JPH04140482A - Variable displacement bent axis type fluid pressure machine - Google Patents

Abstract

PURPOSE:To improve seal performance so as to suppress leakage of oil between the internal peripheral surface of a cylinder hole and a rod part by forming an internal peripheral side of the rod part of a static pressure pad, which constitutes a static pressure bearing, as a tapered surface part over the total length from a point end to a root of the rod part. CONSTITUTION:In a variable displacement oil hydraulic pump, a point end in a casing of a rotary shaft is formed into a drive disk 6 of almost U shape, and this drive disk 6 receives piston oil pressure reaction force supported through a radial static pressure bearing 20 and a thrust static pressure bearing. The radial static pressure bearing 20 is constituted of a plurality of cylinder holes 21 drilled in a radial direction in a peripheral side of a sleeve part 4A of a bearing sleeve 4, static pressure pad 22 and a pressure chamber 23 formed in a recessed groove shape in a sliding surface of a large diameter pad part 22-2 to communicate with a throttle passage 24. Here, a rod part 22-1 is formed into a hollow cylindrical shape, and an internal peripheral side of the rod part is formed as a tapered surface part 22-3. In this way, unevenness of dimension can be absorbed by forming the rod part 22-1 uniformly over the total length in the axial direction to make elastic deformation possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable displacement oblique shaft hydraulic machine used as a variable displacement oblique shaft hydraulic pump or a hydraulic motor, and particularly relates to a variable displacement oblique shaft hydraulic machine with partial hydrostatic bearing support. Alternatively, the present invention relates to a variable capacity oblique shaft hydraulic machine in which the rotating shaft is supported by a full hydrostatic bearing.

[Conventional technology]

Generally, in an oblique shaft type hydraulic machine, a drive disk of a rotating shaft and a cylinder block are connected via a piston that is reciprocatably provided to the cylinder block. Therefore, when a diagonal shaft type hydraulic machine is used as a hydraulic pump, the hydraulic reaction force that acts on the high pressure side piston during the discharge stroke is received by the rotating shaft via the drive disk, and similarly it can be used as a hydraulic motor. When applied, the hydraulic reaction force acting on the high pressure side piston during the suction (supply) stroke is received by the rotating shaft via the drive disk.

Therefore, in this type of oblique shaft type hydraulic machine, since radial loads and thrust loads due to hydraulic reaction force act on the rotating shaft, the rotating shaft must be supported in a suspended state to support these loads. There is.

For this reason, in the conventional technology, a mechanical support type that mechanically supports a rotary shaft rotatably through a rolling bearing such as a roller bearing or a ball bearing that can receive radial load and thrust load, Partial hydrostatic bearing support type, in which one load is mechanically supported by a rolling bearing and the other load is supported hydraulically in a static pressure bearing, and fully hydrostatic bearing support type, in which the entire load is supported hydraulically by a pressure bearing, are known. It is being

Of these bearing support types, in hydraulic machines with partial hydrostatic bearing support or full hydrostatic bearing support, a radial hydrostatic bearing or thrust hydrostatic bearing is installed in the cylinder hole drilled on the casing side, and the rod section is a static pressure pad that is slidably inserted into the cylinder hole, the sliding surface side of the pad part slidingly contacts the drive disk side that is integrated with the rotating shaft, and the non-sliding surface side contacting the casing; and the static pressure pad. The pressure chamber is recessed on the sliding surface side of the pad section and is supplied with bearing control pressure. Then, a part of the high-pressure oil sucked and discharged by the hydraulic machine is guided into the pressure chamber as bearing control pressure, and acts on the drive disk through the oil film formed between the sliding surface of the pad section and the drive disk. The radial load and thrust load due to piston hydraulic reaction force are received between the non-sliding surface side and the casing.

[Problem to be solved by the invention]

However, in the prior art, as a means to minimize the leakage flow generated from the gap between the rod part of the hydrostatic bearing part, especially the rod part of the static pressure pad, and the cylinder hole, O2 is installed on the outer periphery of the rod part.
A shaft sealing member such as a ring or a piston ring is provided. Alternatively, the seal between the rod portion of the static pressure pad and the cylinder hole may be determined by regulating the gap size between the two members to a predetermined value.

However, among the former conventional technologies, O-ring seals have a short seal length, and assuming that they support variable loads at high temperatures, this sealing method has the disadvantages of ensuring seal reliability and durability for long-term use. There are problems with this. In addition, in the case of piston ring seals,
If the piston ring is used for a long period of time under a fluctuating load, the outer periphery of the piston ring will wear out, making it impossible to seal reliably.

On the other hand, in the latter prior art, when manufacturing a hydrostatic bearing, variations may occur in the gap size between the rod portion of the hydrostatic pad and the cylinder hole. This leaves some concerns from the perspective of achieving a reliable seal without being affected by dimensional variations.

Therefore, there is a problem in that the leakage flow rate increases in proportion to the increase in the bearing control pressure used and the tilting angle of the cylinder block, and as a result, the power loss increases due to the leakage flow rate.

The present invention has been made in view of the problems of the prior art, and is free from the influence of variations in the gap size between the rod portion of the static pressure pad and the cylinder hole, and is capable of eliminating the conventional shaft sealing member. For example, we have developed a variable capacity oblique shaft type hydraulic machine that can keep the leakage flow rate generated from the gap between the rod part of the static pressure pad and the cylinder hole to a minimum without using O-rings, piston rings, etc. [Means for Solving the Problem] In order to achieve the above object, the present invention provides a cylindrical casing provided with a head casing having a suction and exhaust passage, and a head casing rotatably provided in the casing. a rotating shaft having a drive disk at its end on the side inserted into the casing; a cylinder block disposed within the casing and having a plurality of cylinders bored in the axial direction; and each cylinder of the cylinder block. It has a plurality of pistons that are reciprocably movable on the cylinder block, one end of which is swingably supported by the drive disk, and a pair of suction/exhaust ports. At least a valve plate that slides on the tilting sliding surface of the head casing, a tilting mechanism that tilts the valve plate together with the cylinder block, and hydraulic reaction forces in the radial direction and the thrust direction that act on the drive disk. A variable capacity oblique shaft comprising at least one of a radial static pressure bearing and a thrust static pressure bearing provided between the drive disk and the casing in order to receive one load. In the hydrostatic machine, the hydrostatic bearing has a cylinder hole drilled in the casing, a rod part is slidably inserted into the cylinder hole, and the sliding surface side of the pad part slides against the drive disk side. A fixed hydrostatic bearing consisting of a static pressure pad that contacts the casing on the non-sliding surface side, and a pressure chamber that is recessed in the sliding surface side of the pad portion of the static pressure pad and is supplied with bearing control pressure. The rod portion of the static pressure pad is formed into a hollow cylindrical shape, and the inner peripheral side of the rod portion is formed as a tapered surface portion whose diameter continuously decreases from the tip to the root. It is something.

Further, the present invention provides the above-mentioned variable capacity oblique shaft type hydraulic machine, wherein the static pressure bearing has a cylinder hole bored on the casing side, and a rod portion is slidably inserted into the cylinder hole, A static pressure pad whose sliding surface side of the pad portion slides on the drive disk side and whose non-sliding surface side contacts the casing, and a recess is provided on the sliding surface side of the pad portion of the static pressure pad to supply bearing control pressure. The rod part of the static pressure pad is formed into a stepped hollow cylindrical shape with different outer diameters, a large diameter at the tip side and a small diameter at the base side. The inner peripheral side of the rod portion is characterized in that a tapered surface portion located on the tip side and whose diameter gradually decreases and a straight surface portion located on the root side are continuously connected.

Here, the static pressure bearing is a plurality of fixed radial static pressure bearings, and each of the radial static pressure bearings is configured to generate a moment about the rotation axis at the point of application of the resultant force of the average hydraulic reaction force in the radial direction acting on the drive disk. can be placed in a balanced position.

Furthermore, at least one of the hydrostatic bearings made up of the plurality of hydrostatic pads may be a floating hydrostatic bearing. In this case, the floating hydrostatic bearing can be provided in the direction in which the hydraulic reaction force acts.

Furthermore, the variable capacity oblique shaft type hydraulic machine according to the present invention can be applied as a main hydraulic power source pump or drive motor in a hydraulic system of construction machinery.

[Effect]

The structure of the rod part of the hydrostatic pad that constitutes a radial hydrostatic bearing or a thrust hydrostatic bearing is a hollow cylindrical shape with an open tip, and the inner circumference tapers so that the diameter decreases from the tip to the root. By forming the rod into a planar shape, the wall thickness of the hollow cylindrical portion changes so that it becomes thicker continuously from the tip on the open side of the rod to the root.

Therefore, even if a constant bearing control pressure acts on the inner periphery of the rod and a bearing control pressure with a pressure gradient that decreases from the tip to the root on the outer periphery, the inner and outer peripheries of the rod The rod part can be elastically deformed over its entire length without depending on the magnitude of the differential pressure between the rod part and the cylinder hole. It is possible to improve the sealing performance between.

As a result, by eliminating the gaps between the cylinder holes and the rods of multiple hydrostatic bearings that are installed independently with respect to the casing, the leakage flow rate from the rods of the hydrostatic pads is minimized. can be suppressed to

On the other hand, the structure of the rod part of the static pressure pad is formed into a stepped hollow cylindrical shape with different outer diameters, with the tip side having a large diameter and the base side having a small diameter. By forming the tapered surface section whose diameter is reduced and the straight surface section located on the root side to be continuously connected, it is possible not only to improve the sealing performance over the entire length as described above, but also to prevent the static pressure pad from tilting. Even if
By locally elastically deforming the large-diameter tip side that is a tapered surface portion, the leakage flow rate can be suppressed to a minimum.

On the other hand, the piston hydraulic reaction force acting on the drive disk is expressed as "■" centered on the point of force of the resultant force of the average hydraulic reaction force.
It fluctuates as if drawing a letter. Therefore, multiple fixed type hydrostatic bearings are used as radial static pressure bearings, and each of these fixed type radial static pressure bearings is placed around the rotation axis at the point of application of the resultant force of the average hydraulic reaction force in the radial direction acting on the drive disk. This rotational moment can be balanced by arranging it at a position where the moment of rotation is balanced.

Furthermore, at least one of the plurality of hydrostatic bearings provided at a location where a hydraulic reaction force acts in the radial direction is a floating type hydrostatic bearing provided in the direction where the hydraulic reaction force acts, and Even when the anti-sliding surface of the pad part of the hydrostatic pad of a floating hydrostatic bearing moves away from the fixed side casing and follows the drive disk to perform the hydrostatic bearing support function, the structure of the rod part is fixed as described above. By doing the same as in the case of the fixed type hydrostatic bearing, the leakage flow rate from the outer periphery of the rod portion of all the static pressure bearings including the fixed type hydrostatic bearing can be suppressed to a minimum.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail using a variable displacement hydraulic pump as an example, with reference to the accompanying drawings.

1 to 5 show a first embodiment of the invention.

In the drawings, 1 indicates a casing, and the casing 1
The casing main body 2 is composed of a cylindrical casing body 2 consisting of a small diameter cylindrical portion 2A and a large diameter slanted cylindrical portion 2B, and a head casing 3 that closes the opening side of the slanted cylindrical portion 2B of the casing body 2.

Reference numeral 4 denotes a bearing sleeve as a supporting member that is provided in the small diameter cylindrical portion 2A of the casing body 2 and constitutes a part of the casing 1.
A sleeve part 4A located in the space between the cylindrical part 6B of the drive disk 6, and a collar located on the outer periphery of the sleeve part 4A and supported by contacting the inner step part 2C of the small diameter cylindrical part 2A. It is composed of a section 4B.

Reference numeral 5 denotes a rotating shaft with a shaft portion 5A extending through the bearing sleeve 4, and the tip of the rotating shaft 5 inside the casing 1 is connected to the rotating shaft 5.
The drive disk 6 is integrally molded with the drive disk 6 and has a substantially inverted U-shaped cross section. Here, the drive disk 6 is composed of a large-diameter disk portion 6A and a cylindrical portion 6B extending from the outer periphery of the disk portion 6A toward the flange portion 4B of the bearing sleeve 4. The rotating shaft 5 is axially supported by the bearing sleeve 4 via a bearing 7, and the drive disk 6 receives piston hydraulic reaction force via radial static pressure bearings 20, 25 and a thrust static pressure bearing 30, which will be described later. It is supposed to be done.

Reference numeral 8 denotes a cylinder block that is provided in the casing 1 and rotates integrally with the rotating shaft 5. The cylinder block 8 is provided with a plurality of cylinders 9° 9, . . . bored in the axial direction, and each cylinder 9 have pistons 10, 10., respectively.・
... is provided so that it can move back and forth. A spherical portion 10A is formed at the tip of each piston 10, and each spherical portion 10A is swingably connected to a disc portion 6A of the drive disk 6.

Reference numeral 11 denotes a square valve plate, one end surface of the valve plate 11 is in sliding contact with the end surface of the cylinder block 8, and the other end surface has a concave arc-shaped tilting sliding surface 12 formed on the helad casing 3.
A through hole 11A is formed in the center of the valve plate 11, into which a center shaft 13 and a tip end of a swing bottle 19, which will be described later, are respectively inserted from both sides. A pair of supply/discharge ports (not shown) are bored in the valve plate 11 and communicate with each cylinder 9 intermittently as the cylinder block 8 rotates. Regardless of the rotation position, a pair of supply/discharge passages (
(not shown).

Reference numeral 13 denotes a center shaft that rotatably supports the cylinder block 8 between the drive disk 6 and the valve plate 11. The center shaft 13 has a spherical portion 13A formed at one end thereof, and the spherical portion 13A is connected to the drive disk 13. It is swingably supported at the axial center position of the disk 6. On the other hand, the other end of the center shaft 13 that protrudes through the cylinder block 8 is rotatably inserted into a through hole 11A drilled at the center of the valve plate 11, and the center shaft 13 is rotatably inserted into the through hole 11A formed at the center of the valve plate 11. It is carried out. 14 is a compression spring for applying preload to the sliding surface between the cylinder block 8 and the valve plate 11.

Reference numeral 15 denotes a tilting mechanism provided in the head casing 3 in order to tilt the valve plate 11 along the tilting sliding surface 12. a stepped cylinder hole 16 having holes 16A and 16B;
A servo piston 18 is slidably inserted into the cylinder hole 16 and defines oil chambers 17A and 17B on both sides in the axial direction.
The swing bottle 19 is swingably inserted into the through hole 11A of the swing bottle 19. Then, pressure oil from the auxiliary pump (not shown) is supplied to the oil passage hole 16A through the tilt control valve.
Or by supplying oil to the oil chamber 17A or 17B via 16B, the servo piston 18 is driven and the valve plate 11
, the cylinder block 8 is driven to tilt.

Next, the configuration of the hydrostatic bearing according to this embodiment will be described.

2OA, 20B, and 20C are the first parts that receive the radial load component of the average hydraulic reaction force acting on the drive disk 6.
．． Second. As shown in FIGS. 2 and 3, each of the third fixed type radial hydrostatic bearings 20A to 20G has an outer periphery of the sleeve portion 4A of the bearing sleeve 4 that forms a part of the casing. Cylinder holes 21A, 21B, 2 that are bored in the radial direction with a specific positional relationship that will be described later.
1C and small diameter rod parts 22A-1, 22B-422C
-1 and large diameter pad portions 22A-2, 22B-2, 22C
-2 consisting of static pressure pads 22A22B, 22C, and large diameter pad portions 22A- of each of the static pressure pads 22A to 22C.
Pressure chambers 23A, 23B, and 23C formed in a groove shape on the sliding surface side of 2 to 22C-2, and the sill holes 21A to 2
It is generally composed of throttle passages 24A, 24B, and 24C provided in the axial direction of the static pressure pads 22A to 22C so as to communicate the chambers in 1C with the pressure chambers 23A to 23C, respectively.

The rod portions 22A-1 to 22C-1 are formed in a hollow cylindrical shape, and the inner peripheral side thereof has tapered surface portions 22A-3 and 22B whose diameter continuously decreases from the opening side tip to the root.
-3, 22C-3, cylinder hole 21A~
Micro gaps 22A-4, 22B-4, 22 for 2IC
They are each slidably inserted through C-4. Further, the pad portions 22A-2 to 22C-2 have their sliding surfaces in sliding contact with the inner circumferential surface (bearing guide surface) 6B of the cylindrical portion 6B of the drive disk 6 via an oil film, and their anti-sliding A plurality of relief grooves 22A-5, 2 are provided in the radial direction on the surface side.
2B-5 and 22C-5 are provided, and the sliding surfaces thereof are in contact with the outer circumferential surface 4A of the sleeve portion 4A of the bearing sleeve 4.

By configuring the hydrostatic bearing as described above, it is necessary to install a shaft sealing member such as an O-ring or a piston ring on the rod portion as in the prior art for reasons described later. (Moreover, the rod part 2
Even if there are manufacturing variations in the dimensions of 2A-1 to 22C-1 and cylinder holes 21A to 22C, the tapered surface portion 22
Rod portions 22A-1 to 22 having A-3 to 22C-3
By uniformly and -like elastic deformation of C-1 over its entire axial length, minute gaps associated with dimensional variations can be eliminated.

As a result, 20A to 2 of the static pressure pads arranged in multiple locations
The leakage flow rate from the rod portions 22A-1 to 22C-1 of 2C can be suppressed to the minimum.

In addition, fixed radial static pressure bearings 20A to 20C, cylinders 21A to 2IC5 static pressure pads 22A to 22C1 pressure chambers 23A to 23C1 throttle passages 24A to 24C1, small diameter rod portions 22A-1 to 22C-1, and large diameter pad portion 22A. −
2 to 22C-2, tapered surface portions 22A-3 to 22C-3,
Small gaps 22A-4 to 22C-4, relief grooves 22A-5 to
22C-5 as a whole, a fixed radial static pressure bearing 20, a cylinder hole 21, a static pressure pad 22, a pressure chamber 23, a throttle passage 24, a rod part 22-1, and a pad part 22.
-2, tapered surface portion 22-3, minute gap 22-4, and clearance groove 22-5.

On the other hand, reference numeral 25 denotes a floating radial static pressure bearing that cooperates with the fixed radial static pressure bearing 20 to receive the radial load component acting on the drive disk 6. The floating radial static pressure bearing 25 also has a second As shown in FIG. 4, there is a cylinder hole 26 radially bored at a specific position (to be described later) on the outer circumferential side of the bearing sleeve 4A, a small diameter rod portion 27-1, and a large diameter pad portion 27-2. a static pressure pad 27 consisting of a pressure chamber 28 formed in a groove shape on the sliding surface side of the static pressure pad 27; It is composed of a throttle passage 29 provided in the axial direction of the pressure pad 27.

The rod portion 27-1 is formed into a hollow cylindrical shape, and the inner circumferential side thereof is formed as a tapered surface portion 27-3 whose diameter is continuously reduced from the opening side tip to the root, and a minute gap is formed between the rod portion 27-1 and the cylinder hole 26. It is slidably inserted through 27-4. Further, the pad portion 27-2 has a sliding surface side that is connected to the inner circumferential surface 6B of the cylindrical portion 6B of the drive disk 6;
It is designed to slide into contact with the surface through an oil film, and to face the non-sliding surface side with a gap .beta..

Here, a special arrangement relationship between each of the fixed radial hydrostatic bearings 20A to 20C and the floating radial hydrostatic bearing 25 will be described.

First, in FIG. 2, assuming that the axes orthogonal to the axis of the rotating shaft 5 are the X-axis and the y-axis, and that the rotating shaft 5 rotates in the direction of arrow A, the average The force application point of the resultant force of the hydraulic reaction force F is P, and the force application point P of this resultant force is located at a position displaced to the right from the intersection of the X axis and the y axis. Note that the point P is called the point of application of the resultant force of the average hydraulic reaction force because the hydraulic reaction force F varies in the shape of a "■" depending on the number of pistons on the high pressure side.

And when the tilt angle of the cylinder block 8 is α,
It is given by the radial load F, I, and S due to the hydraulic reaction force F. When the tilt angle α is the minimum, the radial load
l is minimum and thrust load FT is maximum. On the other hand, when the tilt angle α is the maximum, the radial load F1. l is maximum and thrust load FT is minimum.

When such a hydraulic reaction force F acts in the direction of the arrow in FIG.
+ and the inner circumferential surface 6B of the cylindrical portion 6B of the drive disk 6, on the positive side of the y-axis (above the intersection with the X-axis), the outer circumferential surface 4A1 and the inner circumferential surface 6B, The load acts as a load that causes the space between the outer peripheral surface 4A and the inner peripheral surface 6B to narrow on the negative side of the y-axis (below the intersection with the X-axis).

Further, side force is generated in the sliding portion of the valve plate 11 due to the shape of the suction/exhaust port on the high pressure side. This side force acts on the drive disk 6 via the piston 10 or the center joint 13 in the direction indicated by the arrow FV in FIG.

Now, based on the above-mentioned force relationships, the first fixed radial static pressure bearing 2OA is on the side of the point P of the resultant force, and the variation of the point P of the resultant force fluctuates in the shape of the letter "ψ". The second fixed radial static pressure bearing 20B is disposed outside the range (on the right side of the point P of the resultant force in FIG. The third radial fixed hydrostatic bearing 20C is located on the origin force point side of the resultant force P (on the left side of the y-axis) and is located below the y-axis. The floating radial static pressure bearing 25 is disposed on or near the X-axis, and is disposed above the y-axis and on or near the y-axis in order to receive the hydraulic reaction force F. .

With this arrangement, the moment load around the rotating shaft 5 caused by the radial load is balanced by the first and second fixed radial static pressure bearings 2OA and 20B, and the third fixed radial static pressure bearing The pressure bearing 20C receives the side force F9, and even if the resultant force of the hydraulic reaction force fluctuates, the floating radial static pressure bearing 25 can absorb and support this fluctuation.

Next, reference numeral 30 denotes a fixed type thrust static pressure bearing, which receives the thrust load acting on the drive disk 6, and the axial end surface 4 A z of the sleeve portion 4A of the bearing sleeve 4. The drive disk 6 is provided between the disk portion 6A of the drive disk 6 and the back surface of the disk portion 6A. here,
As shown in FIGS. 1 and 5, the fixed type thrust hydrostatic bearing 30 has the same configuration as the fixed type radial hydrostatic bearing 20 described above, and includes an end surface 4A of the sleeve portion 4A of the bearing sleeve 4, A cylinder hole 31 is bored in the axial direction, and the cylinder hole 31 is slidably inserted into the cylinder hole 31 with a small gap 32-4, and a tapered surface portion 32-3 is formed on the inner circumferential side. Small diameter rod part 32-1 and large diameter pad part 32
-2, a pressure chamber 33, a throttle passage 34, and a plurality of relief grooves formed radially on the non-sliding surface side of the large-diameter pad portion 32-2 of the static pressure pad 32. 32-
It is composed of 5. In addition, in FIG. 1, only one fixed type thrust static pressure bearing 30 is shown as a representative, but
Similar to the fixed radial hydrostatic bearing 20 described above, the y-axis,
A plurality of bearings can be arranged around the sleeve portion 4A of the bearing sleeve 4 so that the moment load around the y-axis is balanced, and they can also be arranged in combination with a floating type thrust hydrostatic bearing (not shown). .

35 is an oil passage that constantly supplies bearing control pressure to each of the aforementioned radial static pressure bearings 20, 27 and thrust static pressure bearing 30;
The oil passage 35 is formed from the casing l to the bearing sleeve 4. One end of the oil passage 35 guides high-pressure oil to be sucked and discharged through the high-pressure side port of a pair of suction and discharge ports bored in the valve plate 11. The oil passage 35 opens at either the high pressure side suction and exhaust passage or the high pressure side piping outside the casing 1, and the other end of the oil passage 35 is connected to the fixed radial static pressure bearings 20A to 20C1 and the floating radial static pressure bearing 25.
, each cylinder hole 21A to 21 of the fixed thrust bearing 30
C, 26, and 31, respectively, to supply bearing control pressure. Note that the oil passage 35 may be constituted by an external pipe passing outside the casing 1.

In FIG. 1, reference numeral 36 denotes a shaft sealing member, and the sealing member 41 is provided between the rotating shaft 5 and the small diameter cylindrical portion 2A of the casing body 2.

Although the present embodiment is constructed as described above, the operation when used as a hydraulic pump will be explained next.

First, the tilt mechanism 15 tilts the valve plate 11 together with the cylinder block 8 to the maximum tilt position shown in FIG. Therefore, the pressure oil from the auxiliary pump is transferred to the oil chamber 1 of the cylinder hole 16.
7 to displace the servo piston 18. As a result, the swing pin 19 is displaced together with the servo piston 18, and the valve plate 11 is guided by the tilting sliding surface 12 and tilted. As a result, the cylinder block 8 is tilted together with the center shaft 13, and the cylinder block 8 is tilted integrally with the center shaft 13. The center of rotation is tilted with respect to the axis of the rotation shaft 5,
The state shown in the figure will be reached.

Next, when the rotating shaft 5 is rotated by a drive source such as an engine or an electric motor, the drive disk 6 of the rotating shaft 5 is connected to the piston 10 inserted into each cylinder 9 of the cylinder block 8, so that the rotating shaft 5 is rotated. The cylinder block 8 is rotated together. As a result, each piston lO reciprocates within the cylinder 9 while the cylinder block 8 is rotating. While each piston 10 is retracting from the cylinder 9, there is a suction stroke in which hydraulic oil is sucked into the cylinder 9 from the suction/discharge passage through the suction/discharge port, and while each piston 10 is moving into the cylinder 9, the hydraulic oil is sucked into the cylinder 9. This is a discharge stroke in which the hydraulic oil inside is pressurized and discharged through the suction/discharge port and the suction/discharge passage.

Here, in a diagonal shaft type hydraulic pump, the number of pressurizing pistons to generate discharge pressure (for example, if the total number of pistons is 7, the maximum number of pressurizing pistons is 4, and the minimum number of pressurizing pistons is 3). , the average number of pressurized pistons is 3.5), the piston hydraulic reaction force load and moment load are twice the rotation speed of the rotating shaft 5 (top dead center and bottom dead center in one rotation speed). pulsation is generated), and acts on the drive disk 6 so as to draw an "ω" shape centered on the point of force P of the resultant force of the average hydraulic reaction force. The load acting on the drive disk 6 is expressed as a radial load FR1, which is a radial component force, and a thrust load Fr, which is an axial component force, on the X- and Y-axes on the support surface of the spherical portion 10A of the piston rod 10 of the drive disk 6. spread in the direction.

In this way, the load consisting of the piston hydraulic reaction force diffused in the X-axis and y-axis directions, the moment load induced by the hydraulic reaction force, the side force Fv, etc. is transferred to the bearing sleeve 4 which forms a part of the casing 1. It is supported by radial static pressure bearings 20, 25 and a thrust static pressure bearing 30 provided in the. That is, the static pressure in the pressure chambers 23, 28, 33 provided in the static pressure pads 22, 27, 32 of each of these hydrostatic bearings 20, 25, 30 acts hydrostatically and hydrodynamically. , the static pressure pad 22.27.3
2 operates as a sliding bearing and supports radial load and thrust load respectively.

Here, of the loads acting on the drive disk 6, the support form for the radial load will be discussed with reference to FIG.

As mentioned above, since the point P of the resultant force of the average hydraulic reaction force is eccentric by a predetermined distance with respect to the axis of the rotating shaft 5, the radial load F, l acts on the point P of the resultant force. At this time, a moment load around the rotation axis is generated as a moment about the force application point P of the resultant force.

However, in this embodiment, the first fixed radial static pressure bearing 2OA is provided on the side of the force application point P of the resultant force of the average hydraulic reaction force, and the second fixed radial static pressure bearing 2OA is located on the side opposite to the force application point of the resultant force. 2
Since 0B is provided, the radial loads F and I can be supported while the moment loads around the rotational axis regarding the point P of the resultant force are balanced.

Also, due to the shape of the suction and exhaust ports on the high pressure side, the sliding portion of the valve plate 11 has a side force Fv in the direction shown in FIG.
is generated, and this side force acts on the drive disk 6 via the piston 10 or the center joint 13. However, in this embodiment, a third fixed radial static pressure bearing 20C is provided on the origin force point side of the resultant force and on the X axis, and high pressure oil is introduced into the pressure chamber 23C. , the side force Fv can be supported by the third radial static pressure bearing 20C.

Furthermore, the piston hydraulic reaction force F changes in synchronization with twice the number of revolutions due to changes in the number of pistons on the high pressure side.
Varies in the y-axis direction (upward, downward direction). However, in this embodiment, the floating radial static pressure bearing 25 is disposed above the X-axis and on the y-axis.

As a result, even if the hydraulic reaction force F fluctuates due to a change in the number of high-pressure side pistons, this fluctuation can be supported in a floating manner by the floating radial static pressure bearing 25. That is, since the gap 4 is provided between the non-sliding surface side of the pad portion 27-2 and the outer circumferential surface 4A of the sleeve portion 4A of the bearing sleeve 4, the static pressure pad 27 is 6B, by slidingly contacting the inner circumferential surface 6B and following and supporting the drive disk 6 via an oil film, vertical fluctuations in hydraulic reaction force can be reliably supported.

In this way, the first to third fixed radial static pressure bearings 20
A to 20C and the floating radial static pressure bearing 25 are such that the static pressure pads 22A to 22C, 27 are always kept in a constant posture, and the sliding surface of each of the static pressure pads 22A to 22C, 27 is normally maintained. It is possible to apply surface pressure in a stable posture and prevent extremely tilted support. As a result, uneven wear of the static pressure pads 22A to 22C, 27 can be prevented, and the thickness of the oil film formed between the pads and the cylindrical portion 6B of the drive disk 6 can be maintained uniform. Therefore, the leakage flow rate of oil from the sliding surfaces of each of the static pressure pads 22A to 22C, 27 can be minimized, and the power loss associated with this leakage flow rate can be minimized.

Note that the above description also applies to the case where the thrust load F7 is supported by the thrust static pressure bearing 30.

However, according to this embodiment, the first. Second. The third radial static pressure bearings 2OA, 20B, and 20C are fixed type static pressure bearings, and the rod portions 22A-
1 to 22C-1 to tapered surface portions 22A-3 to 22
C-3, and the rod portions 22A-1 to 22C
-1 is a minute gap 22 with respect to the cylinder holes 21A to 21G.
A-4 to 22C-4, and the sliding surfaces of the pad portions 22A-2 to 22C-2 are brought into sliding contact with the inner peripheral surface 6B of the cylindrical portion 6B of the drive disk 6, The non-sliding surface side is the outer peripheral surface 4A of the sleeve portion 4A of the bearing sleeve 4.
, and is provided with an escape groove 22-5 that opens into the casing 1.

To explain this in detail with reference to FIG. 3, the rod portion 22-1 of the static pressure pad 22 has a tapered surface portion 22-3 whose inner peripheral surface side is tapered in diameter from the tip to the root. A constant bearing control pressure f acts on the surface portion 22-3 in a direction perpendicular to the surface portion 22-3. On the other hand, the rod portion 22
A bearing control pressure f2 acts on the outer circumferential surface of -1 through a minute gap 22-4, and this bearing control pressure f2 is a pressure that gradually decreases from the tip on the opening side to the relief groove 22-5 at the root. The pressure distribution has a gradient. Therefore, the bearing control pressure f on the inner circumferential side and the bearing control pressure f on the outer circumferential side described above are
2 acts on the rod part 22-1, but since the rod part 22-1 has a wall thickness corresponding to this pressure difference from the tip to the root, the wall thickness corresponds to this pressure difference. maintain seal rigidity.

As a result, the rod portions 2 of the static pressure pads 22A to 22C
2A-1 to 22C-1 are uniformly and uniformly deformed elastically over the entire length without depending on the differential pressure between the inner and outer circumferences of the rod portions 22A-1 to 22C-1. ~22C-1 and cylinder hole 21A~21
The aim is to improve the sealing performance between C and C. As a result, the cylinder holes 21A to 21G and the rod portions 22A-1 to 22A-2
2G-1 can be suppressed, and power loss due to this leakage flow rate can be reduced.

Note that this is not limited to the first to third fixed radial static pressure bearings 20A to 20C, and applies to the floating radial static pressure bearing 25 shown in FIG. 4 and the fixed thrust static pressure bearing 30 shown in FIG. Also, the sealing performance can be improved for the same reason as mentioned above.

Next, FIGS. 6 and 7 show a second embodiment of the present invention.

Note that the same components as in the first embodiment described above are denoted by the same reference numerals, and the explanation thereof will be omitted.

However, the feature of this embodiment is that the drive disk is formed into a disk shape, and a seal hydrostatic bearing is provided at a specific position on the casing side, and the hydrostatic pad is brought into sliding contact with the outer peripheral surface of the drive disk. There is a particular thing.

That is, in FIG. 6, 41 indicates the casing of this embodiment, and the casing 41 has a cylindrical casing body 42 consisting of a small diameter cylindrical portion 42A and a large diameter slanted cylindrical portion 42B, similar to the first embodiment. and a head casing 43 that closes the opening side of the inclined cylindrical portion 42B of the casing body 42, the inclined cylindrical portion 42B is formed with a thick wall and has a radial station on its inner peripheral side. Pressure bearing 20', 2
The difference is that 5' is arranged so that it can be hung.

Reference numeral 44 denotes a bearing sleeve forming a part of the casing 41 provided in the small diameter cylindrical portion 42A of the casing body 42. The bearing sleeve 44 is formed in a substantially cylindrical shape, unlike the first embodiment, and has one end in the axial direction. is the inner step portion 42 of the small diameter cylindrical portion 42A.
C, and only the thrust static pressure bearing 30 similar to the first embodiment is provided.

Reference numeral 45 denotes a rotating shaft with a shaft portion 45A extending through the bearing sleeve 44, and the tip inside the casing 41 of the rotating shaft 45 is a drive disk 46, but the drive disk 46 in this embodiment is disc-shaped. in that it is formed in
This is different from the first embodiment. The rotating shaft 45 is axially supported by a bearing sleeve 44 via a bearing 7, and the drive disk 46 is supported by radial static pressure bearings 20' and 25, which will be described later.
, the piston hydraulic reaction force is received through the thrust static pressure bearing 30 according to the first embodiment.

20A', 20B', and 20C' are fixed radial hydrostatic bearings used in this embodiment (referred to as fixed radial static bearing 20' as a whole), and 25' is a floating radial hydrostatic bearing also used in this embodiment. , and the same components as each radial static pressure bearing 20.25 according to the first embodiment are marked with a dash ('), and the explanation thereof will be omitted. 20", 25' is the 7th
It differs in that it is located on one end side of the large-diameter cylindrical portion 42B of the casing body 42 and disposed on its inner circumferential surface in the specific arrangement relationship shown in the figure.

That is, the piston hydraulic reaction force F acting on the drive disk 46 acts on the force point P of the resultant force of the average hydraulic reaction force so as to draw the character "■".
6 is only formed in the shape of a disk, and each radial static pressure bearing 20', 25' is arranged on the inner peripheral side of the casing body 42. For this reason, the fixed radial static pressure bearing 2 receives the radial loads F and l due to the hydraulic reaction force F.
0A' and 20B' are placed on the left and right positions across the positive side of the y-axis (above the intersection with the X-axis), and the side force F is
The fixed radial static pressure bearing 20C' that receives the force V is placed on the side of the point P of the resultant force on the X axis, and the floating radial static pressure bearing 25' is placed on the negative side of the y axis (the point of intersection with the (lower).

Although the present embodiment is constructed as described above, by arranging the four radial static pressure bearings 20' and 25' in the specific positional relationship shown in FIG. You can obtain the same action and effect as.

Next, FIG. 8 shows a third embodiment of the present invention. Note that the same components as in FIG. 3 according to the first embodiment described above are given the same reference numerals, and their explanations will be omitted.

However, the feature of this embodiment is that the rod portion of the static pressure pad is formed in a stepped shape with different outer diameter dimensions, and the inner peripheral side of the rod portion is such that the tapered surface portion and the straight surface portion are continuously connected. On the other hand, a sial hydrostatic bearing is provided at a specific position on the casing side as in FIG. 2 or 7, and the sliding surface side of the hydrostatic pad is brought into sliding contact with the drive disk.

Here, the configuration of the hydrostatic bearing according to this embodiment will be described.

Reference numeral 50 designates a plurality of fixed radial static pressure bearings according to this embodiment for receiving the radial load component of the average hydraulic reaction force acting on the drive disk 6. As shown in FIG. 8, the fixed radial static pressure bearing 50 includes a cylinder which is bored in the radial direction in the above-described specific positional relationship on the outer circumferential side of the sleeve portion 4A of the bearing sleeve 4 that forms a part of the casing. A hole 51, a stepped hollow cylindrical rod portion 52-1 with different outer diameter dimensions, and a large-diameter pad portion 52-.
A device consisting of a static pressure pad 52 consisting of a pressure chamber 53 and a throttle passage 54, which will be described later;
The inner circumferential side of 2-1 has two different tapered surfaces 52-3A, 52- so that the diameter decreases within the size range from the opening side tip.
3B is formed continuously, and a straight surface part 52-4 having the same inner diameter is formed from the back of the tapered surface part 52-3 to the base. Further, the outer circumferential side of the rod portion 52-1 gradually expands in diameter within the dimensional range, and the outer circumference on the distal end side slides into contact with the cylinder hole 51, and the tapered surface 52-3A on the distal end side becomes thin. The outer peripheral side of the straight surface portion 52-4 is formed to have a small diameter, and an annular space 52-5 having a relief dimension d is formed between the straight surface portion 52-4 and the cylinder hole 52.

Furthermore, the sliding surface side of the large-diameter pad portion 52-2 is the inner circumferential surface (bearing guide surface) 6B of the cylindrical portion 6B of the drive disk 6,
A pressure chamber 53 is formed in the shape of a concave groove on the sliding surface side of the pad portion 52-2, and a chamber in the cylinder hole 52 is communicated with the pressure chamber 53. As such, a throttle passage 54 is provided in the axial direction.

By configuring the fixed radial static pressure bearing 50 of this embodiment as described above, even if the static pressure pad 52 and the drive disk 6 are tilted by the angle α as shown in FIG. 8 due to load fluctuation, the static pressure pad An annular space 5 having a relief dimension d is formed between the rod portion 52-1 of 52 and the cylinder hole 51.
2-5 is formed, the rod portion 52-1 does not contact the corner portion 55 of the sleeve portion 4A, and the rod portion 52-1 does not touch the tapered surface portion 52-3 of the rod portion 52-1, especially the tapered surface 52.
-3A is elastically deformed by internal pressure so as to eliminate a minute gap, thereby ensuring sealing performance between the cylinder hole 51 and the rod portion 52-1.

On the other hand, even if only the static pressure pad 52 is tilted by the angle α, the length of the rod portion 52-1 is short (and the wall thickness is thin, so local elastic bending deformation is possible). .

As a result, the leakage flow rate from the rod portion 52-1 of the static pressure pad 52 disposed at a plurality of specific locations can be suppressed to a minimum.

Note that the structure of the static pressure pad 52 in this embodiment can be expected to have particularly remarkable effects when applied to a static pressure pad constituting a floating radial static pressure bearing as shown in FIG. 4 described above. This is because the hydrostatic pads in floating radial hydrostatic bearings are susceptible to fluctuations from the drive disk.

Thus, even in such a case, the static pressure pad of the present invention functions to minimize leakage from the rod portion for the above reasons.

Furthermore, FIG. 9 shows a hydraulic circuit configuration diagram of a hydraulic system when the variable capacity oblique shaft type hydraulic machine according to each of the embodiments described above is applied to a construction machine such as a hydraulic excavator.

In the figure, 101 is an engine as a driving source;
2,103 is a hydrostatic bearing supported cedar hydraulic pump according to an embodiment of the present invention; 104 is a group of control valves for controlling the destination of fluid power supplied from the pump 102103; 105 is a swing motor; Center joint indicating the relay point of fluid power, 107.1
08 is a travel hydraulic motor provided on the lower traveling body, 109 is a packet hydraulic cylinder, 110 is an arm hydraulic cylinder, 111, 111 is a boom hydraulic cylinder, 112 -
120 is a conduit connecting the hydraulic equipment elements.

In the hydraulic system of the construction drilling machine configured in this way, when the hydraulic pumps 102 and 103 are driven by the engine 101 to discharge high-pressure fluid, this high-pressure fluid is supplied to the swing hydraulic motor that drives the swing system at the control valve 104. 105, or travel hydraulic motors 107 and 108 that drive the traveling system, and further to boom, arm, and packet hydraulic cylinders 109, 110, and 111, respectively, to perform excavation work.

However, when the hydraulic machine of the present invention is used as the hydraulic pumps 102 and 103 of the construction machine having the above configuration, the hydraulic pump 1 is used to increase running force and digging force and improve performance.
Even if the tilting angles 02 and 103 are large, a hydraulic pump with low leakage flow rate, high stability, and high reliability can be obtained. Note that the swing motor 105 and the travel hydraulic motor 1
Similar effects can be obtained when applied as o7°108.

In addition, in the embodiment of the present invention, a fully static pressure supported type hydraulic pump was illustrated, but in the present invention, the thrust static pressure bearing 30 is abolished, and the radial static pressure bearing 20.25 (20', 25") is used.
) and mechanical thrust circumferential rolling bearings (for example, roller bearings) may be configured as a partial hydrostatic bearing supported hydraulic machine, or conversely, radial hydrostatic bearings 20.25
(20'25') may be abolished, and a partial static pressure bearing support may be used in combination with the thrust static pressure bearing 30 and a mechanical radial circumferential rolling bearing.In short, at least one of the radial static pressure bearing and the thrust static pressure bearing may be used. It is only necessary to have a hydrostatic bearing of

Furthermore, in the embodiment, the fixed radial static pressure bearing 20 (20') and the floating radial static pressure bearing 25 (25') are used together as the radial static pressure bearing, but the floating radial static pressure bearing 25 (25') is used in combination. 25') may be eliminated, and all fixed radial static pressure bearings 20 (20') may be used.

In addition, when the hydraulic machine of the present invention is applied to a hydraulic motor capable of forward and reverse rotation, a pair of intake and exhaust ports formed on the valve plate,
Since both of the pair of suction and discharge passages formed in the head casing serve as high pressure ports, a shuttle valve is provided between the pair of suction and discharge ports or between the suction and discharge passages, and the high pressure side pressure is led out through the shuttle valve. A configuration may be adopted in which the high pressure side pressure is supplied as the bearing control pressure.

On the other hand, in the embodiment, the tilting mechanism 15 is provided in the head casing 3, but the tilting mechanism is provided in the casing body 2. (42), one end of which is attached to the inside of the casing via the ear shaft by the tilting mechanism to tilt the yoke, and the cylinder block 8 and valve plate 11 to be tilted by the yoke.

Furthermore, the hydraulic machine of the present invention is not limited to the above-mentioned application examples.
It can also be widely applied to hydraulic systems such as hydraulic reduction devices of rolling mills, powder molding machines, injection molding machines, high-speed forging machines in high-temperature environments, and tunnel boring machines.

〔Effect of the invention〕

The present invention has been described in detail above, and the inner peripheral side of the rod portion of a static pressure pad constituting a fixed or floating type hydrostatic bearing is formed as a tapered surface portion over the entire length from the tip to the root of the rod portion. By forming or configuring the tip of the rod part as a tapered surface part, there is variation in the minute gap size between the rod part of the plurality of static pressure pads and the cylinder hole, and the static pressure pad and drive disk Even if at least one of them is tilted, the rod part will not depend on the differential pressure between the inside and outside of the rod part (, -
It can be elastically deformed smoothly and uniformly, and the sealing performance can be improved.

As a result, oil leakage from between the inner circumferential surface of the cylinder hole and the rod portion can be suppressed, and power loss based on this leakage flow rate can be reduced.

[Brief explanation of drawings]

1 to 5 relate to a first embodiment of the present invention, FIG. 1 is a longitudinal cross-sectional view showing a variable capacity oblique shaft type hydraulic machine according to the first embodiment, and FIG. 3 is an enlarged sectional view showing a fixed type radial static pressure bearing, FIG. 4 is an enlarged sectional view showing a floating type radial static pressure bearing, and FIG. The enlarged sectional views of the fixed thrust hydrostatic bearing, FIGS. 6 and 7, relate to the second embodiment of the present invention.
FIG. 6 is a longitudinal cross-sectional view of a variable capacity oblique shaft type hydraulic machine according to the second embodiment, FIG. 7 is a cross-sectional view taken in the direction of the arrow ■-■ in FIG. 6, and FIG. 8 is a cross-sectional view of the present invention. FIG. 9 is an enlarged sectional view showing a fixed radial static pressure bearing according to the third embodiment of the present invention, and FIG. 9 is a circuit configuration diagram when the hydraulic machine of the present invention is applied to a hydraulic system of a construction machine. 1.41...Casing, 2,42...Casing body, 3.43...Head casing, 5,45...
・Rotating shaft, 6... Drive disk, 8... Cylinder block, 9... Cylinder, 10... Piston,
DESCRIPTION OF SYMBOLS 11... Valve plate, 12... Tilt sliding surface, 13... Center shaft 15... Tilt mechanism, 20.20", 50
... Fixed type radial static pressure bearing, 25.25'... Floating type radial static pressure bearing, 21, 26, 31.51...
Cylinder hole, 22, 27, 32.52...Static pressure pad, 22-1.27-1.32-1.52-1...Rod part 22-2.27-2.32-2.52 -2...Pad part, 22-3.27-3.32-3.52-3...
・Tapered surface part, 52-4...Straight surface part, 22-
4.27-4.32-4...Small gap, 22-5.3
2-5... Relief groove, 23.28, 33.53... Pressure chamber, 24.29, 34.54... Throttle passage, 30.
・Fixed type thrust static pressure bearing.

Claims (9)

[Claims] (1) A cylindrical casing provided with a head casing having a suction/exhaust passage, a rotary shaft rotatably provided in the casing and having a drive disk at its tip end on the insertion side into the casing; a cylinder block disposed in the cylinder block and having a plurality of cylinders bored in the axial direction, and a plurality of pistons provided in each cylinder of the cylinder block so as to be reciprocally movable, and one end side of which is swingably supported by the drive disk. a valve plate having a pair of suction/exhaust ports, one end surface of which is in sliding contact with the cylinder block, and the other end surface of which is in sliding contact with the tilting sliding surface of the head casing; A tilting mechanism for tilting the drive disk, and a casing provided between the drive disk and the casing in order to receive the load of at least one of the hydraulic reaction forces in the radial direction and the thrust direction acting on the drive disk. In a variable capacity oblique shaft type hydraulic machine comprising at least one of a radial hydrostatic bearing and a thrust hydrostatic bearing, the hydrostatic bearing has a cylinder hole bored in the casing side and a rod portion. is slidably inserted into the cylinder hole, the sliding surface side of the pad portion slides on the drive disk side, and the non-sliding surface side contacts the casing; It is a fixed type static pressure bearing consisting of a pressure chamber recessed on the moving surface side and supplied with bearing control pressure, and the rod part of the static pressure pad is formed in a hollow cylindrical shape, and the inner circumference of the rod part is A variable capacity oblique shaft type hydraulic machine whose side is formed as a tapered surface that continuously reduces in diameter from the tip to the base. (2) The static pressure bearing is a plurality of fixed radial static pressure bearings, and each of the radial static pressure bearings generates a moment about the rotation axis at the point of application of the resultant force of the average hydraulic reaction force in the radial direction acting on the drive disk. A variable capacity oblique shaft type hydraulic machine according to claim (1), wherein the variable capacity oblique shaft hydraulic machine is arranged at a position where it is balanced. (3) The hydrostatic bearing is a plurality of radial hydrostatic bearings,
At least one of the radial static pressure bearings has a cylinder hole bored on the casing side, a rod part is slidably inserted into the cylinder hole, and a pad part is fitted on the drive disk side. A floating hydrostatic bearing consisting of a static pressure pad that is in sliding contact, and a pressure chamber that is recessed on the sliding surface side of a pad portion of the static pressure pad and to which bearing control pressure is supplied, and a rod portion of the static pressure pad. is formed into a hollow cylindrical shape, and the inner peripheral side of the rod portion is formed as a tapered surface portion whose diameter continuously decreases from the tip to the root, and the other hydrostatic pressure bearings are the fixed type hydrostatic bearings. A variable capacity oblique shaft hydraulic machine according to claim (1) or (2). (4) The variable capacity oblique shaft type hydraulic machine according to claim (3), wherein the floating hydrostatic bearing is provided in a direction in which a hydraulic reaction force acts. (5) A cylindrical casing provided with a head casing having suction and exhaust passages, a rotary shaft rotatably provided in the casing and having a drive disk at its tip end on the insertion side into the casing; a cylinder block disposed in the cylinder block and having a plurality of cylinders bored in the axial direction, and a plurality of pistons provided in each cylinder of the cylinder block so as to be reciprocally movable, and one end side of which is swingably supported by the drive disk. a valve plate having a pair of suction/exhaust ports, one end surface of which is in sliding contact with the cylinder block, and the other end surface of which is in sliding contact with the tilting sliding surface of the head casing; A tilting mechanism for tilting the drive disk, and a casing provided between the drive disk and the casing in order to receive the load of at least one of the hydraulic reaction forces in the radial direction and the thrust direction acting on the drive disk. In a variable capacity oblique shaft type hydraulic machine comprising at least one of a radial hydrostatic bearing and a thrust hydrostatic bearing, the hydrostatic bearing has a cylinder hole bored in the casing side and a rod portion. is slidably inserted into the cylinder hole, the sliding surface side of the pad portion slides on the drive disk side, and the non-sliding surface side contacts the casing; It is a fixed type static pressure bearing consisting of a pressure chamber recessed on the moving surface side and supplied with bearing control pressure, and the rod portion of the static pressure pad has an outer diameter with a large diameter on the tip side and a small diameter on the base side. It is formed into a stepped hollow cylindrical shape with different dimensions, and the inner circumferential side of the rod part is formed so that a tapered surface part located at the tip side and whose diameter gradually decreases and a straight face part located at the base side are continuously connected. A variable capacity oblique shaft type hydraulic machine characterized by: (6) The static pressure bearing is a plurality of fixed radial static pressure bearings, and each of the radial static pressure bearings generates a moment about the rotation axis at the point of application of the resultant force of the average hydraulic reaction force in the radial direction acting on the drive disk. A variable capacity oblique shaft type hydraulic machine according to claim (5), wherein the variable capacity oblique shaft hydraulic machine is arranged at a position where it is balanced. (7) The hydrostatic bearing is a plurality of radial hydrostatic bearings,
At least one of the radial static pressure bearings has a cylinder hole bored on the casing side, a rod part is slidably inserted into the cylinder hole, and a pad part is fitted on the drive disk side. A floating hydrostatic bearing consisting of a static pressure pad that is in sliding contact, and a pressure chamber that is recessed on the sliding surface side of a pad portion of the static pressure pad and to which bearing control pressure is supplied, and a rod portion of the static pressure pad. The rod is formed into a stepped hollow cylindrical shape with different outer diameters, with a large diameter on the tip side and a small diameter on the base side, and the inner circumferential side of the rod part has a tapered surface part located on the tip side and gradually decreasing in diameter, and a tapered surface part on the root side. The variable capacity oblique shaft type hydraulic fluid according to claim (5) or (6), wherein the straight surface portion located at pressure machine. (8) A variable capacity oblique shaft type hydraulic machine according to claim (7), wherein the floating hydrostatic bearing is provided in a direction in which a hydraulic reaction force acts. (9) A variable capacity oblique shaft hydraulic machine according to claims (1) and (5), which is applied as a main hydraulic power source pump or drive motor for use in a hydraulic system of construction machinery.