JP6916938B2 - Hydraulic piston pump - Google Patents

Description

Embodiments of the present invention relate to hydraulic piston pumps.

For example, as a hydraulic piston pump used in construction machinery and the like, there is a swash plate type hydraulic piston pump. The swash plate type hydraulic piston pump includes a bottomed tubular housing and a housing cover that closes an opening of the housing. A swash plate, a piston, a cylinder block, and the like are provided in the housing. The cylinder block is rotatably provided in the housing, and a plurality of cylinder holes (cylinder chambers) are formed along the circumferential direction.

Each cylinder hole is formed through along the axial direction, and the piston is housed in the cylinder hole. A shoe slidably contacting the swash plate is oscillatingly connected to the end of the piston. Then, when the cylinder block and the piston rotate together, the piston repeats sliding movement (piston movement) in the cylinder hole. At this time, due to the change in the space volume in the cylinder hole, the hydraulic oil is sucked into the cylinder hole or the hydraulic oil is discharged from the cylinder hole.

Here, a valve plate formed in a substantially annular shape is provided between the end of the cylinder block opposite to the swash plate and the housing cover. The valve plate is provided with a substantially crescent-shaped (substantially cocoon-shaped) discharge port and a suction port at positions corresponding to the cylinder holes. Hydraulic oil is sucked into the cylinder hole through these discharge ports and suction ports, and hydraulic oil (pressure oil) is discharged from the cylinder hole.

By the way, in order to increase the discharge amount of the hydraulic piston pump, it is necessary to improve the self-priming performance of the hydraulic oil. When improving the self-priming performance of the hydraulic oil, it is conceivable to form a large suction port to facilitate suction of the hydraulic oil. However, if the pressure oil intake / exhaust port is simply increased, the rigidity of the valve plate is reduced. Therefore, there is a possibility that the hydraulic piston pump becomes large in order to secure the rigidity of the valve plate.
Further, if the suction port is simply enlarged, the balance of the volume ratio between the cylinder hole and the suction port may be lost, and cavitation may occur.

JP-A-2002-39047

An object to be solved by the present invention is to provide a hydraulic piston pump capable of effectively improving the self-absorption property of hydraulic oil while suppressing the increase in size.

Hydraulic piston pumps embodiment has a casing, a cylinder block, and valves plate, a. The casing has a suction flow path through which the liquid is guided. The cylinder block is rotatably provided in the casing, has a plurality of cylinder holes into which pistons are fitted, and has cylinder ports provided on the axial end faces of the cylinder holes. The cylinder port is formed at a round hole portion formed in a circular cross section on the cylinder hole side and at the end portion of the round hole portion on the cylinder hole side, and is concave and hemispherical so as to be convex toward the cylinder hole side. It has a cut portion that is an arc surface and a cut portion.

The vertical sectional view which shows the tandem type hydraulic piston pump of an embodiment. FIG. 3 is a cross-sectional perspective view showing the first pump unit of the embodiment. FIG. 5 is a cross-sectional view showing a cylinder port of an embodiment. FIG. 3 is a cross-sectional perspective view of a cylinder block at a position corresponding to a suction port of the valve plate of the embodiment. Cross-sectional perspective view of the cylinder block at the position corresponding to the suction port of the conventional valve plate.

Hereinafter, the hydraulic piston pump of the embodiment will be described with reference to the drawings.

FIG. 1 is a vertical cross-sectional view showing a tandem type hydraulic piston pump 1.
The tandem type hydraulic piston pump 1 (hereinafter, may be simply referred to as "hydraulic piston pump 1") is a tandem type swash plate type axial piston pump mounted as a hydraulic source in a construction machine such as a hydraulic excavator.

The hydraulic piston pump 1 has a casing 10 forming the entire outer shell, and an input shaft 20 rotatably arranged at the center of the casing 10. The input shaft 20 is rotationally driven by a rotary drive source such as an engine (not shown) provided outside the hydraulic piston pump 1. Two pump units 30A and 30B are housed in the casing 10 so as to be separated from each other in the axial direction of the input shaft 20 (the left-right direction in FIG. 1).
In the following description, the left end side in FIG. 1 is referred to as a front end side, the right end side is referred to as a rear end side, the front end side pump unit 30A is referred to as a first pump unit 30A, and the rear end side pump unit 30B is referred to as a second pump unit 30B. It will be referred to as a pump unit 30B. Further, the axial direction of the input shaft 20 will be simply referred to as an axial direction, and the direction around the input shaft 20 will be referred to as a circumferential direction.

The casing 10 includes a first casing main body 11A on the front end side, a second casing main body 11B on the rear end side, a front cover 12A that closes the front end opening of the first casing main body 11A, and a second casing main body 11B. It is composed of a rear cover 12B that closes the rear end opening and an intermediate casing 13 sandwiched between the first and second casing main bodies 11A and 11B.

These are arranged in the order of the front cover 12A, the first casing main body 11A, the intermediate casing 13, the second casing main body 11B, and the rear cover 12B from the front end side to the rear end side in the axial direction. The intermediate casing 13 constitutes an axially intermediate region of the casing 10. The first pump unit 30A is housed in the tubular first casing main body 11A arranged on the front end side, and the second pump unit 30B is accommodated in the tubular second casing arranged on the rear end side. It is housed in the casing main body 11B of the above.

The casing 10 is composed of a first casing main body 11A having a reference numeral "A" on the front end side and a second casing main body 11B having a reference numeral "B" on the rear end side with the intermediate casing 13 as a boundary. Has been done. Therefore, among the members paired with the casing 10 and the front end side and the rear end side of the pump units 30A and 30B, the members provided on the front end side are designated by the symbol "A" and are provided on the rear end side. Is designated by the symbol "B".

FIG. 2 is a cross-sectional perspective view of the first pump unit 30A.
Since the first pump unit 30A and the second pump unit 30B have the same configuration, in the following, both pump units 30A and 30B are described only by reference numerals, and only the first pump unit 30A is shown. It may be shown and explained.

As shown in FIGS. 1 and 2, both pump units 30A and 30B are configured as variable-capacity swash plate type axial piston pumps whose discharge capacities can be adjusted respectively. Each pump unit 30A and 30B configured as a swash plate type axial piston pump has an annular plate-shaped swash plate 36A and 36B, a plurality of pistons 33A and 33B, a cylinder block 31A and 31B, and a valve plate (valve). Plate) 34A, 34B and rotating shafts 21 and 22 and the like. Each of these members is arranged line-symmetrically in the axial direction with respect to the intermediate casing 13. That is, the valve plates 34A and 34B are arranged so as to face the axial end faces 13A and 13B of the intermediate casing 13.

The swash plates 36A and 36B are provided on the inner surfaces of the front cover 12A and the rear cover 12B so that the tilt angle can be adjusted. As a result, the swash plates 36A and 36B can be tilted about the point O in FIG. 1, including the central axis of the input shaft 20.
Further, the swash plates 36A and 36B are slidably in contact with the shoes 39A and 39B via the plates 35A and 35B. The shoes 39A and 39B are swingably engaged with pistons 33A and 33B having spherical heads 33a and 33b at their tips.

The shoes 39A and 39B are supported by the retainer members 38A and 38B mounted on the outer periphery of the input shaft 20 via the retainer plates 37A and 37B so as to be tiltably supported together with the swash plates 36A and 36B.
Further, in the vicinity of the swash plates 36A and 36B, regulators (tilt angle adjusting means) 70A and 70B for adjusting the tilt angles of the swash plates 36A and 36B are provided.

The regulators 70A and 70B adjust the tilt angles of the swash plates 36A and 36B via the tilt pistons 72A and 72B. The tilting pistons 72A and 72B are integrally provided with operating levers 73A and 73B. The tips of the operating levers 73A and 73B are swingably connected to the swash plates 36A and 36B.

Under such a configuration, the tilt angle adjusting mechanism in the regulators 70A and 70B moves along the axial direction by the pilot pressure output from the operation unit (not shown), so that the tilt pistons 72A and 72B are moved. It slides along the axial direction. Then, the tilt angle of the swash plates 36A and 36B is controlled based on the slide movement of the tilt pistons 72A and 72B. As will be described later, when the tilt angle of the swash plates 36A and 36B changes, the stroke amount of each piston 33A and 33B changes, and the flow rate of the pressure oil discharged from the pump units 30A and 30B is controlled.

The pistons 33A and 33B are slidably held by the cylinder blocks 31A and 31B. The cylinder blocks 31A and 31B are formed in a columnar shape, and are rotatably housed in the casing main bodies 11A and 11B. A plurality of cylinder holes 32A and 32B formed along the axial direction are formed in the cylinder blocks 31A and 31B, and the pistons 33A and 33B are slidably held in the cylinder holes 32A and 32B. There is.

The plurality of cylinder holes 32A and 32B are formed at equal intervals in the circumferential direction about the rotation axis of the cylinder blocks 31A and 31B (corresponding to the central axis of the input shaft 20). Further, in the cylinder blocks 31A and 31B, cylinder ports 90A and 90B are formed at the ends on the valve plates 34A and 34B sides so as to communicate with the cylinder holes 32A and 32B. Details of the shapes of the cylinder ports 90A and 90B will be described later.

Further, the cylinder block 31A of the first pump unit 30A penetrates the cylinder block 31A with the first rotating shaft 21 spline-fitted into the center hole. Further, the cylinder block 31B of the second pump unit 30B is penetrated through the center hole with the second rotating shaft 22 spline-fitted.
The first rotating shaft 21 is rotatably supported by a taper roller bearing 26A on the front side mounted on the front cover 12A and a needle bearing 27A on the rear side mounted on the intermediate casing 13. The second rotating shaft 22 is rotatably supported by a rear tapered roller bearing 26B mounted on the rear cover 12B and a front needle bearing 27B mounted on the intermediate casing 13.

The first rotating shaft 21 and the second rotating shaft 22 are arranged on the front side and the rear side on the same axis. Further, they are connected to each other so as to rotate synchronously via a coupling 25 spline-fitted to the rear end of the first rotating shaft 21 and the front end of the second rotating shaft 22. The first rotating shaft 21 and the second rotating shaft 22 connected by the coupling 25 constitute one input shaft 20 penetrating the inside of the casing 10.

The front end of the first rotary shaft 21 projects outward from the front cover 12A, and a rotary drive source such as an engine is connected to the protruding end. Further, the rear end of the second rotating shaft 22 projects outward from the rear cover 12B, and the drive shaft of the pilot pump 80 is connected to the protruding end.
The pilot pump 80 is operated by the rotation of the input shaft 20. Then, hydraulic oil is supplied to an operation unit (not shown), and the operation unit (not shown) generates a pilot pressure by the hydraulic oil.

An annular bearing support members 14A and 14B for fixing the tapered roller bearings 26A and 26B in the thrust direction while projecting the end of the input shaft 20 to the outside are provided on the outside of the tapered roller bearings 26A and 26B. The bearing support members 14A and 14B are fastened and fixed by bolts 81 in a state of being fitted to the inner circumferences of the front cover 12A and the rear cover 12B.

The cylinder blocks 31A and 31B are integrated with the first rotating shaft 21 and the second rotating shaft 22 in a state where the end faces on the side facing the intermediate casing 13 are slidably brought into close contact with the valve plates 34A and 34B. Rotate to. At this time, the cylinder ports 90A and 90B formed on the valve plates 34A and 34B sides of the cylinder blocks 31A and 31B are intermittently connected to the suction ports 61A and 61B and the discharge ports 51A and 51B formed on the valve plates 34A and 34B. Communicate with each other. The suction ports 61A and 61B and the discharge ports 51A and 51B are formed so as to have a substantially crescent shape (substantially cocoon shape), respectively.

FIG. 3 is a cross-sectional view of the cylinder ports 90A and 90B, and FIG. 4 is a cross-sectional perspective view of the cylinder blocks 31A and 31B at positions corresponding to the suction port 61A of the valve plate 34A.
As shown in detail in FIGS. 3 and 4, the cylinder ports 90A and 90B formed in the cylinder blocks 31A and 31B are formed on the valve plates 34A and 34B sides, and have an elongated hole 91 extending in an arc shape and a cylinder hole. The round hole portions 92 formed on the 32A and 32B sides are communicated with each other. The round hole portion 92 has a smaller diameter than the cylinder holes 32A and 32B through a step.

Here, a cut portion 93 is formed at the corner of the step between the round hole portions 92 of the cylinder ports 90A and 90B and the cylinder holes 32A and 32B. The cutting portion 93 is machined by a machining tool having a hemispherical tip (for example, an end mill), and has a concave arc surface so as to correspond to the tip shape of the machining tool. By forming the cut portion 93, the opening areas of the cylinder ports 90A and 90B gradually increase from the suction ports 61A and 61B sides (intermediate casing 13 side) of the valve plates 34A and 34B toward the cylinder holes 32A and 32B. It's getting smaller.

That is, as shown in FIG. 5, in a state where the cut portion 93 is not formed as in the conventional cylinder port, the corner portion 94 is formed on the step between the round hole portions 92 of the cylinder ports 90A and 90B and the cylinder holes 32A and 32B. Is in the remaining state. Therefore, in the conventional cylinder port, the opening area of the valve plates 34A and 34B is sharply reduced from the suction ports 61A and 61B sides to the cylinder holes 32A and 32B side through the step (corner portion 94). However, as shown in FIG. 4, since the cut portion 93 is formed in the cylinder ports 90A and 90B of the present embodiment, the cylinder ports 90A and 90B face the cylinder holes 32A and 32B from the intermediate casing 13 side. The opening area gradually decreases.

As shown in detail in FIG. 2, the intermediate casing 13 is provided with a suction flow path 54 for guiding hydraulic oil to the suction ports 61A and 61B at positions corresponding to the suction ports 61A and 61B of the valve plates 34A and 34B. ing. Further, the intermediate casing 13 is provided with a hydraulic piston pump 1 for hydraulic oil (pressure oil) discharged from the discharge ports 51A and 51B at positions corresponding to the discharge ports 51A and 51B of the valve plates 34A and 34B. A discharge flow path 53 that leads to a hydraulic circuit (not shown) is provided.

Next, the operation of the hydraulic piston pump 1 will be described.
First, when the input shaft 20 is rotationally driven by operating a rotational drive source such as an engine, the cylinder blocks 31A and 31B of both pump units 30A and 30B rotate in synchronization with each other. When the cylinder blocks 31A and 31B rotate, the pistons 33A and 33B engaged with the shoes 39A and 39B that are in sliding contact with the swash plates 36A and 36B via the plates 35A and 35B reciprocate in the cylinder holes 32A and 32B ( Piston movement). Since the pistons 33A and 33B reciprocate along the swash plates 36A and 36B, the stroke amount of the pistons 33A and 33B is determined by the tilt angle of the swash plates 36A and 36B.

As a result, the hydraulic oil is sucked into the cylinder holes 32A and 32B of the cylinder blocks 31A and 31B through the suction flow paths 54 of the intermediate casing 13 and the suction ports 61A and 61B and the cylinder ports 90A and 90B of the valve plates 34A and 34B. NS.
Here, the cylinder ports 90A and 90B are composed of an elongated hole 91 formed on the valve plates 34A and 34B sides and extending in an arc shape, and a round hole 92 formed on the cylinder holes 32A and 32B. Further, a cut portion 93 is formed at the corner of the step between the round hole portion 92 and the cylinder holes 32A and 32B. Therefore, the opening areas of the cylinder ports 90A and 90B gradually decrease from the suction ports 61A and 61B sides (intermediate casing 13 side) of the valve plates 34A and 34B toward the cylinder holes 32A and 32B. As a result, the hydraulic oil passing through the cylinder ports 90A and 90B is sucked in greatly and is smoothly guided to the cylinder holes 32A and 32B while suppressing the generation of turbulent flow.

Subsequently, the hydraulic oil sucked into the cylinder holes 32A and 32B is pressurized by the pistons 33A and 33B to become pressure oil. Then, this pressure oil is discharged to an external hydraulic circuit through the discharge ports 51A and 51B and the discharge flow path 53 of the intermediate casing 13, and is supplied to the hydraulic equipment connected to the hydraulic circuit.
Further, when the tilt angles of the swash plates 36A and 36B change, the stroke amounts of the pistons 33A and 33B are appropriately adjusted. As a result, the flow rate of the pressure oil discharged from each of the pump units 30A and 30B is variably controlled.

As described above, in the above-described embodiment, the cylinder ports 90A and 90B are formed on the valve plates 34A and 34B sides, and the elongated hole portion 91 extending in an arc shape and the round hole portion formed on the cylinder holes 32A and 32B side. 92, and further, a cut portion 93 is formed at the corner of the step between the round hole portion 92 and the cylinder holes 32A and 32B. Therefore, the opening areas of the cylinder ports 90A and 90B gradually decrease from the suction ports 61A and 61B sides (intermediate casing 13 side) of the valve plates 34A and 34B toward the cylinder holes 32A and 32B. Therefore, the hydraulic oil passing through the cylinder ports 90A and 90B is sucked in greatly and is smoothly guided to the cylinder holes 32A and 32B while suppressing the generation of turbulent flow. Therefore, the hydraulic oil in the hydraulic piston pump 1 is effectively used. The self-priming property can be improved. In addition to this, since it is not necessary to unnecessarily open the cylinder ports 90A and 90B to a large extent, it is possible to suppress an increase in the size of the valve plates 34A and 34B. As a result, it is possible to suppress the increase in size of the hydraulic piston pump 1.

In the above-described embodiment, the tandem type hydraulic piston pump 1 has been described as an example, but the configuration of the valve plates 34A and 34B can also be applied to the hydraulic piston pump having one pump unit (30A and 30B).
Further, in the above-described embodiment, the cylinder ports 90A and 90B are moved from the suction ports 61A and 61B sides of the valve plates 34A and 34B to the cylinder holes 32A and 32B by the elongated hole portion 91, the round hole portion 92 and the cutting portion 93. The case where the opening area is gradually reduced toward the above side has been described. However, the present invention is not limited to this, and the cut portion 93 may be formed in a tapered shape or a plurality of steps toward the cylinder holes 32A and 32B.

According to at least one embodiment described above, the cylinder ports 90A and 90B are gradually opened from the suction ports 61A and 61B sides (intermediate casing 13 side) of the valve plates 34A and 34B toward the cylinder holes 32A and 32B. By configuring the area to be small, the hydraulic oil passing through the cylinder ports 90A and 90B can be smoothly guided to the cylinder holes 32A and 32B while suppressing the generation of turbulent flow while sucking in a large amount of hydraulic oil. Therefore, the self-priming property of the hydraulic oil in the hydraulic piston pump 1 can be effectively improved. In addition to this, since it is not necessary to unnecessarily open the cylinder ports 90A and 90B to a large extent, it is possible to suppress an increase in the size of the valve plates 34A and 34B. As a result, it is possible to suppress the increase in size of the hydraulic piston pump 1.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Hydraulic piston pump, 10 ... Casing, 11A ... First casing body (casing), 11B ... Second casing body (casing), 12A ... Front cover (casing), 12B ... Rear cover (casing), 13 ... Intermediate Casing (casing), 31A, 31B ... Cylinder block, 32A, 32B ... Cylinder hole, 32a, 32b ... Small diameter hole (cylinder hole), 33A, 33B ... Piston, 34A, 34B ... Valve plate, 53 ... Discharge flow path, 54 ... suction flow path, 61A, 61B ... suction port, 90A, 90B ... cylinder port, 91 ... long hole, 92 ... round hole, 93 ... excision, 94 ... corner (corner)

Claims (2)

A casing with a suction flow path through which the liquid is guided,
A cylinder block rotatably provided in the casing, having a plurality of cylinder holes into which a piston is fitted, and having a cylinder port provided on an axial end surface of the cylinder hole, and a cylinder block.
And provided, the valve plate suction port is formed which communicates with said suction flow path and the cylinder port between the cylinder port side end face of the front Symbol cylinder block and said casing,
With
The cylinder port
A round hole formed in a circular cross section on the cylinder hole side,
A cut portion formed at the end of the round hole portion on the cylinder hole side and having a concave and hemispherical arc surface so as to be convex toward the cylinder hole side.
<br/> hydraulic piston pump with. The hydraulic piston pump according to claim 1, wherein the cut portion projects from the inner peripheral surface of the round hole portion toward the cylinder hole side.

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