amount of leakage is reduced, and the lift due to pressure build-up is increased.

  Further, the second curved surface 21 and the first curved surface 19 are extended at a position of an end point 24 where a line BB orthogonal to the piston axis AA crosses the spherical surface of the joint portion 17 through the spherical center O1 of the first curved surface 19. In this case, the dimensional difference ΔD from the virtual line 25 is set to 12.5 μm or more and 30 μm or less.

  Thereby, the flow area of the lubricating oil at the position of the end point 24 is secured, and the amount of leakage of the lubricating oil can be appropriately maintained, so that the floating of the taper piston 13 due to the pressurization of the lubricating oil can be reduced. When the dimensional difference ΔD is smaller than 12.5 μm, the amount of leakage is reduced, and the lifting due to pressure build-up is increased. On the other hand, if the dimensional difference ΔD exceeds 30 μm, the amount of leakage increases and the mechanical efficiency decreases.

  Further, at an end point 20 where the first curved surface 19 and the second curved surface 21 are connected, the tangent to the first curved surface 19 and the tangent to the second curved surface 21 are common (common tangent 23) and connected. As a result, the connecting portion (end point 20) between the first curved surface 19 and the second curved surface 21 can be made smooth, so that an increase in surface pressure at the end point 20 can be suppressed and lubrication at the end point 20 can be suppressed. Oil flow can be performed smoothly.

  Next, FIG. 4 shows a second embodiment of the present invention. The feature of the second embodiment resides in that a joint portion 31 is provided with a third curved surface 32 in addition to the first curved surface 19 and the second curved surface 21. In this embodiment, the same components as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 4, the center (O1, O2, O3) and the radii (Ra, Rb, Rc) and the like are shown for the spherical surface of the joint portion 31 located on the upper side of the paper of FIG. The description is omitted because it is the same.

  The joint portion 31 has a spherical surface and is swingably (slidably) connected to the concave spherical surface 6B for the taper piston of the drive disk 6. The joint portion 31 has a flat surface 18 located on one side (tip side) in the piston axial direction and a large-diameter portion extending from the flat surface 18 toward the other side (piston main body portion 14 side) in the piston axial direction. A first curved surface 19, a second curved surface 21 as a small-diameter portion extending from the first curved surface 19 toward the other side in the piston axial direction, and a third curved surface extending from the second curved surface 21 toward the other side in the piston axial direction. 32. That is, the first curved surface 19 forms the distal end side of the spherical surface of the joint portion 31. Further, the second curved surface 21 forms a central portion of the spherical surface of the joint portion 31. The third curved surface 32 constitutes the base end side of the spherical surface of the joint portion 31.

  As shown in FIG. 4, the third curved surface 32 is formed as a curved surface (arc shape) having a center O3 of an arc forming the third curved surface 32 and a radius Rc (Rb <Ra <Rc). To the other side (the piston body 14 side). The third curved surface 32 is a curved surface formed by rotating an arc having a radius Rc around O3 around the piston axis AA. The center O3 of the arc forming the third curved surface 32 is located on a dotted line 33 connecting the center O2 of the arc forming the second curved surface 21 and the end point 24.

  Thus, at the end point 24 where the second curved surface 21 and the third curved surface 32 are connected, the tangent of the second curved surface 21 and the tangent of the third curved surface 32 are connected to each other as a common tangent 34. As a result, the second curved surface 21 and the third curved surface 32 at the end point 24 are smoothly connected (connected), so that the lubricating oil flowing through the end point 24 can be efficiently circulated.

  The dimensional difference ΔD between the second curved surface 21 and the imaginary line 25 when the first curved surface 19 is extended at the position of the end point 24 is set in a range represented by the following Expression 3. The radius Rb of the second curved surface 21 based on the dimensional difference ΔD is set by an experiment or the like from the relationship with the first curved surface 19.

  The radius Rc of the third curved surface 32 is formed larger than the radius Ra of the first curved surface 19 and the radius Rb of the second curved surface 21 (Rb <Ra <Rc). That is, the third curved surface 32 has a gentler curved surface shape than the first curved surface 19 and the second curved surface 21. Thereby, the gap size between the third curved surface 32 and the concave spherical surface 6B for taper piston (virtual line 25) gradually decreases from the above-mentioned dimensional difference ΔD from the end point 24 to the other side in the piston axial direction. Therefore, the amount of leakage of the lubricating oil from between the tapered piston concave spherical surface 6B and the joint portion 31 at the time of high pressure can be reduced.

  Thus, in the second embodiment configured as described above, the same operation and effect as those in the first embodiment can be obtained. In particular, in the second embodiment, the other side of the joint portion 31 in the piston axial direction has a curved surface shape (arc shape) that is gentler than the first curved surface 19 and the second curved surface 21. Thereby, the amount of leakage of the lubricating oil at the time of high pressure can be reduced, and the mechanical efficiency can be improved. That is, by increasing the radius Rc of the third curved surface 32, the gap between the joint portion 17 and the concave spherical surface 6B for the taper piston on the other side (the piston main body portion 14 side) is reduced, so that leakage of lubricating oil can be prevented even at a high pressure. Can be reduced. Thereby, the mechanical efficiency can be improved.

  Next, FIG. 5 shows a third embodiment of the present invention. The feature of the third embodiment is that the joint portion 41 is provided with a mesh-shaped processing groove 42. In this embodiment, the same components as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

  The joint portion 41 has a spherical surface and is swingably (slidably) connected to the concave spherical surface 6B for the taper piston of the drive disk 6. The joint portion 41 has a flat surface 18 located on one side (tip side) in the piston axial direction, and a large-diameter portion extending from the flat surface 18 toward the other side (piston body portion 14 side) in the piston axial direction. , And a second curved surface 21 as a small-diameter portion extending from the first curved surface 19 toward the other side in the piston axial direction.

  As shown in FIG. 5, the joint 41 has a mesh-shaped processing groove 42 extending in a direction inclined with respect to the piston axis A-A. The processing groove 42 allows the lubricating oil discharged from the discharge passage 26B to flow, and can spread the lubricating oil over the entire sliding surface between the first curved surface 19 and the concave spherical surface 6B for the taper piston. As a result, the pressure loss can be further reduced and the friction loss due to the improved lubrication of the sliding surface can be reduced, so that the mechanical efficiency can be further improved.

  In the first embodiment described above, the case where the taper piston 13 having the taper portion 14B in the piston body 14 is used has been described as an example. However, the present invention is not limited to this, and may be applied to, for example, a piston in which the piston body has a single radial radius in the piston axial direction. That is, any piston or rod having a spherical joint can be applied. This is the same for the second and third embodiments.

  Further, in the first embodiment described above, the case where the first curved surface 19 and the second curved surface 21 have the common tangent 23 at the end point 20 has been described as an example. However, the present invention is not limited to this. For example, the tangent of the first curved surface 19 and the tangent of the second curved surface 21 at the end point 20 may be different. This is the same for the end point 24 which is a connection portion between the second curved surface 21 and the third curved surface 32 in the second embodiment and the third embodiment.

  Further, in the above-described second embodiment, the case where the spherical surface of the joint portion 31 includes the first curved surface 19, the second curved surface 21, and the third curved surface 32 has been described as an example. However, the present invention is not limited to this, and for example, the spherical surface of the joint portion may be configured by four or more curved surfaces. This is the same for the third modification.

  Further, in each embodiment, the oblique-axis fixed-displacement type hydraulic motor 1 has been described as an example of the oblique-axis hydraulic rotating machine. However, the present invention is not limited to this, and may be applied to, for example, an oblique-axis variable displacement hydraulic motor. Further, the present invention may be applied to an oblique axis type fixed displacement or variable displacement hydraulic pump.

1. Hydraulic motor (oblique-axis hydraulic rotary machine)
2 Casing 5 Rotating shaft 6 Drive disk 6B Concave spherical surface for tapered piston 7 Cylinder block 9 Cylinder hole 13 Tapered piston (piston)
14 Piston main body part 17, 31, 41 Joint part 19 First curved surface (large diameter part)
20 endpoints (first endpoint)
21 2nd curved surface (small diameter part)
23 common tangent line 24 endpoint (second endpoint)
42 Machining groove AA Piston axis BB Intersection line O1 Center of spherical surface of first curved surface O2 Center of arc of second curved surface

Claims (3)

A cylindrical casing, a rotating shaft located on one side of the casing and rotatably provided via a bearing, and a plurality of concave spherical surfaces located in the casing and provided at an end of the rotating shaft. A drive disk, a cylinder block provided in the casing so as to rotate integrally with the rotating shaft, and having a plurality of cylinder holes extending in the axial direction while being spaced apart in the circumferential direction, and one side in the axial direction is spherical. And a plurality of pistons, each of which has a joint body rotatably supported by the concave spherical surface of the drive disk and a piston body part whose other axial side is reciprocally fitted into each cylinder hole of the cylinder block. In the oblique axis type hydraulic rotary machine provided with
The piston is configured to include an oil hole formed in the piston in the axial direction and through which lubricating oil flows,
The joint portion of the piston is located on one side of the piston in the axial direction and is formed so as to be orthogonal to a piston axis serving as a central axis of the piston. A first curved surface formed into a spherical surface toward the other side, and a second curved surface formed from the first curved surface of the piston toward the other side in the axial direction with a smaller diameter than the first curved surface. Has been
The first curved surface is a curved surface having a radius Ra having a spherical center on the piston axis, and the first curved surface and the second curved surface are connected from the distal end side to the proximal end side of the joint portion. Constitutes the range up to the end point of
Has an angle θ between the first end point and the piston axis passing through the center of the spherical surface,
The second curved surface has a center on an imaginary line connecting the center of the spherical surface of the first curved surface and the first end point, and forms an arc having a radius Rb smaller than the radius Ra of the first curved surface with the piston shaft. As a curved surface formed by rotating about the joint from the first end point of the joint portion toward the other side in the axial direction,
At the first end point, a tangent to the first curved surface and a tangent to the second curved surface are connected to each other as a common tangent,
A case where the second curved surface and the first curved surface are extended at a position of a second end point where an intersection line orthogonal to the piston axis passes through the center of the spherical surface of the first curved surface and intersects with the second curved surface. The dimensional difference from the imaginary line is set to 12.5 μm or more and 30 μm or less,
The first curved surface is a portion that slides on the concave spherical surface in an arc shape having the center of the spherical surface and the radius Ra equivalent to the concave spherical surface of the drive disk,
The oblique-axis hydraulic rotary machine according to claim 1, wherein the second curved surface is a portion through which lubricating oil flows between the concave surface and the concave surface of the drive disk by setting the dimensional difference. The joint portion of the piston is configured to include a third curved surface in addition to the first curved surface and the second curved surface,
The third curved surface is formed from the second end point toward the other side in the piston axial direction,
The center of the arc forming the third curved surface is located on an imaginary line connecting the center of the arc forming the second curved surface and the second end point,
The oblique axis type liquid according to claim 1, wherein a radius Rc of an arc forming the third curved surface is set to be larger than a radius Ra of the first curved surface and a radius Rb of the second curved surface. Pressure rotary machine.   2. The oblique-axis hydraulic rotary machine according to claim 1, wherein a mesh-like processed groove through which lubricating oil flows is formed on the first curved surface of the joint portion of the piston. 3.

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