Hydraulic rotating equipment, and working machine provided with this hydraulic rotating equipment

Abstract

Disclosed is hydraulic rotating equipment provided with a rotating shaft, a cylinder block including a plurality of cylinders, a like plurality of pistons accommodated in the cylinders, respectively, and a valve plate maintained in slide contact with a rear end surface of the cylinder block. The valve plate includes a low-pressure port communicable with the cylinders, a high-pressure port formed in an arcuate shape over a predetermined angle along a circumferential direction of the rotating shaft and communicable with the cylinders, a seal land maintained in slide contact with the rear end surface, and a sliding contact member arranged on a periphery of the seal land in a range of the predetermined angle along the circumferential direction of the rotating shaft and maintained in slide contact with the rear end surface. A working machine provided with the hydraulic rotating equipment is also disclosed.

Claims

1. An hydraulic rotating equipment provided with: a rotating shaft, a cylinder block including a plurality of cylinders formed at intervals in a circumferential direction of the rotating shaft, said cylinder block being rotatable in an interlocked manner in association with the rotating shaft, a like plurality of pistons accommodated in the plurality of cylinders, respectively, of the cylinder block, said pistons being reciprocable with rotation of the cylinder block, and a valve plate maintained in slide contact with a rear end surface of the cylinder block, said rear end surface being an end surface on sides opposite to open sides of the plurality of cylinders out of opposite end surfaces of the cylinder block, wherein the valve plate comprises: a low-pressure port communicable with the plurality of cylinders to supply or drain low-pressure side hydraulic oil, a high-pressure port formed in an arcuate shape over a predetermined angle along the circumferential direction of the rotating shaft and communicable with the plurality of cylinders to supply or drain high-pressure side hydraulic oil, a seal land maintained in slide contact with the rear end surface to seal hydraulic oil from the low-pressure port or high-pressure port, and a sliding contact member arranged on a periphery of the seal land in a range of the predetermined angle, which is a rotary angle of the rotating shaft from one end of the high-pressure port to the other end of the high-pressure port, along the circumferential direction of the rotating shaft and maintained in slide contact with the rear end surface, wherein the sliding contact member is arranged deviating to a downstream side relative to a direction of rotation of the rotating shaft in the range of the predetermined angle along the circumferential direction of the rotating shaft and is arranged on an inner side relative to the high-pressure port in a radial direction of the rotating shaft, the rear end surface of the cylinder block and a slide contact surface of the valve plate sliding to the cylinder block are curved surfaces respectively, a curvature of the slide contact surface of the valve plate is greater than a curvature of the rear end surface of the cylinder block.

2. A working machine provided with the hydraulic rotating equipment according to claim 1.

3. The hydraulic rotating equipment according to claim 1, wherein: the sliding contact member comprises a pad arranged on an outer side relative to the high-pressure port in the radial direction of the rotating shaft.

4. A working machine provided with the hydraulic rotating equipment according to claim 3.

5. The hydraulic rotating equipment according to claim 1, wherein: the sliding contact member comprises plural pads arranged on inner side and an outer side, respectively, relative to the high-pressure port in the radial direction of the rotating shaft.

6. A working machine provided with the hydraulic rotating equipment according to claim 5.

7. The hydraulic rotating equipment according to claim 1, wherein: the sliding contact member comprises plural pads arranged at intervals along the circumferential direction of the rotating shaft, and groove portions are formed as flow passages for hydraulic oil between the individual pads.

8. A working machine provided with the hydraulic rotating equipment according to claim 7.

9. The hydraulic rotating equipment according to claim 1, wherein: the high-pressure port includes notches formed at opposite ends thereof, respectively, along the circumferential direction of the rotating shaft.

10. A working machine provided with the hydraulic rotating equipment according to claim 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a view illustrating the configurations of a hydraulic excavator taken as an example of a working machine in which a first embodiment of the hydraulic rotating equipment according to the present invention can be arranged.

(2) FIG. 2 is a view showing the configurations of swash-plate hydraulic rotating equipment applied as the first embodiment of the hydraulic rotating equipment according to the present invention.

(3) FIG. 3 is a front view of a valve plate shown in FIG. 2 as viewed from a cylinder block.

(4) FIG. 4 is a front view of a valve plate in hydraulic rotating equipment of related art as viewed from a cylinder block.

(5) FIG. 5 is a view illustrating a state of sliding contact of the valve plate in the hydraulic rotating equipment of the related art with the cylinder block.

(6) FIG. 6 is a view depicting on an enlarged scale a state of sliding contact in a vicinity A in FIG. 5 when the rotational speed of the cylinder block in the hydraulic rotating equipment of the related art is low.

(7) FIG. 7 is a view depicting on an enlarged scale a state of sliding contact in a vicinity B in FIG. 5 when the rotational speed of the cylinder block in the hydraulic rotating equipment of the related art has increased from the low speed.

(8) FIG. 8 is a view illustrating the configurations of essential parts of a second embodiment of the present invention, and is a front view of a valve plate as viewed from a cylinder block.

(9) FIG. 9 is a view illustrating the configurations of essential parts of a third embodiment of the present invention, and is a front view of a valve plate as viewed from a cylinder block.

(10) FIG. 10 is a view illustrating the configurations of essential parts of a fourth embodiment of the present invention, and is a schematic cross-sectional view depicting on an enlarged scale slide contact surfaces of a valve plate and cylinder block on a side of a rotating shaft.

(11) FIG. 11 is a view illustrating the configurations of essential parts of the fourth embodiment of the present invention, and is a front view of the valve plate as viewed from the cylinder block.

(12) FIG. 12 is a view illustrating the configurations of essential parts of a fifth embodiment of the present invention, and is a front view of a valve plate as viewed from a cylinder block.

(13) FIG. 13 is a view illustrating the configurations of essential parts of a sixth embodiment of the present invention, and is a front view of a valve plate as viewed from a cylinder block.

(14) FIG. 14 is a view illustrating the configurations of essential parts of a seventh embodiment of the present invention, and is a front view of a valve plate as viewed from a cylinder block.

(15) FIG. 15 is a view showing the configurations of angled-piston hydraulic rotating equipment applied as a yet further embodiment of the hydraulic rotating equipment according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(16) Based on the drawings, a description will hereinafter be made of modes for carrying out the hydraulic rotating equipment according to the present invention.

First Embodiment

(17) FIG. 1 is a view illustrating the configurations of a hydraulic excavator taken as an example of a working machine in which a first embodiment of the hydraulic rotating equipment according to the present invention can be arranged.

(18) The first embodiment of the hydraulic rotating equipment according to the present invention can be arranged in a working machine, for example, a crawler hydraulic excavator 1 that is shown in FIG. 1 and performs work such as digging. This hydraulic excavator 1 is constructed of a travel base 2, a revolving upperstructure 3 arranged on an upper side of the travel base 2 and having a revolving frame 3a, a swing mechanism 3A interposed between these travel base 2 and revolving upperstructure 3 for swinging the revolving upperstructure 3, and a front working mechanism 4 attached to a front part of the revolving upperstructure 3 such that the front working mechanism is pivotal in an up-to-down direction.

(19) The front working mechanism 4 includes a boom 4A, boom cylinders 4a, an arm 4B, an arm cylinder 4b, a bucket 4C, and a bucket cylinder 4c. The boom 4A is pivotally attached at a basal end thereof to the revolving frame 3a and is pivotal in the up-and-down direction. The boom cylinders 4a connect the revolving upperstructure 3 and the boom 4A together, and extend and retract to pivot the boom 4A. The arm 4B is pivotally attached to a free end of the boom 4A. The arm cylinder 4b is arranged on an upper side of the boom 4A, connects the boom 4A and the arm 4B together, and extends and retracts to pivot the arm 4B. The bucket 4C is pivotally attached to a free end of the arm 4B. The bucket cylinder 4c connects the arm 4B and the bucket 4C together, and extends and retracts to pivot the bucket 4C.

(20) The above-mentioned revolving upperstructure 3 is provided with a counterweight 5, a cab 6, an engine compartment 7, and a body cover 8. The counterweight 5 is disposed, for example, on a rear part of a body, and maintains balance of the body. The cab 6 is disposed on a front left part of the body, and houses an operator who operates the front working mechanism 4. The engine compartment 7 is disposed between these counterweight 5 and cab 6. The body cover 8 is disposed on an upper part of the engine compartment 7, and forms the exterior of an upper part of the body. It is to be noted that, although not shown in the figure, an engine as a drive source of operations of the body, control valves for controlling the flow rates and directions of hydraulic oil to be fed to the respective cylinders 4a-4c, a hydraulic oil tank for storing hydraulic oil therein, and the like are disposed in the engine compartment 7.

(21) FIG. 2 is a view showing the configurations of swash-plate hydraulic rotating equipment applied as the first embodiment of the hydraulic rotating equipment according to the present invention.

(22) As shown by way of example in FIG. 2, the first embodiment of the present invention is comprised of swash-plate hydraulic rotating equipment 11 that functions as a hydraulic pump or hydraulic motor. This swash-plate hydraulic rotating equipment 11 is provided with a casing 12, a rotating shaft 13, a cylinder block 14, and a plurality of pistons 15. The casing 12 forms an outer shell. The rotating shaft 13 is disposed rotatably about an axis thereof in a central part of the casing 12. The cylinder block 14 includes a plurality of cylinders 14A formed at intervals in a circumferential direction of the rotating shaft 13, and rotates in an interlocked manner with the rotating shaft 13. The plurality of pistons 15 are accommodated in the plurality of cylinders 14A, respectively, of the cylinder block 14, and reciprocate in association with rotation of the cylinder block 14.

(23) The swash-plate hydraulic rotating equipment 11 is also provided with a valve plate 16, a plurality of shoes 17, a swash plate 18, and a retainer 19. The valve plate 16 is maintained in slide contact with a rear end surface 14R of the cylinder block 14. Of opposite end faces of the cylinder block 14, the rear end surface 14R is an end surface on a side opposite to open ends of the plurality of cylinders 14A. The plurality of shoes 17 are rockably held on end portions of the individual pistons 15, respectively, on a side of the open ends of the plurality of cylinders 14A out of the opposite end surfaces of the cylinder block 14, and rotate together with the cylinder block 14. The swash plate 18 is tiltably disposed on a side of a below-mentioned front casing 12A in the casing 12, and the respective shoes 17 are maintained in slide contact with the swash plate 18. The retainer 19 holds via a retainer guide 19A the respective shoes 17 in a state that the shoes 17 are pressed toward the swash plate 18 under pressing force of the cylinder block 14, and stabilizes the state of sliding contact of the respective shoes 17 with the swash plate 18.

(24) The casing 12 is comprised of the above-mentioned front casing 12A and a rear casing 12B. The front casing 12A is formed in a cylindrical shape, accommodates therein members such as the rotating shaft 13 and cylinder block 14, and is bottomed. The rear casing 12B closes up an opening of the front casing 12A. The rotating shaft 13 is supported rotatably about the axis thereof via bearings 21,22 and the like between the front casing 12A and the rear casing 12B. One end of the rotating shaft 13, said one end being on a side of the front casing 12A out of opposite ends of the rotating shaft 13, is connected to an output shaft of the engine in the engine compartment 7, so that the rotating shaft 13 rotates by drive force of the engine.

(25) The cylinder block 14 is disposed with the end surface on the side of the open ends of the plurality of cylinders 14A, out of the opposite end surfaces thereof, facing the swash plate 18, and is splined on a side of an outer circumference of the rotating shaft 13. By rotation of the cylinder block 14 integrally with the rotating shaft 13, the cylinder block 14 slides on the valve plate 16 while maintaining the respective shoes 17 in slide contact with the swash plate 18. The respective cylinders 14A of the cylinder block 14 are spaced at certain constant intervals therebetween about the axis of the cylinder block 14 with the rotating shaft 13 serving as a center, and are disposed in parallel with the direction of the axis of the cylinder block 14, in other words, the direction of the axis of the rotating shaft 13. Through the end of the cylinder block 14 on the side of the rear casing 12B, cylinder ports 14B are formed, as flow passages for hydraulic oil, extending from the surface toward inner ends of the respective cylinders 14A.

(26) FIG. 3 is a front view of the valve plate shown in FIG. 2 as viewed from the cylinder block.

(27) As shown in FIG. 3, the valve plate 16 includes a low-pressure port 16A, a high-pressure port 16B, and a seal land 16C. The low-pressure port 16A is formed in an arcuate shape over a predetermined angle 24A (see FIG. 13) along the circumferential direction of the rotating shaft 13 (see FIG. 2), and is communicable with the plurality of cylinders 14A via the cylinder ports 14B to supply or drain low-pressure side hydraulic oil. The high-pressure port 16B is formed in an arcuate shape over a predetermined angle 26A along the circumferential direction of the rotating shaft 13, and is communicable with the plurality of cylinders 14A via the cylinder ports 14B to supply or drain high-pressure side hydraulic oil. The seal land 16C is maintained in slide contact with the rear end surface 14R of the cylinder block 14, and seals hydraulic oil from the low-pressure port 16A or high pressure port 16B.

(28) This seal land 16C is formed in an annular shape extending from the surface of the valve plate 16 toward the cylinder block 14 such that the hydraulic oil, which flows between the valve plate 16 and the cylinder block 14, does not leak to the outside, and an oil film of hydraulic oil is formed between the valve plate 16 and the cylinder block 14. The low-pressure port 16A of the valve plate 16 includes notches 16A1 formed at opposite ends thereof along the circumferential direction of the rotating shaft 13, while the high-pressure port 16B includes notches 16B1 at opposite ends thereof along the circumferential direction of the rotating shaft 13.

(29) When the swash-plate hydraulic rotating equipment 11 (see FIG. 2) functions as a hydraulic pump, the cylinder block 14, therefore, rotates together with the rotating shaft 13 in a forward direction (clockwise as shown in FIG. 3) 25A so that the respective pistons 15 reciprocate. Therefore, the hydraulic oil supplied from the hydraulic oil tank to the valve plate 16 flows from the low-pressure port 16A and through the cylinder ports 14B into the cylinders 14A, is pressurized by the pistons 15 and is delivered from the high-pressure port 16B of the valve plate 16, and subsequently, is supplied to the respective cylinders 4a-4c of the front working mechanism 4 (see FIG. 1) via control valves. As a result, the respective cylinders 4a-4c extend or retract by the hydraulic pressure of the hydraulic oil so supplied, and the front working mechanism 4 can be operated to perform work such as digging.

(30) When the swash-plate hydraulic working machine 11 functions as a hydraulic motor, on the other hand, the pistons 15 are pressed toward the side of the swash plate 18 under the hydraulic pressure of the hydraulic oil by allowing high-pressure hydraulic oil to flow from the high-pressure port 16B of the valve plate 16 into the cylinders 14 via the cylinder ports 14B. Therefore, the rotating shaft 13 rotates together with the cylinder block 14 in a reverse direction 25B (see FIG. 13) that is opposite to the forward direction 25A. As a result, rotational motion of the rotating shaft 13 can be taken out from the hydraulic pressure of the hydraulic oil.

(31) Based on FIGS. 4 to 6, the valve plate 16 in the first embodiment of the present invention will now be described in detail in comparison with the valve plate in the related art to facilitate the understanding of the configurations of the valve plate 16 in the first embodiment of the present invention. It is to be noted that with respect to the valve plate in the related art, the same or corresponding parts as in the first embodiment of the present invention are identified by like reference signs in the following description.

(32) FIG. 4 is a front view of a valve plate in hydraulic rotating equipment of related art as viewed from a cylinder block, FIG. 5 is a view illustrating a state of sliding contact of the valve plate in the hydraulic rotating equipment of the related art with the cylinder block, and FIG. 6 is a view depicting on an enlarged scale a state of sliding contact in the vicinity A in FIG. 5 when the rotational speed of the cylinder block in the hydraulic rotating equipment of the related art is low.

(33) As shown in FIGS. 4 and 5, a valve plate 16 in the related art is common to the valve plate 16 in the first embodiment of the present invention in that the former valve plate 16 is provided with a low-pressure port 16A, a high-pressure port 16B and a seal land 16C. However, the valve plate 16 in the related art is provided with pads 50 disposed over the entire circumference of a surface on an outer side of the seal land 16C.

(34) As the rotational speed of the cylinder block 14 increases, the dynamic pressure of an oil film between the valve plate 16 and the cylinder block 14 generally rises, thereby tending to form a wedge film due to this dynamic pressure. When the rotational speed of the cylinder block 14 is low, a wedge film is hence hardly formed between the valve plate 16 and the cylinder block 14 so that in an oil film formed between the seal land 16C of the valve plate 16 and the cylinder block 14, the oil film in a vicinity A of the center of the high-pressure port 16B becomes thinnest as depicted in FIG. 6. Therefore, the sliding contact pressure between the valve plate 16 and the cylinder block 14 in this vicinity A of the center tends to become higher compared with those at other parts.

(35) In the first embodiment of the present invention, the valve plate 16, therefore, includes a sliding contact member, which as shown in FIG. 3, is arranged in a range 26B of a predetermined angle 26A along the circumferential direction of the rotating shaft 13 out of the periphery of the seal land 16C and is maintained in slide contact with the rear end surface 14R of the cylinder block 14. This sliding contact member is comprised of a pad 30 arranged, for example, on an outer side relative to the high-pressure port 16B in the radial direction of the rotating shaft 13. It is to be noted that the above-mentioned range 26B of the predetermined angle 26A is set in the region of a rotary angle of the rotating shaft 13, for example, from the notch 16B1 at the one end of the high-pressure port 16B of the valve plate 16 to the notch 16B1 at the other end and that the pad 30 is arranged over the entire surface on the outer side of the seal land 16C in this region.

(36) According to the first embodiment of the present invention configured as described above, the arrangement of the pad 30 only in the range 26B, in which the sliding contact pressure between the valve plate 16 and the cylinder block 14 tends to become high, can appropriately protect the slide contact surfaces of the valve plate 16 and cylinder block 14 by the pad 30 and can hence sufficiently suppress the occurrence of seizure on the slide contact surfaces of the valve plate 16 and cylinder block 14, while reducing the area of sliding contact between the valve plate 16 and the cylinder block 14, even when the pad 50 is not arranged over the entirety of the outer circumference of the end surface of the valve plate 16, said outer circumference being maintained in slide contact with the cylinder block 14, as in the related art. As a consequence, the torque loss associated with rotation of the cylinder block 14 can be decreased, thereby providing the swash-plate hydraulic rotating equipment 11 with high reliability. In particular, this swash-plate hydraulic rotating equipment 11 is suited for the hydraulic excavator 1 useful in high-load work such as digging, and can provide the hydraulic excavator 1 with improved work performance.

(37) In the first embodiment of the present invention, the reaction force by an oil film between an outer circumferential part 16C1 of the seal land 16C of the valve plate 16 on the side of the high-pressure port 16B and the cylinder block 14 becomes greater than the reaction force by an oil film between an inner circumferential part 16C2 of the seal land 16 on the side of the high-pressure port 16B, because the circumferential speed of the cylinder block 14 relative to the valve plate 16 becomes faster toward an outer side in the radial direction of the rotating shaft 13.

(38) On the other hand, the pad 30 on the valve plate 16 is arranged on the outer side relative to the high-pressure port 16B in the radial direction of the rotating shaft 13, so that the effect of the reaction force by the oil film between the outer circumferential part 16C1 of the seal land 16C on the side of the high-pressure port 16B and the cylinder block 14 can be reduced by the pad 30. As a consequence, the slide contact surfaces of the valve plate 16 and cylinder block 14 can be effectively protected by the pad 30, so that the valve plate 16 and cylinder block 14 can be provided with longer service life.

(39) In the first embodiment of the present invention, the notches 16B1 are formed at the opposite ends of the high-pressure port 16B of the valve plate 16 along the circumferential direction of the rotating shaft 13. Upon changing of a port, to which the cylinder port 14B of each cylinder 14A is to be connected by rotation of the cylinder block 14 in the forward direction 25A in an interlocked manner with the rotating shaft 13, from the low-pressure port 16A to the high-pressure port 16B or from the high-pressure port 16B to the low-pressure port 16A of the valve plate 16, any sudden pressure change in hydraulic oil flowing between the high-pressure port 16B and the cylinder 14A can be reduced by the notches 16B1. It is, therefore, possible to suppress the occurrence of cavitations in a flow passage for the hydraulic oil, and to prevent damage to the valve plate 16 or cylinder block 14 or the occurrence of vibration and noise during rotation of the cylinder block 14.

Second Embodiment

(40) FIG. 7 is a view depicting on an enlarged scale a state of sliding contact in a vicinity B in FIG. 5 when the rotational speed of the cylinder block in the hydraulic rotating equipment of the related art has increased from the low speed, and FIG. 8 is a view illustrating the configurations of essential parts of a second embodiment of the present invention, and is a front view of a valve plate as viewed from a cylinder block.

(41) As depicted in FIG. 7, when the rotational speed of the cylinder block 14 increases from a low speed, the dynamic pressure of an oil film between the valve plate 16 and the cylinder block 14 rises and a wedge film tends to be formed between the valve plate 16 and the cylinder block 14. In an oil film formed between the seal land 16C of the valve plate 16 on the side of the high-pressure port 16B and the cylinder block 14, the oil film in a downstream vicinity B relative to the direction of rotation (forward direction) 25A of the cylinder block 14 becomes thinnest. Therefore, the sliding contact pressure between the valve plate 16 and the cylinder block 14 in this downstream vicinity B tends to become higher compared with those at other parts.

(42) The pad 30 in the first embodiment of the present invention is arranged over the entirety of the surface of the valve plate 16 on the outer side of the seal land 16C in the above-mentioned range 26B of the predetermined angle 26A, while a pad 30 in the second embodiment of the present invention is arranged deviating to a downstream side relative to the direction of rotation (forward direction) 25A of the rotating shaft 13 in the above-mentioned range 26B of the predetermined angle 26A along the circumferential direction of the rotating shaft 13 as illustrated, for example, in FIG. 8. The remaining configurations are similar to those of the above-mentioned first embodiment, and the same or corresponding parts as in the first embodiment are identified by like reference signs.

(43) According to the second embodiment of the present invention configured as described above, similar advantageous effects as the above-mentioned first embodiment are obtained. In addition, the pad 30 is arranged deviating to the part where, in the slide contact surfaces of the seal land 16C of the valve plate 16 on the side of the high-pressure port 16B and cylinder block 14, the sliding contact pressure between the valve plate 16 and the cylinder block 14 tends to become relatively high. It is, therefore, possible to cope with variations in the sliding contact pressure between the valve plate 16 and the cylinder block 14 in association with a rise in the rotational speed of the cylinder block 14 even if the use amount of the pad 30 is smaller than that of the pad 30 in the first embodiment. As a consequence, a high volumetric efficiency can be assured even when the work by the hydraulic excavator 1 is under use conditions of high load or the like.

Third Embodiment

(44) FIG. 9 is a view illustrating the configurations of essential parts of a third embodiment of the present invention, and is a front view of a valve plate as viewed from a cylinder block.

(45) The third embodiment of the present invention is different from the above-mentioned second embodiment in that as illustrated, for example, in FIG. 9, a sliding contact member in the third embodiment is comprised of three pads 30A-30C arranged at intervals along the circumferential direction of the rotating shaft 13 and groove portions 31 are formed as flow passages for hydraulic oil between these individual pads 30A-30C, while as illustrated in FIG. 8, the sliding contact member in the second embodiment is comprised of the pad 30 arranged deviating to the downstream side relative to the direction of rotation (forward direction) 25A of the rotating shaft 13 in the above-mentioned range 26B of the predetermined angle 26A along the circumferential direction of the rotating member 13. It is to be noted that the number of the pads 30A-30C is not limited to three and may be 2 or 4 or more. The remaining configurations are similar to those of the above-mentioned second embodiment, and the same or corresponding parts as in the second embodiment are identified by like reference signs.

(46) According to the third embodiment of the present invention configured as described above, similar advantageous effects as the above-mentioned second embodiment are obtained. In addition, hydraulic oil leaked out of the low-pressure port 16A or high-pressure port 16B of the valve plate 16 is allowed to flow from the groove portions 31 between the individual pads 30A-30C to the outside of the valve plate 16. As a result of rotation of the cylinder block 14 together with the rotating shaft 13 and its sliding on the valve plate 16, heated hydraulic oil can be prevented from staying at a part 16C1 between the seal land 16C of the valve plate 16 and the individual pads 30A-30C. As a consequence, the lubrication performance of hydraulic oil between the valve plate 16 and the cylinder block 14 can be retained so that the sliding motion of the cylinder block 14 on the valve plate 16 can be performed well.

Fourth Embodiment

(47) FIG. 10 is a view illustrating the configurations of essential parts of a fourth embodiment of the present invention, and is a schematic cross-sectional view depicting on an enlarged scale slide contact surfaces of a valve plate and cylinder block on a side of a rotating shaft, and FIG. 11 is a view illustrating the configurations of essential parts of the fourth embodiment of the present invention, and is a front view of the valve plate as viewed from the cylinder block.

(48) When the curvature of a slide contact surface of a valve plate 16 is greater than the curvature of a slide contact surface of a cylinder block 14 as illustrated in FIG. 10, a seal land 16C of the valve plate 16 on the side of the rotating shaft 13 and the slide contact surface of the cylinder block 14 on the side of the rotating shaft 13 come close to each other, and therefore, large reaction force is produced by an oil film formed in an area C between the seal land 16C of the valve plate 16 on the side of the rotating shaft 13 and the slide contact surface of the cylinder block 14 on the side of the rotating shaft 13.

(49) While the individual pads 30A-30C in the third embodiment of the present invention are arranged on the outer side relative to the high-pressure port 16B in the radial direction of the rotating shaft 13 as illustrated in FIG. 9, pads 30a,30b in the fourth embodiment are arranged on an inner side relative to the high-pressure port 16B in the radial direction of the rotating shaft 13 as illustrated, for example, in FIG. 11. The size of the individual pads 30a,30b in the fourth embodiment of the present invention is set smaller than the size of the individual pads 30A-30C in the above-mentioned third embodiment. It is to be noted that the number of the pads 30a, 30b are not limited to two and a single pad may be arranged without forming such a groove portion as the groove portions 31 in FIG. 9 or three or more pads may be arrange as in the third embodiment of the present invention. The remaining configurations are similar to those of the above-mentioned third embodiment, and the same or corresponding parts as in the third embodiment are identified by like reference signs.

(50) According to the fourth embodiment of the present invention configured as described above, the individual pads 30a, 30b of the valve plate 16 are arranged on the inner side relative to the high-pressure port 16B in the radial direction of the rotating shaft 13 unlike the above-mentioned third embodiment, so that in the slide contact surfaces of the valve plate 16 and cylinder block 14, the parts where the sliding contact pressure has become high due to the difference in curvature can be sufficiently protected by the pads 30a, 30b. The individual pads 30a, 30b can also be applied to the valve plate 16 having the different curvature from the slide contact surface of the cylinder block 14 as described above, and therefore, are excellent in general versatility. Further, these pads 30a,30b are close to the rotating shaft 13, and can have a size smaller than the size of the individual pads 30A-30C in the third embodiment. It is, therefore, possible to decrease the slide contact area between the valve plate 16 and the cylinder block 14 and to improve the volumetric efficiency still further.

Fifth Embodiment

(51) FIG. 12 is a view illustrating the configurations of essential parts of a fifth embodiment of the present invention, and is a front view of a valve plate as viewed from a cylinder block.

(52) A sliding contact member in the fifth embodiment of the present invention is comprised of pads 30A-30C and 30c-30e, which as illustrated, for example, in FIG. 12, are arranged on an inner side and outer side, respectively, relative to the high-pressure port 16B in the radial direction of the rotating shaft 13. Of these pads 30A-30C and 30c-30e, the pads 30A-30C are the same as the pads 30A-30C in the above-mentioned third embodiment, and the pads 30a-30c correspond to the pads 30a, 30b in the above-mentioned fourth embodiment. The remaining configurations are similar to those of the above-mentioned third and fourth embodiments, and the same or corresponding parts as in the third and fourth embodiment are identified by like reference signs.

(53) According to the fifth embodiment of the present invention configured as described above, similar advantageous effects as the above-mentioned third and fourth embodiments are obtained. In addition, the individual pads 30A-30C and 30c-30e are arranged with a proper balance in the radial direction of the rotating shaft 13, so that the effect of reaction force by an oil film between a seal land 16C of the valve plate 16 and the cylinder block 14 can be effectively reduced to realize providing the cylinder block 14 with stable sliding performance. As a consequence, the valve plate 16 and cylinder block 14 can be provided with improved durability.

Sixth Embodiment

(54) FIG. 13 is a view illustrating the configurations of essential parts of a sixth embodiment of the present invention, and is a front view of a valve plate as viewed from a cylinder block.

(55) When the swash-plate hydraulic rotating equipment 11 functions as a hydraulic motor, the cylinder block 14 rotates in the reverse direction 25B opposite to the forward direction 25A. The low-pressure port 16B and high-pressure port 16B of the valve plate 16, therefore, change with each other. As illustrated in FIG. 13, a sliding contact member in the sixth embodiment of the present invention is hence comprised, in addition to the pad 30 in the second embodiment, of a pad 32 that is arranged in the range 24B of the predetermined angle 24A along the circumferential direction of the rotating shaft 13 in the periphery of the seal land 16C and is maintained in slide contact with the rear end surface 14R of the cylinder block 14.

(56) This pad 32 is arrange on an outer side relative to the low-pressure port (the high-pressure port during rotation in the reverse direction 25B) 16A of the valve plate 16 in the radial direction of the rotating shaft 13, and further, is arranged deviating to a downstream side relative to the direction of rotation (reverse direction 25B) of the rotating shaft 13 in a range 24B of a predetermined angle 24A along the circumferential direction of the rotating shaft 13. In addition, the shape and size of the pad 32 are set in the same shape and size as the pad 30 in the above-mentioned second embodiment. It is to be noted that the pad 32 may be arranged on an inner side relative to the low-pressure port (the high-pressure port during rotation in the reverse direction 25B) 16A of the valve plate 16 in the radial direction of the rotating shaft 13. The remaining configurations are similar to those of the second embodiment, and the same or corresponding parts as in the second embodiment are identified by like reference signs.

(57) According to the sixth embodiment of the present invention configured as described above, similar advantageous effects as in the above-mentioned case of functioning as a hydraulic pump can be also obtained when the swash-plate hydraulic rotating equipment 11 functions as a hydraulic motor.

Seventh Embodiment

(58) FIG. 14 is a view illustrating the configurations of essential parts of a seventh embodiment of the present invention, and is a front view of a valve plate as viewed from a cylinder block.

(59) The seventh embodiment of the present invention is different from the above-mentioned sixth embodiment in that the shape and size of a pad 32 in the seventh embodiment are set beforehand corresponding to the maximum rotational speed of the rotating shaft 13 which rotates in the reverse direction 25B as illustrated, for example, in FIG. 14, while the shape and size of the pad 32 in the sixth embodiment are set in the same shape and size of the pad 30 in the second embodiment as illustrated in FIG. 13. Therefore, the shapes and sizes of a pad 30 and the pad 32 in the seventh embodiment of the present invention may be different from each other. The remaining configurations are similar to those of the sixth embodiment, and the same or corresponding parts as in the sixth embodiment are identified by like reference signs.

(60) According to the seventh embodiment of the present invention configured as described above, similar advantageous effects as the above-mentioned sixth embodiment are obtained. In addition, even in the case that the maximum rotational speed differs depending on the direction of rotation of the rotating shaft 13, the swash-plate hydraulic rotating equipment 11 can be used according to the rotation characteristics of the rotating shaft 13, and can bring about high convenience.

(61) It is to be noted that the foregoing embodiments have been described in detail to facilitate the understanding of the present invention and are not necessarily limited to those including all the described configurations. Further, a part or parts of the configurations of one of the embodiments can be replaced by the corresponding part or parts of the configurations of another one of the embodiments. Furthermore, a part or parts of the configurations of one of the embodiments can be added to the configurations of another one of the embodiments.

(62) The swash-plate hydraulic rotating equipment 11 of each of the foregoing embodiments has been described based on its arrangement in the hydraulic excavator 1, but is not limited to such an application and may be mounted on a working machine such as a wheel loader.

(63) Each of the foregoing embodiments has been described taking, as illustrative hydraulic rotating equipment, the swash-plate hydraulic rotating equipment 11 that functions as a hydraulic pump or a hydraulic motor. However, the hydraulic rotating equipment is not limited to such a case, and as shown by way of example in FIG. 15, may be comprised of angled-piston hydraulic rotating equipment 41 that is provided with a center cylinder 14a arranged centrally in a cylinder block 14, a center piston 15A inserted in the center cylinder 14a, a plurality of spherical seats 13a formed on one end of a rotating shaft 13, said one end being on a side of pistons 15, at intervals in a circumferential direction of the rotating shaft 13 and supporting rod ends of the respective pistons 15 resting thereon, and a central spherical seat 13b formed on the one end of the rotating shaft 13, said one end being on the side of the piston 15, at a central part of the rotating shaft 13, supporting the center piston 15A resting thereon and serving to perform positioning of the cylinder block 14.