Hydraulic Rotating Machine

Abstract

To secure the favorable slide performance of a rotor and a slide face, and to reduce manufacturing costs of the rotor and a valve plate.SOLUTION: A rotor 7 has a recessed curved face part 7c abutting on a valve plate 15 so as to be slidable, the valve plate 15 has a protruded curved face part 15A on which the recessed curved face part 7C of the rotor 7 abuts so as to be slidable, a cross section of the recessed curve face part 7C of the rotor 7 is formed of a homogeneous circular arc radius SRr, and a cross section of the protruded curved face part 15A of the valve plate 15 is formed of a homogeneous circular arc radius SRp. Also, a circular arc center of at least either of a circular arc center of the cross section of the recessed curved face part 7C and a circular arc center of the cross section of the protruded curve face part 15A is moved in a radial direction of a rotating shaft 4, and at least either of the recessed curve face part 7C of the rotor 7 and the protruded curved face part 15A of the valve plate 15 is formed of a curved face which is obtained by rotating a circular arc which is moved with the rotating shaft 4 as a center.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a hydraulic rotating machine that is mounted as a hydraulic motor or a hydraulic pump on a construction machine such as a hydraulic excavator. [Background technology]

[0002] A hydraulic excavator, a typical example of construction machinery, comprises a self-propelled lower traveling body and an upper rotating body rotatably mounted on the lower traveling body, and hydraulic motors are typically used for the traveling device that moves the lower traveling body and the rotating device that rotates the upper rotating body. The hydraulic motor comprises a rotating shaft rotatably mounted within a casing, a rotor formed with a plurality of cylinders and cylinder ports and rotating integrally with the rotating shaft, a plurality of pistons reciprocally inserted into the cylinders of the rotor, and a valve plate formed with supply and discharge ports that intermittently communicate with the cylinder ports as the rotor rotates.

[0003] When pressure oil is discharged from the hydraulic pump and supplied to the hydraulic motor, it is sucked into the multiple cylinders of the rotor through the supply and discharge ports of the valve plate and the cylinder ports of the rotor, and multiple pistons inserted in these cylinders extend toward the swash plate. Then, shoes attached to the tips of the pistons slide along the sliding surface of the swash plate in a circular trajectory, causing the rotor to rotate, and the rotating shaft splined to the rotor to rotate.

[0004] Because the rotor and valve plate slide against each other when the rotating shaft rotates, the rotor is formed with a concave curved surface portion having a concave cross-sectional arc shape (concave arc surface shape), and the valve plate is formed with a convex curved surface portion having a convex cross-sectional arc shape (convex arc surface shape). In this way, the spherical concave curved surface portion of the rotor slides against the convex curved surface portion of the valve plate, providing a self-aligning property in which the center of rotation of the rotor moves along the curved surface toward the center of the rotating shaft when the rotor tilts due to bending of the rotating shaft. This ensures a seal between the cylinder port of the rotor, where high pressure acts, and the supply and discharge port of the valve plate.

[0005] However, when the concave curved surface of the rotor slides against the convex curved surface of the valve plate, the peripheral speed of the rotor is greater on the outer periphery than on the inner periphery, and therefore, when the rotor rotates at high speed, the concave curved surface of the rotor and the convex curved surface of the valve plate come into contact on the outer periphery, causing a problem of seizure between the sliding surfaces of the two.

[0006] In response to this, hydraulic rotating machines have been proposed that have a structure in which the radius of the arc (arc radius) of the concave curved surface portion of the rotor is set larger than the radius of the arc of the convex curved surface portion of the valve plate, and a structure in which the outer periphery of the concave curved surface portion of the rotor is formed as a tapered surface (Patent Document 1).With the hydraulic rotating machine of Patent Document 1, a gap is secured between the outer periphery of the concave curved surface portion of the rotor and the outer periphery of the convex curved surface portion of the valve plate, making it possible to prevent seizure on the outer periphery sides of both. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6276911 Summary of the Invention [Problem to be solved by the invention]

[0008] However, when the outer periphery of the concave curved surface of the rotor is formed as a tapered surface, as in Patent Document 1, the structure of the concave curved surface becomes complicated, and lapping of the concave curved surface requires a lot of time, resulting in problems such as increased rotor manufacturing costs. Moreover, in the hydraulic rotating machine of Patent Document 1, the arc radius of the concave curved surface of the rotor is set larger than the arc radius of the convex curved surface of the valve plate, so the concave curved surface of the rotor contacts the innermost periphery of the convex curved surface of the valve plate. This causes a problem of gaps being created between the cylinder ports of the rotor and the supply and discharge ports of the valve plate, reducing the sealing performance between them.

[0009] Furthermore, in the hydraulic rotary machine disclosed in Patent Document 1, the concave curved surface of the rotor and the convex curved surface of the valve plate have different arc radii. Therefore, it is not possible to perform lapping (co-lapping) while the concave curved surface of the rotor and the convex curved surface of the valve plate are in direct contact with an abrasive via the abrasive. As a result, a significant amount of time is required for break-in to ensure good sliding between the concave curved surface of the rotor and the convex curved surface of the valve plate, resulting in problems such as increased manufacturing costs for the rotor and the valve plate.

[0010] An object of the present invention is to provide a hydraulic rotary machine that can ensure good sliding properties between the sliding surfaces of the rotor and the valve plate and can reduce the manufacturing costs of the rotor and the valve plate. [Means for solving the problem]

[0011] The present invention relates to a hydraulic rotary machine comprising: a rotary shaft rotatably provided within a casing; a rotor provided within the casing so as to rotate integrally with the rotary shaft and having a plurality of cylinders and cylinder ports formed therein; a plurality of pistons reciprocatingly inserted into the plurality of cylinders of the rotor; and a valve plate with supply and discharge ports formed therein, through which the rotor slidably abuts against the valve plate and through which the plurality of cylinder ports are intermittently connected by rotation of the rotor; the rotor having a concave curved surface portion slidably abutting against the valve plate; and the valve plate having a convex curved surface portion against which the concave curved surface portion of the rotor slidably abuts. In this hydraulic rotary machine, at least one of the concave curved surface portion of the rotor and the convex curved surface portion of the valve plate has a curved surface obtained by rotation of an arc having an arc center displaced in the radial direction of the rotary shaft around the rotary shaft. The concave curved surface portion has a uniform arc radius in its cross section, and the convex curved surface portion has a uniform arc radius in its cross section, and the arc radius of the concave curved surface portion is set to be equal to or larger than the arc radius of the convex curved surface portion. It is characterized by: [Effects of the Invention]

[0012] According to the present invention, it is possible to form sliding surfaces with high sealing properties that are aligned with the positions of the ports on the rotor and valve plate, ensuring good sliding performance between them over a long period of time. In addition, it is possible to simplify the structure of the rotor and valve plate, thereby reducing manufacturing costs. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a swash plate type hydraulic motor as a hydraulic rotating machine according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing a rotor and a valve plate according to the first embodiment. [Figure 3] 3 is a conceptual diagram conceptually showing a concave curved surface portion of a rotor and a convex curved surface portion of a valve plate according to the first embodiment. FIG. [Figure 4] 4 is an enlarged view of a main part showing a part IV in FIG. 3 in an enlarged manner. [Figure 5] 10 is a conceptual diagram showing a state in which the concave curved surface portion of the rotor and the convex curved surface portion of the valve plate are in contact with each other. FIG. [Figure 6] FIG. 10 is a cross-sectional view showing a rotor and a valve plate according to a comparative example. [Figure 7] FIG. 10 is a conceptual diagram conceptually showing a concave curved surface portion of a rotor and a convex curved surface portion of a valve plate according to a comparative example. [Figure 8] 10 is a conceptual diagram showing a state in which a concave curved surface portion of a rotor and a convex curved surface portion of a valve plate are in contact with each other according to a comparative example. FIG. [Figure 9] FIG. 6 is a cross-sectional view showing a rotor and a valve plate according to a second embodiment. [Figure 10] 10 is a conceptual diagram conceptually showing a concave curved surface portion of a rotor and a convex curved surface portion of a valve plate according to a second embodiment. FIG. [Figure 11] 11 is an enlarged view of a main part showing an enlarged portion XI in FIG. 10. FIG. [Figure 12] 10 is a conceptual diagram showing a state in which the concave curved surface portion of the rotor and the convex curved surface portion of the valve plate are in contact with each other. FIG. [Figure 13] FIG. 10 is a cross-sectional view showing a rotor and a valve plate according to a third embodiment. [Figure 14] FIG. 10 is a conceptual diagram conceptually showing a concave curved surface portion of a rotor and a convex curved surface portion of a valve plate according to a third embodiment. [Figure 15] 10 is a conceptual diagram showing a state in which the concave curved surface portion of the rotor and the convex curved surface portion of the valve plate are in contact with each other. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a hydraulic rotating machine according to the present invention will be described in detail below with reference to FIGS. 1 to 15, taking as an example a case where the hydraulic rotating machine is applied to a variable displacement swash plate type hydraulic motor.

[0015] Figures 1 to 5 show a first embodiment of the present invention. In Figure 1, a variable displacement swash plate hydraulic motor 1 (hereinafter referred to as hydraulic motor 1) is connected to a hydraulic pump (neither of which is shown) via a hydraulic line, and a rotary shaft 4 is rotated by hydraulic oil (pressurized oil) supplied from the hydraulic pump. The hydraulic motor 1 is made up of a casing 2, rotary shaft 4, rotor 7, swash plate 12, valve plate 15, etc., which will be described later.

[0016] The casing 2 constitutes the outer shell of the hydraulic motor 1. The casing 2 is formed into a cylindrical shape with a bottom, with a cylindrical portion 2A and a bottom portion 2B, and the open end side of the cylindrical portion 2A is closed by a cover 3. A shaft insertion hole 2C is formed in the bottom portion 2B. The casing 2 accommodates a rotating shaft 4, a rotor 7, a swash plate 12, a valve plate 15, etc.

[0017] The rotating shaft 4 is provided in the cylindrical portion 2A of the casing 2 and is rotatable about an axial center AA relative to the casing 2. One axial end of the rotating shaft 4 is supported by the bottom portion 2B of the casing 2 via a bearing 5 attached to the shaft insertion hole 2C, and the other axial end of the rotating shaft 4 is supported by the cover 3 via a bearing 6.

[0018] The rotor 7 is rotatably provided within the cylindrical portion 2A of the casing 2. The rotor 7 is cylindrical, and a central hole 7A that penetrates in the axial direction and a hole spline 7B are concentrically formed in the center of the rotor 7. The rotating shaft 4 is inserted into the central hole 7A of the rotor 7, and an intermediate portion of the rotating shaft 4 is spline-connected to the hole spline 7B of the rotor 7. This allows the rotor 7 to rotate integrally with the rotating shaft 4. The rotor 7 is formed with a plurality of cylinders 8 that are spaced apart in the circumferential direction and extend in the axial direction, and a plurality of cylinder ports 9 that communicate with these plurality of cylinders 8 and open to a concave curved surface portion 7C, which will be described later.

[0019] A plurality of pistons 10 (only two shown) are reciprocally inserted into a plurality of cylinders 8 formed in the rotor 7. A disk-shaped shoe 11 is attached to the tip (protruding end) of each piston 10 protruding from the cylinder 8 so that the shoe 11 can swing. The shoe 11 is pressed against a sliding surface 12A of a swash plate 12 by the pistons 10, and slides along a circular path on the sliding surface 12A as the rotor 7 rotates.

[0020] The swash plate 12 is disposed within the casing 2 between the bottom 2B of the casing 2 and the rotor 7. The swash plate 12 is formed in a disk shape surrounding the rotary shaft 4. The back surface of the swash plate 12 facing the bottom 2B is tiltably supported by a swash plate support member 13 having a convex arcuate surface protruding from the bottom 2B of the casing 2. On the other hand, the surface of the swash plate 12 facing the rotor 7 is a flat sliding surface 12A, and shoes 11 attached to the tips of the pistons 10 slide along this sliding surface 12A in a circular path as the rotor 7 rotates.

[0021] The tilt actuator 14 is provided between the bottom 2B of the casing 2 and the swash plate 12. The tilt actuator 14 is composed of a tilt cylinder 14A formed in the bottom 2B and a tilt piston 14B inserted into the tilt cylinder 14A. When pressure oil (tilt control pressure) is supplied to the tilt cylinder 14A, the tilt actuator 14 presses the swash plate 12 with the tilt piston 14B. As a result, the swash plate 12 tilts relative to the bottom 2B, with the swash plate support member 13 as a fulcrum. The rotation speed of the hydraulic motor 1 is variably controlled by changing the stroke amount of the piston 10 according to the tilt angle.

[0022] Valve plate 15 is provided in casing 2, positioned between cover 3 and rotor 7. Valve plate 15 is attached to cover 3 using a knock pin (not shown) or the like. Valve plate 15 has a pair of supply / discharge ports 16 that intermittently communicate with a plurality of cylinders 8 formed in rotor 7, and this pair of supply / discharge ports 16 communicates with a pair of supply / discharge passages (not shown) formed in cover 3, respectively. A convex curved surface portion 15A is formed on the end surface of valve plate 15 facing rotor 7.

[0023] Next, the shape of the concave curved surface portion 7C of the rotor 7 and the shape of the convex curved surface portion 15A of the valve plate 15 according to the first embodiment will be described with reference to FIGS.

[0024] The concave curved surface portion 7C is provided on the end surface of the rotor 7 that faces the valve plate 15. A plurality of cylinder ports 9 formed in the rotor 7 open into this concave curved surface portion 7C. The concave curved surface portion 7C of the rotor 7 has an arc-shaped cross-sectional shape with a uniform arc radius SRr centered (arc center) at point B on the axial center AA of the rotation shaft 4 that serves as the rotation center of the rotor 7. In other words, the concave curved surface portion 7C of the rotor 7 is formed as a concave arc surface with an arc radius SRr centered at point B on the axial center AA.

[0025] The convex curved surface portion 15A is provided on the end surface of the valve plate 15 that faces the rotor 7. The convex curved surface portion 15A is formed, for example, by welding a copper alloy to the surface of the valve plate 15, and the concave curved surface portion 7C of the rotor 7 slidably abuts against the convex curved surface portion 15A. The convex curved surface portion 15A of the valve plate 15 has an arc-shaped cross-sectional shape with a uniform arc radius SRp, with the arc center at point C, which is shifted by a length σ in the radial direction of the rotation shaft 4 (direction perpendicular to the axis AA) from point B on the axis AA of the rotation shaft 4. In other words, the convex curved surface portion 15A, which is one of the concave curved surface portion 7C of the rotor 7 and the convex curved surface portion 15A of the valve plate 15, has a curved surface obtained by rotating an arc having an arc center shifted by a length σ in the radial direction of the rotation shaft 4 around the rotation shaft 4. Specifically, convex curved surface portion 15A is formed as a convex arc surface of arc radius SRp, having a curved surface obtained by rotating an arc centered at point C, which is moved a length σ from point B on axis center AA in the radial direction of rotation axis 4, around rotation axis 4. In this case, the arc radius SRr of concave curved surface portion 7C and the arc radius SRp of convex curved surface portion 15A have the relationship given by the following equation 1.

[0026]

number

[0027] In this way, the concave curved surface portion 7C of the rotor 7 is formed as a concave arc surface with an arc radius SRr and a point B on the axial center AA as the arc center, and the convex curved surface portion 15A of the valve plate 15 is formed as a convex arc surface with an arc radius SRp and a point C, which is shifted from point B by a length σ in the radial direction of the rotating shaft 4, as the arc center.

[0028] Here, a method for calculating the amount of movement σ of the arc center C of the convex curved surface portion 15A from the axis center AA of the rotation axis 4 will be described.

[0029] FIG. 3 conceptually illustrates the shapes of the concave curved surface portion 7C of the rotor 7 and the convex curved surface portion 15A of the valve plate 15, with the concave curved surface portion 7C and the convex curved surface portion 15A arranged at a distance from each other on the axial center AA of the rotating shaft 4. In FIG. 3, the concave curved surface portion 7C of the rotor 7 is formed as a concave arc surface with an arc radius SRr and a center point B on the axial center AA of the rotating shaft 4. Furthermore, the imaginary convex curved surface portion 15A' of the valve plate, indicated by a two-dot chain line in FIG. 3, is formed as a convex arc surface with an arc radius SRp and a center point B. The arc radius SRr of the concave curved surface portion 7C is set larger than the arc radius SRp of the convex curved surface portion 15A' (SRr > SRp).

[0030] Here, the center of cylinder port 9 opening in concave curved surface portion 7C is defined as D, the line connecting point B and point D is defined as E, and the intersection of line E and convex curved surface portion 15A' is defined as F. As shown enlarged in FIG. 4, between point D and intersection point F, there is a distance SRr-SRp in the radial direction, and there is also a distance of length σ in the radial direction of rotating shaft 4. Therefore, by moving intersection point F of line E and convex curved surface portion 15A' by the length σ in the radial direction of rotating shaft 4, it is possible to bring convex curved surface portion 15A' into contact with concave curved surface portion 7C at the position of center D of cylinder port 9. In this case, if the angle formed by line E and shaft center AA is defined as θ, the amount of movement σ can be calculated by the following equation 2.

[0031]

number

[0032] In this way, convex curved surface portion 15A is formed as a convex arc surface with an arc radius SRp, with point C as the arc center, which is shifted by a length σ in the radial direction of rotation shaft 4 from point B, which is the arc center of imaginary convex curved surface portion 15A', and intersection F between convex curved surface portion 15A and straight line E abuts against concave curved surface portion 7C at the position of center D of cylinder port 9. Therefore, by opening supply / discharge port 16 formed in valve plate 15 at the position of intersection F, with concave curved surface portion 7C abutting against convex curved surface portion 15A, the portion of concave curved surface portion 7C where cylinder port 9 opens can be brought into contact with the portion of convex curved surface portion 15A where supply / discharge port 16 opens. 5, the concave curved surface portion 7C of the rotor 7 and the convex curved surface portion 15A of the valve plate 15 have annular sliding regions 19 that rotate relative to each other while in contact with each other at the portions of the concave curved surface portion 7C where the multiple cylinder ports 9 open and the portions of the convex curved surface portion 15A where the supply and discharge ports 16 open. This allows the cylinder ports 9 of the rotor 7 and the supply and discharge ports 16 of the valve plate 15 to be aligned, ensuring sealing between the cylinder ports 9 and the supply and discharge ports 16.

[0033] The hydraulic motor 1 according to the first embodiment has the above-described configuration, and pressure oil discharged from the hydraulic pump is supplied from a hydraulic line through the supply / discharge port 16 of the valve plate 15 and the cylinder port 9 of the rotor 7 into the cylinder 8. As a result, the piston 10 inserted in the cylinder 8 extends from the rotor 7 toward the swash plate 12, and the shoe 11 attached to the tip of the piston 10 slides along a circular path on the sliding surface 12A of the swash plate 12 while pressing against the swash plate 12. This rotates the rotor 7, which in turn rotates the rotating shaft 4 spline-coupled to the rotor 7. The torque of this rotating shaft 4 can be increased by a reducer or the like to drive the traveling device and swing device of the hydraulic excavator.

[0034] In this embodiment, the arc radius SRr of the concave arc surface of the concave curved surface portion 7C formed on the rotor 7 is set to be larger than the arc radius SRp of the convex arc surface of the convex curved surface portion 15A formed on the valve plate 15 (SRr > SRp). Furthermore, as shown in FIG. 2, the convex curved surface portion 15A is formed as a convex arc surface with an arc radius SRp, which is a curved surface obtained by rotating an arc having an arc center offset by a length σ in the radial direction of the rotation shaft 4 around the rotation shaft 4, that is, a curved surface (spherical surface) obtained by rotating an arc centered on point C, which is offset by a length σ from point B on the axis center AA in the radial direction of the rotation shaft 4, around the rotation shaft 4. As a result, as shown in FIG. 5, when the concave curved surface portion 7C of the rotor 7 abuts against the convex curved surface portion 15A of the valve plate 15, the supply / discharge ports 16 of the valve plate 15 and the cylinder ports 9 of the rotor 7 can be accurately aligned, thereby ensuring sealing between the supply / discharge ports 16 and the cylinder ports 9. As a result, when high-pressure oil discharged from the pump is supplied to the cylinder 8 of the rotor 7 through the supply / discharge port 16 and the cylinder port 9, leakage of the pressure oil from between the supply / discharge port 16 and the cylinder port 9 can be suppressed.

[0035] On the other hand, the arc radius SRr of the concave curved surface portion 7C of the rotor 7 is set larger than the arc radius SRp of the convex curved surface portion 15A of the valve plate 15, so that an outer gap 17 can be secured between the outer periphery of the concave curved surface portion 7C of the rotor 7 and the outer periphery of the convex curved surface portion 15A of the valve plate 15. Also, an inner gap 18 can be secured between the inner periphery of the concave curved surface portion 7C of the rotor 7 and the inner periphery of the convex curved surface portion 15A of the valve plate 15 (see FIG. 5).

[0036] That is, the concave curved surface portion 7C of the rotor 7 and the convex curved surface portion 15A of the valve plate 15 come into contact with each other at the portion of the concave curved surface portion 7C where the multiple cylinder ports 9 open and at the portion of the convex curved surface portion 15A where the supply / discharge ports 16 open, and have an annular sliding region 19 on the inside (inner circumferential side) thereof where they rotate relative to each other with an inner gap 18 (see FIG. 5). Therefore, even when the rotor 7 rotates at high speed, the concave curved surface portion 7C of the rotor 7 and the convex curved surface portion 15A of the valve plate 15 are prevented from coming into contact on the outer circumferential side and the inner circumferential side, thereby preventing seizure between the concave curved surface portion 7C and the convex curved surface portion 15A.

[0037] Furthermore, the concave curved surface portion 7C of the rotor 7 is formed as a concave arc surface with a uniform arc radius SRr, and the convex curved surface portion 15A of the valve plate 15 is also formed as a convex arc surface with a uniform arc radius SRp. Therefore, compared to a structure in which the arc radius of the outer periphery of the rotor is large or the outer periphery of the rotor is tapered, the structure of the rotor 7 having the concave curved surface portion 7C and the valve plate 15 having the convex curved surface portion 15A can be simplified. As a result, the manufacturing costs of the rotor 7 and the valve plate 15 can be reduced.

[0038] Furthermore, by adjusting the dimensional difference between the arc radius SRr of the concave curved surface portion 7C and the arc radius SRp of the convex curved surface portion 15A and the amount of movement σ of the arc center C of the convex curved surface portion 15A relative to point B on the axis AA of the rotating shaft 4, it is possible to appropriately set the contact surface between the concave curved surface portion 7C and the convex curved surface portion 15A, the outer gap 17 formed on the outer periphery between the concave curved surface portion 7C and the convex curved surface portion 15A, and the inner gap 18 formed on the inner periphery between the concave curved surface portion 7C and the convex curved surface portion 15A. As a result, the degree of freedom in designing the concave curved surface portion 7C of the rotor 7 and the convex curved surface portion 15A of the valve plate 15 can be increased.

[0039] Next, the reason why the arc center C of the convex arc surface of the convex curved surface portion 15A of the valve plate 15 is moved by a length σ in the radial direction of the rotation shaft 4 will be explained based on a comparison with the comparative examples shown in Figures 6 to 8.

[0040] 6 shows a rotor 101 and a valve plate 102 that are comparative examples of the rotor 7 and the valve plate 15 according to the first embodiment. A concave curved surface portion 101A of the rotor 101 has a plurality of cylinder ports 101B opening therein, and a convex curved surface portion 102A of the valve plate 102 has a pair of supply and discharge ports 102B opening therein.

[0041] 6, the concave curved surface portion 101A of the rotor 101 is formed as a concave arc surface with an arc radius SRr and a point B on the axial center AA as its arc center. On the other hand, the convex curved surface portion 102A of the valve plate 102 is formed as a convex arc surface with an arc radius SRp and a point B on the axial center AA as its arc center. In other words, the convex curved surface portion 102A of the valve plate 102 corresponds to the convex curved surface portion 15A' indicated by the two-dot chain line in FIGS. 3 and 4. The arc radius SRr of the concave curved surface portion 101A is set larger than the arc radius SRp of the convex curved surface portion 102A (SRr > SRp).

[0042] Fig. 7 shows a state in which the concave curved surface portion 101A and the convex curved surface portion 102A face each other with a gap therebetween, and Fig. 8 shows a state in which the concave curved surface portion 101A and the convex curved surface portion 102A abut against each other when the rotor 101 rotates. In the comparative example, the arc radius SRr of the concave curved surface portion 101A is set larger than the arc radius SRp of the convex curved surface portion 102A (SRr>SRp), and the arc centers of the concave curved surface portion 101A and the convex curved surface portion 102A both coincide with point B on the axial center AA.

[0043] 8, when the rotor 101 rotates, the concave curved surface portion 101A and the convex curved surface portion 102A come into contact at their innermost peripheries and are not in contact at their outer peripheries, forming an outer gap 103. This prevents seizure from occurring at the outer periphery where the peripheral speed is high when the rotor 101 rotates. However, when the concave curved surface portion 101A and the convex curved surface portion 102A come into contact at their innermost peripheries, a minute gap 104 is also formed between the cylinder port 101B of the rotor 101 and the supply / discharge port 102B of the valve plate 102. This causes a problem of leakage of pressurized oil when high pressure acts between the supply / discharge port 102B and the cylinder port 101B.

[0044] In contrast, in this embodiment, the convex curved surface portion 15A of the valve plate 15 has a curved surface obtained by rotating an arc having an arc center offset by a length σ in the radial direction of the rotary shaft 4 around the rotary shaft 4. The concave curved surface portion 7C of the rotor 7 and the convex curved surface portion 15A of the valve plate 15 have annular sliding regions 19 that rotate relative to each other while in contact with each other at the portions of the concave curved surface portion 7C where the multiple cylinder ports 9 open and the portions of the convex curved surface portion 15A where the supply / discharge ports 16 open. As a result, when the concave curved surface portion 7C of the rotor 7 abuts against the convex curved surface portion 15A of the valve plate 15, the supply / discharge ports 16 of the valve plate 15 are accurately aligned with the cylinder ports 9 of the rotor 7, preventing gaps from occurring between them. As a result, sealing is ensured between the supply / discharge ports 16 and the cylinder ports 9, preventing leakage of high-pressure oil from between the supply / discharge ports 16 and the cylinder ports 9 when the hydraulic motor 1 is operating.

[0045] Thus, the hydraulic motor 1 according to the first embodiment comprises a rotating shaft 4 rotatably mounted within a casing 2, a rotor 7 mounted within the casing 2 so as to rotate integrally with the rotating shaft 4 and having a plurality of cylinders 8 and cylinder ports 9 formed therein, a plurality of pistons 10 reciprocatingly inserted into the plurality of cylinders 8 of the rotor 7, and a valve plate 15 in slidable contact with the rotor 7 and having formed therein supply and discharge ports 16 through which the plurality of cylinder ports 9 intermittently communicate with each other as the rotor 7 rotates, the rotor 7 having a concave curved surface portion 7C in slidable contact with the valve plate 15, and the valve plate 15 having a convex curved surface portion 15A against which the concave curved surface portion 7C of the rotor 7 slidably contacts, and at least one of the concave curved surface portion 7C of the rotor 7 and the convex curved surface portion 15A of the valve plate 15 has a curved surface obtained by rotation of an arc having an arc center C shifted radially from the rotating shaft 4, around the rotating shaft 4.

[0046] This configuration ensures good sliding properties between the sliding surfaces of the concave curved surface portion 7C of the rotor 7 and the convex curved surface portion 15A of the valve plate 15. Moreover, compared to a structure in which the arc radius of the outer periphery of the rotor is large or the outer periphery of the rotor is tapered, the structure of the rotor 7 having the concave curved surface portion 7C and the valve plate 15 having the convex curved surface portion 15A can be simplified. As a result, the manufacturing costs of the rotor 7 and the valve plate 15 can be reduced.

[0047] In this embodiment, the concave curved surface portion 7C of the rotor 7 and the convex curved surface portion 15A of the valve plate 15 come into contact with each other at a portion of the concave curved surface portion 7C where the multiple cylinder ports 9 open and a portion of the convex curved surface portion 15A where the supply / discharge ports 16 open, and have annular sliding regions 19 inside which they rotate relative to each other with an inner gap 18. With this configuration, when the concave curved surface portion 7C of the rotor 7 abuts against the convex curved surface portion 15A of the valve plate 15, the supply / discharge ports 16 of the valve plate 15 and the cylinder ports 9 of the rotor 7 can be accurately aligned, ensuring sealing between the supply / discharge ports 16 and the cylinder ports 9.

[0048] In this embodiment, the concave curved surface portion 7C of the rotor 7 has a concave arc surface with a predetermined arc radius SRr in its cross section, and the convex curved surface portion 15A of the valve plate 15 has a convex arc surface with an arc radius SRp smaller than the arc radius SRp of the concave arc surface of the concave curved surface portion 7C in its cross section. With this configuration, by making the arc radius SRp of the convex curved surface portion 15A of the valve plate 15 smaller than the arc radius SRr of the concave curved surface portion 7C of the rotor 7, an outer gap 17 is secured between the outer periphery of the concave curved surface portion 7C and the outer periphery of the convex curved surface portion 15A, and an inner gap 18 is secured between the inner periphery of the concave curved surface portion 7C and the inner periphery of the convex curved surface portion 15A. As a result, seizure between the concave curved surface portion 7C and the convex curved surface portion 15A during rotation of the rotor 7 can be prevented.

[0049] 9 to 12 show a second embodiment of the present invention. A feature of this embodiment is that the center of the arc of the concave curved surface portion formed on the rotor is shifted by a length σ in the radial direction of the rotating shaft 4. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted.

[0050] 9 shows a rotor 21 and a valve plate 22 according to the second embodiment. The convex curved surface portion 22A of the valve plate 22 has an arc-shaped cross-sectional shape with a uniform arc radius SRp and the arc center at point B on the axial center AA of the rotating shaft 4. That is, the convex curved surface portion 22A of the valve plate 22 is formed as a convex arc surface with an arc radius SRp and the arc center at point B on the axial center AA.

[0051] On the other hand, the concave curved surface portion 21A of the rotor 21 has an arc-shaped cross-sectional shape of a uniform arc radius SRr with its arc center at point C, which is shifted by a length σ in the radial direction of the rotating shaft 4 (direction perpendicular to the axis AA) from point B on the axis center AA of the rotating shaft 4. That is, the concave curved surface portion 21A of the rotor 21 is formed as a concave arc surface of arc radius SRr, having a curved surface obtained by rotating an arc centered at point C, which is shifted by a length σ from point B on the axis center AA in the radial direction of the rotating shaft 4, around the axis center AA. Furthermore, the arc radius SRr of the concave curved surface portion 21A of the rotor 21 is set larger than the arc radius SRp of the convex curved surface portion 22A of the valve plate 22 (SRr>SRp).

[0052] Here, a method for calculating the amount of movement σ of the arc center C of the concave curved surface portion 21A from the axis center AA of the rotation axis 4 will be described.

[0053] 10 conceptually illustrates the shapes of the concave curved surface portion 21A of the rotor 21 and the convex curved surface portion 22A of the valve plate 22, and shows a state in which the concave curved surface portion 21A and the convex curved surface portion 22A are arranged with a gap between them on the axial center AA of the rotating shaft 4. In Fig. 10, the convex curved surface portion 22A of the valve plate 22 is formed as a convex arc surface with an arc radius SRp and a point B on the axial center AA of the rotating shaft 4 as its arc center. In addition, the imaginary concave curved surface portion 21A' of the rotor, indicated by a two-dot chain line in Fig. 10, is formed as a concave arc surface with an arc radius SRr and a point B as its arc center.

[0054] The center of supply / discharge port 16 opening in convex curved surface portion 22A is defined as D, the line connecting point B and point D is defined as E, and the intersection of line E and concave curved surface portion 21A' is defined as F. As shown enlarged in FIG. 11 , there is a radial distance SRr-SRp between point D and intersection F, and there is also a distance of length σ in the radial direction of rotating shaft 4. Therefore, by shifting intersection F of line E and concave curved surface portion 21A' in the radial direction of rotating shaft 4 by length σ, concave curved surface portion 21A' can be brought into contact with convex curved surface portion 22A at the position of center D of supply / discharge port 16. In this case, if the angle formed by line E and axis center AA is defined as θ, length σ can be calculated using equation 2 above.

[0055] In this way, concave curved surface portion 21A is formed as a concave arc surface with an arc radius of SRr, with its arc center at point C, which is shifted by a length σ in the radial direction of rotation shaft 4 from the arc center B of imaginary concave curved surface portion 21A'. Concave curved surface portion 21A abuts against convex curved surface portion 22A at the position of center D of supply / discharge port 16. Therefore, by opening cylinder ports 9 formed in rotor 21 at the position of intersection F, the portion of concave curved surface portion 21A where cylinder ports 9 open can be brought into contact with the portion of convex curved surface portion 22A where supply / discharge ports 16 open, with concave curved surface portion 21A abutting against convex curved surface portion 22A. This allows the supply / discharge ports 16 of valve plate 22 to be aligned with the cylinder ports 9 of rotor 21, as shown in FIG. 12 .

[0056] The hydraulic motor according to the second embodiment has the rotor 21 and valve plate 22 as described above. As in the first embodiment, in the second embodiment, the concave curved surface portion 21A of the rotor 21 is formed as a concave arc surface with a uniform arc radius SRr, and the convex curved surface portion 22A of the valve plate 22 is also formed as a convex arc surface with a uniform arc radius SRp. Therefore, compared to a structure in which the arc radius of the outer periphery of the rotor is large or the outer periphery of the rotor is tapered, the structure of the rotor 21 having the concave curved surface portion 21A and the valve plate 22 having the convex curved surface portion 22A can be simplified, and the processing costs of the rotor 21 and the valve plate 22 can be reduced. Furthermore, the arc radius SRp of the convex arc surface of the convex curved surface portion 22A of the valve plate 22 is set smaller than the arc radius SRr of the concave arc surface of the concave curved surface portion 21A of the rotor 21. As a result, as shown in Figure 12, an outer gap 23 is secured between the outer periphery of the concave curved surface portion 21A of the rotor 21 and the outer periphery of the convex curved surface portion 22A of the valve plate 22, and an inner gap 24 is secured between the inner periphery of the concave curved surface portion 21A of the rotor 21 and the inner periphery of the convex curved surface portion 22A of the valve plate 22.

[0057] In this way, concave curved surface portion 21A of rotor 21 and convex curved surface portion 22A of valve plate 22 come into contact with each other at a portion of concave curved surface portion 21A where multiple cylinder ports 9 open and at a portion of convex curved surface portion 22A where supply / discharge ports 16 open, and have an annular sliding region 25 on the inside (inner circumferential side) thereof where they rotate relative to each other with an inner gap 24 (see FIG. 12 ). Therefore, even when rotor 21 rotates at high speed, contact between concave curved surface portion 21A of rotor 21 and convex curved surface portion 22A on the outer circumferential side and the inner circumferential side can be suppressed, and seizure between concave curved surface portion 21A and convex curved surface portion 22A can be prevented.

[0058] Furthermore, in the second embodiment, the arc center C of the convex arc surface of the convex curved surface portion 22A is shifted by a length σ in the radial direction of the rotation shaft 4. As a result, as in the first embodiment, when the concave curved surface portion 21A of the rotor 21 abuts against the convex curved surface portion 22A of the valve plate 22, the supply / discharge port 16 of the valve plate 22 and the cylinder port 9 of the rotor 7 can be accurately aligned, and the sealing between the supply / discharge port 16 and the cylinder port 9 can be ensured.

[0059] 13 to 15 show a third embodiment of the present invention. This embodiment is characterized in that the arc radii of the concave curved surface portion of the rotor and the convex curved surface portion of the valve plate are set equal, and the concave curved surface portion of the rotor and the convex curved surface portion of the valve plate are configured to contact each other in the central region of the rotating shaft and rotate relative to each other with a gap in the outer circumferential region. In this embodiment, the same components as in the first embodiment are designated by the same reference numerals, and their description will be omitted.

[0060] 13 shows a rotor 31 and a valve plate 32 according to the third embodiment. The concave curved surface portion 31A of the rotor 31 has an arc-shaped cross-sectional shape with a uniform arc radius SRr and the arc center at point B on the axial center AA of the rotating shaft 4. That is, the concave curved surface portion 31A of the rotor 31 is formed as a concave arc surface with an arc radius SRr and the arc center at point B on the axial center AA.

[0061] On the other hand, the convex curved surface portion 32A of the valve plate 32 has an arc-shaped cross-sectional shape of a uniform arc radius SRp with the arc center at point C, which is shifted by a length σ in the radial direction of the rotation shaft 4 from point B on the axial center AA of the rotation shaft 4. That is, the convex curved surface portion 32A of the valve plate 32 is formed as a convex arc surface of arc radius SRp, having a curved surface obtained by rotating an arc centered at point C, which is shifted by a length σ in the radial direction of the rotation shaft 4 from point B on the axial center AA, around the rotation shaft 4. Here, in this embodiment, the arc radius SRr of the concave curved surface portion 31A of the rotor 31 and the arc radius SRp of the convex curved surface portion 32A of the valve plate 32 satisfy the relationship given by the following equation 3.

[0062]

number

[0063] Here, the arc center C of the convex curved surface portion 32A of the valve plate 32 is shifted by a length σ in the radial direction of the rotary shaft 4 from point B on the axial center AA of the rotary shaft 4. The amount of movement σ of this arc center C is geometrically set, for example, in accordance with the required amount of outer gap 33 (required gap amount) between the outermost peripheral portion of the concave curved surface portion 31A and the outermost peripheral portion of the convex curved surface portion 32A when the concave curved surface portion 31A of the rotor 31 is abutted against the convex curved surface portion 32A of the valve plate 32. As a result, the concave curved surface portion 31A of the rotor 31 and the convex curved surface portion 32A of the valve plate 32 are configured to come into contact with each other in the central region of the rotary shaft 4 and to rotate relative to each other with the outer gap 33 remaining in the outer peripheral region.

[0064] The hydraulic motor according to the third embodiment has the rotor 31 and valve plate 32 as described above, and the arc radius SRr of the concave arc surface of the concave curved surface portion 31A formed on the rotor 31 is set equal to the arc radius SRp of the convex arc surface of the convex curved surface portion 32A formed on the valve plate 32 (SRr = SRp). Furthermore, the arc center C of the convex arc surface of the convex curved surface portion 32A is shifted by a length σ in the radial direction of the rotating shaft 4 from a point B on the axial center AA of the rotating shaft 4. As a result, as shown in Figure 15, the concave curved surface portion 31A of the rotor 31 and the convex curved surface portion 32A of the valve plate 32 are in contact with each other at their innermost peripheries, which are the central region of the rotating shaft 4, and an outer gap 33 is formed between the outermost peripheries of the concave curved surface portion 31A and the convex curved surface portion 32A, which are the outer periphery region.

[0065] As described above, in the third embodiment, even when the arc radius SRr of the concave curved surface portion 31A and the arc radius SRp of the convex curved surface portion 32A are set equal (SRr=SRp), the outer gap 33 can be secured at the outermost periphery between the concave curved surface portion 31A and the convex curved surface portion 32A, just as in the case where the arc radius SRr of the concave curved surface portion 31A is set larger than the arc radius SRp of the convex curved surface portion 32A (SRr>SRp). This makes it possible to prevent seizure between the concave curved surface portion 31A and the convex curved surface portion 32A in this embodiment as well.

[0066] Furthermore, in the third embodiment, the concave curved surface portion 31A of the rotor 31 has an arc radius SRr equal to the arc radius SRp of the convex curved surface portion 32A of the valve plate 32. This allows for lapping (co-lapping) of the concave curved surface portion 31A and the convex curved surface portion 32A in direct contact with each other via an abrasive. This reduces the time and cost required for lapping compared to lapping the concave curved surface portion and the convex curved surface portion separately when the arc radii of the concave curved surface portion of the rotor and the convex curved surface portion of the valve plate are different. Furthermore, after lapping the concave curved surface portion 31A and the convex curved surface portion 32A, it is not necessary to perform a long break-in period in which the concave curved surface portion 31A and the convex curved surface portion 32A are in contact with each other. This reduces the manufacturing costs of the rotor 31, including the concave curved surface portion 31A, and the valve plate 32, including the convex curved surface portion 32A.

[0067] Thus, in the third embodiment, the arc radius SRr of the cross section of the concave curved surface portion 31A of the rotor 31 and the arc radius SRp of the cross section of the convex curved surface portion 32A of the valve plate 32 are set equal to each other, and the concave curved surface portion 31A and the convex curved surface portion 32A contact each other on the inner periphery, which is the central region of the rotating shaft 4, and rotate relative to each other with an outer gap 33 in the outer periphery. With this configuration, the outer gap 33 is secured at the outermost peripheries of the concave curved surface portion 31A and the convex curved surface portion 32A, preventing seizure between the concave curved surface portion 31A and the convex curved surface portion 32A. Furthermore, lapping (co-lapping) can be performed with the concave curved surface portion 31A and the convex curved surface portion 32A in direct contact with each other via an abrasive, thereby reducing the time and cost required for processing the concave curved surface portion 31A and the convex curved surface portion 32A.

[0068] In the first embodiment, an example is shown in which the arc center C of the convex curved surface portion 15A of the valve plate 15 is moved by a length σ in the radial direction of the rotating shaft 4, and in the second embodiment, an example is shown in which the arc center C of the concave curved surface portion 21A of the rotor 21 is moved by a length σ in the radial direction of the rotating shaft 4. However, the present invention is not limited to this. For example, the arc center of the convex curved surface portion of the valve plate may be moved by a length σp in the radial direction of the rotating shaft 4, and the arc center of the concave curved surface portion of the rotor may be moved by a length σr in the radial direction of the rotating shaft 4, so that the sum of the movement amount σp of the arc center of the convex curved surface portion and the movement amount σr of the arc center of the concave curved surface portion is the movement amount σ (σ = σp + σr).

[0069] In addition, in the embodiment, a variable displacement swash plate hydraulic motor 1 is exemplified as the hydraulic rotating machine, but the present invention is not limited to this and can be widely applied to various hydraulic rotating machines equipped with a rotor and a valve plate, such as a variable displacement swash plate hydraulic pump, a bent axis hydraulic motor, and a bent axis hydraulic pump. [Explanation of symbols]

[0070] 2 Casing 4 rotation axes 7,21,31 rotor 7C,21A,31A Concave curved part 8 cylinders 9 Cylinder Port 10 pistons 15, 22, 32 Valve plate 15A, 22A, 32A Convex curved surface 16 Intake and exhaust port 17, 23, 33 Outer gap (gap) 18,24 Inner gap (gap) 19,25 Sliding area

Claims

1. a rotor provided in the casing so as to rotate integrally with the rotary shaft and having a plurality of cylinders and cylinder ports formed therein; a plurality of pistons inserted into the plurality of cylinders of the rotor so as to be able to reciprocate; and a valve plate formed with supply and discharge ports against which the rotor slidably abuts and through which the plurality of cylinder ports are intermittently connected by rotation of the rotor; a hydraulic rotating machine in which the rotor has a concave curved surface portion that slidably contacts the valve plate, and the valve plate has a convex curved surface portion that the concave curved surface portion of the rotor slidably contacts, at least one of the concave curved surface portion of the rotor and the convex curved surface portion of the valve plate has a curved surface obtained by rotating an arc having an arc center displaced in the radial direction of the rotation shaft around the rotation shaft, the concave curved surface portion has a uniform arc radius in its cross section, and the convex curved surface portion has a uniform arc radius in its cross section, A hydraulic rotating machine, characterized in that the arc radius of the concave curved surface portion is set to be equal to or larger than the arc radius of the convex curved surface portion.

2. 2. The hydraulic rotating machine according to claim 1, wherein the concave curved surface portion of the rotor and the convex curved surface portion of the valve plate contact each other at a portion of the concave curved surface portion where the plurality of cylinder ports open and a portion of the convex curved surface portion where the supply / discharge ports open, and have annular sliding regions inside which the concave curved surface portion and the convex curved surface portion rotate relative to each other with a gap therebetween.

3. 2. The hydraulic rotating machine according to claim 1, wherein the concave curved surface portion of the rotor has a concave arc surface with a predetermined arc radius in cross section, and the convex curved surface portion of the valve plate has a convex arc surface with a smaller arc radius in cross section than the concave arc surface.

4. the radius of the arc of the cross section of the concave curved surface portion of the rotor and the radius of the arc of the cross section of the convex curved surface portion of the valve plate are set equal to each other; 2. The hydraulic rotating machine according to claim 1, wherein the concave curved surface portion of the rotor and the convex curved surface portion of the valve plate are configured to contact each other in an inner circumferential region and rotate relative to each other with a gap in an outer circumferential region.

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