JPH1182321A - Hydraulic rotary machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve operating efficiency and reliability by lubricating a space between a cylinder and a piston with drain oil inside a casing. SOLUTION: A hydraulic rotary machine is structured so that an oil groove 15 corresponding to a seal section in which a piston 9 is always inserted is disposed on the inner periphery side of each cylinder 7, a communicating path 16 which always communicate the oil groove 15 to a drain oil chamber 4 is disposed in a cylinder block 6, and the communicating path 16 is formed in the cylinder block 6 in radial direction so that an flow inlet is open to a shaft inserting hole 6A and a flow outlet is open to an outer peripheral surface 6C. Therefore, by rotating the cylinder block 6, the oil inside the drain oil chamber 4 can be fed from the communicating path 16 to the oil groove 15 using a centrifugal force caused by this rotation, and also the space between the cylinder 7 and the piston 9 can be lubricated with the oil inside the oil groove 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic rotating machine suitably used as an axial piston or radial piston type hydraulic pump, hydraulic motor or the like.

[0002]

2. Description of the Related Art Generally, a hydraulic rotating machine includes a casing,
A rotating shaft rotatably supported by the casing, a cylinder block that rotates integrally with the rotating shaft in the casing, and is provided with a plurality of cylinders, and is slidably inserted into each cylinder of the cylinder block. A pair of pistons fitted and provided between the casing and the cylinder block and intermittently communicating with the cylinders of the cylinder block, the plurality of pistons being reciprocated in the respective cylinders as the cylinder block rotates. And a valve member formed with a discharge port (for example, Japanese Patent Publication No. 3-47437).

When the conventional hydraulic rotary machine is used as, for example, a swash plate type hydraulic pump, a swash plate having an inclined surface facing the piston is provided in a casing.

When the swash plate type hydraulic pump is operated, the cylinder block is driven to rotate together with the rotating shaft by a driving source such as an engine, and each piston slides along the inclined surface of the swash plate. Reciprocate in the cylinder. Thereby, the hydraulic oil sucked into the cylinder from one supply / discharge port formed in the valve plate by the reciprocating motion of the piston is discharged as pressure oil to the other supply / discharge port, and supplied to the hydraulic equipment.

[0005]

By the way, in the above-described hydraulic rotary machine according to the prior art, when the load during operation increases, the frictional force between the cylinder and the piston increases.
In particular, there is a problem that the frictional force on the opening side of the cylinder is large, and the frictional loss due to the frictional force causes a decrease in the operating efficiency.

In addition, when the operation is performed for a long time, there is a problem that seizure may occur between the cylinder and the piston or oil leakage due to wear may occur.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to lubricate between a cylinder and a piston with drain oil in a casing,
An object of the present invention is to provide a hydraulic rotary machine capable of improving operation efficiency and reliability.

[0008]

SUMMARY OF THE INVENTION The hydraulic rotating machine of the present invention comprises:
A casing, a rotating shaft rotatably supported by the casing, a cylinder block provided in the casing so as to rotate integrally with the rotating shaft, and a plurality of cylinder-drilled bores; A plurality of pistons slidably inserted into the cylinders and reciprocating in each of the cylinders with the rotation of the cylinder block;
Provided between the casing and the cylinder block,
A valve member formed with a pair of supply / discharge ports intermittently communicating with each cylinder of the cylinder block.

Then, in order to solve the above-mentioned problem,
The feature of the structure adopted by the invention of claim 1 is that an oil groove is provided on the inner peripheral side of the cylinder in a seal section where the piston is always inserted, and the oil groove and the oil groove are provided in the cylinder block. There is provided a communication passage which always communicates with the drain oil chamber in the casing.

With this configuration, when the cylinder block rotates together with the rotating shaft, the oil in the drain oil chamber of the casing flows into the communication passage, and is supplied to the oil groove via the communication passage. Thereby, the space between the cylinder and the piston can be lubricated by the oil in the oil groove. Also,
Since the oil groove is provided in the seal section where the piston is always inserted, the oil supplied to and discharged from the cylinder by the reciprocating motion of the piston does not flow out of the communication passage into the drain oil chamber.

According to a second aspect of the present invention, the communication path is provided in the radial direction of the cylinder block, the inflow port is opened in the shaft insertion hole of the cylinder block, and the outflow port is opened in the outer peripheral surface of the cylinder block. It is in.

With this configuration, when the cylinder block rotates together with the rotating shaft, the oil in the drain oil chamber flows in from the inflow port of the communication passage opened in the shaft insertion hole, and the oil is connected by centrifugal force due to the rotation of the cylinder block. The passage flows radially outward. As a result, the oil is forcibly supplied to the oil groove, so that the oil can lubricate between the cylinder and the piston. Then, the oil that has lubricated between the cylinder and the piston is discharged into the drain oil chamber from the outlet opening on the outer peripheral surface of the cylinder block by centrifugal force. Therefore, the oil in the drain oil chamber can be forcibly circulated between the oil groove and the communication passage.

[0013] According to a third aspect of the present invention, the communication path is radially disposed about the axis of the rotating shaft, whereby oil can be smoothly circulated in the communication path.

According to a fourth aspect of the present invention, the communication passage is formed so as to be inclined in the circumferential direction. For example, when the communication passage is inclined in a direction opposite to the rotation direction of the cylinder block, the rotation of the cylinder block is prevented. Centrifugal force can effectively act on the oil in the communication passage.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hydraulic rotary machine according to an embodiment of the present invention will be described below in detail with reference to FIGS.

1 and 2 show a first embodiment of the present invention. In this embodiment, a swash plate type hydraulic pump will be described as an example of a hydraulic rotating machine.

Reference numeral 1 denotes a casing which forms an outer shell of the swash plate type hydraulic pump. The casing 1 has a closed portion 2A at one end in the axial direction.
And a rear casing 3 for closing the other end of the casing main body 2 which is an opening side of the casing main body 2
It is roughly composed of The inside of the casing 1 is
A drain oil chamber 4 in which oil leaking from between a cylinder block 6 and a valve plate 8, which will be described later, between a cylinder 7 and a piston 9, and the like stays.

A rotary shaft 5 is inserted into the casing 1 in the axial direction thereof. The rotary shaft 5 is rotatably supported between the closing portion 2A side and the rear casing 3 side, and has an axial intermediate portion. Is formed with a male spline 5A. Further, a pair of supply / discharge passages 2B, 2B for supplying / discharging the pressure oil to / from the cylinder 7 through respective supply / discharge ports 8A of the valve plate 8 described later are formed in the closing portion 2A of the casing body 2.

Reference numeral 6 denotes a cylinder block rotatably provided in the casing 1 via a rotation shaft 5. The cylinder block 6 is formed in a stepped cylindrical shape, and the rotation shaft 5 is provided at the center thereof.
A shaft insertion hole 6A through which the shaft insertion hole 6A is formed is formed.
A is formed with a female spline 6B that engages with the male spline 5A of the rotating shaft 5. The cylinder block 6
The shaft insertion hole 6A has an inflow port 16A of a communication path 16 described later.
Is opened, and an outlet 16B of the communication passage 16 is opened on the outer peripheral surface 6C.

Are a plurality of cylinders formed in the cylinder block 6 at equal intervals in the circumferential direction around the rotation shaft 5 and in the axial direction, and each cylinder 7 is formed on the bottom side. It communicates intermittently with the supply / discharge port 8A of the valve plate 8 via the communication port 7A. Also, the open end 7 of each cylinder 7
A piston 9 is slidably inserted on the B side.

Reference numeral 8 denotes a valve plate fixed to the inner surface of the closed portion 2A of the casing body 2. The valve plate 8 has a top dead center position of each piston 9 (a position where the piston 9 has entered the cylinder 7 most). A pair of eyebrow-shaped supply / discharge ports 8A are formed so as to sandwich the bottom dead center position (the position where the piston 9 projects most from the cylinder 7). Each supply / discharge port 8A of the valve plate 8 intermittently communicates with a communication port 7A of each cylinder 7 while the cylinder block 6 is rotating. Exhaust passage 2B
Is always in communication with

Are a plurality of pistons slidably inserted into the respective cylinders 7 of the cylinder block 6. Each piston 9 reciprocates in the cylinder 7 while the cylinder block 6 rotates. With a shoe 1 on the protruding end side.
0 is swingably mounted.

Here, each piston 9 has a top dead center position where it enters the cylinder 7 the most, a bottom dead center position where it protrudes from the cylinder 7, and a top dead center position and a bottom dead center position. Reciprocating between In addition, each piston 9
Many parts are inserted into the cylinder 7 even at the bottom dead center position protruding from the cylinder 7, and the part always inserted into the cylinder 7 is the seal section L1 at the bottom dead center position.
It has become.

Reference numeral 11 denotes a swash plate provided on the rear casing 3 side. The swash plate 11 slides and guides each shoe 10 on the surface while the cylinder block 6 rotates.
Each piston 9 is reciprocated in the cylinder 7. When the swash plate 11 is tilted by a tilting mechanism (not shown) or the like, the tilt angle is variably controlled, and the reciprocating stroke of each piston 9 can be freely adjusted within a certain range. It is a configuration that can be done.

Reference numeral 12 denotes a ring-shaped shoe holder for holding each shoe 10 in a sliding state with respect to the swash plate 11, and reference numeral 13 denotes a retainer ball engaged with the male spline 5A of the rotary shaft 5 together with the cylinder block 6. The retainer ball 13 has an inner peripheral side spline-coupled to the male spline 5A of the rotating shaft 5, and an outer peripheral side having a spherical shape.
2 is fitted on the inner peripheral side.

A pressing spring 14 is compressed between the retainer ball 13 and the cylinder block 6, and the pressing spring 14 directs each shoe 10 toward the swash plate 11 via the retainer ball 13 and the shoe presser 12. While being pressed, the cylinder block 6 is pressed toward the valve plate 8.

Are oil grooves provided on the inner peripheral side of each cylinder 7, and each oil groove 15 is disposed at a position corresponding to a seal section L1 in which the piston 9 is always inserted into the cylinder 7. It is formed as an annular groove having a U-shaped cross section surrounding the piston 9. Thereby, when the piston 9 reciprocates in the cylinder 7, the piston 9 is prevented from being caught in the oil groove 15 and the pressure oil in the cylinder 7 is prevented from leaking into the drain oil chamber 4 via the communication passage 16. ing. Further, by providing the oil groove 15 in the seal section L1, oil can be supplied to the opening end 7B side of the cylinder 7 where the frictional force between the cylinder 7 and the piston 9 increases.

Are communication passages formed in the cylinder block 6 and always communicating with the oil groove 15;
6, the inlet 16A is open to the shaft insertion hole 6A, and the outlet 1
6B so that the cylinder block 6 is opened to the outer peripheral surface 6C.
Are radially extended around the axis of the rotating shaft 5 as a whole.

When the cylinder block 6 rotates, the communication passage 16 allows the oil in the drain oil chamber 4 to flow from the inlet 16A and supplies the oil to the oil groove 15 by the centrifugal force generated by the rotation of the cylinder block 6. The oil supplied to the oil groove 15 is discharged from the outlet 16B to the drain oil chamber 4. As described above, the oil is forcibly circulated between the drain oil chamber 4 and the oil groove 15 by using the centrifugal force when the cylinder block 6 rotates, and the new oil is replaced in the oil groove 15. To supply.

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

First, when the rotating shaft 5 is driven to rotate together with the cylinder block 6 by an engine, a motor (not shown) or the like serving as a rotation source, the shoe 10 moves on the swash plate 11 with the rotation of the cylinder block 6. Slide. Thereby, each piston 9 reciprocates in each cylinder 7, and at this time, each cylinder 7 intermittently communicates with each supply / discharge port 8A via each communication port 7A, and each port 7A, 8A The oil liquid sucked into the cylinder 7 is sequentially discharged to the outside as pressure oil.

In the above-described operation, the cylinder block 6 rotates, so that the oil in the drain oil chamber 4 flows into the inflow ports 16A of the communication passages 16 by the centrifugal force at this time. The oil is supplied to the oil groove 15. Thus, the oil supplied to the oil groove 15 lubricates between the cylinder 7 and the piston 9.

In particular, since the oil groove 15 is formed corresponding to the seal section L1 on the side of the opening end 7B of the cylinder 7 having a large frictional force, the oil in the oil groove 15 reciprocates the piston 9 with respect to the cylinder 7. The operation can be performed smoothly.

The oil lubricated in the oil groove 15 is
The liquid is discharged from the outlet 16B to the drain oil chamber 4 by centrifugal force. As a result, the oil is forcibly circulated by the centrifugal force in the order of the drain oil chamber 4, the communication passage 16, and the oil groove 15,
Fresh oil can always be supplied between the cylinder 7 and the piston 9.

Therefore, according to this embodiment, when the swash plate type hydraulic pump is operated, the oil staying in the drain oil chamber 4 of the casing 1 can be supplied to the oil groove 15 through the communication passage 16. This oil allows the cylinder 7 and piston 9
Can be lubricated between. As a result, the frictional resistance between the cylinder 7 and the piston 9 can be reduced, so that the friction loss during operation can be reduced and the operation efficiency (pump efficiency) can be improved.

Further, by lubricating between the cylinder 7 and the piston 9, it is possible to prevent the cylinder 7, the piston 9, and the like from being worn due to seizure or friction, thereby improving reliability and durability. Can be. Particularly, since the oil groove 15 is formed on the opening end 7B side of the cylinder 7 having a large frictional force and this portion is lubricated, the cylinder 7 and the piston 9 can be further slid smoothly.

Further, each communication path 16 is radially arranged,
Since the oil is circulated using the centrifugal force when the cylinder block 6 rotates, the structure can be simplified without using a separate pump or the like, and the oil can be circulated forcibly. By supplying new oil between the cylinder 7 and the piston 9, the lubrication effect can be maintained.

FIG. 3 shows a second embodiment of the present invention. The feature of this embodiment is that the communication passage is formed to be inclined in the circumferential direction. In this embodiment, the same components as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

Are communication paths according to the present embodiment which are used in place of the communication paths 16 according to the first embodiment, and each communication path 21 is a communication path 1 according to the first embodiment.
6, the cylinder block 6 is formed such that the inflow port 21A opens in the shaft insertion hole 6A and the outflow port 21B opens in the outer peripheral surface 6C. However, the communication passage 21 according to the present embodiment is formed with an inclination in the arrow B direction opposite to the rotation direction (the arrow A direction) of the cylinder block 6, and extends substantially along the tangential direction of the shaft insertion hole 6A. This point is different from the communication path 16 according to the first embodiment.

Thus, in this embodiment having the above-described structure, substantially the same operation and effect as those of the first embodiment can be obtained. In particular, in this embodiment, each communication passage 2 is provided.
1 is formed with a constant inclination so as to extend substantially tangentially to the shaft insertion hole 6A of the cylinder block 6, so that the centrifugal force generated when the cylinder block 6 is rotationally driven in the direction of arrow A is transmitted to the communication passage 21. Oil between the cylinder 7 and the piston 9 (the oil groove 1).
5) The oil can be more positively supplied.

Next, FIG. 4 shows a third embodiment of the present invention. The feature of this embodiment is that the oil groove and the communication passage are applied to a diagonal shaft type hydraulic pump.

Reference numeral 31 denotes a cylindrical casing.
1 generally comprises a stepped tubular casing body 32 and a head casing 33 having one end of the casing body 32 closed. The casing 31 has a space between a cylinder block 36 and a valve plate 41, which will be described later. A drain oil chamber 34 in which oil leaking from between the cylinder 37 and the piston 38 or the like stays.

Reference numeral 35 denotes a rotating shaft rotatably provided in the casing main body 32, and 36 denotes a cylinder block which is located in the casing main body 32 and rotates together with the rotating shaft 35. A shaft insertion hole 36A is formed as a shaft insertion hole through which a center shaft 43 described later is inserted. Further, an inlet 49A of a communication passage 49 to be described later is opened in a shaft insertion hole 36A of the cylinder block 36, and an outlet 49B of the communication passage 49 is opened in an outer peripheral surface 36B.

Reference numerals 37, 37,... Denote a plurality of cylinders bored in the cylinder block 36 at equal intervals in the circumferential direction around the rotation shaft 35 and in the axial direction. A piston 38 is slidably inserted.

Are a plurality of pistons slidably inserted into the respective cylinders 37 of the cylinder block 36. Each piston 38 reciprocates in the cylinder 37 while the cylinder block 36 rotates. Is what you do. A connecting rod 39 is provided on the protruding end side of each piston 38, and each piston 38 is swingably supported by a drive disk 40 formed at the tip of the rotating shaft 35 via the connecting rod 39.

Here, each piston 38 is connected to a cylinder 37.
The position that has entered the inside of the
7 is the bottom dead center position, and reciprocates between the top dead center position and the bottom dead center position. Further, even at the bottom dead center position where the piston 38 protrudes most from the cylinder 37, a large part is inserted into the cylinder 37, and the part always inserted into the cylinder 37 becomes the seal section L2 at the bottom dead center position. ing.

The reciprocating stroke of each piston 38 is determined by the cylinder block 36 and the valve plate 4 with respect to the rotating shaft 35.
The tilt angle θ can be adjusted by operating the tilt mechanism 44 described later.

Reference numeral 41 denotes a valve plate. The other end of the valve plate 41 slides on a concavely curved tilting sliding surface 42 formed on the head casing 33, and one end of the valve plate 41 slides on the cylinder block 36. I have. A through hole 41A is formed in the center of the valve plate 41, and a center shaft 43 is inserted into the through hole 41A, and a swing pin 47 is engaged. Further, the valve plate 4
1, each cylinder 3 rotates when the cylinder block 36 rotates.
7, a pair of supply / discharge ports (not shown) intermittently communicating with each other, and a pair of supply / discharge passages (not shown) opened in the tilting sliding surface 42 of the head casing 33 are provided. It is in communication with the port.

Reference numeral 43 denotes a center shaft which supports the cylinder block 36 between the drive disk 40 and the valve plate 41.
It is swingably supported at the center position of zero. On the other hand, the base end side of the center shaft 43 is slidably inserted into the through hole 41A of the valve plate 41.

A tilting mechanism 44 tilts the valve plate 41 along the tilting slide surface 42. The tilting mechanism 44 includes a cylinder chamber 45 formed in the head casing 33 and a cylinder chamber 45 formed in the cylinder chamber 45. The servo piston 46 is roughly constituted by a slidably inserted servo piston 46, and a swing pin 47 is attached to an intermediate portion in the axial direction of the servo piston 46, and the swing pin 47 swings through a through hole 41 </ b> A of the valve plate 41. Movably engaged.

Are oil grooves provided on the inner peripheral side of each cylinder 37. Each oil groove 48 is arranged at a position corresponding to the seal section L2 in which the piston 38 is always inserted into the cylinder 37. It is formed as an annular groove having a U-shaped cross section surrounding the piston 38.

Are communication passages formed in the cylinder block 36 and always communicating with the oil groove 48. In each communication passage 49, an inlet 49A opens in the shaft insertion hole 36A and an outlet 49B has an outer periphery. It is formed in the radial direction of the cylinder block 36 so as to open to the surface 36B. And
The communication passage 49 allows the oil in the drain oil chamber 34 to flow from the inflow port 49A to the oil groove 48 when the cylinder block 36 rotates.
And the oil is discharged from the oil groove 48 to the drain oil chamber 34 via the outlet 49B.

The oblique shaft type hydraulic pump according to the present embodiment has the above-described configuration, and the operation thereof will be described below.

First, when the rotation shaft 35 is driven to rotate by an engine or the like serving as a rotation source, the drive disk 40 of the rotation shaft 35 and each cylinder 37 of the cylinder block 36 are rotated.
The cylinder block 36 rotates together with the rotating shaft 35 because the connecting rod 39 is connected to each of the pistons 38 inserted into the cylinder block 36. As a result, each piston 38 reciprocates in each cylinder 37, and at this time, each cylinder 37 intermittently communicates with the supply / discharge passage via each supply / discharge port, so that the oil liquid sucked into each cylinder 37 is released. The oil is sequentially discharged to the outside as pressure oil.

Further, pressure oil is supplied to the cylinder chamber 45 of the tilting mechanism 44, and the servo piston 46 is moved to rotate the rotary shaft 35.
, The reciprocating stroke (pump capacity) of each piston 38 can be variably adjusted.

Further, during the above-described operation, the cylinder block 36 rotates, and the oil in the drain oil chamber 34 is caused to flow by the centrifugal force at this time.
9A is supplied to the oil groove 48. Thereby, the oil groove 48
Between the cylinder 37 and the piston 38 can be lubricated by the oil supplied to the cylinder 37. The oil lubricated in the oil groove 48 is discharged to the drain oil chamber 34 through the outlet 49B by centrifugal force.

Thus, also in the present embodiment configured as described above, it is possible to obtain substantially the same operation and effects as those of the above-described embodiments.

In the first and second embodiments, the case where eight cylinders 7 are provided in the cylinder block 6 is shown as an example. However, the present invention is not limited to this. It is good also as a structure provided with seven or less or nine or more. In this case, oil grooves and communication passages may be provided in accordance with the number of cylinders 7. This is the same for the third embodiment.

In the first and second embodiments, the swash plate type hydraulic pump is taken as an example of the hydraulic rotary machine, and in the third embodiment, the swash shaft type hydraulic pump is taken as an example. However, the present invention is not limited to this, and may be applied to other hydraulic rotating machines such as a swash plate type hydraulic motor or a swash shaft type hydraulic motor, and may be applied to a radial piston type hydraulic rotating machine. Can be done.

Further, in each embodiment, each communication path 16, 2
Although the description has been given by taking as an example the case where the communication passages 1, 49 are provided so as to penetrate in the radial direction of the cylinder blocks 6, 36, the communication passages 16, 21, 49 are provided with the drain oil chambers 4, 34,
48 may be used as long as it is always possible to communicate with the oil groove, for example, it is only necessary to form a communication passage that allows the outer peripheral surface of the cylinder block to communicate with the oil groove.

[0061]

As described above in detail, according to the first aspect of the present invention, by rotating the cylinder block together with the rotating shaft, the oil in the drain oil chamber flows into the communication passage, and the oil in the drain oil passage is passed through the communication passage. Can be supplied to the groove. As a result, the space between the cylinder and the piston can be lubricated by the oil in the oil groove, so that the frictional resistance between the cylinder and the piston can be reduced, and the friction loss during operation can be reduced. Efficiency (pump efficiency) can be improved.

Further, since the oil groove is provided corresponding to the seal section where the piston is always inserted, it is possible to prevent oil supplied to and discharged from the cylinder from flowing into the drain oil chamber from the communication passage when the piston reciprocates. In addition to this, it is possible to lubricate the open end side of the cylinder, which has a large frictional force, and to prevent seizure and wear due to friction on the cylinder and piston, thereby improving reliability and durability. be able to.

According to the invention of claim 2, the oil in the drain oil chamber can be forcibly supplied to the oil groove from the communication passage opened in the shaft insertion hole by utilizing the centrifugal force generated by the rotation of the cylinder block. Further, the oil supplied to the oil groove can be discharged from the outlet opening on the outer peripheral surface of the cylinder block to the drain oil chamber. Therefore, the oil in the drain oil chamber can be forcibly circulated between the oil groove and the communication passage without using a separate pump or the like. The lubrication effect can be maintained by circulating the oil.

According to the third aspect of the present invention, since the communication path is radially arranged about the axis of the rotating shaft, oil can be smoothly circulated in the communication path by centrifugal force.
The oil in the drain oil chamber can be efficiently supplied to the oil groove.

According to the fourth aspect of the present invention, since the communication passage is formed to be inclined in the circumferential direction, for example, when the communication passage is inclined in a direction opposite to the rotation direction of the cylinder block, the communication passage is formed by rotation of the cylinder block. The centrifugal force can be effectively applied to the oil in the communication passage, and the oil can be more positively supplied between the cylinder and the piston.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a swash plate type hydraulic pump according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing an oil groove and a communication path together with a cylinder block and a cylinder as viewed from the direction of arrows II-II in FIG.

FIG. 3 shows a communication path according to a second embodiment of the present invention.
FIG. 4 is an enlarged cross-sectional view of the cylinder block as viewed from the same position as in FIG.

FIG. 4 is a longitudinal sectional view showing a slant shaft type hydraulic pump according to a third embodiment of the present invention.

[Explanation of symbols]

 1,31 Casing 4,34 Drain oil chamber 5,35 Rotary shaft 6,36 Cylinder block 6A Shaft insertion hole 6C, 36B Outer peripheral surface 7,37 Cylinder 8,41 Valve plate 8A Supply / discharge port 9,38 Piston 15,48 Oil Grooves 16, 21, 49 Communication passages 16A, 21A, 49A Inlet 16B, 21B, 49B Outlet 36A Shaft insertion hole (shaft insertion hole) L1, L2 Seal section

Claims (4)

[Claims] 1. A casing, a rotating shaft rotatably supported by the casing, and a cylinder block provided in the casing so as to rotate integrally with the rotating shaft and having a plurality of cylinders drilled therein. A plurality of pistons that are slidably inserted into the respective cylinders of the cylinder block, reciprocate in the respective cylinders with the rotation of the cylinder block, and are provided between the casing and the cylinder block; In a hydraulic rotary machine comprising a pair of supply / discharge ports intermittently communicating with each cylinder of a cylinder block, a hydraulic rotary machine includes: a seal section in which the piston is always inserted on the inner peripheral side of the cylinder; And an oil groove is provided in the cylinder block, and the cylinder block is provided with a communication passage that constantly communicates the oil groove with a drain oil chamber in the casing. Hydraulic rotary machine, characterized in that. 2. The communication path according to claim 1, wherein the communication path is provided in a radial direction of the cylinder block, an inflow port is opened in a shaft insertion hole of the cylinder block, and an outflow port is opened in an outer peripheral surface of the cylinder block. 2. The hydraulic rotating machine according to 1. 3. The hydraulic rotary machine according to claim 1, wherein the communication path is radially provided around an axis of the rotary shaft. 4. The hydraulic rotary machine according to claim 1, wherein the communication passage is formed to be inclined in a circumferential direction.