JP6307015B2 - Axial piston type hydraulic rotating machine - Google Patents

Description

  The present invention relates to an axial piston type hydraulic rotating machine used for, for example, a work machine, and more particularly to an axial piston type hydraulic rotating machine with improved lubricity of a hydrostatic bearing between its valve plate and a cylinder block.

  As an axial piston type hydraulic rotating machine which is a kind of motor or pump using hydraulic pressure, for example, the one described in Patent Document 1 is known. When this axial piston type hydraulic rotating machine is used as a pump, the shoe pad at the tip of the piston built in the cylinder in the cylinder block presses against the swash plate as the cylinder block rotates in conjunction with the shaft. As a result, the piston built in the cylinder reciprocates to suck and discharge the hydraulic fluid. In the hydraulic rotating machine described in Patent Document 1, a rotating cylinder block is slidably brought into contact with a valve plate (valve plate) or a floating plate, and a liquid film is generated on a sliding surface between the two. Let it lubricate.

  In the axial piston type hydraulic rotary machine described in Patent Document 1, a liquid reservoir recess is provided on the seal surface of the valve plate so as to communicate with a case drain, a suction port or a discharge port provided on the valve plate, and the liquid reservoir recess In this case, the hydraulic fluid is accumulated in the liquid so that the liquid film is prevented from being cut and seizure or galling due to the liquid film is cut.

Japanese Utility Model Publication No. 58-12682

  However, as in the axial piston type hydraulic rotary machine of Patent Document 1, in the configuration in which the liquid reservoir recess is provided on the seal surface of the valve plate so as to communicate with a part of the case drain, the suction port or the discharge port. The lubricity between the suction port and the discharge port, and hence the lubricity between the cylinder block and the valve plate cannot be improved so much. In addition, when the liquid reservoir recess is provided so as to communicate with the case drain, the liquid film pressure on the sealing surface is reduced to reduce the area for generating the liquid film reaction force, and the lubricity is lowered accordingly.

  An object of the present invention is to provide an axial piston type hydraulic rotating machine with improved lubricity between the sealing surfaces of a cylinder block and a valve plate.

The axial piston type hydraulic rotating machine of the present invention is
A valve plate fixed in the casing, and a cylinder block that is rotatably accommodated in the casing and is in sliding contact with the valve plate via a seal surface;
The valve plate has an arcuate suction port and a discharge port opened in a sealing surface;
The cylinder block has a plurality of cylinder ports communicating with each of a plurality of cylinders inside which is arranged circumferentially are pistons respectively housed Rutotomoni, One only opening the seal surface on each cylinder,
In the axial piston type fluid pressure rotating static pressure bearings Ru is configured between the sealing surface and the sealing surface of the cylinder block of the valve plate,
The sealing surface of the valve plate is formed in the curved shape of a convex sphere,
The sealing surface of the cylinder block is formed in a curved surface of a concave sphere so as to overlap the sealing surface of the valve plate ,
A shallow groove connecting the suction port and the discharge port is provided in a circumferential direction on the seal surface of the valve plate,
Since the radius of curvature of a part of the seal surface of the valve plate is formed larger than the radius of curvature of the seal surface of the valve plate, the shallow groove is formed in the shallow direction in the radial direction of the seal surface of the valve plate. It is characterized in that it is formed so as to be deep at the center of the groove and become shallower toward the outside and inside .

According to the present invention , since the shallow groove connected between the ports is provided on the sealing surface of the valve plate, the working fluid enters the shallow groove. The working fluid in the shallow groove improves the lubricity between the valve plate and the seal surface of the cylinder block.

Further , since the shallow groove is formed so as to be deep in the central portion in the radial direction of the seal surface of the valve plate and becomes shallower toward the outer side and the inner side of the seal surface, the shallow portion corresponds to the seal surface of the valve plate and the cylinder block. When the hydraulic oil flows into the shallow groove, it becomes difficult to make a vortex of the hydraulic oil. For this reason, it is possible to prevent the lubricity from being impaired by the vortex of the hydraulic oil or reducing the efficiency of the hydraulic rotating machine.

Further , a surface having a radius of curvature larger than the radius of curvature of the seal surface of the valve plate is formed as a shallow groove, and this shallow groove is formed relatively easily by a grinding apparatus having a grinding surface having a radius of curvature larger than that of the seal surface, for example. can do.

It is sectional drawing which shows an example of the axial piston type hydraulic rotating machine to which this invention is applied, and shows the case where the sealing surface of a val plate makes a spherical surface. It is a figure explaining the flow of the liquid production oil of the axial piston type hydraulic rotary machine of FIG. In the hydraulic rotating machine of this example, it is an end view showing a seal surface side of a valve plate not provided with a shallow groove. In the hydraulic rotating machine of this example, it is an end elevation showing the seal surface side of the valve plate which is one embodiment of the present invention. (A) is AA sectional drawing of FIG. 3, (B) is BB sectional drawing of FIG. (A) is CC sectional drawing of FIG. 4, (B) is DD sectional drawing of FIG. In the valve plate of the present embodiment, (A) is a view showing that the working fluid flows into the shallow groove, and (B) is an enlarged view of the shallow groove of (A). It is an end view which shows the other example of arrangement | positioning of the shallow groove | channel on the seal surface side of the valve plate of this invention, and is the example which provided the shallow groove near the inner side of the seal surface. It is an end view which shows the other example of arrangement | positioning of the shallow groove | channel on the seal surface side of the valve plate of this invention, and is an example which provided the shallow groove near the outer side of the seal surface. It is an end view which shows the other example of arrangement | positioning of the shallow groove | channel on the seal surface side of the valve plate of this invention, and is an example which provided the thin shallow groove | channel. It is an end elevation which shows the other example of arrangement | positioning of the shallow groove | channel on the seal surface side of the valve plate of this invention, and is the example which provided two shallow grooves.

  FIG. 1 is a cross-sectional view showing an example of an axial piston type hydraulic rotating machine to which the present invention is applied, and the following description will be made on the case where the hydraulic fluid is oil (hydraulic oil). This axial piston type hydraulic rotating machine 1 is used as an axial piston pump, and a casing 2 is constituted by a cylindrical casing body 2a and a rear casing 2b. Inside the casing 2, a valve plate 4, a cylinder The block 9, the piston 10 in the cylinder block 9, the shoe pad 15, the swash plate 3, and the shaft 5 are accommodated.

  As shown in FIGS. 3 and 4, the valve plate 4 has a circular shape, is fixed to the inner surface of the rear casing 2 b, and includes an arcuate intake port 4 a and a discharge port 4 b as hydraulic oil supply / discharge ports. The suction port 4a and the discharge port 4b communicate with a suction flow path 2d and a discharge flow path 2e provided in the rear casing 2b, respectively. As shown in FIG. 2, the valve plate 4 has a spherical seal surface 4c that makes the seal surface 9c of the cylinder block 9 slide.

  The cylinder block 9 has a cylindrical shape, a plurality of cylinders 9b are arranged at equal intervals in the circumferential direction, and the piston 10 is accommodated in the cylinder 9b so as to be able to reciprocate. Each cylinder 9b communicates with a cylinder port 9a opened in the seal surface 9c. A shoe pad 15 is rotatably coupled to the tip of the piston 10 by fitting a mutual coupling portion with a spherical surface. Each shoe pad 15 is mounted in a support hole of a disc-like retainer 16. A sliding contact portion 14 is fixed to the shoe pad 15, and the sliding contact portion 14 is pressed against the swash plate 3. The swash plate 3 may be attached to the shaft 5 at a fixed inclination angle or may be attached so that the inclination angle can be changed.

  Reference numerals 6 and 7 denote bearings provided on the rear casing 2b and the casing body 2a, respectively, and the shaft 5 is rotatably supported by these bearings 6 and 7 and attached thereto. A portion of the shaft 5 that protrudes from the casing 2 has spline teeth 5 a that are coupled to an output shaft of an engine or a motor (not shown). Further, the portion of the shaft 5 located in the casing 2 has male spline teeth 5b. The spline fitting structure of the male spline teeth 5b and the female spline teeth 9d provided in the center hole of the cylinder block 9 allows the shaft to 5 and the cylinder block 9 are coupled together.

  In the hydraulic rotating machine 1, the shaft 5 is rotated by an engine or a motor, whereby the cylinder block 9 is rotated. As the cylinder block 9 rotates, the piston 10, the retainer 16, and the shoe pad 15 also rotate. At this time, in the drawing of FIG. 1, the lower piston 10 moves upward and the shoe pad 15 slides on the surface of the swash plate 3, and at the same time, the piston 10 is moved by the swash plate 3 in the cylinder block 9. Press to move to the left. By the movement of the piston 10 to the left side, the hydraulic oil in the cylinder 9b is discharged through the cylinder port 9a, the discharge port 4b of the valve plate 4 and the discharge flow path 2e. Similarly, when the piston 10 on the upper side moves downward in the drawing of FIG. 1 as the cylinder block 9 rotates, the piston 10 moves to the right swash plate 3 side. Then, hydraulic oil is sucked into the cylinder 9b of the cylinder block 9 through the suction flow path 2d, the suction port 4a of the valve plate 4, and the cylinder port 9a.

  Thus, the cylinder block 9 rotates in the casing 2 and rotates in a contact state with the valve plate 4 fixed to the rear casing 2b. At this time, the seal surface 4c of the valve plate 4 has a convex spherical shape, and the seal surface 9c of the cylinder block 9 has a concave spherical shape so as to be in sliding contact with the seal surface 4c. 4c and the seal surface 9c slide through an oil film of hydraulic oil described later.

  A hydrostatic bearing structure for generating an oil film when the cylinder block 9 rotates will be described with reference to FIG. When the hydraulic oil in the cylinder block 9 is supplied and discharged as indicated by arrows M and L, high pressure is applied to the cylinder 9b. As the cylinder block 9 and the valve plate 4 perform relative motion, a minute gap is formed, and there is a pressure difference between the pressure in the case drain 2c and the pressure in the cylinder 9b. The hydraulic oil from the block 9 flows out to the case drain 2c. Further, since the hydraulic oil flowing through the minute gap receives pressure from the cylinder 9b, an oil film reaction force that pushes the cylinder block 9 back is generated. On the other hand, when the shoe pad 15 pushes the swash plate 3 as shown by the arrow P, the piston 10 moves to the cylinder 9b side and hydraulic pressure is generated in the cylinder 9b. Therefore, the cylinder block 9 tries to move to the valve plate 4 side. The power to be generated. The hydrostatic bearing structure is formed by the balance between the force acting on the cylinder block 9 and the above-described oil film reaction force.

  In this hydrostatic bearing, if the oil film reaction force is too larger than the force acting on the cylinder block 9, the amount of hydraulic oil that leaks to the case drain 2c increases, and the efficiency of the pump becomes poor. On the contrary, if the oil film reaction force is too weak than the force acting on the cylinder block 9, the oil film breaks, and there is a possibility that seizure or galling will occur between the cylinder block 9 and the valve plate at the portion where the oil film breaks. . In general, as in the latter case, the oil film reaction force is often set slightly smaller than the force acting on the cylinder block 9.

  Next, the shallow groove provided in the valve plate 4 will be described. As described above, the valve plate 4 has a case where the seal surface 4c is spherical and a case where the seal surface 4c is planar. First, the case where the seal surface 4c is spherical will be described.

  FIG. 3 is an end view showing the valve plate when the shallow groove 20 is not provided, and FIG. 4 is an end view showing an embodiment of the valve plate provided with the shallow groove 20 (the shallow groove forming portion is indicated by hatching). FIG. As shown in FIG. 3 and FIG. 4, the valve plate 4 has a circular seal surface 4c from the cylinder block 9 side, and is open to the seal surface 4c to form an arc-shaped elongated hole along the circumferential direction. A suction port 4a and a discharge port 4b are provided. As shown in FIG. 4, the shallow groove 20 is provided between the suction port 4a and the discharge port 4b so as to connect them. In the present embodiment, the shallow groove 20 is provided not only between the suction port 4a and the discharge port 4b but also inside and outside the suction port 4a and the discharge port 4b in the radial direction of the valve plate 4. Shallow grooves 20 are provided except for the outer peripheral side and the inner peripheral side of the surface 4c.

  5A is a cross-sectional view taken along the line AA in FIG. 3, and FIG. 5B is a cross-sectional view taken along the line BB in FIG. The sealing surface 4c of the valve plate 4 has a spherical shape, and in these sectional views, the sealing surface 4c is formed along the arc L1. In these sectional views, the shape of the seal surface 4c and the arc L1 is exaggerated for the sake of understanding.

  On the other hand, the cross-sectional structure of the valve plate 4 of one embodiment of the present invention is shown in FIGS. 6 (A) and 6 (B). FIGS. 6A and 6B are a CC sectional view and a DD sectional view, respectively, in FIG. As shown in FIGS. 6A and 6B, the seal surface 4c of the valve plate 4 is larger than the arc L1 of the seal surface 4c from the state where the shallow groove of FIGS. 5A and 5B is not provided. The shallow groove 20 is formed by cutting the seal surface 4c along the arc L2 having a large curvature radius.

  FIG. 7A is a diagram showing that the hydraulic oil 30 flows into the shallow groove 20. FIG. 7B is an enlarged view of FIG. The cylinder block 9 facing the valve plate 4 is indicated by an imaginary line. The seal surface 9c of the cylinder block 9 forms a spherical surface having substantially the same radius of curvature so as to be in sliding contact with the seal surface 4c when there is no shallow groove 20 indicated by the arc L2, and faces the seal surface 4c. Thus, since the shallow groove 20 is provided and the portion that is recessed from the seal surface 4c by the amount corresponding to the arc L2 is provided, the hydraulic oil 30 flows into the shallow groove 20.

  The shallow groove 20 is deep in the central portion of the shallow groove 20 in the radial direction of the valve plate 4 in the cross-sectional views of FIGS. 6 (A), 6 (B), and 7, and on the outer side and the inner side of the seal surface 4c. It is formed to become shallower as it goes. For this reason, the hydraulic oil 30 flowing into the shallow groove 20 is also thicker at the center and becomes thinner toward the outside and inside.

  As described above, since the shallow groove 20 is provided, the hydraulic oil 30 flows between the seal surface 4c of the valve plate 4 and the seal surface 9c of the cylinder block 9, so that the hydraulic oil 30 Lubricity of the cylinder block 9 is increased.

  Further, when the hydraulic rotary machine 1 operates as a pump on the seal surface 4c, the oil pressure of the suction port 4a becomes relatively low. However, when the shallow groove 20 is provided in a circumferential shape as shown in FIG. 4, it is possible to prevent such oil film breakage.

  Further, the shallow groove 20 is formed in the seal surface 4c of the valve plate 4 so that the shallow groove 20 is deep at the center in the radial direction of the valve plate 4 and becomes shallower toward the outside and inside of the seal surface 4c. It becomes narrow between the surface 4c and the seal surface 9c, and it becomes difficult for the hydraulic oil to vortex when the hydraulic oil flows into the shallow groove 20. For this reason, it is possible to prevent the lubricity from being impaired by the vortex of the hydraulic oil or to reduce the efficiency of the hydraulic rotating machine 1.

  Further, since the surface having a radius of curvature larger than the radius of curvature of the seal surface 4c of the valve plate 4 is formed as the shallow groove 20, the shallow groove 20 is formed by a grinding apparatus having a grinding surface having a radius of curvature larger than that of the seal surface 4c, for example. Since the shallow groove 20 may be formed by performing additional processing, it can be formed relatively easily.

  Further, the surface of the arc L2 having a radius of curvature larger than the radius of curvature of the arc L1 of the seal surface 4c of the valve plate 4 is formed as a shallow groove 20, and the shallow groove 20 is a ground surface having a radius of curvature larger than the seal surface, for example. It can be formed relatively easily by a grinding apparatus having

In the end view of FIG. 4, the shallow groove 20 is configured to connect the suction port 4a and the discharge port 4b. However, by setting the shallow groove 20 shallow, these ports 4a and 4b can be connected to the shallow groove. Since the port restriction (choke) is formed between the two, the efficiency of the hydraulic rotating machine 1 can be prevented from being reduced due to the connection between the suction port 4a and the discharge port 4b. On the other hand, if the lubricity of the valve plate 4 and the cylinder block 9 is improved, the efficiency (output / input) of the hydraulic rotating machine 1 is increased. For this reason, the depth of the shallow groove is determined by considering the balance between the point that the lubricity increases when the shallow groove is deepened and the above-mentioned degree of choke increases when the shallow groove is shallow. The efficiency of the hydraulic rotating machine 1 can be increased by selecting. By setting the depth D of the shallowest groove 20 to be equal to or less than the value of D obtained by the equation (1), a good value can be obtained as the efficiency of the hydraulic rotating machine 1.
D (mm) = port PCD (mm) × circumferential ratio / 10000 (1)
Here, the port PCD is a diameter Q of a circle E passing through the centers of the ports 4a and 4b shown in FIG.

  8 to 11 show other arrangement examples of the shallow grooves. The shallow groove 20A in FIG. 8 is an example provided near the inside of the ports 4a and 4b. The shallow groove 20B in FIG. 9 is an example provided near the outside of the ports 4a and 4b. The shallow groove 20C in FIG. 10 is an example in which the shallow groove 20C is formed thin except for the inner peripheral side and the outer peripheral side of the ports 4a and 4b. In the example of FIG. 11, two shallow grooves 20D and 20E are provided, and three or more shallow grooves may be further provided. In the embodiment shown in FIGS. 8 to 11, since the radial width of the shallow grooves 20A to 20E is narrower than the width of the shallow groove 20, the radius of curvature of the arc L2 for forming the shallow grooves 20A to 20E is reduced. May be larger than when the shallow groove 20 is formed, or may be formed in a concave groove shape.

In the above embodiment, the axial piston type hydraulic rotating machine has been described as operating as a hydraulic pump. However, when operating as a hydraulic motor, the suction port is 4b and the discharge port is 4a.

  In the above-described embodiment, the swash plate type axial piston hydraulic rotary machine has been described. However, the present invention is also applicable to an oblique axis type axial piston hydraulic rotary machine. In addition, when carrying out the present invention, the specific shape and structure of each part can be appropriately changed and added without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Axial piston type hydraulic rotary machine 2 Casing 2a Casing main body 2b Rear casing 2c Case drain 2d, 2e Flow path 3 Swash plate 4 Valve plate 4a Intake port 4b Discharge port 4c Seal surface 5 Shaft 9 Cylinder block 9a Cylinder port 9b Cylinder 9c Seal surface 10 Piston 14 Sliding contact portion 15 Shoe pad 16 Retainer 20, 20A to 20E Shallow groove 30 Hydraulic oil

Claims (1)

A valve plate fixed in the casing, and a cylinder block that is rotatably accommodated in the casing and is in sliding contact with the valve plate via a seal surface;
The valve plate has an arcuate suction port and a discharge port opened in a sealing surface;
The cylinder block has a plurality of cylinder ports communicating with each of a plurality of cylinders inside which is arranged circumferentially are pistons respectively housed Rutotomoni, One only opening the seal surface on each cylinder,
In the axial piston type fluid pressure rotating static pressure bearings Ru is configured between the sealing surface and the sealing surface of the cylinder block of the valve plate,
The sealing surface of the valve plate is formed in the curved shape of a convex sphere,
The sealing surface of the cylinder block is formed in a curved surface of a concave sphere so as to overlap the sealing surface of the valve plate ,
A shallow groove connecting the suction port and the discharge port is provided in a circumferential direction on the seal surface of the valve plate,
Since the radius of curvature of a part of the seal surface of the valve plate is formed larger than the radius of curvature of the seal surface of the valve plate, the shallow groove is formed in the shallow direction in the radial direction of the seal surface of the valve plate. An axial piston type hydraulic rotating machine characterized in that it is deep at the center of the groove and becomes shallower toward the outside and inside .

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