JP2013130138A - Axial piston type hydraulic pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an axial piston type hydraulic pump which can ensure a strength of a cylinder block while enhancing self-priming capability.SOLUTION: Cylinder ports 9 and 10 interconnecting with cylinders 7 and 8 are opened onto a slide face 6A which slides in contact with a valve plate 18 of a cylinder block 6. Further, apertures 9A and 10A of the cylinder ports 9 and 10 are configured to have arrangement of at least two pairs of a plurality of internal diameter side apertures 9A disposed on the internal diameter side of the cylinder block 6 and a plurality of external diameter side apertures 10A disposed outside in a radial direction of the internal diameter side apertures 9A. In each internal diameter side aperture 9A, an inner fringe 9B forming the internal diameter side aperture 9A is formed longer in a circumferential direction than an outer fringe 9C, and in each external diameter side aperture 10A, an outer fringe 10C forming the external diameter side aperture 10A is formed longer in a circumferential direction than an inner fringe 10B.

Description

  The present invention relates to an axial piston type hydraulic pump suitable for use in, for example, a swash plate type hydraulic pump and an inclined axis type hydraulic pump.

  In general, a hydraulic pump as a representative example of an axial piston hydraulic pump has a casing, a rotating shaft that extends in the axial direction in the casing and is rotatably provided, and rotates integrally with the rotating shaft. A cylinder block in which a plurality of cylinders provided in a casing and spaced apart in the circumferential direction and extending in the axial direction are formed together with a cylinder port; a plurality of pistons removably fitted to each cylinder of the cylinder block; and a cylinder It is roughly constituted by a cylinder provided on the casing side in sliding contact with the end face of the block, and a valve plate provided with a suction port and a discharge port that are intermittently communicated with each other via each cylinder port. In this case, the opening of each cylinder port is arranged in two sets of a plurality of inner diameter side openings arranged on the inner diameter side of the cylinder block and a plurality of outer diameter side openings arranged radially outward from the inner diameter side opening. (For example, refer to Patent Document 1).

  In this type of conventional hydraulic pump, the cylinder block is driven to rotate, so that each cylinder circulates around the rotating shaft and alternately communicates with the suction port and the discharge port of the valve plate, and corresponds to this communication timing. The piston acts as a reciprocating motion within each cylinder.

  That is, in the suction stroke in which each cylinder communicates with the suction port, the piston extends from the inside of the cylinder, and for example, hydraulic oil is sucked into the cylinder from the suction port, and in the discharge stroke in which each cylinder communicates with the discharge port, the piston Shrinks into the cylinder, discharges hydraulic oil from the discharge port, and supplies the hydraulic oil as pressure oil to a hydraulic pipe connected to the outside.

  On the other hand, Patent Document 2 is provided with a recess for reducing resistance due to suction of hydraulic oil at a position facing the suction port of the valve plate in the casing, and the suction performance (self-priming performance) can be improved by the recess. Such a configuration is disclosed.

JP-A-10-141212 JP 2006-152819 A

  By the way, when the hydraulic oil is sucked into the cylinder by the piston, the opening of the cylinder port (the inner diameter side opening, the outer diameter side opening) is narrowest on the hydraulic oil suction path. For this reason, the self-priming performance of the hydraulic pump is limited by the size of the opening area of the cylinder port.

  That is, if the opening area of the cylinder port is small, the flow resistance in the suction stroke increases and the self-priming performance of the pump decreases. Such a decrease in the self-priming performance may lead to a decrease in pump efficiency, a vibration due to cavitation, an increase in noise, and a decrease in durability due to erosion. In addition, in order to suppress such an increase in vibration and noise and a decrease in durability, it is necessary to suppress the operating rotational speed (allowable rotational speed) of the hydraulic pump, which reduces pump capacity and pump efficiency. There's a problem.

  On the other hand, it is conceivable to improve the self-priming performance by increasing the opening area of the cylinder port. However, simply increasing the opening angle of the cylinder port opening (the circumferential length of the cylinder port opening) in order to increase the opening area of the cylinder port makes the adjacent cylinder port openings close to each other (cylinder port openings). The circumferential edges of the openings are close to each other), and the separation dimension (thickness) between the cylinder ports is reduced. Thereby, there exists a problem that it becomes difficult to ensure the intensity | strength of a cylinder block.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide an axial piston hydraulic pump that can improve self-priming performance while ensuring the strength of a cylinder block.

  An axial piston hydraulic pump according to the present invention is provided in a casing, a rotating shaft that extends axially in the casing so as to be rotatable, and the casing so as to rotate integrally with the rotating shaft. A cylinder block in which a plurality of cylinders that are spaced apart in the circumferential direction and extend in the axial direction are formed together with a cylinder port, a plurality of pistons that are reciprocally inserted in the cylinders of the cylinder block, and an end face of the cylinder block A valve plate provided with a suction port and a discharge port provided on the casing side in sliding contact and intermittently communicating with each of the cylinders via each cylinder port; An opening of each cylinder port is formed on the contacting end surface, and a plurality of inner diameter side openings arranged on the inner diameter side of the cylinder block, and the inner diameter A plurality of outer diameter side opening which is located radially outwardly from the opening, consisting configured as at least two sets of sequences.

  In order to solve the above-described problem, the feature of the configuration adopted by the invention of claim 1 is that each inner diameter side opening is formed such that the inner peripheral edge forming the inner diameter side opening is longer in the circumferential direction than the outer peripheral edge. And each said outer diameter side opening exists in the structure which forms the outer periphery which forms the said outer diameter side opening longer in the circumferential direction than an inner periphery.

  According to a second aspect of the present invention, each cylinder port is inclined in a direction approaching the rotating shaft as it goes from the cylinder side toward the opening, and the openings are arranged in the vicinity of the rotating shaft. .

  According to a third aspect of the present invention, an opening of each of the cylinder ports is formed on an end face of the cylinder block that is in sliding contact with the valve plate, each of the inner diameter side openings, each of the outer diameter side openings, and each of these outer diameter sides. A plurality of intermediate openings arranged between the opening and each of the inner diameter side openings are arranged in three sets, and each of the intermediate openings has circumferential ends at the circumferential edges forming the intermediate opening. It is that it was made the structure made to protrude in.

  According to a fourth aspect of the present invention, each of the cylinder ports has a radial dimension that increases from the opening toward the bottom of the cylinder, and a cross-sectional area is constant between the opening and the bottom of the cylinder. The configuration is to be formed.

  The invention according to claim 5 is that each of the cylinders is provided with a diameter-expanded portion located on the bottom side and having an increased inner diameter.

  According to the invention of claim 1, the inner peripheral edge of each inner diameter side opening of each cylinder port is formed longer in the circumferential direction than the outer peripheral edge, and the outer peripheral edge of each outer diameter side opening is formed longer in the circumferential direction than the inner peripheral edge. It is configured to do. For this reason, while increasing the opening area of each inner diameter side opening and each outer diameter side opening, it is possible to secure a separation dimension (thickness) between the inner diameter side opening and the outer diameter side opening adjacent in the circumferential direction. .

  Thereby, the self-priming performance (suction performance) can be improved while ensuring the strength of the cylinder block. As a result, it is possible to suppress (avoid) the occurrence of vibration and noise due to cavitation and the decrease in durability due to erosion, and to improve the pump efficiency, the pump capacity, and the use rotation speed (allowable rotation speed).

  According to the invention of claim 2, since the opening of each cylinder port is arranged in the vicinity of the rotating shaft, the peripheral speed of the opening of the cylinder port can be reduced. Can be improved.

  According to the invention of claim 3, each cylinder port opening is constituted by a plurality of inner diameter side openings, a plurality of outer diameter side openings, and a plurality of intermediate side openings, and both circumferential edges of each intermediate side opening are circumferentially surrounded. It is configured to project in the direction. Therefore, while increasing the opening area of each inner diameter side opening, each outer diameter side opening, and each intermediate side opening, the separation dimension between the inner diameter side opening, the intermediate side opening, and the outer diameter side opening that are adjacent to each other in the circumferential direction. (Thickness) can be secured. Thereby, even when the opening of the cylinder port is configured as an array of three sets of each inner diameter side opening, each outer diameter side opening, and each intermediate side opening, the self-priming performance is improved while ensuring the strength of the cylinder block. be able to.

  According to the invention of claim 4, the radial dimension of each cylinder port is increased as it goes to the bottom of the cylinder, and the cross-sectional area of each cylinder port is made constant between the opening and the bottom of the cylinder. ing. For this reason, the separation dimension (thickness) between the cylinder ports adjacent to each other in the circumferential direction can be ensured while ensuring the cross-sectional area of each cylinder port. Thereby, it is possible to further improve the self-priming performance and secure the strength of the cylinder block.

  According to the fifth aspect of the present invention, since the enlarged diameter portion is provided on the bottom side of each cylinder, the communication area between the cylinder port and the cylinder can be increased, and the cross-sectional area of the cylinder port can be increased with a simple shape. Can be enlarged. Thereby, the improvement of the further self-priming performance can be aimed at.

1 is a longitudinal sectional view showing a variable displacement swash plate hydraulic pump according to a first embodiment of the present invention. It is the expanded side view which took out the valve plate and was seen from the right side of FIG. It is the expanded sectional view which took out the cylinder block and was seen from the same direction as FIG. It is the side view which looked at the cylinder block in FIG. 3 from the left. It is the side view which looked at the cylinder block in FIG. 3 from the right side. It is an enlarged view of the (VI) part in FIG. 4 which shows a cylinder block. It is an enlarged view of the same position as FIG. 6 which shows the cylinder block by the 2nd Embodiment of this invention. It is an enlarged view of the same position as FIG. 6 which shows the cylinder block by the 3rd Embodiment of this invention. It is an enlarged view of the same position as FIG. 6 which shows the cylinder block by the 4th Embodiment of this invention. It is an expanded sectional view of the position similar to FIG. 3 which shows the cylinder block by the 5th Embodiment of this invention. It is sectional drawing seen from the arrow XI-XI direction in FIG. 10 which shows the cylinder port of a cylinder block. It is sectional drawing seen from the arrow XII-XII direction in FIG. 10 which shows the cylinder port of a cylinder block. It is sectional drawing seen from the arrow XIII-XIII direction in FIG. 10 which shows the cylinder port of a cylinder block. It is sectional drawing seen from the arrow XIV-XIV direction in FIG. 10 which shows the cylinder port of a cylinder block. It is sectional drawing seen from the arrow XV-XV direction in FIG. 10 which shows the cylinder port of a cylinder block. It is sectional drawing seen from the arrow XVI-XVI direction in FIG. 10 which shows the cylinder port of a cylinder block. It is an expanded sectional view of the position similar to FIG. 3 which shows the cylinder block by the 6th Embodiment of this invention. It is the side view which looked at the cylinder block in FIG. 17 from the left.

  Hereinafter, an embodiment of an axial piston type hydraulic pump according to the present invention will be described in detail with reference to the accompanying drawings, taking as an example the case of application to a variable displacement swash plate type hydraulic pump.

  1 to 6 show a first embodiment of the present invention. In the figure, 1 is a variable displacement swash plate type hydraulic pump (hereinafter referred to as a hydraulic pump 1) as an axial piston type hydraulic pump employed in the present embodiment, and 2 is a casing constituting an outer shell of the hydraulic pump 1. The casing 2 includes a stepped cylindrical casing body 3 whose one end is a front bottom portion 3A, and a rear casing 4 provided on the casing body 3 so as to close the other end of the casing body 3. Has been.

  In addition, the casing body 3 of the casing 2 is provided with an actuator mounting portion 3B at a position axially separated from the front bottom portion 3A as shown in FIG. Protrusively. A tilt actuator 26, which will be described later, is provided in the actuator mounting portion 3B. On the other hand, the rear casing 4 of the casing 2 is formed with a later-described suction passage 23, discharge passages 24, 25, and the like, and these passages 23, 24, 25 are disposed in the cylinders 7, 8 via a valve plate 18 described later. The hydraulic oil (oil liquid) is supplied and discharged (intake and discharge) to the head.

  Reference numeral 5 denotes a rotating shaft that extends in the axial direction in the casing 2 so as to be rotatable. The rotating shaft 5 is rotatable on one side in the axial direction in the front bottom portion 3A of the casing body 3 via a bearing or the like. The other side is rotatably attached to the rear casing 4 via a bearing or the like. And, for example, a prime mover of a hydraulic excavator is connected to one side (projecting end side) of the rotating shaft 5 that protrudes in the axial direction from the front bottom 3A of the casing body 3 via a power transmission mechanism (not shown), The rotating shaft 5 is rotationally driven by this prime mover.

  Reference numeral 6 denotes a cylinder block that is rotatably provided in the casing 2 via a rotary shaft 5. The cylinder block 6 is attached to the outer peripheral side of the rotary shaft 5 by spline coupling, and is driven to rotate integrally with the rotary shaft 5. Is done. A plurality of cylinders 7 and 8 to be described later are formed (perforated) in the cylinder block 6 together with cylinder ports 9 and 10, and a rear end surface of the cylinder block 6 has a concave spherical shape in sliding contact with a valve plate 18 to be described later. This is a sliding contact surface 6A.

  Reference numeral 7 denotes a first cylinder that is formed (perforated) at five intervals on a concentric circle spaced apart from the cylinder block 6 in the circumferential direction. The first cylinder 7 is provided to extend in the axial direction in the cylinder block 6. The first cylinder 7 includes a cylinder portion 7A having a front end side (the right end side in FIGS. 1 and 3) that is one end side opened on the front end surface of the cylinder block 6, and a rear end that is the other end side of the cylinder portion 7A. It is comprised by the bottom part 7B which obstruct | occludes an end side (left end side of FIG. 1 and FIG. 3). A first cylinder port 9 described later is opened on the bottom 7B side of the first cylinder 7.

  Reference numeral 8 denotes a second cylinder that is formed (perforated) by five cylinders 6 on a concentric circle spaced apart from each other in the circumferential direction at intervals of 72 °, for example. The second cylinders 8 are arranged alternately (alternately) with the first cylinders 7 in the circumferential direction of the cylinder block 6, and are provided extending in the axial direction in the cylinder block 6. The second cylinder 8 includes a cylindrical portion 8A having a front end side (the right end side in FIGS. 1 and 3) that is one end side opened on the front end surface of the cylinder block 6 and the cylindrical portion, as in the first cylinder 7. The bottom portion 8B closes the rear end side (the left end side in FIGS. 1 and 3) which is the other end side of 8A. A second cylinder port 10 described later is opened on the bottom 8B side of the second cylinder 8.

  Reference numeral 9 denotes a plurality (the same number as the first cylinders) of first cylinder ports that are opened in a sliding contact surface 6A that is in sliding contact with a later-described valve plate 18 of the cylinder block 6. Each of the first cylinder ports 9 is intermittently connected to the suction port 19 of the valve plate 18 and the inner port portion 21 of the discharge port 20, and allows hydraulic oil (oil fluid) to flow into and out of the first cylinder 7. Is.

  Here, each first cylinder port 9 has a front end side (the right end side in FIGS. 1 and 3) that is one end side communicates (connects) to the bottom 7B of each first cylinder 7 and a rear end that is the other end side. The end side (the left end side in FIGS. 1 and 3) is an inner diameter side opening 9 </ b> A that opens to the sliding contact surface 6 </ b> A of the cylinder block 6. The inner diameter side opening 9A is disposed at a position corresponding to an inner port portion 21 of the discharge port 20 described later on the sliding contact surface 6A of the cylinder block 6, and each first cylinder port 9 is interposed via the inner diameter side opening 9A. Thus, communication with the inner port portion 21 is possible.

  Reference numeral 10 denotes a plurality (the same number as the second cylinders 8) of second cylinder ports that are opened in a sliding contact surface 6A that is in sliding contact with a later-described valve plate 18 of the cylinder block 6. Each of the second cylinder ports 10 is intermittently connected to the suction port 19 of the valve plate 18 and the outer port portion 22 of the discharge port 20, and allows hydraulic oil (oil fluid) to flow into and out of the second cylinder 8. Is.

  Here, each second cylinder port 10 has a front end side (the right end side in FIG. 1 and FIG. 3) that is one end side communicates (connects) to the bottom portion 8B of each second cylinder 8 and a rear end that is the other end side. The end side (the left end side in FIGS. 1 and 3) is an outer diameter side opening 10 </ b> A that opens to the sliding contact surface 6 </ b> A of the cylinder block 6. The outer diameter side opening 10A is disposed at a position corresponding to an outer port portion 22 of the discharge port 20 described later on the sliding contact surface 6A of the cylinder block 6, and each second cylinder port 10 has an outer diameter side opening 10A. It is possible to communicate with the outer port portion 22 via the.

  That is, in the case of the present embodiment, as shown in FIG. 4, the openings 9A, 10A of the cylinder ports 9, 10 have a plurality (five) of inner diameter side openings 9A arranged on the inner diameter side of the cylinder block 6. And a plurality of (five) outer diameter side openings 10A arranged on the radially outer side from the inner diameter side opening 9A.

  In this case, as shown in FIG. 3, each first cylinder port 9 is inclined in a direction approaching the rotation shaft 5 toward the inner diameter side opening 9 </ b> A from the bottom 7 </ b> B side of each first cylinder 7. 10 inclines in the direction approaching the rotating shaft 5 toward the outer diameter side opening 10A from the bottom 8B side of each first cylinder 8. Accordingly, the inner diameter side opening 9 </ b> A and the outer diameter side opening 10 </ b> A are arranged in the vicinity of the rotation shaft 5 (on the rotation center side) on the sliding contact surface 6 </ b> A of the cylinder block 6. That is, in the case of the present embodiment, the inner diameter side opening 9A and the outer diameter side opening 10A are arranged near the rotating shaft 5 (the inner diameter side of the cylinder block 6) by arranging the inner diameter side opening 9A and the outer diameter side opening 10A. The peripheral speed of the hydraulic pump 1 is reduced, and the self-priming performance of the hydraulic pump 1 can be improved.

  Furthermore, as shown in FIG. 6, the inner diameter side opening 9 </ b> A of each first cylinder port 9 has an opening edge (outline) having an arcuate inner peripheral edge 9 </ b> B, an arcuate outer peripheral edge 9 </ b> C, and these inner peripheral edges. 9B and the outer peripheral edge 9C are formed by substantially linear end edges 9D and 9E. Of these, the inner peripheral edge 9B is longer than the outer peripheral edge 9C in the circumferential direction. More specifically, each inner diameter side opening 9 </ b> A extends in the circumferential direction at both circumferential ends of the inner peripheral edge 9 </ b> B with respect to the eyebrow-shaped virtual opening 11 curved in an arc shape with a curvature corresponding to an inner port portion 21 described later. I am letting. As a result, extension portions 9F extended (expanded) in a substantially triangular shape with respect to both ends in the circumferential direction of the virtual opening 11 are formed on both ends in the circumferential direction of each inner diameter side opening 9A. As a whole, it is formed as a substantially trapezoidal opening.

  On the other hand, as shown in FIG. 6, the outer diameter side opening 10A of each second cylinder port 10 has an opening edge (outline) having an arcuate inner peripheral edge 10B, an arcuate outer peripheral edge 10C, It is formed by substantially linear end edges 10D and 10E that connect the peripheral edge 10B and the outer peripheral edge 10C. Of these, the outer peripheral edge 10C is longer than the inner peripheral edge 10B in the circumferential direction. More specifically, each outer diameter side opening 10 </ b> A has both ends in the circumferential direction of the outer peripheral edge 10 </ b> C in the circumferential direction with respect to an eyebrow-shaped virtual opening 12 curved in an arc shape with a curvature corresponding to an outer port portion 22 described later. It is extended. As a result, extension portions 10F extended (expanded) in a substantially triangular shape with respect to both ends in the circumferential direction of the virtual opening 12 are formed on both ends in the circumferential direction of each outer diameter side opening 10A. 10A is formed as a substantially trapezoidal opening as a whole.

  Thereby, while increasing the opening area of each inner diameter side opening 9A and each outer diameter side opening 10A, the separation dimension L1 between the inner diameter side opening 9A and the outer diameter side opening 10A adjacent in the circumferential direction, that is, the inner diameter side The thickness L1 of the cylinder block 6 between the opening 9A and the outer diameter side opening 10A can be ensured. As a result, it is possible to improve the self-priming performance when hydraulic fluid flows into the cylinders 7 and 8 through the inner diameter side openings 9A and the outer diameter side openings 10A, and to secure the strength of the cylinder block 6.

  The inner diameter side opening 9A and the outer diameter side opening 10A are opened when the tips (tops) of the extension portions 9F and 10F on both ends in the circumferential direction which are extended in a substantially triangular shape are sharpened (sharpened). The area becomes the largest. That is, in the case of the inner diameter side opening 9A, the connecting portion 9G between the inner peripheral edge 9B and the end edges 9D, 9E is made an acute angle, and in the case of the outer diameter side opening 10A, the connecting portion between the outer peripheral edge 10C and the end edges 10D, 10E. When 10G is set to an acute angle, the opening area of the inner diameter side opening 9A and the outer diameter side opening 10A becomes the largest.

  However, for the convenience of processing, the same effect can be obtained even if the connecting portions 9G and 10G are formed in a smooth R shape (curved shape) as shown in FIG. For example, the radii of curvature R1 and R2 of the connecting portions 9G and 10G can be less than or equal to half of the radii of curvature R3 and R4 of the circumferential edges (semicircular arc portions) of the virtual openings 11 and 12.

  Next, 13 is a piston inserted in the cylinders 7 and 8 of the cylinder block 6 so as to be able to reciprocate. The pistons 13 are connected to the first and second cylinders 7 and 7 as the cylinder block 6 rotates. 8 is slid in the axial direction. At this time, the working oil is sucked into the first and second cylinders 7 and 8 from the suction passage 23 described later, and the sucked working oil is used as high-pressure pressure oil. Are discharged to the discharge passages 24 and 25 side.

  That is, while the cylinder block 6 rotates once, each piston 13 slides and displaces in the cylinders 7 and 8 from the top dead center to the bottom dead center, and from the bottom dead center to the top dead center. Repeat the discharge stroke that slides and displaces. In the suction stroke of the piston 13 corresponding to the half rotation of the cylinder block 6, the working oil is sucked into the cylinders 7 and 8 from the suction passage 23 described later, and the piston corresponding to the remaining half rotation of the cylinder block 6. In the 13 discharge strokes, the piston 13 discharges hydraulic oil in the cylinders 7 and 8 as high pressure oil from the discharge passages 24 and 25 described later to an external discharge pipe.

  Reference numeral 14 denotes a shoe that is swingably provided at one end (protrusion side) in the axial direction of each piston 13, and each shoe 14 is a swash plate 16 that will be described later by a pressing force (hydraulic pressure) from the piston 13. The smooth surface 16B is pressed. Each shoe 14 slides on the smooth surface 16B so as to draw a ring-shaped locus by rotating together with the rotating shaft 5, the cylinder block 6 and the piston 13 in this state.

  Reference numeral 15 denotes a swash plate support provided on the front bottom portion 3A of the casing body 3. The swash plate support 15 is disposed around the rotary shaft 5 on the back side of the swash plate 16 as shown in FIG. The casing body 3 is fixed to the front bottom 3A. The swash plate support 15 is formed with a pair of tilting sliding surfaces 15A that support the swash plate 16 so as to be tiltable, and the tilting sliding surfaces 15A sandwich the rotating shaft 5 therebetween. At left and right (or up and down).

  Reference numeral 16 denotes a swash plate provided in the casing 2 so as to be tiltable. The swash plate 16 is attached to the front bottom 3 </ b> A side of the casing body 3 via a swash plate support 15. Here, the swash plate 16 includes a swash plate main body 16A and a smooth plate 16C which is provided fixedly on the surface side of the swash plate main body 16A and has a smooth surface 16B as a sliding surface. Further, insertion holes 16A1 and 16C1 through which the rotary shaft 5 is inserted with a gap are formed in the center portion of the swash plate 16 (swash plate body 16A, smooth plate 16C). The swash plate 16 constitutes a capacity variable portion of the hydraulic pump 1, and the back side of the swash plate 16 (swash plate main body 16 </ b> A) can be tilted on each tilt sliding surface 15 </ b> A of the swash plate support 15. It is in contact. The swash plate 16 is tilted by a tilt actuator 26 described later.

  Reference numeral 17 denotes a tilt lever integrally formed on the side portion of the swash plate 16, and the tilt lever 17 is directed from the side portion of the swash plate 16 (swash plate body 16A) toward the tilt actuator 26 described later. The tip end side of the tilting actuator 26 is rotatably connected. The swash plate 16 is tilted by the tilt actuator 26 via the tilt lever 17.

  A valve plate 18 is provided between the sliding surface 6A of the cylinder block 6 and the rear casing 4 and is fixed to the rear casing 4 side. The valve plate 18 is formed in a disc shape as a whole. Has been. One side surface (the right side surface in FIG. 1) of the valve plate 18 is a convex spherical sliding contact surface 18A, and a cylinder block is interposed on the sliding contact surface 18A via a dynamic pressure pad 18B (see FIG. 2). 6 slidable contact surfaces 6A are in slidable contact.

  Further, the valve plate 18 is provided with a suction port 19 and a discharge port 20 that are in intermittent communication with the cylinders 7 and 8 via the cylinder ports 9 and 10. Specifically, as shown in FIG. 2, the valve plate 18 is provided with a single suction port 19 extending in an arc shape along the circumferential direction and a discharge port 20 described later. The cylinder ports 9 and 10 are communicated simultaneously.

  A discharge port 20 is formed in the valve plate 18 so as to face the suction port 19 in the radial direction. The discharge port 20 includes an inner port portion 21 and an outer port portion 22. Here, the inner port portion 21 and the outer port portion 22 are formed as eyebrow-shaped elongated holes that are separated from each other in the radial direction of the valve plate 18 and extend in the circumferential direction. The inner port portion 21 is disposed radially inward corresponding to the inner diameter side opening 9 </ b> A of the first cylinder port 9 communicating with the first cylinder 7, and the outer port portion 22 communicates with the second cylinder 8. The second cylinder port 10 is arranged on the radially outer side corresponding to the outer diameter side opening 10A.

  In the intake stroke in which each piston 13 strokes in the first and second cylinders 7 and 8 from the top dead center position to the bottom dead center position, both cylinder ports 9 and 10 communicate with the intake port 19, Hydraulic fluid is sucked into the first and second cylinders 7 and 8 from the port 19.

  In the discharge stroke in which each piston 13 strokes in the first and second cylinders 7 and 8 from the bottom dead center position to the top dead center position, the first cylinder port 9 and the second cylinder port 10 are respectively connected to the discharge port. 20, the inner port portion 21 and the outer port portion 22 communicate with each other individually, so that the hydraulic oil in the first and second cylinders 7 and 8 is separately discharged toward the inner port portion 21 and the outer port portion 22, respectively. Is done.

  Reference numeral 23 denotes a single suction passage provided in the rear casing 4. The suction passage 23 has one end communicating with the suction port 19 and the other end connected to an external tank via a pipe (both not shown). To be connected.

  Reference numeral 24 denotes a first discharge passage provided in the rear casing 4. The first discharge passage 24 has one end communicating with the inner port portion 21 of the discharge port 20, and the other end connected to a hydraulic actuator (both not shown). Or the like).

  Reference numeral 25 denotes a second discharge passage provided in the rear casing 4. The second discharge passage 25 has one end communicating with the outer port portion 22 of the discharge port 20, and the other end connected to another hydraulic actuator (both (Not shown) or the like.

  Reference numeral 26 denotes a tilting actuator provided in the actuator mounting portion 3B of the casing body 3. The tilting actuator 26 is supplied together with the tilting lever 17 by supplying and discharging a tilting control pressure from a regulator (not shown). The swash plate 16 is driven to tilt.

  Reference numeral 27 denotes a retainer that is positioned between each shoe 14 and the protruding end of each piston 13 and is inserted through the rotary shaft 5. Is. Here, the retainer 27 is formed of an annular plate body as a whole, and a shaft insertion hole 27A is formed at the center thereof. It is the structure which touches. In addition, a plurality of shoe holding holes 27B are provided around the shaft insertion hole 27A in the retainer 27 at a predetermined angular interval. It is the structure hold | maintained in the state contact | abutted to.

  Reference numeral 28 denotes a retainer guide that is positioned between the retainer 27 and the cylinder block 6 and is fitted to the rotary shaft 5. The retainer guide 28 has an outer peripheral surface that comes into contact with the inner peripheral surface of the retainer 27. The retainer 27 is pressed toward the swash plate 16 by the surface. Here, the inner peripheral side of the retainer guide 28 is spline-coupled to the rotary shaft 5 so as to be movable in the axial direction, and a plurality of springs (not shown) are provided between the retainer guide 28 and the cylinder block 6. It has been. The retainer guide 28 rotates integrally with the cylinder block 6 and constantly presses the retainer 27 toward the swash plate 16 by the spring force of each spring, and the cylinder block 6 presses the valve plate 18 by the spring force of each spring. It is the structure always pressed toward.

  The hydraulic pump 1 according to the present embodiment has the above-described configuration, and the operation thereof will be described next.

  First, when the rotary shaft 5 is driven to rotate by the prime mover, the cylinder block 6 rotates together with the rotary shaft 5 and the shoe 14 provided at the tip of the piston 13 slides on the smooth surface 16B of the swash plate 16. Then, at this time, each piston 13 strokes the inside of the first and second cylinders 7 and 8 from the top dead center position to the bottom dead center position, and the inside of the first and second cylinders 7 and 8 is lowered. The discharge stroke that strokes from the dead center position to the top dead center position is repeated.

  As a result, while the hydraulic oil (oil liquid) in the tank is sucked into the first and second cylinders 7 and 8 from the cylinder ports 9 and 10 through the suction passage 23 and the suction port 19, Pressure oil is discharged from the first and second cylinders 7 and 8 to the separate discharge passages 24 and 25 through the discharge port 20 (inner port portion 21 and outer port portion 22) (divided into two hydraulic systems and discharged) And actuate multiple hydraulic actuators independently.

  Further, when adjusting the pump capacity (pressure oil discharge amount) of the hydraulic pump 1, the tilt angle of the swash plate 16 is changed by the tilt actuator 26 to increase or decrease the stroke amount of each piston 13. Thus, the pump capacity is variably controlled.

  By the way, in order to improve the self-priming performance of the hydraulic pump 1, it is preferable to increase the opening areas of the openings 9A and 10A of the cylinder ports 9 and 10, respectively. Here, for example, the shapes of the openings 9A and 10A of the cylinder ports 9 and 10 are formed into arcs with curvatures corresponding to the inner and outer port portions 21 and 22, respectively, like the virtual openings 11 and 12 shown in FIG. Consider the case of a curved eyebrow shape.

  In this case, in order to increase the opening area of the eyebrows-shaped virtual openings 11 and 12, for example, when the opening angle, that is, the circumferential lengths M1 and M2 of the virtual openings 11 and 12 are increased, the adjacent virtual openings 11 and 12 are increased. Twelve circumferential edges (semi-arc-shaped portions) are close to each other, and the separation dimension (thickness) L1 between these virtual openings 11 and 12 is reduced. Since a large pressure of 35 MPa, for example, is applied to the inside of each cylinder port 9, 10, if the separation dimension (thickness) L1 is small, it is difficult to ensure the strength of the cylinder block 6, which is not preferable.

  On the other hand, if the radial dimensions N1 and N2 of the eyebrows-shaped virtual openings 11 and 12 are increased, it becomes difficult to balance the hydraulic pressure of the cylinder block 6, and for example, the peripheral speed on the radially outer side of the virtual openings 11 and 12 increases. The self-priming performance may be difficult to secure.

  On the other hand, according to the present embodiment, the inner peripheral edge 9B of each inner diameter side opening 9A is formed longer in the circumferential direction than the outer peripheral edge 9C, and the outer peripheral edge 10C of each outer diameter side opening 10A is longer than the inner peripheral edge 10B. The structure is formed to be long in the circumferential direction. For this reason, while increasing the opening area of each inner diameter side opening 9A and each outer diameter side opening 10A, the separation dimension (thickness) L1 between the inner diameter side opening 9A and the outer diameter side opening 10A adjacent in the circumferential direction is set. Can be secured.

  That is, as shown in FIG. 6, each inner diameter side opening 9 </ b> A has both ends in the circumferential direction of the inner peripheral edge 9 </ b> B in the circumferential direction with respect to the eyebrow-shaped virtual opening 11 curved in an arc shape with a curvature corresponding to the inner port portion 21. By extending, the opening area is made larger than the opening area of the virtual opening 11 by the extension portion 9F. Further, each outer diameter side opening 10A extends in the circumferential direction at both ends in the circumferential direction of the outer peripheral edge 10C with respect to the eyebrow-shaped virtual opening 12 curved in an arc shape with a curvature corresponding to the outer port portion 22. The opening area is larger than the opening area of the virtual opening 12 by the extension portion 10F.

  In this case, each inner diameter side opening 9A lengthens the radially inner inner peripheral edge 9B on the side away from each outer diameter side opening 10A, and each outer diameter side opening 10A is separated from each inner diameter side opening 9A. The outer peripheral edge 10C on the outer side in the radial direction is made longer. For this reason, while maintaining the separation dimension L1 between the inner diameter side opening 9A and each outer diameter side opening 10A, that is, the same as the separation dimension L1 of the virtual openings 11, 12, each inner diameter side opening 9A and each The opening area with the outer diameter side opening 10 </ b> A can be made larger than the opening area of the virtual openings 11 and 12. Accordingly, it is possible to secure the wall thickness L1 of the cylinder block 6 between the inner diameter side opening 9A and the outer diameter side opening 10A while increasing the opening area of each inner diameter side opening 9A and each outer diameter side opening 10A. it can.

  In other words, compared with the case where the openings of the cylinder ports 9 and 10 are the eyebrows-shaped virtual openings 11 and 12, the area of the flow path of the hydraulic oil when the hydraulic oil is sucked in as much as the opening area is increased. The self-priming performance (suction performance) can be improved accordingly. Moreover, the opening area of the inner diameter side opening 9A and the outer diameter side opening 10A can be increased while the thickness L1 of the cylinder block 6 is secured, and the strength of the cylinder block 6 can be prevented from being lowered. As a result, generation of vibration and noise due to cavitation and reduction in durability due to erosion can be suppressed (avoided), and pump efficiency, pump capacity, and rotational speed of the rotating shaft 5 (allowable rotational speed) can be improved. be able to.

  Further, according to the present embodiment, as shown in FIG. 3, the cylinder ports 9 and 10 become closer to the inner diameter side opening 9A and the outer diameter side opening 10A from the bottom portions 7B and 8B of the cylinders 7 and 8, respectively. It is inclined in a direction approaching the rotating shaft 5. Accordingly, the inner diameter side opening 9 </ b> A and the outer diameter side opening 10 </ b> A are arranged in the vicinity of the rotation shaft 5 (on the rotation center side) on the sliding contact surface 6 </ b> A of the cylinder block 6. For this reason, the peripheral speeds of the inner diameter side opening 9A and the outer diameter side opening 10A can be reduced, and the self-priming performance of the hydraulic pump 1 can be improved also from this surface.

  Next, FIG. 7 shows a second embodiment of the present invention. The feature of this embodiment is that the inner diameter side half of the inner diameter side opening is extended in the circumferential direction with a narrow eyebrow shape and the outer diameter side half portion of the outer diameter side opening is extended in the circumferential direction with a narrow eyebrow shape. It is in the configuration to do. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, 31 indicates a plurality of first cylinder ports communicating (connected) to the bottom 7B of the first cylinder 7, and 32 indicates a plurality of second cylinder ports communicating (connected) to the bottom 8B of the second cylinder 8. ing. Here, the openings 31A and 32A of the cylinder ports 31 and 32 have a plurality of inner diameter side openings 31A disposed on the inner diameter side of the cylinder block 6 and a plurality of inner diameter side openings 31A disposed on the radially outer side. It is configured as two sets of arrays with the outer diameter side opening 32A.

  Each of the inner diameter side openings 31A has an opening edge (outline) having an arcuate inner peripheral edge 31B, an arcuate outer peripheral edge 31C, a substantially half arcuate inner diameter side edge 31D, A quarter arc-shaped outer diameter side edge 31E and a connection edge 31F that connects the outer diameter side edge 31E and the inner diameter side edge 31D are formed. Of these, the inner peripheral edge 31B is formed longer in the circumferential direction than the outer peripheral edge 31C.

  More specifically, each inner diameter side opening 31 </ b> A has both ends in the circumferential direction of the inner peripheral edge 31 </ b> B extended in the circumferential direction with respect to the eyebrow-shaped virtual opening 11 curved in an arc shape with a curvature corresponding to the inner port portion 21. Yes. And the extension part 31G extended in the eyebrow shape narrower than the circumferential direction both ends of the virtual opening 11 is formed on the inner diameter side of the circumferential direction both ends of each inner diameter side opening 31A. The opening 31A is formed as a substantially convex opening as a whole.

  On the other hand, each outer diameter side opening 32A has an opening edge (outline) having an arc-shaped inner peripheral edge 32B, an arc-shaped outer peripheral edge 32C, and a substantially quarter-arc inner diameter-side edge 32D, The outer-diameter side end edge 32E having a substantially half arc shape and a connection edge 32F that connects the outer-diameter side end edge 32E and the inner-diameter side end edge 32D. Of these, the outer peripheral edge 32C is longer than the inner peripheral edge 32B in the circumferential direction.

  More specifically, each outer diameter side opening 32 </ b> A extends both ends in the circumferential direction of the outer peripheral edge 32 </ b> C in the circumferential direction with respect to the eyebrow-shaped virtual opening 12 curved in an arc shape with a curvature corresponding to the outer port portion 22. ing. Then, on the outer diameter side of each outer diameter side opening 32A in the circumferential direction both ends, extending portions 32G that are extended (expanded) in a narrow eyebrow shape with respect to the both ends in the circumferential direction of the virtual opening 12 are formed, The outer diameter side opening 32A is formed as a substantially convex opening as a whole.

  In the present embodiment, the working oil is sucked into the cylinders 7 and 8 through the inner diameter side opening 31A and the outer diameter side opening 32A as described above, and the working oil is discharged from the cylinders 7 and 8 to the outside. Regarding the operation, there is no particular difference from that according to the first embodiment described above.

  In particular, in the case of the present embodiment, the opening areas of the inner diameter side opening 31A and the outer diameter side opening 32A are further set to be larger than the opening areas of the inner diameter side opening 9A and the outer diameter side opening 10A of the first embodiment described above. The self-priming performance can be further improved.

  In addition, the inner diameter side opening 31A and the outer diameter side opening 32A are formed with the eyebrows-shaped virtual openings 11 and 12 and then formed with extensions 31G and 32G on both ends in the circumferential direction of the virtual openings 11 and 12 using an end mill or the like. By doing so, it can be formed as a substantially convex opening as a whole. For this reason, it is possible to facilitate the processing of the inner diameter side opening 31A and the outer diameter side opening 32A.

  Next, FIG. 8 shows a third embodiment of the present invention. The feature of this embodiment is that the inner diameter side half of the inner diameter side opening is extended in the circumferential direction with a narrow eyebrow shape and the outer diameter side half portion of the outer diameter side opening is extended in the circumferential direction with a narrow eyebrow shape. It is in the configuration to do. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, 41 indicates a first cylinder port, and 42 indicates a second cylinder port. The openings 41A and 42A of the first and second cylinder ports 41 and 42 are arranged on the radially inner side of the plurality of inner diameter side openings 41A arranged on the inner diameter side of the cylinder block 6 and the inner diameter side openings 41A. It is configured as two sets of arrays with a plurality of outer diameter side openings 42A.

  Each inner diameter side opening 41A has an opening edge (outline) having an arc-shaped inner peripheral edge 41B, an arc-shaped outer peripheral edge 41C, a substantially one-half arc-shaped inner diameter side edge 41D, It is formed by a curved connection edge 41E that smoothly connects the inner diameter side edge 41D and the outer peripheral edge 41C. Of these, the inner peripheral edge 41B is longer than the outer peripheral edge 41C in the circumferential direction.

  More specifically, each inner diameter side opening 41 </ b> A has both ends in the circumferential direction of the inner peripheral edge 41 </ b> B extended in the circumferential direction with respect to the eyebrow-shaped virtual opening 11 curved in an arc shape with a curvature corresponding to the inner port portion 21. Yes. And the extension part 41F extended in the shape of a narrow eyebrow with respect to the circumferential direction both ends of the virtual opening 11 is formed on the inner diameter side of the circumferential direction both ends of each inner diameter side opening 41A. The opening 41A as a whole is formed as a substantially convex opening. In this case, the extension part 41F can be made larger in area than the extension part 31G of the second embodiment described above by being formed by the smoothly curved connection edge 41E.

  On the other hand, each outer diameter side opening 42A has an opening edge (outline) having an arc-shaped inner peripheral edge 42B, an arc-shaped outer peripheral edge 42C, and an outer diameter-side edge 42D having a substantially half arc shape. The outer-diameter side end edge 42D and the inner peripheral edge 42B are formed by a curved connection edge 42E that smoothly connects. Of these, the outer peripheral edge 42C is formed longer in the circumferential direction than the inner peripheral edge 42B.

  More specifically, each outer diameter side opening 42 </ b> A extends both circumferential ends of the outer peripheral edge 42 </ b> C in the circumferential direction with respect to the eyebrow-shaped virtual opening 12 curved in an arc shape with a curvature corresponding to the outer port portion 22. ing. Then, on the outer diameter side of each outer diameter side opening 42A in the circumferential direction both ends, an extension portion 42F that extends (expands) in a narrow eyebrow shape with respect to the both circumferential direction ends of the virtual opening 12 is formed. The outer diameter side opening 42A is formed as a substantially convex opening as a whole. In this case, the extension portion 42F can be made larger in area than the extension portion 32G of the second embodiment described above by being formed by the smoothly curved connection edge 42E.

  In the present embodiment, the working oil is sucked and discharged through the inner diameter side opening 41A and the outer diameter side opening 42A as described above, and the basic operation thereof is as described in the first embodiment. There is no particular difference.

  In particular, in the case of the present embodiment, the opening areas of the inner diameter side opening 41A and the outer diameter side opening 42A are further made larger than the opening areas of the inner diameter side opening 31A and the outer diameter side opening 32A of the second embodiment described above. The self-priming performance can be further improved.

  In the first embodiment described above, both circumferential edges of the inner diameter side opening 9A and the outer diameter side opening 10A are opposed to each other by substantially linear end edges 9D, 9E, 10D, and 10E. On the other hand, in the case of the present embodiment, both circumferential edges of the inner diameter side opening 41A and the outer diameter side opening 42A are opposed to each other by smoothly curved curved connection edges 41E and 42E. ing. Thus, a sufficient thickness between the inner diameter side opening 41A and the outer diameter side opening 42A can be secured.

  Next, FIG. 9 shows a fourth embodiment of the present invention. The feature of this embodiment is that the opening of the cylinder port is configured as three sets of inner diameter side openings, outer diameter side openings, and intermediate side openings, and both circumferential edges of each intermediate side opening are circumferentially arranged. The configuration is such that it projects in a triangular shape in the direction. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, 51 indicates a first cylinder port, 52 indicates a second cylinder port, and 53 indicates a third cylinder port. The openings 51A, 52A, 53A of the cylinder ports 51, 52, 53 are arranged on the radially inner side of the plurality of inner diameter side openings 51A arranged on the inner diameter side of the cylinder block 6 and the inner diameter side openings 51A. A plurality of outer diameter side openings 52A and a plurality of intermediate side openings 53A arranged between the outer diameter side openings 52A and the inner diameter side openings 51A are configured as three sets of arrays.

  Each inner diameter side opening 51A is the same as the inner diameter side opening 9A of the first embodiment described above, and the opening edge (outline) thereof is an arc-shaped inner peripheral edge 51B and an arc-shaped outer peripheral edge. 51C and linear edge 51D, 51E which connects these inner periphery 51B and outer periphery 51C. Then, on both ends in the circumferential direction of each inner diameter side opening 51A, extension portions 51F extended (expanded) in a substantially triangular shape with respect to both ends in the circumferential direction of the virtual opening 11 are formed. As a whole, it is formed as a substantially trapezoidal opening.

  Further, each outer diameter side opening 52A is the same as the outer diameter side opening 10A of the first embodiment described above, and the opening edge (outline) thereof has an arcuate inner peripheral edge 52B and an arcuate shape. The outer peripheral edge 52C and linear end edges 52D and 52E that connect the inner peripheral edge 51B and the outer peripheral edge 52C are formed. Then, on both ends in the circumferential direction of each outer diameter side opening 52A, extension portions 52F that are extended (expanded) in a substantially triangular shape with respect to both ends in the circumferential direction of the virtual opening 12 are formed. 51A is formed as a substantially trapezoidal opening as a whole.

  On the other hand, each of the intermediate side openings 53A has an opening edge (outline) having an arc-shaped inner peripheral edge 53B, an arc-shaped outer peripheral edge 53C, and an edge 53D that connects the inner peripheral edge 53B and the outer peripheral edge 53C. 53E. The end edges 53D and 53E have a substantially isosceles triangular shape projecting in the circumferential direction, thereby projecting both circumferential ends of each intermediate opening 53A in the circumferential direction. That is, on both ends in the circumferential direction of each intermediate-side opening 53A, extension portions 53F that are extended (expanded) in the circumferential direction with respect to the virtual opening 54 having an eyebrow shape curved in an arc shape are formed.

  Although not shown in the drawings, in the present embodiment, the discharge port provided in the valve plate includes an inner port portion corresponding to each inner diameter side opening 51A, an outer port portion corresponding to each outer diameter side opening 52A, and each The intermediate opening 53A and the corresponding intermediate port portion are configured. And it discharges to a separate discharge passage through an inner port part, an outer port part, and an intermediate side port part (it branches and discharges to three sets of hydraulic systems), and operates a plurality of hydraulic actuators independently.

  In the present embodiment, hydraulic oil is sucked and discharged through the inner diameter side opening 51A, the outer diameter side opening 52A, and the intermediate side opening 53A as described above. The basic operation of the first embodiment is described above. There is no particular difference from the form.

  In particular, according to the present embodiment, the openings 51A, 52A, 53A of the cylinder ports 51, 52, 53 are configured by a plurality of inner diameter side openings 51A, a plurality of outer diameter side openings 52A, and a plurality of intermediate side openings 53A. In addition, both end edges in the circumferential direction of each intermediate opening 53A are configured to protrude in the circumferential direction. Therefore, while increasing the opening area of each inner diameter side opening 51A, each outer diameter side opening 52A, and each intermediate side opening 53A, the inner diameter side opening 51A, the intermediate side opening 53A, and the outer diameter side opening 52A that are adjacent to each other in the circumferential direction. The separation dimension (wall thickness) can be ensured. Thereby, even when the openings 51A, 52A, 53A of the cylinder ports 51, 52, 53 are configured as three sets of the inner diameter side openings 51A, the outer diameter side openings 52A, and the intermediate side openings 53A, the cylinders The self-priming performance can be improved while ensuring the strength of the block 6.

  Next, FIGS. 10 to 16 show a fifth embodiment of the present invention. The feature of this embodiment is that the sectional shape of each cylinder port is changed from a substantially trapezoidal shape to a substantially semicircular shape as it goes from the opening to the bottom of the cylinder. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, 61 indicates a first cylinder port, and 62 indicates a second cylinder port. The openings 61A, 62A of the first and second cylinder ports 61, 62 are arranged on the radially inner side of the plurality of inner diameter side openings 61A disposed on the inner diameter side of the cylinder block 6 and the inner diameter side openings 61A. It is configured as two sets of arrays with a plurality of outer diameter side openings 62A.

  Each of the inner diameter side openings 61A is the same as the inner diameter side opening 9A of the first embodiment described above, and the opening edge (outline) is formed in a substantially trapezoidal shape as a whole. Each outer diameter side opening 62A is the same as the outer diameter side opening 10A of the first embodiment described above, and the opening edge (outline) is formed in a substantially trapezoidal shape as a whole.

  Further, in the case of the present embodiment, as shown in FIGS. 11 to 16, the cross-sectional shape of each cylinder port 61, 62 is advanced from the opening 61A, 62A to the bottom 7B, 8B of the cylinder 7, 8, It is configured to change from a substantially trapezoidal shape to a substantially semicircular shape. More specifically, each first cylinder port 61 has a radial dimension K1 that increases from the opening 61A to the bottom 7B of the cylinder 7 such that K11 <K12 <K13. The cross-sectional area between the bottom portion 7B and the bottom portion 7B is substantially constant. Each of the second cylinder ports 62 also increases so that the radial dimension K2 becomes K21 <K22 <K23 as it advances from the opening 62A to the bottom 8B of the cylinder 8, and between the opening 62A and the bottom 8B of the cylinder 8 The cross-sectional area is formed so as to be substantially constant.

  That is, the cylinder ports 61 and 62 have the radial dimensions K1 and K2 that are increased from the openings 61A and 62A to the bottoms 7B and 8B of the cylinders 7 and 8, respectively. This is different from the cylinder ports 9 and 10.

  In this embodiment, hydraulic oil is sucked and discharged through the cylinder ports 61 and 62 as described above, and the basic action is not different from that in the first embodiment described above.

  In particular, according to the present embodiment, the radial dimensions K1 and K2 of the cylinder ports 61 and 62 are increased toward the bottoms 7B and 8B of the cylinders 7 and 8, and the cross-sectional areas of the cylinder ports 61 and 62 are increased. Is configured to be substantially constant between the openings 61A, 62A and the bottom portions 7B, 8B of the cylinders 7, 8. For this reason, the separation dimension (thickness) between the cylinder ports 61 and 62 adjacent to the circumferential direction can be ensured while ensuring the cross-sectional area of each cylinder port 61 and 62. Thereby, the improvement of the further self-priming performance and the ensuring of the intensity | strength of the cylinder block 6 can be aimed at.

  Next, FIGS. 17 to 18 show a sixth embodiment of the present invention. A feature of the present embodiment is that a diameter-enlarged portion having a larger inner diameter is provided on the bottom side of the cylinder. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  Reference numeral 71 denotes a first cylinder, and the front end side which is one end side (the right end side in FIG. 10) is the front side of the cylinder block 6 as in the first cylinder 7 of the first embodiment described above. The tube portion 71A is open to the end surface, and is formed of a bottom portion 71B that closes the rear end side (the left end side in FIG. 10) that is the other end side of the tube portion 71A. And the 1st cylinder 71 by this Embodiment is provided in the bottom part 71B side and the enlarged diameter part 71C which the internal diameter dimension became large.

  Reference numeral 72 denotes a second cylinder, and the second cylinder is, as in the second cylinder 8 of the first embodiment described above, the front end side (the right end side in FIG. 10) which is one end side is the front side of the cylinder block 6. A cylindrical portion 72A that is open to the end surface and a bottom portion 72B that closes the rear end side (the left end side in FIG. 10) that is the other end side of the cylindrical portion 72A. And the 2nd cylinder 72 by this Embodiment is provided in the bottom part 72B side and the enlarged diameter part 72C which the internal diameter dimension became large.

  Here, when a polishing process such as a honing process is used to process the inner peripheral surfaces of the first and second cylinders 71 and 72, the inner diameter dimension of the bottoms 71B and 72B of the cylinders 71 and 72 is increased from the shape of the tool. In the case of the present embodiment, an enlargement for increasing the communication area between the cylinder ports 9 and 10 and the cylinders 71 and 72 is required in the case of the present embodiment. The diameter portions 71C and 72C are provided.

  In the present embodiment, the working oil is sucked and discharged through the cylinders 71 and 72 provided with the enlarged diameter portions 71C and 72C as described above. The basic operation of the first embodiment is described above. There is no particular difference from the form.

  In particular, according to the present embodiment, since the enlarged diameter portions 71C and 72C are provided on the bottom portions 71B and 72B of the cylinders 71 and 72, the communication area between the cylinder ports 9 and 10 and the cylinders 71 and 72 is increased. It is possible to enlarge the cross-sectional area of the cylinder ports 9 and 10 with a simple shape. Thereby, the improvement of the further self-priming performance can be aimed at.

  In each of the above-described embodiments, the case where the first and second cylinders 7 and 8 are arranged concentrically on the cylinder block 6 has been described as an example. However, the present invention is not limited to this, and, for example, the second cylinder may be arranged so as to be shifted radially outside or inside the cylinder block with respect to the first cylinder.

  Furthermore, in each of the above-described embodiments, a variable displacement swash plate hydraulic pump has been described as an example of the axial piston hydraulic pump. However, the present invention is not limited to this, and may be applied to other types of hydraulic pumps such as a fixed capacity swash plate type hydraulic pump and an inclined axis type hydraulic pump.

1 Hydraulic pump (Axial piston type hydraulic pump)
2 Casing 5 Rotating shaft 6 Cylinder block 6A Sliding surface (end surface)
7, 71 First cylinder 7B, 71B Bottom 8, 72 Second cylinder 8B, 72B Bottom 9, 31, 41, 51, 61 First cylinder port 9A, 31A, 41A, 51A, 61A Inner diameter side opening 9B, 31B, 41B , 51B Inner peripheral edge 9C, 31C, 41C, 51C Outer peripheral edge 10, 32, 42, 52, 62 Second cylinder port 10A, 32A, 42A, 52A, 62A Outer diameter side opening 10B, 32B, 42B, 52B Inner peripheral edge 10C, 32C, 42C, 52C Outer peripheral edge 13 Piston 18 Valve plate 19 Suction port 20 Discharge port 53 Third cylinder port 53A Middle side opening 53D, 53E End edge 71C, 72C Expanded diameter portion

Claims (5)

A casing, a rotating shaft that extends in the axial direction in the casing so as to be rotatable, and a casing that is provided in the casing so as to rotate integrally with the rotating shaft and is spaced apart in the circumferential direction and extends in the axial direction. A cylinder block in which a plurality of cylinders are formed together with a cylinder port, a plurality of pistons that are reciprocally inserted in the cylinders of the cylinder block, and a sliding contact with an end surface of the cylinder block, provided on the casing side. A suction port that intermittently communicates with the cylinder via each cylinder port, and a valve plate provided with a discharge port, and an end surface of the cylinder block that is in sliding contact with the valve plate has an opening of each cylinder port. A plurality of inner diameter side openings disposed on the inner diameter side of the cylinder block, and a plurality of outer diameter side openings disposed on the radially outer side from the inner diameter side opening. In a, the axial piston type hydraulic pump comprising configured as at least two sets of sequences,
Each said inner diameter side opening forms the inner peripheral edge which forms the said inner diameter side opening longer in the circumferential direction than an outer peripheral edge,
Each of the outer diameter side openings is an axial piston hydraulic pump characterized in that an outer peripheral edge forming the outer diameter side opening is formed longer in the circumferential direction than the inner peripheral edge.   2. The axial piston type liquid according to claim 1, wherein each of the cylinder ports is inclined in a direction approaching the rotation shaft toward the opening from the cylinder side, and the openings are arranged in the vicinity of the rotation shaft. Pressure pump. On the end face of the cylinder block that is in sliding contact with the valve plate, an opening of each cylinder port is formed, each opening on each inner diameter side, each opening on the outer diameter side, each outer diameter side opening, and each inner diameter side opening. Configured as three sets of arrays, with a plurality of intermediate openings arranged between
3. The axial piston hydraulic pump according to claim 1, wherein each of the intermediate side openings has a configuration in which both circumferential edges of the intermediate side opening project in the circumferential direction.   Each of the cylinder ports is configured to have a radial dimension that increases from the opening toward the bottom of the cylinder and has a constant cross-sectional area between the opening and the bottom of the cylinder. An axial piston hydraulic pump according to 1, 2 or 3.   5. The axial piston hydraulic pump according to claim 1, 2, 3, or 4, wherein each of the cylinders is provided with an enlarged diameter portion that is located on a bottom side and has an increased inner diameter.

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