JP6665125B2 - Hydraulic rotating machine - Google Patents

Description

  The present invention relates to a hydraulic rotary machine suitably used as a hydraulic pump or a hydraulic motor mounted on construction machines such as a hydraulic excavator and a wheel loader, and various industrial machines.

2. Description of the Related Art In general, construction machines such as a hydraulic shovel and a wheel loader are equipped with a hydraulic rotary machine such as a hydraulic pump used as a hydraulic source of hydraulic equipment and a hydraulic motor used as a driving source for traveling or turning.

  Here, a variable displacement oblique shaft type hydraulic pump as a hydraulic rotary machine includes a casing, a rotating shaft rotatably provided in the casing and having a drive disk at the tip, and a casing that rotates together with the rotating shaft. A plurality of cylinders and a cylinder port are provided therein, and a cylinder block is formed therein. A reciprocatingly inserted fit is inserted into each cylinder of the cylinder block, and a protruding end is swingably supported by a drive disk of a rotating shaft. A plurality of pistons, a valve plate that slides on the one end surface side serving as the cylinder block side and a convex curved sliding surface is formed on the other end surface side and is provided to be tiltable together with the cylinder block; The head casing has a sliding surface of the valve plate and a concavely curved inclined sliding surface that slides.

  Then, the displacement of the hydraulic pump is changed by moving (tilting) the valve plate along the tilting sliding surface of the head casing by the tilting mechanism and changing the tilt angle of the cylinder block with respect to the rotating shaft. be able to.

  By the way, hydraulic excavators are often used in work sites where there is a lot of dust, such as dust and sand, such as dismantling work of structures and restoration work at disaster sites. For this reason, dust containing silica (contaminant) intrudes into the sliding portion of the hydraulic rotating machine mounted on the hydraulic excavator from the outside. Silica contained in dust contains silicon oxide as a main component and has a Vickers hardness of about Hv900. Therefore, when dust enters the sliding part of the hydraulic rotating machine, this sliding part Will wear out.

  For example, a sliding surface between a valve plate and a head casing (tilting sliding surface) constituting the oblique-axis hydraulic pump is lubricated by an oil liquid filled in the casing. Due to the pressure pulsation, the sliding surface between the valve plate and the head casing generates minute vibration, and the oil film of the lubricating oil between the two tends to break. For this reason, when dust enters the sliding surface between the valve plate and the head casing, the dust relatively moves between the valve plate and the head casing due to the influence of minute vibration due to pressure pulsation, and the valve plate or the head casing is worn. Could be

  On the other hand, a technique (DLC coating) for increasing the hardness of the sliding surface to about Vickers hardness Hv1000 to 2500 by forming a high hardness film called a DLC (diamond-like carbon) film on the sliding surface is proposed. Have been. The DLC coating is performed by using, for example, a PVD (physical vapor deposition) method. The PVD method is a technique for forming a thin film using a physical action of ions or the like in plasma in a vacuum environment ( Reference 1).

JP 2009-052067 A

  However, since the above-mentioned PVD method utilizes a physical action of ions and the like in plasma in a vacuum environment, the sliding parts on which a thin film is to be formed evaporate in a vacuum environment such as lead or zinc. When a metal is contained, the coating treatment by the PVD method is hindered. When the coating treatment is hindered, the adhesion of the coating to the sliding parts decreases, and the risk of peeling increases. The coating peeled off from the sliding parts becomes dust of high hardness and wears the sliding parts.

  On the other hand, a cylinder block slides on the surface of the valve plate of the oblique-axis hydraulic pump opposite to the surface on which the head casing slides. Since the cylinder block is pressed against the valve plate by pressure from a piston inserted into each cylinder, seizure may occur on the sliding surface between the valve plate and the cylinder block. To avoid this seizure, a copper alloy containing a sliding material such as lead is usually used for at least one of the sliding surface on the valve plate side and the sliding surface on the cylinder block side.

  However, in a sliding part using a copper alloy for the sliding surface, the lead contained in the copper alloy hinders the coating process by the PVD method, so that a high-hardness film by the DLC coating is formed on the sliding surface. There is a problem that it is difficult.

  Further, for example, sliding parts having a complicated shape such as a head casing are desirably manufactured at low cost by casting using a cast iron material. However, since a carbon hole having a diameter of about 50 μm is formed on the surface of the cast iron, it is discontinuous. A smooth sliding surface is formed. When the DLC coating is applied to such a discontinuous sliding surface, there is a problem that the carbon hole serves as a starting point of the peeling of the coating and the coating is easily peeled.

  SUMMARY OF THE INVENTION 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 provide a hydraulic rotating machine capable of suppressing abrasion of a sliding surface due to intrusion of dust and the like. It is in.

  The present invention includes a first member having a first sliding surface, and a second member having a second sliding surface sliding on the first sliding surface, wherein the first member has a first sliding surface. The present invention is applied to a hydraulic rotating machine having a configuration in which one end of an oil passage through which an oil liquid flows is opened on at least one of the sliding surface and the second sliding surface.

The feature of the present invention is that the first member is formed using a bimetal of alloy steel and a copper alloy, and the first sliding surface is set to a hardness of Vickers hardness Hv900 or more by nitriding treatment, The second member is formed using a metal material different from the first member, and sulfur or phosphorus having a Vickers hardness lower than the Vickers hardness of the first sliding surface is formed on the second sliding surface. Is that a conformable layer containing the same is formed.

  According to the present invention, the conforming layer formed on the second sliding surface is partially shaved by the first sliding surface, so that the gap between the first sliding surface and the second sliding surface is reduced. Can be reduced, and the intrusion of dust into the sliding surface can be suppressed. Further, even if the dust enters, the dust is buried in the conformable layer, so that the relative movement of the dust between the first and second sliding surfaces can be suppressed. As a result, the wear of the first and second sliding surfaces can be suppressed.

FIG. 1 is a cross-sectional view illustrating a variable displacement oblique axis type hydraulic rotary machine according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a sliding surface between a valve plate and a head casing in FIG. 1. It is sectional drawing which shows the variable displacement type swash plate type hydraulic rotary machine which concerns on 2nd Embodiment of this invention. It is a perspective view which shows the swash plate in FIG. 3 by itself. FIG. 4 is a perspective view showing the cradle in FIG. 3 alone.

  Hereinafter, a first embodiment of a hydraulic rotary machine according to the present invention will be described in detail with reference to FIGS. 1 and 2, taking a variable displacement oblique shaft type hydraulic rotary machine as an example.

  In FIG. 1, an oblique-axis hydraulic pump 1 serving as a variable-capacity oblique-axis hydraulic rotating machine sucks hydraulic oil from a hydraulic oil tank and pressurizes the hydraulic oil. ).

  The casing 2 forms an outer shell of the oblique-axis hydraulic pump 1. The casing 2 includes a casing main body 3 and a head casing 4. Here, the casing body 3 is constituted by a bearing portion 3A which is located on one side in the axial direction and is formed in a substantially cylindrical shape, and a cylinder block housing portion 3B which extends obliquely from the other end of the bearing portion 3A. ing. A head casing 4 is attached to the other end of the cylinder block housing 3B.

  The head casing 4 is provided with the other end of the cylinder block housing 3B closed. The head casing 4 has a concave curved inclined sliding surface 4B on one end surface 4A located on the casing body 3 side. Here, the tilt sliding surface 4B is formed as a concave curved surface formed along a swing radius when a valve plate 11 described later swings around the center shaft 8 as a fulcrum. On the other hand, the head casing 4 is provided with a cylinder hole 12A of the tilting mechanism 12, which will be described later, located at the back of the tilting sliding surface 4B. Further, the head casing 4 is provided with a suction passage and a discharge passage (both not shown) on both sides of the cylinder hole 12A.

  The rotating shaft 5 is rotatably supported by a bearing 3A of the casing body 3. The rotating shaft 5 is rotatably supported by a bearing portion 3A via a bearing 6, and a protruding end protruding from the casing body 3 serves as a spline portion 5A connected to an output shaft or the like (not shown) of a motor. I have. On the other hand, a disk-shaped drive disk 5 </ b> B is provided at the tip of the rotating shaft 5 housed in the casing body 3.

  The cylinder block 7 is provided in the cylinder block housing 3 </ b> B of the casing body 3. The cylinder block 7 is formed as a column having a center shaft insertion hole 7A at the center. The cylinder block 7 is provided with a plurality (only one is shown) of cylinders 7B around the center shaft insertion hole 7A. These cylinders 7B are arranged at equal intervals in the circumferential direction of the cylinder block 7, and extend in the axial direction.

  Here, the end surface of the cylinder block 7 on the head casing 4 side becomes a concave spherical portion 7C, and the concave spherical portion 7C is formed in a concave spherical shape, and slides against a convex spherical portion 11C of the valve plate 11 described later. Is what you do. A plurality of cylinder ports 7D (only one is shown) are opened in the concave spherical portion 7C at positions corresponding to the respective cylinders 7B. An annular spring receiving portion 7E having a smaller hole diameter than the center shaft insertion hole 7A is provided in the concave spherical portion 7C of the cylinder block 7.

  The center shaft 8 is inserted into the center shaft insertion hole 7A of the cylinder block 7. The center shaft 8 supports the cylinder block 7 between the drive disk 5B of the rotating shaft 5 and the valve plate 11 so as to be tiltable. One end of the center shaft 8 is a spherical portion 8A, and the spherical portion 8A is swingably connected to the rotation center position of the drive disk 5B. On the other hand, the other end 8B of the center shaft 8 protrudes from the concave spherical portion 7C of the cylinder block 7, and is inserted into a shaft hole 11E of the valve plate 11 described later.

  A disk-shaped spring receiving portion 8C is provided at an axially intermediate portion of the center shaft 8, and a compression spring 9 is provided between the spring receiving portion 8C and the spring receiving portion 7E of the cylinder block 7. Have been. The compression spring 9 presses the cylinder block 7 and the valve plate 11 toward the head casing 4.

  The plurality of pistons 10 are reciprocally inserted into the respective cylinders 7B of the cylinder block 7. Each piston 10 has a protruding end protruding from the cylinder 7 </ b> B swingably supported by the drive disk 5 </ b> B of the rotating shaft 5. Each of the pistons 10 reciprocates in the cylinder 7B by rotating the cylinder block 7 tilted with respect to the rotation shaft 5, and performs suction and discharge of the oil liquid.

  The valve plate 11 is provided between the head casing 4 and the cylinder block 7. The valve plate 11 is tilted together with the cylinder block 7 around a spherical portion 8A (valve plate support point) of the center shaft 8 by a tilting mechanism 12 described later. The valve plate 11 is formed with a pair of supply / discharge ports 11A, 11B having an eyebrow shape, and these supply / discharge ports 11A, 11B are connected to the respective cylinder ports 7D of the cylinder block 7 via the respective cylinder ports 7D. It communicates with the cylinder 7B.

  Here, a convex spherical portion 11 </ b> C having a convex spherical shape is provided on one end surface side (the cylinder block 7 side) of the valve plate 11. The convex spherical portion 11C slides facing the concave spherical portion 7C of the cylinder block 7. On the other hand, a convex curved sliding surface 11D having a convex curved surface is provided on the other end surface side (head casing 4 side) of the valve plate 11 opposite to the convex spherical portion 11C. The convex curved sliding surface 11D is formed in a convex curved surface shape corresponding to the tilt sliding surface 4B of the head casing 4, and slides facing the tilt sliding surface 4B. In the center of the valve plate 11, a shaft hole 11E penetrating in the axial direction is provided. The other end 8B of the center shaft 8 is inserted into the shaft hole 11E.

  The tilting mechanism 12 is provided on the head casing 4. The tilting mechanism 12 tilts the valve plate 11 together with the cylinder block 7 with respect to the rotation shaft 5. The tilt mechanism 12 is provided at a position deeper than the tilt slide surface 4B of the head casing 4 and extends linearly in the tilt direction of the valve plate 11, and is slidably inserted into the cylinder hole 12A. The servo piston 12B includes a fitted servo piston 12B, and a link pin 12C that is provided at an intermediate portion in the longitudinal direction of the servo piston 12B so as to protrude in the radial direction. At both ends of the cylinder hole 12A, oil holes 12D and 12E for supplying an oil liquid for operating the servo piston 12B into the cylinder hole 12A are provided. The tip of the link pin 12C is inserted into the shaft hole 11E of the valve plate 11.

  The servo piston 12B of the tilting mechanism 12 moves along the cylinder hole 12A by supplying the oil liquid from the oil hole 12D or 12E into the cylinder hole 12A. The movement of the servo piston 12B is transmitted to the valve plate 11 via the link pin 12C, and the valve plate 11 slides along with the cylinder block 7 along the tilting sliding surface 4B of the head casing 4 to thereby rotate the rotary shaft 5. The tilt angle of the cylinder block 7 and the valve plate 11 with respect to is adjusted.

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

  When the rotating shaft 5 is driven to rotate by a prime mover (not shown) such as an engine or a motor, the cylinder block 7 rotates together with the drive disk 5B of the rotating shaft 5. Since the rotation center of the cylinder block 7 is inclined with respect to the rotation center of the rotation shaft 5, the rotation of the cylinder block 7 causes the piston 10 to reciprocate in each cylinder 7B.

  The concave spherical portion 7C of the cylinder block 7 rotates and slides on the convex spherical portion 11C of the valve plate 11, and the cylinder port 7D of each cylinder 7B provided on the cylinder block 7 has a supply port 7D provided on the valve plate 11. It communicates intermittently with the discharge ports 11A and 11B. During a half rotation in which the cylinder port 7D communicates with the suction side port among the supply / discharge ports 11A and 11B, the piston 10 is in a suction stroke in which it protrudes from the cylinder 7B, and hydraulic oil is sucked into the cylinder 7B. On the other hand, during a half rotation in which the cylinder port 7D communicates with the discharge side port of the supply / discharge ports 11A and 11B, the piston 10 enters the cylinder 7B during the discharge stroke, and is sucked into the cylinder 7B during the suction stroke. The hydraulic oil is pressurized and discharged to a discharge port of the valve plate 11. By repeating the suction stroke and the discharge stroke in this manner, the pump operation of the oblique-axis hydraulic pump 1 is performed.

  Here, when changing the capacity of the oblique-axis hydraulic pump 1, the servo piston 12B is displaced by supplying pressurized oil into the cylinder hole 12A through the oil hole 12D or the oil hole 12E of the tilting mechanism 12. . As a result, the operation of the servo piston 12B is transmitted to the valve plate 11 via the link pin 12C, and the valve plate 11 slides along with the cylinder block 7 along the tilt sliding surface 4B of the head casing 4. As a result, the tilt angle of the cylinder block 7 and the valve plate 11 with respect to the rotary shaft 5 changes, and the stroke of each piston 10 changes, whereby the capacity of the oblique-axis hydraulic pump 1 can be changed.

  Here, the oblique-axis hydraulic pump 1 according to the first embodiment includes a convex curved sliding surface 11D as a first sliding surface provided on a valve plate 11 as a first member, and a second curved surface. It is configured so that the wear of the sliding surface with the tilting sliding surface 4B as the second sliding surface provided on the head casing 4 as a member of the above can be suppressed. The configuration of the head casing 4 will be described in detail.

  First, the configuration of the valve plate 11 as the first member will be described. The valve plate 11 has a layered shape obtained by bonding two kinds of different metals, such as nitrided steel such as SACM645 (aluminum chromium molybdenum steel 645) containing Al (aluminum), Cr (chromium), and Mo (molybdenum), and a copper alloy. And formed using a bimetal made of a composite alloy (combined material). Here, since the copper alloy is expensive, the powdered copper alloy is put into a furnace together with the nitride steel as a base material and sintered, so that the copper alloy is arranged on the convex spherical portion 11C side, The valve plate 11 in which the nitrided steel is arranged in a portion other than the above can be formed.

  Then, a gas nitriding process using, for example, NH 3 (ammonia gas) is performed on the valve plate 11. As a result, nitrogen diffused from the surface of the raw material is combined with various metal elements, and the valve plate 11 having a hardened surface can be formed. In this case, the valve plate 11 has a copper alloy layer formed on the convex spherical portion 11C. As described above, since the copper alloy layer containing the sliding material such as lead forms the convex spherical portion 11C of the valve plate 11, seizure with the concave spherical portion 7C of the cylinder block 7 can be avoided. . The surface hardness of the convex spherical portion 11C is set so that the Vickers hardness is about Hv50 to 150.

  On the other hand, the convex curved sliding surface 11D of the valve plate 11 is made of nitrided steel. In the production process, a nitrogen compound layer is formed at a depth of, for example, 10 to 30 μm from the surface by a gas nitriding process. To a depth of 0.2 to 0.5 mm. Then, since the formed nitrogen compound layer is fragile and may be a factor of contamination, it is removed by grinding. After the removal of the nitrogen compound layer, a convex curved sliding surface 11D having a nitrogen diffusion layer 11D1 near the surface is formed as shown in FIG. The Vickers hardness of the formed convex curved sliding surface 11D is set to Hv900 or more (Hv900 to 1200). Thus, even if dust containing silica having a Vickers hardness of about Hv900 intrudes into the sliding portion between the convex curved sliding surface 11D of the valve plate 11 and the tilting sliding surface 4B of the head casing 4, Wear of the convex curved sliding surface 11D of the plate 11 can be suppressed.

  Next, the configuration of the head casing 4 as the second member will be described. The head casing 4 is formed using a metal material different from the nitride steel that is the material of the valve plate 11. In this case, since the head casing 4 has a complicated shape, it is formed, for example, as a casting using a cast iron material.

  Then, the head casing 4 is subjected to a nitrosulphurizing process using NH3, CO2 (carbon dioxide), H2S (hydrogen sulfide), or the like. As a result, the nitrogen that has diffused and entered from the surface of the material is combined with various metal elements, and the head casing 4 having a hardened surface can be formed. In this case, as shown in FIG. 2, at a depth of 15 μm or less from the surface of the tilting sliding surface 4B of the head casing 4, a conforming layer (soft coating) 4B1, which is a sulfur-containing sulfurized layer, is formed. A nitrogen compound layer 4B2 is formed at a depth of 10 to 30 μm from the surface. Further, a nitrogen diffusion layer 4B3 is formed at a depth of 0.05 to 0.1 mm from the surface.

  The Vickers hardness of the tilting sliding surface 4B on which the conformable layer 4B1 is formed is set to, for example, Hv300 to Hv500, and is lower than the Vickers hardness of the convex curved sliding surface 11D of the valve plate 11. Therefore, when the tilting sliding surface 4B of the head casing 4 slides on the convex curved sliding surface 11D of the valve plate 11, as shown in FIG. In a portion where the contact with the moving surface 4B is strong, the conformable layer 4B1 is partially cut away, and the contact area between the convex curved sliding surface 11D and the tilting sliding surface 4B increases accordingly. As a result, the tilting sliding surface 4B is adapted to the convex curved sliding surface 11D to reduce a gap generated therebetween, and dust is formed between the tilting sliding surface 4B and the convex curved sliding surface 11D. Intrusion can be suppressed. In addition, the surface pressure when the convex curved sliding surface 11D and the tilting sliding surface 4B slide can be suppressed, and the lubricating property is secured by the sulfur contained in the conformable layer 4B1, so that the tilting is ensured. Premature wear of the conforming layer 4B1 of the rolling sliding surface 4B can be suppressed.

  Further, as shown in FIG. 2, even if the dust D enters between the tilting sliding surface 4B and the convex curved sliding surface 11D of the valve plate 11, the dust D is transferred to the tilting sliding surface 4B. Embedded in the conformable layer 4B1. As a result, relative movement of the dust D between the tilting sliding surface 4B of the head casing 4 and the convex curved sliding surface 11D of the valve plate 11 can be suppressed, and the wear of the tilting sliding surface 4B is reduced. Can be suppressed.

  Further, even if the conformable layer 4B1 of the tilt sliding surface 4B is worn out and disappears during the operation of the oblique-axis hydraulic pump 1 for a long time, the head casing 4 is made of a metal material different from that of the valve plate 11. Therefore, the risk of the valve plate 11 seizing to the head casing 4 can be reduced.

  Moreover, the valve plate 11 is formed of a bimetal (composite alloy) in which two kinds of dissimilar metals, nitrided steel and a copper alloy, are combined, and the convex spherical portion 11C on which the cylinder block 7 slides is a copper alloy layer. The surface of the convex curved sliding surface 11D that slides on the head casing 4 is a nitrogen diffusion layer 11D1. Thereby, while ensuring the mass productivity of the valve plate 11, the risk of seizure between the valve plate 11 and the cylinder block 7 can be avoided, and the abrasion of the convex curved sliding surface 11D due to dust D can be reduced.

  Further, even when the head casing 4 having a complicated shape is formed at low cost using cast iron, the head casing 4 made of the cast iron material is subjected to the nitrosulphurizing treatment, whereby the tilting sliding surface 4B of the head casing 4 is formed. The conformable layer 4B1 can be formed. For this reason, even when the head casing 4 is formed of an inexpensive material, the abrasion between the tilting sliding surface 4B of the head casing 4 and the convex curved sliding surface 11D of the valve plate 11 can be suppressed. This can also contribute to a reduction in the manufacturing cost of the entire hydraulic pump 1.

  Next, FIGS. 3 to 5 show a second embodiment of the present invention. In the second embodiment, a variable displacement swash plate type hydraulic rotary machine is taken as an example of the hydraulic rotary machine.

  In the figure, a swash plate type hydraulic pump 21 as a variable displacement swash shaft type hydraulic rotating machine includes a casing 22, a rotating shaft 25, a cylinder block 27, a piston 28, a shoe 29, a valve plate 33, a swash plate 34, a cradle, which will be described later. 35 and the like.

  The casing 22 forms an outer shell of the swash plate type hydraulic pump 21. The casing 22 includes a casing main body 23 formed in a bottomed cylindrical shape and having an opening 23A and a bottom 23B, and a front casing 24 closing the opening 23A of the casing main body 23.

  A pair of supply / discharge passages 23C and 23D are provided on the bottom 23B of the casing body 23. One of the supply and discharge passages 23C and 23D serves as a low pressure side suction passage and is connected to a tank (not shown), and the other supply and discharge passage 23D serves as a discharge passage and serves as a discharge passage. It is connected to a discharge pipe (not shown). Further, a cradle 35 described later is provided on the front casing 24.

  The rotation shaft 25 is rotatably provided in the casing 22. The rotating shaft 25 is rotatably supported on the bottom 23B of the casing body 23 and the front casing 24 via bearings 26A and 26B, respectively. One end of the rotating shaft 25 projects axially from the front casing 24, and an outer peripheral surface thereof is provided with a spline portion 25A connected to an output shaft or the like (not shown) of a motor.

  The cylinder block 27 is rotatably provided in the casing main body 23. The rotation shaft 25 is inserted through the center of the cylinder block 27, and the cylinder block 27 is rotated integrally with the rotation shaft 25 by being spline-coupled to the rotation shaft 25. The cylinder block 27 is provided with a plurality (only one is shown) of cylinders 27 </ b> A around the rotation shaft 25. These cylinders 27A are arranged at equal intervals in the circumferential direction of the cylinder block 27, and extend in the axial direction. A plurality (only one is shown) of spring mounting holes 27B are provided on the end face of the cylinder block 27 at one end side (front casing 24 side) in the axial direction and are spaced apart in the circumferential direction. Is provided with a spring 31 described later. On the other hand, an end surface on the other end side in the axial direction of the cylinder block 27 becomes a concave spherical portion 27C having a concave spherical shape, and the concave spherical portion 27C slides with respect to a convex spherical portion 33A of the valve plate 33 described later. Is what you do. In the concave spherical portion 27C, a plurality of cylinder ports 27D (only one is shown) are opened at positions corresponding to the respective cylinders 27A.

  The plurality of pistons 28 are reciprocally fitted into the respective cylinders 27A of the cylinder block 27. Each piston 28 reciprocates in the cylinder 27A with the rotation of the cylinder block 27, and repeats a suction stroke and a discharge stroke.

  The plurality of shoes 29 are provided on each piston 28. Each shoe 29 is swingably attached to a projecting end of a piston 28 projecting from each cylinder 27A of the cylinder block 27, and slides on a smooth surface 34A of a swash plate 34 described later.

  The retainer ball 30 is provided between the cylinder block 27 and the swash plate 34. The outer peripheral surface of the retainer ball 30 is formed in a spherical shape. A spring 31 is compressed in a spring mounting hole 27B provided in the cylinder block 27, and the retainer ball 30 is pressed toward the swash plate 34 by the spring 31.

  The retainer 32 is provided between each shoe 29 and the swash plate 34. The retainer 32 is formed of an annular plate in which a plurality of holes for holding the respective shoes 29 are formed at equal intervals in the circumferential direction. The outer peripheral surface of the retainer ball 30 is slidably fitted on the inner peripheral edge of the retainer 32. The retainer 32 presses and holds each shoe 29 toward the smooth surface 34A of the swash plate 34 by the spring force of the spring 31, and slides each shoe 29 so as to draw an annular locus on the smooth surface 34A of the swash plate 34. Dynamic displacement.

  The valve plate 33 is disposed between the casing main body 23 and the cylinder block 27 in the casing 22 and is fixed to the casing main body 23. The valve plate 33 has a convex spherical portion 33A, and the concave spherical portion 27C of the cylinder block 27 is in sliding contact with the convex spherical portion 33A. Thus, the valve plate 33 supports the cylinder block 27 that rotates integrally with the rotation shaft 26.

  A pair of supply / discharge ports 33B, 33C having an eyebrow shape are formed in the valve plate 33, and these supply / discharge ports 33B, 33C communicate with supply / discharge passages 23C, 23D of the casing body 23. The supply / discharge ports 33B and 33C of the valve plate 33 intermittently communicate with the cylinder ports 27D of the cylinders 27A when the cylinder block 27 rotates. At this time, the piston 28 reciprocating in each cylinder 27A sucks hydraulic oil into the cylinder 27A from one of the supply / discharge passages 23C in the suction stroke, and pressurized oil in the cylinder 27A in a high pressure state in the discharge stroke. Is discharged from the other supply / discharge passage 23D.

  The swash plate 34 is tiltably provided in the casing 22 via a cradle 35 described later. A smooth surface 34 </ b> A for slidably guiding each shoe 29 is formed on one end surface side of the swash plate 34 on the cylinder block 27 side. The swash plate 34 is provided with a through hole 34B penetrating in the thickness direction thereof, and the rotating shaft 25 is inserted into the through hole 34B with a gap.

  As shown in FIG. 4, on both sides of the swash plate 34 with the through hole 34B interposed therebetween, a pair of legs 34C, 34D facing the tilt support portions 35C, 35D of the cradle 35 described later are provided. Convex curved sliding surfaces 34E and 34F are formed on the other end surface (front casing 24 side) of the legs 34C and 34D opposite to the smooth surface 34A, respectively. The convex curved sliding surface 34E is slidably engaged with the tilt sliding surface 35E provided on the tilt support portion 35C of the cradle 35, and the convex curved sliding surface 34F is tilted of the cradle 35. It is slidably fitted to the tilting sliding surface 35F provided on the support portion 35D. The swash plate 34 is tilted and driven by tilt actuators 36 and 37 described later about tilt support portions 35C and 35D of the cradle 35 serving as swash plate support points.

  A cradle 35 as a swash plate support member is provided on the front casing 24 so as to surround the rotation shaft 25. As shown in FIG. 5, the cradle 35 includes an annular substrate 35B provided with a shaft insertion hole 35A through which the rotating shaft 25 is inserted, and a pair of tilt support portions 35C and 35D opposed to each other with the shaft insertion hole 35A interposed therebetween. It is comprised including. Concave curved surface tilting sliding surfaces 34E and 34F formed on the legs 34C and 34D of the swash plate 34 are slidably engaged with the respective tilting support portions 35C and 35D. Surfaces 35E and 35F are respectively formed. One end of a cradle-side oil supply passage 35G is opened in each of the tilt sliding surfaces 35E and 35F. The other end of each cradle-side oil supply passage 35G is opened on the outer peripheral surface of the substrate 35B, and is connected to a casing-side oil supply passage 38 described later.

  The pair of tilt actuators 36 and 37 are provided on the casing main body 23, and face each other in the radial direction with the cylinder block 27 interposed therebetween. Each tilt actuator 36, 37 is slidably inserted into a cylinder hole 36A, 37A formed in the casing main body 23, and is slidably inserted into the cylinder hole 36A, 37A. , 37B defining tilting pistons 36C, 37C.

  When the tilt control pressure is externally supplied to and discharged from the hydraulic chambers 36B, 37B of the tilt actuators 36, 37 through a control pressure passage (not shown), the tilt pistons 36C, 37C are formed in the cylinder holes 36A. , 37A, and presses the swash plate 34. Thus, the convex curved sliding surfaces 34E and 34F provided on the legs 34C and 34D of the swash plate 34 are changed to the tilting sliding surfaces 35E and 34E provided on the tilt support portions 35C and 35D of the cradle 35. The swash plate 34 slides along 35F, and the tilt angle of the swash plate 34 is variably controlled.

  The casing side oil supply passage 38 is provided in the casing main body 23 and the front casing 24. One end of the casing side oil supply passage 38 is connected to the high pressure side supply / discharge passage 23D on the casing body 23 side, and the other end of the casing side oil supply passage 38 is formed on the substrate 35B of the cradle 35 on the front casing 24 side. It is connected to the side oil supply passage 35G. Therefore, part of the pressure oil discharged from the high-pressure side supply / discharge passage 23D passes through the cradle-side oil supply passage 35G from the casing-side oil supply passage 38, and the tilting slide provided on each of the tilting support portions 35C and 35D of the cradle 35. It is guided to moving surfaces 35E and 35F.

  Accordingly, the oil liquid (actuated) is applied to the sliding portions between the tilting sliding surfaces 35E and 35F of the cradle 35 and the convex curved sliding surfaces 34E and 34F provided on the legs 34C and 34D of the swash plate 34. Oil) is supplied, and a hydrostatic bearing is formed between each tilting sliding surface 35E, 35F and each convex curved sliding surface 34E, 34F. This makes it possible to always lubricate the sliding surfaces between the tilting sliding surfaces 35E, 35F and the respective convex curved sliding surfaces 34E, 34F, and at the same time, the respective tilting sliding surfaces 35E, 35F and the respective convex curved surfaces. The surface pressure acting between the sliding surfaces 34E and 34F can be reduced by utilizing the hydraulic reaction force of the lubricating oil.

  The swash plate type hydraulic pump 21 according to the second embodiment has the above-described configuration, and its operation will be described below.

  When the rotating shaft 25 is driven to rotate by a prime mover (not shown) such as an engine or a motor, the cylinder block 27 rotates together with the rotating shaft 25. As a result, each shoe 29 held by the retainer 32 is slid and displaced on the smooth surface 34A of the swash plate 34 so as to draw a ring-like trajectory. Thereby, each piston 28 repeats reciprocating motion in each cylinder 27A of the cylinder block 27.

  Thus, while the cylinder block 27 makes one rotation, each piston 28 slides in the cylinder 27A from the top dead center to the bottom dead center, and slides from the bottom dead center to the top dead center. The discharge stroke with dynamic displacement is repeated. In the suction stroke of the piston 28, for example, hydraulic oil is sucked into the cylinder 27A from the supply / discharge passage 23C through the cylinder port 27D, and in the discharge stroke of the piston 28, the hydraulic oil in the cylinder 27A is converted into high-pressure hydraulic oil in the cylinder port 27D. Through the supply / discharge passage 23D.

  When the capacity of the swash plate hydraulic pump 21 is changed, the tilt control pressure is externally supplied to and discharged from the hydraulic chambers 36B, 37B of the tilt actuators 36, 37. Accordingly, the tilt pistons 36C and 37C extend and contract from the cylinder holes 36A and 37A to press the swash plate 34, and the convex curved sliding surfaces 34E and 34E provided on the legs 34C and 34D of the swash plate 34. 34F slides along the tilt sliding surfaces 35E, 35F provided on the tilt support portions 35C, 35D of the cradle 35. As a result, the swash plate 34 is tilted and driven around the tilt support portions 35C and 35D of the cradle 35, and the stroke of each piston 28 changes in accordance with the change in the tilt angle of the swash plate 34, whereby the swash plate 34 is tilted. The capacity of the plate-type hydraulic pump 21 can be changed.

  Here, the swash plate type hydraulic pump 21 according to the second embodiment includes convex curved sliding surfaces 34E and 34F as first sliding surfaces provided on a swash plate 34 as a first member. The cradle 35 serving as a second member is configured so as to be able to suppress abrasion of the sliding surfaces with the tilt sliding surfaces 35E and 35F as the second sliding surfaces provided on the cradle 35. The configuration of the swash plate 34 and the cradle 35 will be described in detail.

  The swash plate 34 as the first member is formed using, for example, nitrided steel such as SACM645. By subjecting the swash plate 34 to a gas nitriding process using, for example, NH 3, the swash plate 34 having a hardened surface can be formed. In the step of forming the convex curved sliding surfaces 34E and 34F provided on the legs 34C and 34D of the swash plate 34, a nitrogen compound layer is formed by gas nitriding at a depth of, for example, 10 to 30 μm from the surface. Then, a nitrogen diffusion layer is formed at a depth of 0.2 to 0.5 mm from the surface.

  Since the nitrogen compound layer is fragile and may cause contamination, it is removed by grinding, and the convex curved sliding surfaces 34E and 34F are formed after the removal. The Vickers hardness of the formed convex curved sliding surfaces 34E and 34F is set to Hv900 or more (Hv900 to 1200). Thus, the Vickers is provided on the sliding portion between the convex curved sliding surfaces 34E and 34F of the swash plate 34 and the tilting sliding surfaces 35E and 35F provided on the tilting support portions 35C and 35D of the cradle 35. Even if dust containing silica having a hardness of about Hv900 invades, it is possible to suppress wear of the convex curved sliding surfaces 34E and 34F of the swash plate 34.

  Next, the cradle 35 as the second member is formed as a casting using a metal material different from the nitrided steel that is the material of the swash plate 34, for example, a cast iron material.

  Then, the cradle 35 is subjected to sulphonitriding using, for example, NH3, CO2, H2S or the like, whereby the cradle 35 having a hardened surface can be formed. As a result, the tilt sliding surfaces 35E and 35F provided on the tilt support portions 35C and 35D of the cradle 35 have a conforming layer (soft coating) which is a sulfurized layer containing sulfur at a depth of 15 μm or less from the surface. ) 35E1 and 35F1 are formed, and a nitrogen compound layer is formed at a depth of 10 to 30 μm from the surface. A nitrogen diffusion layer is formed at a depth of 0.05 to 0.1 mm from the surface.

  In this case, the Vickers hardness of each tilt sliding surface 35E, 35F on which the conformable layers 35E1, 35F1 are formed is set to, for example, Hv300 to Hv500, and the convex curved sliding surface 34E, 34F of the swash plate 34 is set. It is lower than Vickers hardness. Accordingly, the respective sliding sliding surfaces 34E, 34F of the swash plate 34 and the respective tilting sliding surfaces 35E, 35F of the cradle 35 slide, so that the tilting sliding surfaces 35E, 35E, The familiar layers 35E1 and 35F1 of 35F are partially removed. Thereby, each tilting sliding surface 35E, 35F can be adapted to each of the convex curved sliding surfaces 34E, 34F to reduce a gap formed between them, thereby suppressing intrusion of dust.

  In addition, the contact area between each of the convex curved sliding surfaces 34E and 34F and each of the tilt sliding surfaces 35E and 35F increases as much as the conforming layers 35E1 and 35F1 of the tilt sliding surfaces 35E and 35F are cut. As a result, the lubricating properties are secured by the sulfur contained in the conformable layers 35E1 and 35F1, so that the conformable layers 35E1 and 35F1 of the tilt sliding surfaces 35E and 35F can be quickly formed. Wear can be suppressed.

  Further, even if dust enters between the tilting sliding surfaces 35E, 35F and the convex curved sliding surfaces 34E, 34F, the dust is embedded in the conformable layers 35E1, 35F1. As a result, relative movement of dust between each tilting sliding surface 35E, 35F and each convex curved sliding surface 34E, 34F can be suppressed, and wear of each tilting sliding surface 35E, 35F can be reduced. Can be suppressed.

  Furthermore, even if the conformable layers 35E1 and 35F1 of the tilt sliding surfaces 35E and 35F disappear, the cradle 35 is formed of cast iron, which is a metal material different from that of the swash plate 34. The risk of the convex curved sliding surfaces 34E, 34F seizing on the respective tilting sliding surfaces 35E, 35F of the cradle 35 can be reduced.

  Moreover, even when the cradle 35 is formed inexpensively using cast iron, the cradle 35 made of the cast iron material is subjected to the nitrosulphurizing process so that the conformable layers 35E1 and 35F1 are formed on the tilt sliding surfaces 35E and 35F. Can be formed. For this reason, even when the cradle 35 is formed of an inexpensive material, the wear of each tilting sliding surface 35E, 35F and each convex curved sliding surface 34E, 34F can be suppressed, and the entire swash plate type hydraulic pump 21 can be suppressed. Can be reduced.

  In the first embodiment, the nitriding treatment using NH3, CO2, H2S, or the like is performed on the tilting sliding surface 4B that is the second sliding surface provided on the head casing 4. This shows an example in which a conformable layer (soft coating) 4B1, which is a sulfur-containing layer, is formed on the surface of the tilting sliding surface 4B. However, the present invention is not limited to this, and the tilt sliding surface 4B of the head casing 4 is subjected to a manganese phosphate treatment instead of the sulphonitriding process, so that the surface of the tilt sliding surface 4B is formed. A conformable layer containing phosphorus may be formed.

  Here, the manganese phosphate treatment means that a manganese phosphate-based crystalline conforming layer is formed on the tilting sliding surface 4B of the head casing 4 using a treatment solution composed mainly of phosphate ions and manganese ions. This is a surface treatment that produces a (film). The same applies to the tilt sliding surfaces 35E and 35F of the cradle 35 used in the second embodiment.

  Further, in the first embodiment, the case where SACM645 steel specified in JIS standard is used as the nitride steel used as the material of the valve plate 11 is illustrated. However, the present invention is not limited to this. For example, other nitrided steels specified in the DIN standard, for example, 34CrAl6, 34CrAlS5, 34CrAlMo5-10, 41CrAlMo7-10, 31CrMo12, 31CrMoV9, 15CrMoV5-9, 40CrMoV13-9, 34CrAlNi7-10 May be used. This is the same for the swash plate 34 used in the second embodiment.

  The first embodiment exemplifies a case in which the valve plate 11 of the oblique-axis hydraulic pump 1 is applied as a first member, and the head casing 4 is applied as a second member. However, the present invention is not limited to this, and can be widely applied to other two members that slide with each other.

  Furthermore, the hydraulic rotary machine according to the present invention is not limited to hydraulic pumps and hydraulic motors mounted on construction machines such as hydraulic shovels and wheel loaders, and may be applied to hydraulic pumps and hydraulic motors mounted on various industrial machines. Can be.

DESCRIPTION OF SYMBOLS 1 Oblique axis hydraulic pump 2, 22 Casing 4 Head casing (2nd member)
4B Tilt sliding surface (second sliding surface)
4B1, 35E1, 35F1 Familiar layer 5, 25 Rotating shaft 5B Drive disk 7, 27 Cylinder block 7B, 27A Cylinder 7D, 27D Cylinder port 10, 28 Piston 11 Valve plate (first member)
11A, 11B supply / discharge port (oil passage)
11D convex curved sliding surface (first sliding surface)
29 shoe 33 valve plate 34 swash plate (first member)
34E, 34F Convex curved sliding surface (first sliding surface)
35 Cradle (second member: swash plate support member)
35E, 35F Tilt sliding surface (second sliding surface)
35G Cradle side refueling passage (oil passage)

Claims (4)

A first member having a first sliding surface;
A second member having a second sliding surface that slides on the first sliding surface,
In a hydraulic rotating machine having a configuration in which at least one of the first sliding surface and the second sliding surface has one end of an oil passage through which an oil liquid flows,
The first member is formed using a bimetal of alloy steel and a copper alloy, and the first sliding surface is set to a hardness of Vickers hardness Hv900 or more by nitriding treatment,
The second member is formed using a metal material different from that of the first member, and the second sliding surface has sulfur or Vickers hardness lower than the Vickers hardness of the first sliding surface. A hydraulic rotary machine, wherein a conformable layer containing phosphorus is formed. The second member is formed using a cast iron material,
2. The hydraulic pressure according to claim 1, wherein the second sliding surface is formed with the conformable layer by subjecting the second sliding surface to one of a sulphinitriding treatment and a manganese phosphate treatment. 3. Rotating machine. A first member having a first sliding surface;
A second member having a second sliding surface that slides on the first sliding surface,
In a hydraulic rotating machine having a configuration in which at least one of the first sliding surface and the second sliding surface has one end of an oil passage through which an oil liquid flows,
A hollow casing, a rotating shaft rotatably provided in the casing and having a tip as a drive disk, and a plurality of shafts provided in the casing so as to rotate together with the rotating shaft and extending in a circumferential direction and separated in a circumferential direction. A cylinder block formed with a cylinder and a cylinder port opened at an end surface at a position corresponding to each cylinder, and a reciprocatingly inserted and protruding end inserted into each cylinder of the cylinder block, the protruding end of the drive of the rotary shaft. A plurality of pistons swingably supported by the disc, a cylinder block that slides on one end side that is the cylinder block side, and a convex curved sliding surface that is formed on the other end side; A valve plate is provided so as to be tiltable together with the cylinder block with the support point as a tilting center, and a tilting sliding surface having a concave curved surface that slides on a sliding surface of the valve plate is formed. And a head casing,
The first member is the valve plate formed with a supply / discharge port serving as the oil passage communicating with each of the cylinders through the cylinder port, and is formed using a metal material including alloy steel, The first sliding surface is set to a hardness of Vickers hardness Hv900 or more by nitriding treatment,
Said second member, Ri said head casing der which slides with said valve plate, wherein the first member is formed by using a different metal material, the first to the second sliding surface A hydraulic rotary machine , wherein a conformable layer containing sulfur or phosphorus having a Vickers hardness lower than a Vickers hardness of a sliding surface is formed . A first member having a first sliding surface;
A second member having a second sliding surface that slides on the first sliding surface,
In a hydraulic rotating machine having a configuration in which at least one of the first sliding surface and the second sliding surface has one end of an oil passage through which an oil liquid flows,
A hollow casing, a rotating shaft rotatably provided in the casing, a plurality of cylinders provided in the casing so as to rotate with the rotating shaft and extending in a circumferential direction and spaced apart in a circumferential direction, and the respective cylinders A cylinder block formed with a cylinder port opened at the end face at a position corresponding to the above, a plurality of pistons reciprocally inserted into the cylinders of the cylinder block, and swinging toward the protruding end sides of the pistons. A plurality of movably mounted shoes, a valve plate provided between the casing and the cylinder block, and formed with a supply / discharge port communicating with each of the cylinders through the cylinder port; and Each of the shoes slides on one end surface, and a convex curved sliding surface is formed on the other end surface. The inclined swash plate and the inclined sliding surface having a concave curved surface that slides on the sliding surface of the swash plate are formed therein, and an oil supply passage through which the oil liquid discharged from the cylinder port flows is formed. A swash plate support member,
The first member is the swash plate having the convex curved sliding surface, and is formed using a metal material including alloy steel, and the first sliding surface has a Vickers hardness by nitriding. Hv900 or higher hardness,
Said second member, Ri said swash plate support der that the oil supply path is formed to be the fluid passage is formed using a metal material different from the first member, said second sliding A hydraulic rotating machine , characterized in that a familiar layer containing sulfur or phosphorus having a Vickers hardness lower than the Vickers hardness of the first sliding surface is formed on the surface .

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