JP6640140B2 - Hydraulic rotating machine - Google Patents

Description

  The present invention relates to a hydraulic rotary machine such as an axial piston pump / motor suitable for a hydraulic pump or a hydraulic motor provided in a construction machine such as a hydraulic shovel.

  Generally, a valve plate of a hydraulic rotating machine such as a hydraulic pump or a hydraulic motor communicates with a cylinder port during a period from when the communication between the cylinder port and the discharge port is cut off to when the cylinder port and the discharge port communicate with each other. A pressure release hole is formed. The pressure release hole is connected to the drain, and the backflow of the pressure fluid from the cylinder port to the suction port is prevented by allowing the pressure fluid remaining in the cylinder to escape to the drain. Patent Documents 1 and 2 disclose such a hydraulic rotating machine, for example.

  Patent Document 1 discloses that a cylinder port of each cylinder bore is formed in a pre-expansion section (switching land) of a valve plate that switches from the discharge port to the suction port, and has a bag stopper shape having an opening that can communicate with the cylinder port. One hole (a part of the pressure release hole), and a second hole (the other part of the pressure release hole) that branches off from the middle of the opening and the bottom of the first hole and opens from the valve plate. Wherein the second hole is configured to drain the pressurized oil from the first hole.

  Patent Document 2 discloses that a valve plate having a conduit (a part of a pressure release hole) for releasing a residual pressure in a cylinder is provided in a casing forming a main body, and a knock pin for fixing the valve plate to the casing; In an axial piston pump / motor having a drain communicating with a relief passage (the other part of the pressure release hole) of the conduit, a mounting hole for the knock pin is disposed near the conduit, and the mounting hole and the mounting hole are connected to each other. An axial piston pump / motor is described in which a clearance communicating with the drain is provided in a knock pin portion inserted into the mounting hole so as to communicate with the relief passage of the conduit.

JP 2006-207501 A JP-A-8-210242

  In the conventional hydraulic rotating machine, the pressure fluid remaining in the cylinder is discharged as a high-speed jet from the depressurizing hole, and the jet collides with a casing or the like, and the casing is damaged by erosion (erosion). was there.

  As a method of preventing this, it is conceivable to reduce the flow rate by increasing the opening area of the outlet portion of the depressurizing hole. However, in order to sufficiently reduce the flow rate within the thickness dimension of a general valve plate, the opening is required. It is necessary to increase the area abruptly, and there is a risk that cavitation will occur at the exit of the pressure relief hole.

  Therefore, in the hydraulic piston rotating machine described in Patent Literature 1, the kinetic energy of the jet is consumed as collision energy by causing the jet flowing out of the cylinder port to once collide with the bottom of the first hole. Thereby, the pressurized oil having reduced kinetic energy is discharged to the drain in the casing through the second hole branched from the middle of the first hole, so that damage to the casing due to erosion can be suppressed.

  Further, in the axial piston pump / motor described in Patent Document 2, high-pressure oil in the cylinder is released to the drain through a release passage of the conduit and a gap provided in the knock pin portion. At this time, the flow of the pressure oil is narrowed by the gap provided in the knock pin portion, and the momentum of the jet is weakened. Thereby, the flow of the pressurized oil having a weak momentum is discharged to the drain, so that damage to the casing due to erosion can be suppressed.

  However, in the configuration described in Patent Document 1 or 2 described above, since the pressure release hole is largely bent in the valve plate, the jet of the pressurized liquid having high kinetic energy collides with the inner wall of the pressure release hole. In general, as a material constituting the valve plate, there are a hardened steel material, a high-strength brass, and a copper alloy bonded to a steel base material that has not been hardened. For this reason, depending on the material of the valve plate, erosion may be promoted at the bent portion of the pressure release hole. In addition, since the flow direction and the flow velocity of the jet change rapidly when passing through the largely bent pressure relief hole, cavitation due to turbulence of the jet may occur.

  The present invention has been made in view of the above problems, and an object thereof is to prevent erosion of a valve plate and a casing while preventing occurrence of cavitation due to turbulence of a jet flowing through a pressure release hole formed in a valve plate. An object of the present invention is to provide a hydraulic rotary machine that can suppress the rotation.

In order to achieve the above object, the present invention provides a casing, a rotating shaft rotatably supported by the casing, and disposed in the casing so as to rotate integrally with the rotating shaft. And a plurality of pistons reciprocally inserted into the plurality of cylinders, and a valve plate fixed to the casing and in sliding contact with the cylinder block. And a drain comprising a space between an inner peripheral surface of the casing and an outer peripheral surface of the cylinder block, wherein the valve plate is a suction intermittently communicating with the plurality of cylinders when the cylinder block rotates. Ports and discharge ports, the plurality of ports between the suction port and the discharge port and when the cylinder block rotates. A first switching land disposed on the side where the stone switches from the suction step to the discharge step, and the plurality of pistons are moved from the discharge step to the suction step between the suction port and the discharge port and when the cylinder block rotates. A second switching land disposed on a switching side, wherein a pressure release hole for discharging the hydraulic fluid of the plurality of cylinders is formed in the second switching land, and the second switching land is provided with the casing of the valve plate. In a hydraulic rotary machine in which an oil groove communicating with an outlet portion of the pressure release hole to the drain is formed on the contact surface, the pressure release hole is provided on a sliding contact surface side of the valve plate with the cylinder block. A first cylindrical hole formed, and a conical concave portion formed coaxially with the first cylindrical hole on the downstream side of the first cylindrical hole and having an inner diameter size increasing from upstream to downstream. Cage The hydraulic rotating machine is disposed so as to face the conical concave portion, and between the conical concave portion and a conical convex portion that forms an annular flow path whose flow path cross-sectional area increases from upstream to downstream, It is formed integrally with the conical protrusion, a pin member having a first fitting part which is fitted and fixed to a mounting hole formed at the surface in contact with the valve plate of said casing, said pin member The first fitting portion has an outer diameter larger than a maximum inner diameter when the conical surface shape of the conical recess extends to the bottom surface of the casing .

  According to the present invention configured as described above, the high-speed jet flowing out of the first cylindrical hole of the pressure release hole collides with the pin member arranged so as to face the outlet portion of the pressure release hole. The jet that collides with the pin member passes through an annular flow path formed between the conical concave portion of the pressure release hole and the conical convex portion of the pin member. Here, the angle difference between the flow direction immediately after flowing out of the first cylindrical hole and the flow direction immediately after flowing into the annular flow path is as small as about 1/2 of the apex angle of the conical convex portion, Since the cross-sectional area of the road gradually increases from the upstream to the downstream, the flow velocity and the pressure of the jet flow decrease without disturbing the flow of the jet flow when passing through the annular flow passage. The jet that has passed through the annular flow path and has become low-speed and low-pressure is discharged to the drain in the casing via the oil groove. Thus, the high-speed jet flowing out of the first cylindrical hole of the pressure release hole does not directly collide with the valve plate or the casing, so that erosion of the valve plate and the casing can be suppressed. Further, since the flow velocity and pressure of the jet flow are reduced without disturbing the flow of the jet flow when passing through the annular flow path, it is possible to suppress the occurrence of cavitation due to the turbulence of the jet flow.

  According to the present invention, in a hydraulic rotary machine, cavitation due to turbulence of a jet flow is reduced by reducing the flow velocity and pressure of the pressurized liquid passing through a pressure release hole formed in a valve plate without disturbing the flow. Erosion of the valve plate and the casing can be suppressed while preventing occurrence.

1 is a sectional view of a hydraulic piston pump according to a first embodiment of the present invention. FIG. 2 is a plan view of a valve plate provided in the hydraulic piston pump shown in FIG. 1 as viewed from a surface in sliding contact with a cylinder block. FIG. 2 is a plan view of a valve plate provided in the hydraulic piston pump shown in FIG. 1 as viewed from a contact surface side with a casing. FIG. 4 is a partial cross-sectional view of the hydraulic piston pump viewed from a direction AA in FIG. 3. FIG. 5 is an enlarged view showing the vicinity of a pin member shown in FIG. 4. FIG. 7 is a plan view of a valve plate provided in a hydraulic piston pump according to a second embodiment of the present invention, as viewed from a casing contact surface side. FIG. 7 is a partial cross-sectional view of the hydraulic piston pump viewed from a direction AA in FIG. 6. FIG. 7 is a partial cross-sectional view of the hydraulic piston pump viewed from a direction BB in FIG. 6.

  Hereinafter, a swash plate type axial piston pump (hereinafter, referred to as a "hydraulic piston pump") used in a hydraulic excavator will be described as an example of a hydraulic rotary machine according to an embodiment of the present invention with reference to the drawings. In each of the drawings, the same reference numerals are given to the same members, and the repeated description will be appropriately omitted.

  First Embodiment A first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a sectional view of a hydraulic piston pump according to the present embodiment.

  In FIG. 1, a hydraulic piston pump 1 includes a casing 2, a rotating shaft 3, a cylinder block 8, a piston 10, a shoe 11, a swash plate 5, a cam plate 14, a retainer 12, a bushing 13, And a valve plate 7.

  The casing 2 has a cylindrical shape with both ends closed, and a rotating shaft 3 is rotatably supported at both ends of the casing 2 via bearings 4a and 4b. One end of the rotating shaft 3 protrudes from the casing 2, and a spline (not shown) for connecting to a power unit is formed on an outer peripheral surface thereof.

  A cylinder block 8 is arranged in the casing 2 so as to rotate integrally with the rotating shaft 3. A central hole 8a through which the rotating shaft 3 passes is formed in the cylinder block 8, and a spline (not shown) for connecting to the rotating shaft 3 is formed on the inner peripheral surface thereof. A plurality of cylinders 9 are formed in the cylinder block 8 and are spaced apart in the circumferential direction and extend in the axial direction. A piston 10 is inserted into these cylinders 9 so as to reciprocate. Each cylinder 9 is provided with a cylinder port 15 intermittently communicating with a discharge port and a 17 suction port 18 formed in the valve plate 7 described later when the cylinder block 8 rotates.

  The piston 10 reciprocates in the cylinder 9 as the cylinder block 8 rotates. A shoe 11 is swingably fitted to the tip of each piston 10. The shoe 11 is held by a retainer 12, and the retainer 12 is supported by a bushing 13 fitted to the cylinder block 8. A swash plate 5 having a predetermined inclination angle is fixed to an end of the casing 2 on the shoe 11 side. A cam plate 14 is fitted to the swash plate 5, and the shoe 11 circumferentially slides on the cam plate 14 as the cylinder block 8 rotates.

  A valve plate 7 slidably in contact with an end surface of the cylinder block 8 is fixed to an end of the casing 2 opposite to the swash plate 5. The valve plate 7 contacts the casing 2 and is fixed to the casing 2 by a knock pin (not shown). As shown in FIG. 3, a pair of pin holes 22 into which knock pins (not shown) are fitted are formed on the contact surface of the valve plate 7 with the casing 2. A discharge port 17 and a suction port 18 are formed on the valve plate 7 with a pair of switching lands 19a and 19b interposed therebetween. As described above, the discharge port 17 and the suction port 18 intermittently communicate with the cylinders 9 formed in the cylinder block 8 via the cylinder port 15 as the cylinder block 8 rotates.

  FIG. 2 is a plan view of the valve plate 7 provided in the hydraulic piston pump 1 shown in FIG. 1 as viewed from the sliding contact surface side with the cylinder block 8.

  In FIG. 2, an arrow X indicates the rotation direction of the cylinder block 8. Of the pair of switching lands 19a and 19b of the valve plate 7, the switching land 19a on the side where the piston 10 switches from the suction process to the discharge process when the cylinder block 8 rotates is connected to the rotation direction of the cylinder block 8 from the discharge port 17. A relief groove 20 extending in a direction opposite to that of FIG. The relief groove 20 prevents the inside of the cylinder 9 from becoming negative pressure by opening to the cylinder port 15 before the discharge port 17. A pressure release hole 21 is formed in the switching land 19b on the side where the piston 10 switches from the discharge process to the suction process when the cylinder block 8 rotates. The pressure release hole 21 prevents the backflow of the pressure oil from the cylinder port 15 to the suction port 18 by allowing the pressure oil (pressure liquid) remaining in the cylinder 9 to escape to the drain 16 provided in the casing 2. .

  FIG. 3 is a plan view of the valve plate 7 provided in the hydraulic piston pump 1 shown in FIG. 1 as viewed from a contact surface side with the casing 2.

  In FIG. 3, an oil groove 23 that connects an outlet portion of the pressure release hole 21 to the drain 16 is formed on a contact surface of the valve plate 7 with the casing 2. The width of the oil groove 23 is larger than the maximum inner diameter of the conical recess 21 b of the pressure release hole 21 described later, and gradually increases toward the outer peripheral end of the valve plate 7. As a result, the cross-sectional area of the flow path gradually increases from the outlet portion of the pressure release hole 21 to the drain 16, so that the flow velocity of the jet flowing out to the drain 16 can be reduced while suppressing the generation of bubbles. The oil groove 23 does not necessarily need to be formed in the valve plate 7, but may be formed on the surface of the casing 2 in contact with the valve plate 7.

  FIG. 4 is a partial cross-sectional view of the hydraulic piston pump 1 viewed from the AA direction in FIG.

  In FIG. 4, a pressure release hole 21 has a cylindrical hole (first cylindrical hole) 21a formed on a sliding surface of the valve plate 7 in contact with the cylinder block 8, and the first hole 21a is provided downstream of the cylindrical hole 21a. A conical recess 21b is formed coaxially with one cylindrical hole, and has an inner diameter that increases from upstream to downstream.

  The pin member 6 is disposed at the outlet of the pressure release hole 21. The pin member 6 includes a conical convex portion 6a arranged so as to face the conical concave portion 21b of the pressure release hole 21, and a cylindrical fitting portion (first fitting) formed integrally and coaxially with the conical convex portion 6a. 6b). The fitting portion 6b is fitted and fixed in a cylindrical mounting hole 2a formed on the surface of the casing 2 that is in contact with the valve plate 7. Here, since the high-speed jet flowing out of the cylindrical hole portion 21a directly collides with the pin member 6, it is desirable that the pin member 6 be subjected to a hardening treatment for suppressing erosion. Since the pin member 6 is a small component as compared with the valve plate 7 and the casing 2, the hardening process can be performed at low cost.

  FIG. 5 is an enlarged view showing the vicinity of the pin member 6 shown in FIG.

  In FIG. 5, an annular flow path 24 is formed between the conical concave portion 21 b of the pressure release hole 21 and the conical convex portion 6 a of the pin member 6. Here, the vertex angle θ1 of the conical convex portion 6a is set such that the cross-sectional area of the annular flow path 24 formed between the conical concave portion 21b and the conical convex portion 6a increases in the flow direction. I have. That is, the vertex angle θ1 of the conical convex portion 6a is set smaller than the vertex angle (> θ2) of the conical convex portion 6a1 when the cross-sectional area of the annular flow path 24 becomes constant from upstream to downstream. I have.

  The height T1 of the conical projection 6a is set smaller than the height T2 from the bottom surface of the casing 2 to the downstream opening of the cylindrical hole 21a. This is to prevent the flow path on the outlet side of the cylindrical hole portion 21a from being narrowed by the top of the conical convex portion 6a.

  The outer diameter φ1 of the conical convex portion 6a is set to be larger than the inner diameter φ0 of the cylindrical hole 21a. That is, the apex angle θ1 of the conical convex portion 6a is set to be larger than the apex angle of the conical convex portion 6a2 when the outer diameter is the same as the inner diameter φ0 of the cylindrical hole 21a. As a result, all of the jet flow flowing out of the cylindrical hole 21a collides with the inclined side surface of the conical convex portion 6a, and the surface pressure on the pin member 6 decreases, so that erosion of the pin member 6 can be suppressed.

  The outer diameter dimension φ1 of the fitting portion 6b is set to be larger than the maximum inner diameter dimension φ2 when the conical surface shape of the conical recess 21b is extended to the bottom surface of the casing 2. Thus, the jet flowing out along the conical concave portion 21b of the pressure release hole 21 and the conical surface shape of the conical convex portion 6a of the pin member 6 does not directly collide with the casing 2, so that erosion of the casing 2 can be suppressed. In the example shown in FIG. 5, the conical convex portion 6a is arranged coaxially with the cylindrical hole portion 21a. However, the present invention is not limited to this, and the apex of the conical convex portion 6a may be the inner periphery of the cylindrical hole portion 21a. As long as the surface shape is within the inner diameter dimension φ0 when the surface shape is extended to the downstream side, it is not necessary to arrange the coaxial shape with the cylindrical hole 21a.

  In the hydraulic piston pump 1 configured as described above, the pressure formed on the switching land 19b of the valve plate 7 is between the time when the communication with the discharge port 17 is cut off and the time when the communication with the suction port 18 is established. It communicates with the hole 21. As a result, the pressure oil remaining in the cylinder 9 is discharged to the drain 16 through the cylindrical hole 21a, the annular flow path 24, and the oil groove 23, so that the backflow of the pressure oil to the suction port 18 is prevented. it can.

  According to the present embodiment configured as described above, the high-speed jet flowing out of the cylindrical hole portion 21a of the pressure release hole 21 receives the pin member 6 disposed so as to face the downstream opening of the cylindrical hole portion 21a. Collide with The jet colliding with the pin member 6 passes through an annular flow path 24 formed between the conical concave portion 21b of the pressure release hole 21 and the conical convex portion 6a of the pin member 6. Here, the angle difference between the flow direction immediately after flowing out of the cylindrical hole portion 21a and the flow direction immediately after flowing into the annular flow passage 24 is about の of the apex angle θ1 (shown in FIG. 5) of the conical convex portion 6a. And the cross-sectional area of the annular flow path 24 gradually increases from the upstream to the downstream, so that the flow velocity and the pressure of the jet flow are reduced without disturbing the flow of the jet flow when passing through the annular flow path 24. I do. The jet that has passed through the annular flow path 24 and has become low-speed and low-pressure is discharged to the drain 16 in the casing 2 through the oil groove 23. Thus, the high-speed jet flowing out of the cylindrical hole portion 21a of the pressure release hole 21 does not directly collide with the valve plate 7 or the casing 2, so that erosion of the valve plate 7 and the casing 2 can be suppressed. Further, the flow rate and the pressure of the jet flow are reduced without disturbing the flow of the jet flow when passing through the annular flow passage 24, so that the occurrence of cavitation due to the turbulence of the jet flow can be suppressed.

  Second Embodiment A second embodiment of the present invention will be described with reference to FIGS.

  FIG. 6 is a plan view of a valve plate provided in the hydraulic piston pump according to the present embodiment as viewed from the casing contact surface side.

  6, the oil groove 23 according to the present embodiment has a width smaller than the inner diameter of the cylindrical hole 21c of the pressure release hole 21 described later, and intersects the cylindrical hole 21c in the radial direction of the valve plate 7. And has an outer circumferential groove 23a and an inner circumferential groove 23b.

  FIG. 7 is a partial cross-sectional view of the hydraulic piston pump as viewed from the AA direction in FIG. 6, and FIG. 8 is a partial cross-sectional view of the hydraulic piston pump as viewed from the BB direction in FIG.

  In FIG. 7 or FIG. 8, the pressure relief hole 21 according to the present embodiment is formed coaxially with the conical recess 21 b downstream of the conical recess 21 b and has the same inner diameter as the maximum inner diameter of the conical recess 21 b. A portion (second cylindrical hole portion) 21c is further provided. As shown in FIG. 7, the outer circumferential groove 23 a and the inner circumferential groove 23 b have the same depth dimension as the cylindrical hole 21 c near the pressure release hole 21, and the outlet portion of the annular flow path 24. Is connected to Thus, the pressure oil that has passed through the pressure release hole 21 can be discharged toward the outer peripheral side and the inner peripheral side of the valve plate 7.

  The pin member 6 according to the present embodiment is formed coaxially with the conical convex portion 6a between the conical convex portion 6a and the fitting portion (first fitting portion) 6b. It further has a fitting portion (second fitting portion) 6c that is fitted and fixed. As shown in FIG. 8, in the pin member 6, the fitting portion 6 b is fitted and fixed in the mounting hole 2 a on the bottom surface of the casing 2, and the fitting portion 6 c is fitted in the cylindrical hole portion 21 c of the pressure release hole 21. As a result, it functions as a knock pin for fixing the valve plate 7 to the casing 2.

  In the present embodiment configured as described above, the same effects as in the first embodiment can be obtained.

  Furthermore, since the pin member 6 according to the present embodiment has a function as a knock pin, the number of separately provided knock pins can be reduced, so that the number of components and the number of processing steps of the hydraulic piston pump can be reduced.

  As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, in the above-described embodiment, the present invention is applied to a hydraulic pump. However, the present invention is not limited to this, and can be applied to a hydraulic rotating machine such as a hydraulic piston motor. Further, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described above. It is also possible to add a part of the configuration of another embodiment to the configuration of a certain embodiment, delete a part of the configuration of a certain embodiment, or replace it with a part of another embodiment. It is possible.

  DESCRIPTION OF SYMBOLS 1 ... Hydraulic piston pump, 2 ... Casing, 2a ... Mounting hole, 3 ... Rotating shaft, 4a, 4b ... Bearing, 5 ... Swash plate, 6 ... Pin member, 6a ... Conical convex part, 6b ... Fitting part (1st Fitting portion), 6c Fitting portion (second fitting portion), 7 ... Valve plate, 8 ... Cylinder block, 8a ... Central hole, 9 ... Cylinder, 10 ... Piston, 11 ... Shoe, 12 ... Retainer, 13 ... Bushing, 14 ... Cam plate, 15 ... Cylinder port, 16 ... Drain, 17 ... Discharge port, 18 ... Suction port, 19a, 19b ... Switching land, 20 ... Escape groove, 21 ... Pressure release hole, 21a ... Cylinder hole (First cylindrical hole), 21b: conical recess, 21c: cylindrical hole (second cylindrical hole), 22: pin hole, 23: oil groove, 24: annular flow path.

Claims (2)

A casing,
A rotating shaft rotatably supported by the casing,
A cylinder block in which a plurality of cylinders that are arranged in the casing so as to rotate integrally with the rotation shaft and that are located in the circumferential direction and that extend in the axial direction are formed,
A plurality of pistons reciprocally inserted into the plurality of cylinders,
A valve plate fixed to the casing and on which the cylinder block slides;
Drain comprising a space between the inner peripheral surface of the casing and the outer peripheral surface of the cylinder block,
The valve plate includes a suction port and a discharge port that intermittently communicate with the plurality of cylinders when the cylinder block rotates, and the plurality of the plurality of cylinder plates between the suction port and the discharge port and when the cylinder block rotates. A first switching land disposed on a side where the piston switches from the suction step to the discharge step, and the plurality of pistons are moved from the discharge step to the suction step between the suction port and the discharge port and when the cylinder block rotates. A second switching land disposed on the switching side,
A pressure relief hole for discharging the pressure fluid of the plurality of cylinders is formed in the second switching land,
In a hydraulic rotating machine in which an oil groove communicating an outlet portion of the pressure release hole with the drain is formed on a contact surface of the valve plate with the casing,
The pressure relief hole is formed on a side of the valve plate that is in sliding contact with the cylinder block, and a first cylindrical hole is formed coaxially with the first cylindrical hole on a downstream side of the first cylindrical hole. And a conical recess whose inner diameter increases from upstream to downstream,
The hydraulic rotating machine is disposed so as to face the conical concave portion, and between the conical concave portion and a conical convex portion that forms an annular flow path whose flow path cross-sectional area increases from upstream to downstream, A pin member formed integrally with the conical convex portion and having a first fitting portion fitted and fixed in a mounting hole formed in a contact surface of the casing with the valve plate ;
The hydraulic rotating machine according to claim 1, wherein the first fitting portion of the pin member has an outer diameter larger than a maximum inner diameter when the conical surface shape of the conical recess extends to a bottom surface of the casing . The hydraulic rotary machine according to claim 1 ,
The depressurization hole is formed coaxially with the conical recess on the downstream side of the conical recess, and further includes a second cylindrical hole having the same inner diameter as the maximum inner diameter of the conical recess,
The pin member is formed coaxially with the conical convex portion between the conical convex portion and the first fitting portion, and includes a second fitting portion fitted and fixed to the second cylindrical hole portion. Have more,
In the pin member, the first fitting portion is fitted and fixed in a mounting hole of the casing, and the second fitting portion is fitted and fixed in a second cylindrical hole portion of the pressure release hole. Thus, the hydraulic rotary machine functions as a knock pin for fixing the valve plate to the casing.

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