Turbo pump and fluid supply unit

Abstract

To improve fluid compression supply performance during a supply excessive operation in which a consumption flow rate at the downstream side is low for a fluid compression supply capability of an impeller.SOLUTION: A turbo type pump compresses and supplies a fluid to the downstream of a suction passage 32 by rotation of an impeller 34 provided at the suction passage 32. In a portion which is located at the upstream side relative to the impeller 34 in the suction passage 32, an orifice hole 36a which reduces an inner diameter while forming an inversion surface 40 oriented to the downstream side is provided. The inversion surface 40 is provided with an inversion partition wall part 42 which restricts flow of the fluid in a circumferential direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a turbo pump that feeds fluid downstream through an impeller provided in a fluid passage, and a fluid supply unit equipped with the turbo pump.

Background Art

[0002] In a turbo pump equipped with an impeller, there is a concern that various problems may occur due to a swirling reverse flow in the fluid on the inlet side of the impeller when the consumption flow rate on the downstream side is small relative to the fluid pressurization supply capacity. More specifically, even if the rotational speed of the turbo pump is constant, when the opening of the fluid discharge nozzle connected to the downstream side is narrowed, or when the discharge capacity of the variable displacement pump connected to the downstream side is set small, the above-mentioned reverse flow may occur. Also, even if the consumption flow rate on the downstream side is constant, there is a possibility that the above-mentioned reverse flow may occur when the rotational speed of the turbo pump on the upstream side increases (hereinafter, these operating states will be collectively referred to as over-supply operation). For this reason, conventionally, an orifice ring having a reverse surface is provided so as to contact the fluid flowing backward in a portion located upstream of the impeller, and a rectifying means for suppressing the swirling of the fluid is provided between the orifice ring and the impeller (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the fluid after passing through the rectifying means will also diffuse in the circumferential direction when it comes into contact with the reversing surface of the orifice ring. Therefore, depending on the orifice ring, the reverse flow of the fluid cannot be efficiently reversed, and there is still room for improvement when considering the pressurized feeding performance of the fluid during overfeed operation. Note that the above problem is not necessarily limited to those equipped with an inducer, and the same problem can occur as long as the fluid is pressurized and fed downstream by the rotation of the impeller.

[0005] In view of the above circumstances, an object of the present invention is to provide a turbo-type pump and a fluid supply unit capable of improving the pressurized feeding performance of a fluid during overfeed operation.

Means for Solving the Problems

[0006] To achieve the above object, a turbo-type pump according to the present invention is a turbo-type pump that pressurizes and feeds a fluid downstream of the fluid passage by the rotation of an impeller provided in the fluid passage, and a reduced-diameter portion that reduces the inner diameter in a state of forming a reversing surface facing the downstream side is provided in a portion of the fluid passage located upstream of the impeller, and a reversing partition portion that restricts the circumferential flow of the fluid is provided on the reversing surface.

Effects of the Invention

[0007] According to the present invention, since the reversing partition portion is provided on the reversing surface, the fluid coming into contact with the reversing surface is guided toward the center side of the fluid passage without diffusing in the circumferential direction. As a result, even when reverse flow occurs, it can be efficiently reversed, and it is possible to improve the pressurized feeding performance of the fluid even during overfeed operation where the consumption flow rate on the downstream side is small compared to the fluid pressurizing and supplying ability of the impeller.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments of the turbo pump and the fluid supply unit according to the present invention will be described in detail with reference to the accompanying drawings.

[0010] (Embodiment 1) FIGS. 1 and 2 show a fluid supply unit provided with a turbo pump according to Embodiment 1 of the present invention. The fluid supply unit exemplified here is a hydraulic pump unit for supplying oil to various hydraulic devices in a working machine, and an input shaft 10 is provided inside a unit main body 3 composed of a case 1 and a port block 2. One end of the input shaft 10 is exposed outside the case 1, while the other end is supported by the unit main body 3 via bearings 11 and 12 in a state of being housed inside the port block 2, and it can rotate around the axis C. Although not shown in the figure, a drive source such as an engine or an electric motor mounted on the working machine is connected to one end of the input shaft 10.

[0011] In the hollow portion 1a formed in the case 1 of the unit main body 3, a cylinder block 20 is disposed. The cylinder block 20 is for forming a variable displacement swash plate piston pump which is a positive displacement pump, and is disposed in the hollow portion 1a of the unit main body 3 via an input shaft 10 penetrating the center portion. The cylinder block 20 is connected to the input shaft 10 by a spline, and can rotate around the axis C as the rotation axis together with the input shaft 10.

[0012] The cylinder block 20 is provided with a plurality of cylinder bores 20a around the input shaft 10. Each cylinder bore 20a is a cylindrical cavity formed parallel to the axis C of the input shaft 10, and they are arranged at equal intervals along the circumferential direction. One end of each individual cylinder bore 20a opens to one end face of the cylinder block 20 (hereinafter referred to as the open-side end face 20b), while the other end opens to the other end face of the cylinder block 20 (hereinafter referred to as the sliding end face 20d) via a small-diameter cylinder port 20c. A piston 21 is disposed in each of the cylinder bores 20a. The piston 21 is fitted so as to be movable along the axis of the cylinder bore 20a. A piston shoe 22 is attached to the end of each individual piston 21 that protrudes from the open-side end face 20b of the cylinder block 20. The piston shoe 22 is connected to the piston 21 so as to be tiltable. One end of this cylinder block 20 is slidably abutted against the swash plate 23 via the piston shoe 22, and the other end is slidably abutted against a valve plate 24 provided on the port block 2.

[0013] The swash plate 23 has a sliding contact surface 23a inclined with respect to the input shaft 10, and is in contact with the piston shoe 22 via the sliding contact surface 23a. The piston 21 that is in contact with the sliding contact surface 23a of the swash plate 23 via the piston shoe 22 will reciprocate inside the cylinder bore 20a according to the inclination of the sliding contact surface 23a when the cylinder block 20 rotates. Although not shown in the figure, in the hydraulic pump unit exemplified in the first embodiment, it is possible to change the inclination angle of the sliding contact surface 23a with respect to the input shaft 10. When the inclination angle of the sliding contact surface 23a is changed, the reciprocating movement distance of the piston 21 with respect to the cylinder bore 20a when the cylinder block 20 rotates will change.

[0014] The valve plate 24 has a circular shape with inner and outer diameters that can simultaneously block all the cylinder ports 20c opening to the sliding end face 20d of the cylinder block 20. In the first embodiment, the sliding end face 20d of the cylinder block 20 is formed as a concave spherical surface, and the portion of the valve plate 24 facing the sliding end face 20d of the cylinder block 20 is formed as a convex spherical surface so that they can be in sliding contact without a gap.

[0015] On this valve plate 24, a high-pressure port 24a and a low-pressure port 24b are provided on the circumference centered on the axis C of the input shaft 10. The high-pressure port 24a and the low-pressure port 24b are notches penetrating the valve plate 24, and extend in an arc shape so that a plurality of adjacent cylinder ports 20c can communicate with each of them.

[0016] On the other hand, a discharge passage 31 and a suction passage (fluid passage) 32 are provided in the port block 2 of the unit body 3. One end of the discharge passage 31 communicates with the high-pressure port 24a of the valve plate 24, and the other end (not shown) opens to the outer surface of the port block 2. An oil passage (not shown) for supplying oil to various hydraulic devices is connected to the opening end of the discharge passage 31 opening to the outer surface of the port block 2. The suction passage 32 extends linearly along the radial direction from a portion close to the axis C of the input shaft 10. One end communicates with the low-pressure port 24b of the valve plate 24, and the other end opens to the outer surface of the port block 2. As is clear from the figure, the suction passage 32 is configured to have a larger inner diameter than the discharge passage 31, and includes an impeller 34 and a sleeve 35 inside, and an orifice plate 36 at the opening end. The impeller 34, the sleeve 35, and the orifice plate 36 are for constituting a turbo-type pump, which is a non-positive displacement pump, in front of the variable displacement swash plate piston pump described above.

[0017] As shown in FIGS. 1 to 3, the impeller 34 has a support shaft portion 34a at its base end portion, and the support shaft portion 34a is rotatably disposed on the port block 2 via the support shaft portion 34a with the axis 34b (rotation axis) of the support shaft portion 34a aligned with the axis 32a of the suction passage 32. The impeller 34 is provided with a cylindrical portion 34d having an inlet port 34c that opens toward the upstream of the suction passage 32. Inside the cylindrical portion 34d, a plurality of blade plate portions 34e are formed in a curved shape along the radial direction. In the cylindrical portion 34d, at the portions between the blade plate portions 34e, a plurality of discharge ports 34f are provided so as to open to the outer peripheral surface.

[0018] A driven gear 13 is provided at the base end portion of the impeller 34. The driven gear 13 is a bevel gear attached so that its axis coincides with the axis 34b of the support shaft portion 34a, and meshes with a drive gear 14 provided on the input shaft 10. The drive gear 14 is a bevel gear attached so that its axis coincides with the axis C of the input shaft 10, and functions to increase the rotational speed of the impeller 34 via the driven gear 13 when the input shaft 10 rotates. This impeller 34 is interlocked at the speed increase ratio of the drive gear 14 and the driven gear 13 when the input shaft 10 rotates. While sucking the oil in the suction passage 32 from the inlet port 34c by the plurality of blade plate portions 34e, it functions to discharge the sucked oil from the discharge ports 34f on the outer peripheral portion and pressurize and feed it to the low-pressure port 24b of the valve plate 24. This pressurizing ability increases in proportion to the square of the rotational speed of the impeller 34.

[0019] As shown in FIGS. 1 and 2, the sleeve 35 is mounted on a portion of the inner peripheral surface of the suction passage 32 that is located upstream of the impeller 34, thereby guiding the rotation of the impeller 34 and functioning to guide the flow of oil to the inlet port 34c. In the first embodiment, a sleeve 35 having a sleeve body 35a and a flange portion 35b is applied. The sleeve body 35a is configured such that its cross-section is circular and its axis 35c is linear, and it is formed with an outer diameter that can be fitted inside the suction passage 32. The flange portion 35b is in the form of a flat plate that extends outward from one end of the sleeve body 35a. This sleeve 35 is fixed to the port block 2 by inserting the sleeve body 35a inside the suction passage 32 and bringing the flange portion 35b into contact with the outer surface of the port block 2, and then screwing a screw through the flange portion 35b into the port block 2.

[0020] The inner peripheral surface of the sleeve body 35a has a downstream end portion 35d that communicates with the inlet port 34c of the impeller 34 and has substantially the same inner diameter as the inlet port 34c, and a tapered portion 35e whose inner diameter gradually increases toward the upstream side. An outer cylinder portion 35f that is slidably fitted to the outer peripheral portion of the end of the cylindrical portion 34d of the impeller 34 is provided at the end of the sleeve body 35a that is the most downstream.

[0021] As shown in FIGS. 1, 2, 4, and 5, the orifice plate 36 is in the shape of a flat plate having an orifice hole (reduced diameter portion) 36a in the central portion, and is attached to the port block 2 with the axis 36b of the orifice hole 36a aligned with the axis 35c of the sleeve body 35a. The orifice hole 36a is formed to have an inner diameter smaller than the inner diameter of the upstream end portion of the sleeve body 35a. Thereby, when the orifice plate 36 is attached to the port block 2, the orifice plate 36 protrudes to the inner peripheral side of the sleeve body 35a, and an inversion surface 40 is formed between the orifice plate 36 and the sleeve body 35a. That is, in the suction passage 32 in a state where the orifice plate 36 and the sleeve 35 are attached, the inner diameter once increases on the upstream side of the sleeve body 35a after passing through the orifice hole 36a, and gradually decreases until reaching the impeller 34. In the first embodiment, the orifice hole 36a is formed in the orifice plate 36 so as to have an inner diameter smaller than the inlet 34c of the impeller 34.

[0022] The inversion surface 40 extends toward the downstream side so as to be orthogonal to the axis 32a of the suction passage 32. A plurality of inversion concave surfaces 41 are provided at portions around the orifice hole 36a on the inversion surface 40 at equal intervals along the circumferential direction. The inversion concave surface 41 is a recess formed such that the inner bottom surface is flat and parallel to the inversion surface 40, and the outer peripheral end of each inversion concave surface 41 substantially coincides with the inner peripheral surface of the upstream end portion of the sleeve body 35a. The inversion concave surfaces 41 adjacent to each other in the circumferential direction are separated from each other by an inversion partition portion 42 configured by securing a space therebetween. The inversion partition portion 42 is a portion where the inversion surface 40 is exposed, extends radially along the radial direction with respect to the axis 36b of the orifice hole 36a, and is configured to open only to the orifice hole 36a.

[0023] As shown in FIGS. 1 and 2, a suction pipe 50 is connected to the above-described suction passage 32 via an orifice plate 36. The suction pipe 50 connects to an oil tank (not shown). In the first embodiment, a suction pipe 50 having an inner diameter larger than the orifice hole 36a and substantially matching the inner peripheral surface of the upstream end portion of the sleeve body 35a is connected.

[0024] In the hydraulic pump unit configured as described above, when the input shaft 10 rotates due to the rotation of a drive source (not shown), the piston 21 reciprocates as the cylinder block 20 rotates. As a result, the oil sucked into the cylinder bore 20a through the suction pipe 50, the orifice hole 36a, the sleeve body 35a, the impeller 34, and the low-pressure port 24b of the valve plate 24 is supplied to various hydraulic devices through the high-pressure port 24a of the valve plate 24, the discharge passage 31, and an oil passage (not shown).

[0025] During this time, in the suction passage 32, the impeller 34 that rotates at an increased speed via the drive gear 14 and the driven gear 13 functions to increase the oil pressure from the suction pipe 50 to the low-pressure port 24b of the valve plate 24, so that the pump suction performance of the variable displacement swash plate piston pump can be improved.

[0026] Here, when the input shaft 10 rotates at a speed higher than the rated rotational speed due to rotational fluctuations of the drive source, or when the swash plate 23 of the variable displacement side swash plate piston pump is set at a small inclination angle and operated, etc., in a situation where the consumption flow rate on the downstream side is small with respect to the fluid pressurization supply capacity of the impeller 34 (hereinafter simply referred to as during over-supply operation), the pressure in the suction passage 32 will increase, and the oil passing through the discharge port 34f of the impeller 34 will swirl back to the sleeve body 35a through the discharge port 34f again, which may cause surging. Also, when swirling backflows develop in the sleeve body 35a or the suction pipe 50, cavitation may occur in the backflow due to the pressure drop at the center (hereinafter simply referred to as reverse flow vortex cavitation), which may lead to a situation where stable operation becomes difficult.

[0027] However, according to the above hydraulic pump unit, the reverse flow generated in the sleeve body 35a abuts against the orifice plate 36 and then reverses, eliminating the possibility of causing the above problems. That is, the swirling reverse flow of oil generated in the sleeve body 35a during over-supply operation is smoothly introduced into the tapered portion 35e by centrifugal force and reverses when it abuts against the orifice plate 36. The oil that has reversed at the orifice plate 36 merges with the oil that has flowed into the orifice hole 36a from the suction pipe 50, accelerating the flow toward the inlet 34c of the downstream impeller 34. Therefore, even during over-supply operation, it is possible to prevent problems such as surging and unstable operation due to the occurrence of reverse flow vortex cavitation.

[0028] In particular, in Embodiment 1, since the reverse concave surface 41 and the reverse partition portion 42 are provided on the reverse surface 40 of the orifice plate 36, the situation where the oil contacting the reverse concave surface 41 diffuses in the circumferential direction due to the reverse partition portion 42 is restricted, and the oil is fed toward the orifice hole 36a. As a result, the reverse flow of the oil introduced into the tapered portion 35e of the sleeve body 35a is efficiently reversed at the orifice plate 36, making it possible to improve the oil pressurization and feeding performance by the impeller 34 and the pump suction performance of the variable displacement swash plate piston pump during over-supply operation.

[0029] In the above-described Embodiment 1, the reversing partition portion 42 of the orifice plate 36 is provided radially, but the present invention is not limited to this. For example, like the orifice plate 136 of the modified example shown in FIGS. 6 and 7, the reversing partition portion 142 may be provided so as to be inclined (angle: θ) in the rotational direction (arrow A) of the impeller 34 from the outer peripheral side toward the inner peripheral side with respect to the radius passing through the axis 136b of the orifice hole (reduced diameter portion) 136a (see FIG. 7(a)). That is, the reverse flow of oil generated in the sleeve body 35a becomes swirling in the same direction as the rotational direction A of the impeller 34. Therefore, by providing the reversing partition portion 142 so as to extend along the swirling direction of this reverse flow, when the oil contacts the reversing concave surface 141, the flow of oil toward the center side facing the orifice hole 136a becomes smooth, and it can be expected that the above-described operational effects will become more prominent. Note that the orifice plate 136 of this modified example is configured on the premise that it is applied in place of the orifice plate 36 of the hydraulic pump unit exemplified in Embodiment 1. Also, the reversing concave surface 141 is provided at equal intervals in the circumferential direction along the reversing surface 140 of the orifice plate 136, and the inner bottom surface is formed to be flat and parallel to the reversing surface 140, which is the same as in Embodiment 1.

[0030] In addition, in the above-described Embodiment 1 and the modified example, a reversing concave surface with a flat inner bottom surface is exemplified as the reversing concave surface, but the present invention is not limited to this, and a reversing concave surface with a curved inner bottom surface may be provided as in Embodiment 2 shown below.

[0031] (Embodiment 2) FIGS. 8 to 10 show a fluid supply unit provided with a turbo-type pump according to Embodiment 2. The fluid supply unit exemplified here is a hydraulic pump unit for supplying oil to various hydraulic devices in a work machine, similar to Embodiment 1, and mainly differs from Embodiment 1 in the configurations of the sleeve 235 and the orifice plate 236. In the following, the differences from Embodiment 1 will be mainly described, and the same reference numerals will be given to the common configurations.

[0032] As shown in FIGS. 9 to 11, the sleeve 235 is mounted on a portion of the inner peripheral surface of the suction passage 32 that is located upstream of the impeller 34, so as to guide the rotation of the impeller 34 and to function to guide the flow of oil to the inlet 34c. In the second embodiment, a sleeve 235 having a sleeve body 235a and a flange portion 235b is applied. As shown in FIGS. 8 to 12, the sleeve body 235a is configured such that its cross section is circular and its axis 235c is linear, and is formed to have an outer diameter that can be fitted inside the suction passage 32. The flange portion 235b is formed in a flat plate shape extending from one end of the sleeve body 235a toward the outer periphery. This sleeve 235 is fixed to the port block 2 by screwing a screw into the port block 2 through the flange portion 235b with the sleeve body 235a inserted inside the suction passage 32 and the flange portion 235b abutted against the outer surface of the port block 2.

[0033] The inner peripheral surface 235d of the sleeve body 235a is configured such that the end portion located on the upstream side has an inner diameter larger than that of the inlet 34c of the impeller 34, while being tapered so that the inner diameter gradually decreases toward the downstream side. An outer cylinder portion 235e that is slidably fitted to the outer peripheral portion of the impeller 34 is provided at the end portion of the sleeve body 235a that is located most downstream. A flared portion 235f having an inner diameter larger than that of the inner peripheral surface is formed at the end portion of the sleeve body 235a that is located most upstream. The downstream end portion 235g of the inner peripheral surface 235d of the sleeve body 235a that communicates with the inlet 34c of the impeller 34 is formed to have substantially the same inner diameter as the inlet 34c.

[0034] In addition, on the inner peripheral surface 235d of the sleeve body 235a, a plurality of rectifying grooves 235h are arranged in parallel at equal intervals along the circumferential direction. The rectifying grooves 235h are formed in a concave cylindrical shape, and the respective axial centers extend linearly along the axial center 235c of the sleeve body 235a. More specifically, the rectifying grooves 235h are provided with concave spherical surface portions above and below the portion forming the concave cylindrical shape. In the sleeve body 235a, a front-stage partition wall portion 235j is formed by ensuring an interval at a portion between the rectifying grooves 235h. The front-stage partition wall portion 235j is a portion where the inner peripheral surface 235d of the sleeve body 235a is exposed, and extends linearly along the axial center 235c of the sleeve body 235a. As is clear from the figure, the upstream end portions of the rectifying grooves 235h communicate with each other at the wide-mouth portion 235f with the respective concave spherical surface portions. The downstream end portions of the rectifying grooves 235h terminate individually at positions where an interval is ensured from the downstream end portion 235g communicating with the inlet 34c of the impeller 34 to the upstream side with the respective concave spherical surface portions.

[0035] As shown in FIGS. 9, 10, and 13, the orifice plate 236 has a disk-shaped thick plate portion 236a at the center and a thin plate portion 236b around the thick plate portion 236a. The thick plate portion 236a is inserted into the widened portion 235f of the sleeve 235, and the thin plate portion 236b is overlapped with the flange portion 235b of the sleeve 235 and then attached to the port block 2. An orifice hole (reduced diameter portion) 236c is provided at the center of the thick plate portion 236a of the orifice plate 236. The orifice hole 236c is formed to have an inner diameter smaller than that of the upstream end of the sleeve body 235a. Thus, when the orifice plate 236 is attached to the port block 2, the orifice plate 236 protrudes to the inner peripheral side of the sleeve body 235a, and an inversion surface 240 is formed inside the sleeve body 235a. That is, in the suction passage 32 in the state where the orifice plate 236 and the sleeve 235 are attached, after passing through the orifice hole 236c, the inner diameter of the sleeve body 235a once increases and then gradually decreases until reaching the impeller 34. In the second embodiment, the orifice hole 236c is formed in the orifice plate 236 so as to have the same inner diameter as the inlet 34c of the impeller 34.

[0036] The reversing surface 240 extends downstream so as to be orthogonal to the axis 32a of the suction passage 32. A plurality of reversing concave surfaces 241 are provided at portions around the orifice hole 236c on the reversing surface 240 at equal intervals along the circumferential direction. The reversing concave surface 241 is formed in a concave shape of a sphere that bulges toward the upstream side. As shown in FIG. 9, for each reversing concave surface 241, the center 241a of the sphere, which is the center of curvature, is located between the orifice hole 236c and the flared portion 235f, and has a portion that curves so as to gradually become downstream (upper side in FIG. 9) toward the axis 236d of the orifice hole 236c. As shown in FIGS. 9 to 11 and FIG. 13, a reversing partition portion 242 is formed at a portion between the reversing concave surfaces 241 in the thick plate portion 236a by ensuring a space. The reversing partition portion 242 is a portion where the reversing surface 240 is exposed, and extends radially along the radial direction with respect to the axis 236d of the orifice hole 236c. In the second embodiment, the same number of reversing partition portions 242 as the front-stage partition portion 235j are provided in the orifice plate 236 at a position corresponding to the front-stage partition portion 235j formed in the sleeve body 235a.

[0037] In the hydraulic pump unit configured as described above, when the input shaft 10 rotates due to the rotation of a drive source (not shown), the piston 21 reciprocates as the cylinder block 20 rotates. As a result, the oil sucked into the cylinder bore 20a through the suction pipe 50, the orifice hole 236c, the sleeve body 235a, the impeller 34, and the low-pressure port 24b of the valve plate 24 is supplied to various hydraulic devices through the high-pressure port 24a of the valve plate 24, the discharge passage 31, and an oil passage (not shown).

[0038] During this time, in the suction passage 32, the impeller 34 that rotates at an increased speed via the drive gear 14 and the driven gear 13 functions to increase the pressure of the oil from the suction pipe 50 to the low-pressure port 24b of the valve plate 24, so that the pump suction performance of the variable displacement swash plate piston pump can be improved.

[0039] Moreover, according to the above-described hydraulic pump unit, even when a swirling reverse flow occurs in the sleeve body 235a during over-supply operation such as when the input shaft 10 rotates at high speed, the swirling of the reverse flow is suppressed by the front-stage partition wall portion 235j provided on the inner peripheral surface 235d, and then it reverses by coming into contact with the reversing surface 240. That is, the swirling reverse flow of the oil generated in the sleeve body 235a during over-supply operation is rectified into an axial flow by coming into contact with the front-stage partition wall portion 235j, and then reverses by coming into contact with the reversing surface 240 of the orifice plate 236, and merges with the oil flowing into the orifice hole 236c from the suction pipe 50 to accelerate the flow toward the inlet 34c of the downstream impeller 34. Therefore, even during over-supply operation, it is possible to prevent problems such as surging occurring and the operation becoming unstable due to the occurrence of reverse flow vortex cavitation.

[0040] In particular, in the second embodiment, since the rectifying groove 235h has a concave cylindrical shape between the front-stage partition wall portions 235j and further provided with concave spherical surface portions at both upper and lower ends thereof, the swirling oil flow can be efficiently introduced into the rectifying groove 235h regardless of the incident angle of the reverse-flowing oil and arranged into a flow along the axial direction of the sleeve 235. Further, since the reversing surface 240 of the orifice plate 236 is provided with a spherical reversing concave surface 241, the oil flow after passing through the rectifying groove 235h can be guided downstream toward the axis 235c of the sleeve body 235a without disturbing it, and it becomes possible to surely prevent the situation where the reverse-flowing oil reaches the upstream suction pipe 50 beyond the orifice plate 236.

[0041] In addition, the orifice plate 236 is provided with an inversion partition portion 242 between the inversion concave surfaces 241. Therefore, the oil that has come into contact with the inversion surface 240 is guided toward the axis 235c of the sleeve body 235a while the diffusion in the circumferential direction is restricted by the inversion partition portion 242. As a result, the reverse flow of the oil that has reached the sleeve body 235a is efficiently inverted in the orifice plate 236, and it becomes possible to improve the pressurized feeding performance of the oil by the impeller 34 and the pump suction performance in the variable displacement swash plate piston pump during over-supply operation.

[0042] In the above-described Embodiment 1, Modification Example, and Embodiment 2, a turbo-type pump configured in the front stage of the variable displacement swash plate piston pump is exemplified. However, it is not necessarily limited to this, and it may be configured such that oil is directly supplied to a load such as a hydraulic device by a turbo-type pump including an impeller. The fluid does not necessarily have to be oil, and other liquids or gases may be used. As a drive source for driving the turbo-type pump, a hydraulic motor, a turbine, a windmill, or a waterwheel may be used.

[0043] In the above-described Embodiment 1, Modification Example, and Embodiment 2, since the inner diameter of the orifice hole is configured to be smaller than the inner diameter of the suction pipe, the oil that has passed through the suction pipe is constricted when passing through the orifice plate and then expands in the upstream portion of the sleeve body. Therefore, according to the above-described hydraulic pump unit, the oil inverted by the inversion concave surface of the orifice plate flows along the oil that expands upstream of the sleeve body, and there is no concern of causing a situation where reverse flow vortex cavitation occurs. However, the relationship between the inner diameter of the orifice hole of the orifice plate and the inner diameter of the suction pipe is not limited to the above example, and for example, the orifice hole and the suction pipe may be configured to have the same inner diameter.

[0044] Furthermore, in the above-described Embodiment 1, Modification Example, and Embodiment 2, the inner diameter of the upstream portion connected to the orifice plate in the sleeve body is configured in a tapered shape to be larger than that of the downstream portion, but it is not necessarily limited to this. When the sleeve body is configured in a tapered shape as in Embodiment 2, the inner diameter of the orifice hole can be set to the same dimension as the inlet of the impeller, and effects such as preventing a situation where pressure loss occurs in the oil flowing through the suction pipe can be achieved.

[0045] Moreover, in the above-described Embodiment 2, a spherical inversion concave surface is provided on the inversion surface, but it does not necessarily have to be spherical. For example, an inversion concave surface forming a concave shape of a cylinder may be provided so as to curve only from the outer peripheral side toward the inner peripheral side. Also in this case, it is preferable to provide the inversion concave surface such that the axis of the cylinder, which is the center of the curvature, is located on the outer peripheral side of the orifice hole that is the diameter-reduced portion. Further, a rectifying groove and a front-stage partition portion forming a cylindrical concave surface are provided on the inner peripheral surface of the sleeve body, but it is not necessarily required to provide the rectifying groove and the front-stage partition portion. Conversely, a rectifying groove or a front-stage partition portion may be provided on the inner peripheral surface of the sleeve body in Embodiment 1 and the Modification Example.

[0046] In addition, in the above-described Embodiment 1, Modification Example, and Embodiment 2, the inversion partition portions are provided at equal intervals along the circumferential direction, but it is not necessarily required to provide the inversion partition portions at equal intervals. Further, when the inversion partition portions are provided at unequal intervals, it is not necessarily required to provide the inversion concave surfaces to have the same size as each other. For example, the size of the inversion concave surface may be configured to change according to the interval between the inversion partition portions.

Explanation of Reference Numerals

[0047] 2 Port block 32 Suction passage 34 Impeller 35, 235 Sleeve 35a, 235a Sleeve body 235h Rectifying groove 235j Front-stage partition portion 36,136,236 orifice plate 36a,136a,236c orifice hole 40,140,240 inversion surface 41,141,241 inversion concave surface 42,142,242 inversion partition part

Claims

1. A turbo-type pump that pressurizes and feeds a fluid downstream of the fluid passage by the rotation of an impeller provided in the fluid passage, in a portion of the fluid passage located upstream of the impeller, a reduced-diameter portion is provided that reduces the inner diameter in a state of forming a reverse surface facing the downstream side, and on the reverse surface, a reverse partition portion that restricts the circumferential flow of the fluid is provided, a plurality of the reverse partition portions are provided at intervals along the circumferential direction of the fluid passage, a reverse concave surface that is curved from the outer peripheral side to the inner peripheral side of the fluid passage is provided between the reverse partition portions, and the turbo-type pump is characterized by this.

2. The turbo-type pump according to claim 1, wherein the reverse partition portion extends radially with respect to the axis of the reduced-diameter portion.

3. The turbo-type pump according to claim 1, wherein the reverse partition portion extends so as to be inclined in the rotation direction of the impeller from the outer peripheral side to the inner peripheral side with respect to the radius passing through the axis of the reduced-diameter portion.

4. The turbo-type pump according to claim 1, wherein the reverse concave surface is provided such that the center of curvature is located on the outer peripheral side of the reduced-diameter portion.

5. The turbo-type pump according to claim 1, wherein the reverse concave surface is formed to be spherical.

6. The turbo-type pump according to claim 1, wherein a front-stage partition portion that restricts the circumferential flow of the fluid is provided on the inner peripheral surface of a portion of the fluid passage located between the reduced-diameter portion and the impeller.

7. In the fluid passage, the portion located between the reduced-diameter portion and the impeller extends linearly along the rotation axis of the impeller, the front-stage partition portion is provided at a position corresponding to the reverse partition portion, the turbo-type pump according to claim 6, wherein a rectifying groove having a concave cylindrical shape is provided between the front-stage partition portions.

8. The turbo-type pump according to claim 1, wherein the portion of the fluid passage located between the reduced-diameter portion and the impeller is formed in a tapered shape such that the inner diameter gradually increases toward the upstream side.

9. The turbo-type pump according to claim 8, wherein the inner diameter of the portion of the fluid passage communicating with the impeller is the same as the inner diameter of the reduced-diameter portion.

10. A fluid supply unit comprising: a turbo-type pump according to any one of claims 1 to 9; and a positive displacement pump connected to a portion located downstream of the impeller in the fluid passage.

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