Hydraulic piston pump

Abstract

We provide a hydraulic piston pump that can improve the performance of a booster. [Solution] A hydraulic piston pump according to one embodiment includes a rotating shaft 3, an impeller 7 that functions as a booster, and a casing 2. The casing 2 includes an intake passage 21 that guides working fluid from an external intake port 20 to the impeller 7, a booster chamber 24 located around the impeller 7, and a booster passage 25 that guides working fluid from the booster chamber 24 to an internal intake port 41 of the valve plate 4. The intake passage 21 includes a lateral passage 22 and an axial passage 23. When the angular position around the rotating shaft 3 is defined as 0° for the opening direction of the external intake port 20 and increasing in the rotational direction of the rotating shaft 3, at the inlet of the axial passage 23 from the lateral passage 22, the width of the axial passage 23 at an angular position of 90° is greater than the width of the axial passage 23 at an angular position of 270°.

Description

Technical Field

[0001] The present disclosure relates to a hydraulic piston pump.

Background Art

[0002] Conventionally, hydraulic piston pumps such as swash plate pumps and bent axis pumps are known. In such a hydraulic piston pump, a cylinder block rotates together with a rotary shaft inside a casing, so that the cylinder block slides against a valve plate, and pistons slidably held by the cylinder block perform reciprocating motion.

[0003] Higher speed operation is desired for hydraulic piston pumps, but the self-priming performance of the hydraulic piston pump decreases as the speed increases. For this reason, a booster that pressurizes the working fluid on the suction route is sometimes adopted. For example, Patent Document 1 discloses a hydraulic piston pump that employs a centrifugal impeller that functions as a booster by converting axially flowing working fluid into radially flowing fluid and pressurizing the fluid.

[0004] Specifically, in the hydraulic piston pump of Patent Document 1, the impeller is housed in the casing. The casing includes a suction flow path that guides working fluid from an external suction port to the impeller, a booster chamber located around the impeller, and a booster flow path that guides working fluid from the booster chamber to an internal suction port of the valve plate.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0006] For hydraulic pistons equipped with a booster, it is desired to improve the performance of the booster. Therefore, the present disclosure aims to provide a hydraulic piston pump that can improve the performance of a booster. [Means for solving the problem]

[0007] This disclosure provides a hydraulic piston pump comprising, in a first aspect, a rotating shaft, an impeller attached to the rotating shaft and functioning as a booster by converting an axial flow of working fluid into a radial flow and pressurizing it, and a casing housing the impeller, the casing including an intake passage for leading working fluid from an external intake port opening in a direction perpendicular to the axial direction of the rotating shaft to the impeller, a booster chamber located around the impeller, and a booster passage for leading working fluid from the booster chamber to an internal intake port of a valve plate, wherein the intake passage includes an annular axial passage extending from the impeller along the rotating shaft and a lateral passage extending from the opposite side of the axial passage from the impeller to the external intake port, and when the angular position around the rotating shaft is defined as 0° at the opening direction of the external intake port and increasing in the rotational direction of the rotating shaft, the width of the axial passage at the inlet of the axial passage from the lateral passage at an angular position of 90° is greater than the width of the axial passage at an angular position of 270°.

[0008] This disclosure, in a second aspect, provides a hydraulic piston pump comprising: a rotating shaft; an impeller attached to the rotating shaft and functioning as a booster by converting an axially flowing working fluid into a radial flow and pressurizing it; and a casing housing the impeller, the casing including an intake passage for leading working fluid from an external intake port opening in a direction perpendicular to the axial direction of the rotating shaft to the impeller; a booster chamber located around the impeller; and a booster passage for leading working fluid from the booster chamber to an internal intake port of a valve plate, wherein the intake passage includes an annular axial passage extending from the impeller along the rotating shaft and a lateral passage extending from the opposite side of the impeller across the axial passage to the external intake port, and when the angular position around the rotating shaft is defined as 0° at the opening direction of the external intake port and increasing in the rotational direction of the rotating shaft, the cross-sectional area of ​​the lateral passage is expanded radially outward at an angular position of 270°. [Effects of the Invention]

[0009] According to this disclosure, a hydraulic piston pump capable of improving the performance of a booster is provided. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a cross-sectional view of a hydraulic piston pump according to one embodiment. [Figure 2] Figure 2 is a cross-sectional view along the line II-II in Figure 1. [Figure 3] Figure 3 is a cross-sectional view along the line III-III in Figure 2. [Modes for carrying out the invention]

[0011] Figure 1 shows a hydraulic piston pump 1 according to one embodiment. In this embodiment, the hydraulic piston pump 1 is a swashplate pump, but the hydraulic piston pump 1 may also be an oblique-shaft pump. The working fluid used in the hydraulic piston pump 1 is typically oil.

[0012] Specifically, the hydraulic piston pump 1 includes a hollow casing 2, a swash plate 63 housed within the casing 2, a cylinder block 5, and a valve plate 4. The hydraulic piston pump 1 also includes a rotating shaft 3 that rotates the cylinder block 5 and a rotary consisting of a plurality of pistons 61 and a plurality of shoes 62, which will be described later.

[0013] One end of the rotating shaft 3 protrudes from the casing 2, and this end is connected to a prime mover such as an electric motor or engine. For the sake of explanation, the axial direction of the rotating shaft 3 will be referred to as the front-rear direction, with the end of the rotating shaft being referred to as the front and the other end as the rear.

[0014] The casing 2 includes a casing body 2A and a cover 2B attached to the rear surface of the casing body 2A. The casing body 2A includes a peripheral wall 2b that surrounds the swash plate 63 and the cylinder block 5 from the radially outer side of the rotating shaft 3, a first cover portion 2a that closes the front opening of the peripheral wall 2b, and a second cover portion 2c that closes the rear opening of the peripheral wall 2b.

[0015] The rotating shaft 3 passes through the first cover portion 2a and the second cover portion 2c of the casing body 2A. Bearings 11 and 12 are held in the first cover portion 2a and the second cover portion 2c, and the rotating shaft 3 is rotatably supported in the casing 2 via the bearings 11 and 12.

[0016] The valve plate 4 is mounted on the front surface of the second cover portion 2c. The valve plate 4 is provided with an internal suction port 41 and an internal discharge port 42 that are arc-shaped and facing opposite directions. In Figure 1, the internal suction port 41 is depicted as the upper top dead center and the internal discharge port 42 as the lower bottom dead center, but the actual positions of the internal suction port 41 and internal discharge port 42 are on both sides of the rotating shaft 3 in a direction perpendicular to the separation direction between the top dead center and the bottom dead center. The top dead center is the position where the piston 61 is most retracted, and the bottom dead center is the position where the piston 61 is most advanced.

[0017] In the present embodiment, a centrifugal impeller 7 that functions as a booster by converting axially flowing working fluid into radially flowing working fluid and pressurizing the working fluid is adopted, and the impeller 7 is accommodated in the casing 2 at a position rearward of the valve plate 4 and the bearing 12. The impeller 7 is attached to the rear end portion of the rotating shaft 3 via a coupler 32 which will be described later. The second cover portion 2c of the casing main body 2A is provided with a recess opening rearward, the impeller 7 is arranged in the recess, and the recess is covered with the cover 2B.

[0018] For this reason, the second cover portion 2c of the casing main body 2A is provided with a suction flow passage 21 that guides the working fluid from an external suction port 20, which opens in a direction orthogonal to the axial direction of the rotating shaft 3 on the outer peripheral surface of the second cover portion 2c, to the impeller 7, a booster chamber 24 located around the impeller 7, and a booster flow passage 25 that guides the working fluid from the booster chamber 24 to the internal suction port 41 of the valve plate 4. Further, the second cover portion 2c of the casing main body 2A is provided with a discharge flow passage 26 that guides the working fluid from the internal discharge port 42 of the valve plate 4 to an external discharge port, which opens in a direction orthogonal to the axial direction of the rotating shaft 3 on the outer peripheral surface of the second cover portion 2c.

[0019] The cylinder block 5 is attached to the rotating shaft 3, and slides on the valve plate 4 by rotating together with the rotating shaft 3. The cylinder block 5 meshes with the rotating shaft 3 via a spline structure.

[0020] The cylinder block 5 is provided with a plurality of cylinder bores 51 opening forward around the rotating shaft 3. A plurality of pistons 61 are inserted into the cylinder bores 51 respectively. That is, the pistons 61 are slidably held by the cylinder block 5.

[0021] Further, the cylinder block 5 is provided with cylinder ports 52 extending from the respective cylinder bores 51 to the valve plate 4. Some of the cylinder ports 52 communicate with the internal suction port 41 of the valve plate 4, and the other some communicate with the internal discharge port 42 of the valve plate 4.

[0022] A plurality of shoes 62 are respectively attached to the head of the piston 61. In the present embodiment, the shoes 62 slide on the swash plate 63 via an annular shoe plate 64 attached to the swash plate 63. However, the shoe plate 64 may be omitted, and the shoes 62 may slide directly on the swash plate 63.

[0023] The shoes 62 are pressed by a retainer plate 65 so that the state of being in contact with the shoe plate 64 is maintained. Thereby, the piston 61 reciprocates as the cylinder block 5 rotates.

[0024] The swash plate 63 is supported by the first cover portion 2a of the casing main body 2A so as to be swingable about a swing shaft extending in a direction orthogonal to the axial direction of the rotating shaft 3. The swash plate 63 is swung by a servo piston 67. The servo piston 67 is supported by the peripheral wall 2b of the casing main body 2A so as to be slidable in the axial direction of the rotating shaft 3.

[0025] The above-described coupler 32 interposed between the rear end portion of the rotating shaft 3 and the impeller 7 is engaged with the rear end portion of the rotating shaft 3 by a spline structure, and the impeller 7 is engaged with the coupler 32 by a spline structure. However, the impeller 7 may be directly attached to the rear end portion of the rotating shaft 3.

[0026] As shown in FIG. 2 and FIG. 3, the impeller 7 includes a disk portion 71 that is orthogonal to the axial direction of the rotating shaft 3 and penetrated by the coupler 32, and a plurality of blades 72 provided on the front surface of the disk portion 71 and conforming to the swirling flow.

[0027] As shown in FIG. 1, the suction flow passage 21 that guides the working fluid to the impeller 7 includes an annular axial flow passage 23 extending forward from the impeller 7 along the rotating shaft 3, and a lateral flow passage 22 extending in front of the axial flow passage 23, in other words, from the side opposite to the impeller 7 across the axial flow passage 23 to the external suction port 20. That is, the axial flow passage 23 has an inlet opening forward from the lateral flow passage 22, and an outlet opening rearward to the impeller 7.

[0028] In this embodiment, when viewed from the axial direction of the rotating shaft 3, the width of the lateral flow path 22 widens as it approaches the rotating shaft 3 from the external intake port 20. Furthermore, the bottom of the lateral flow path 22 on the side opposite to the opening direction has a larger contour than the inlet of the axial flow path 23, and a step is formed between the bottom of the lateral flow path 22 and the axial flow path 23.

[0029] In this embodiment, as shown in Figure 2, the angular position around the rotating shaft 3 is defined as increasing in the rotational direction of the rotating shaft 3, with the opening direction of the external intake port 20 being 0°.

[0030] In this embodiment, the outlet of the axial flow path 23 is circular, but the inlet of the axial flow path 23 is non-circular. The diameter of the outlet of the axial flow path 23 may be less than or equal to the diameter of a circle inscribed in all of the blades 72 so that each blade 72 is completely hidden, or it may be greater than the diameter of a circle inscribed in all of the blades 72 so that the inner ends of each blade 72 of the impeller 7 are exposed.

[0031] More specifically, the axial flow path 23 expands toward the inlet over an angular range from an angular position smaller than 90° to an angular position larger than 90°. Therefore, at the inlet of the axial flow path 23, the width of the axial flow path 23 at an angular position of 90° is greater than the width of the axial flow path 23 at an angular position of 270°. For example, the lower limit of the angular range is 10° or more, and the upper limit of the angular range is 180° or less.

[0032] It is desirable that the width of the inlet of the axial flow path 23 continuously increases from the lower limit of the angular range up to the 90° angular position, and then continuously decreases from the 90° angular position up to the upper limit of the angular range. In other words, the inlet of the axial flow path 23 may bulge in an arc shape toward the 90° direction. The shape of the widened portion at the inlet of the axial flow path 23 may be a symmetrical arc shape with respect to the 90° angular position, or an asymmetrical arc shape with respect to the 90° angular position.

[0033] In this embodiment, within the aforementioned angular range, the side surface of the axial flow path 23 is linear in a cross-section passing through the centerline of the rotating shaft 3, inclined to move away from the rotating shaft 3 as it moves forward. The inclination angle of the side surface of the axial flow path 23 with respect to the axial direction of the rotating shaft 3 at a 90-degree angular position is, for example, within the range of 10° to 45°. On the other hand, outside the aforementioned angular range, the side surface of the axial flow path 23 is linear in a cross-section passing through the centerline of the rotating shaft 3, parallel to the axial direction of the rotating shaft 3.

[0034] Furthermore, in this embodiment, the cross-sectional area of ​​the lateral flow path 22 is expanded radially outward at an angular position of 270°. In Figures 2 and 3, the shape symmetrical to the shape at an angular position 90° to the centerline of the rotating shaft 3 is shown by a dashed line.

[0035] In this embodiment, the wall surface of the lateral channel 22 gradually moves away from the symmetrical shape with respect to the 90° side from the expansion start position between 180° and 270° to the angular position of 270°, with the distance from the symmetrical shape to the wall surface of the lateral channel 22 being maximum at the angular position of 270°.

[0036] For example, the distance from the center line of the rotating shaft 3 to the wall surface of the lateral channel 22 at an angular position of 270° is between 105% and 130% of the distance from the center line of the rotating shaft 3 to the wall surface of the lateral channel 22 at an angular position of 90°.

[0037] As explained above, in the hydraulic piston pump 1 of this embodiment, the width of the axial passage 23 at an angular position of 90° is greater than the width of the axial passage 23 at an angular position of 270°. Therefore, the inflow of working fluid into the impeller 7 through the axial passage 23 at an angular position of 90° is promoted, that is, the inflow of working fluid into the impeller 7 in a tailwind direction relative to the rotation of the impeller 7. As a result, the inflow of working fluid into the impeller 7 through the axial passage 23 at an angular position of 270° is suppressed, that is, the inflow of working fluid into the impeller 7 in a headwind direction relative to the rotation of the impeller 7. Consequently, the performance of the booster can be improved.

[0038] Furthermore, in this embodiment, the cross-sectional area of ​​the lateral flow path 22 is expanded radially outward at an angular position of 270°, so that the flow through the expanded portion is promoted so as to bypass the axial flow path 23 at the angular position of 270°. As a result, the inflow of working fluid into the impeller 7 through the axial flow path 23 at the angular position of 270° is suppressed, that is, the inflow of working fluid into the impeller 7 in the direction of the wind relative to the rotation of the impeller 7 is suppressed. As a result, the performance of the booster can be further improved.

[0039] <Variation> This disclosure is not limited to the embodiments described above, and various modifications are possible without departing from the gist of this disclosure.

[0040] For example, at the inlet of the axial flow path 23, the width of the axial flow path 23 at an angular position of 90° may be the same as the width of the axial flow path 23 at an angular position of 270°. Even in this case, the configuration in which the cross-sectional area of ​​the lateral flow path 22 is expanded radially outward at an angular position of 270° suppresses the inflow of working fluid into the impeller 7 in the direction of headwind relative to the rotation of the impeller 7, thereby improving the performance of the booster.

[0041] Alternatively, if the width of the axial flow path 23 at an angular position of 90° is greater than the width of the axial flow path 23 at an angular position of 270°, the cross-sectional area of ​​the lateral flow path 22 may not expand radially outward at the 270° angular position, and the shape of the lateral flow path 22 may be symmetrical on the 90° side and the 270° side.

[0042] Alternatively, the hydraulic piston pump 1 may be a tandem pump in which two rotary elements and two rotating shafts 3 are arranged coaxially, and the connector 32 may connect the two rotating shafts 3 to each other.

[0043] <Summary> In a first aspect, the present disclosure provides a hydraulic piston pump comprising: a rotating shaft; an impeller attached to the rotating shaft and functioning as a booster by converting an axial flow of working fluid into a radial flow and pressurizing it; and a casing housing the impeller, the casing including an intake passage for leading working fluid from an external intake port opening in a direction perpendicular to the axial direction of the rotating shaft to the impeller; a booster chamber located around the impeller; and a booster passage for leading working fluid from the booster chamber to an internal intake port of a valve plate, wherein the intake passage includes an annular axial passage extending from the impeller along the rotating shaft and a lateral passage extending from the opposite side of the axial passage from the impeller to the external intake port, and when the angular position around the rotating shaft is defined as 0° at the opening direction of the external intake port and increasing in the rotational direction of the rotating shaft, the width of the axial passage at an angular position of 90° at the inlet of the axial passage from the lateral passage is greater than the width of the axial passage at an angular position of 270°.

[0044] According to the above configuration, at the inlet of the axial flow path, the width of the axial flow path at a 90° angle is greater than the width of the axial flow path at a 270° angle. Therefore, the inflow of working fluid into the impeller through the axial flow path at a 90° angle, i.e., the inflow of working fluid into the impeller in the direction of a tailwind relative to the impeller's rotation, is promoted. As a result, the inflow of working fluid into the impeller through the axial flow path at a 270° angle, i.e., the inflow of working fluid into the impeller in the direction of a headwind relative to the impeller's rotation, is suppressed. Consequently, the performance of the booster can be improved.

[0045] In a second embodiment, in the first embodiment, for example, the axial flow path may expand toward the inlet in an angular range from an angular position smaller than 90° to an angular position larger than 90°.

[0046] In a third embodiment, in the first or second embodiment, the cross-sectional area of ​​the lateral flow path may be expanded radially outward at an angular position of 270°. With this configuration, since the cross-sectional area of ​​the lateral flow path is expanded radially outward at an angular position of 270°, flow through the expanded portion is promoted so as to bypass the axial flow path at the 270° angular position. This suppresses the inflow of working fluid into the impeller through the axial flow path at the 270° angular position, that is, the inflow of working fluid into the impeller in the direction of headwind relative to the rotation of the impeller. As a result, the performance of the booster can be further improved.

[0047] In a fourth aspect, the present disclosure provides a hydraulic piston pump comprising: a rotating shaft; an impeller attached to the rotating shaft and functioning as a booster by converting an axially flowing working fluid into a radial flow and pressurizing it; and a casing housing the impeller, the casing including an intake passage for leading working fluid from an external intake port opening in a direction perpendicular to the axial direction of the rotating shaft to the impeller; a booster chamber located around the impeller; and a booster passage for leading working fluid from the booster chamber to an internal intake port of a valve plate, wherein the intake passage includes an annular axial passage extending from the impeller along the rotating shaft and a lateral passage extending from the opposite side of the impeller across the axial passage to the external intake port, and when the angular position around the rotating shaft is defined as 0° at the opening direction of the external intake port and increasing in the rotational direction of the rotating shaft, the cross-sectional area of ​​the lateral passage is expanded radially outward at an angular position of 270°.

[0048] According to the above configuration, the cross-sectional area of ​​the lateral flow path is expanded radially outward at an angular position of 270°, thereby promoting flow through the expanded portion to bypass the axial flow path at the 270° angular position. This suppresses the inflow of working fluid into the impeller through the axial flow path at the 270° angular position, i.e., the inflow of working fluid into the impeller in the direction of headwind relative to the impeller's rotation. As a result, the booster's performance can be improved. [Explanation of symbols]

[0049] 1. Hydraulic piston pump 2 Casing 20 External intake ports 21 Suction channel 22 Lateral channel 23 Axial flow path 24 Booster Room 25 Booster flow path 3-rotation shaft 4 valve plates 41 Internal intake port 7-inch vane

Claims

1. Rotating shaft and An impeller attached to the aforementioned rotating shaft, which functions as a booster by converting the axial flow of the working fluid into a radial flow and pressurizing it, A casing for housing the impeller, comprising: an intake passage for guiding working fluid from an external intake port opening in a direction perpendicular to the axial direction of the rotating shaft to the impeller; a booster chamber located around the impeller; and a booster passage for guiding working fluid from the booster chamber to an internal intake port of the valve plate, The intake passage includes an annular axial passage extending from the impeller along the rotating shaft, and a lateral passage extending from the opposite side of the impeller to the external intake port, with the axial passage in between. A hydraulic piston pump in which, with respect to the angular position around the rotating shaft, the opening direction of the external suction port is defined as 0° and the angular position increases in the rotational direction of the rotating shaft, the width of the axial flow path at an angular position of 90° is greater than the width of the axial flow path at an angular position of 270° at the inlet of the axial flow path from the lateral flow path.

2. The hydraulic piston pump according to claim 1, wherein the axial flow path expands toward the inlet over an angular range from an angular position smaller than 90° to an angular position larger than 90°.

3. The hydraulic piston pump according to claim 1 or 2, wherein the cross-sectional area of ​​the lateral flow path is expanded radially outward at an angular position of 270°.

4. Rotating shaft and An impeller attached to the aforementioned rotating shaft, which functions as a booster by converting the axial flow of the working fluid into a radial flow and pressurizing it, A casing for housing the impeller, comprising: an intake passage for guiding working fluid from an external intake port opening in a direction perpendicular to the axial direction of the rotating shaft to the impeller; a booster chamber located around the impeller; and a booster passage for guiding working fluid from the booster chamber to an internal intake port of the valve plate, The intake passage includes an annular axial passage extending from the impeller along the rotating shaft, and a lateral passage extending from the opposite side of the impeller to the external intake port, with the axial passage in between. A hydraulic piston pump in which, with respect to the angular position around the rotating shaft, the opening direction of the external suction port is defined as 0°, and the angular position increases in the rotational direction of the rotating shaft, the cross-sectional area of ​​the lateral flow path is expanded radially outward at an angular position of 270°.

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