Non-positive displacement pump

Abstract

To provide a non-positive displacement pump capable of reducing slide resistance between a pump case and an impeller and improving pump performance.SOLUTION: An impeller 40 has a plurality of blade parts 62 and a plurality of through-flow paths 63 formed in a circumferential row radially inward of an outer peripheral surface 40a. A pump case 41 has a bracket 45, an inlet 42, a suction port 53 formed in the inlet 42, and a discharge port 48 formed in the bracket 45. An outside recess part 73 having an annular shape when viewed from a rotational axis direction is formed on a second slide contact surface of the inlet 42 radially outward of the blades parts 62 and the through-flow paths 63 and at a position overlapping with the outer peripheral surface 40a of the impeller 40 in the rotational axis direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a non-positive displacement pump. [Background technology]

[0002] Non-positive displacement pumps are used as liquid supply devices (fuel pumps) for vehicles such as motorcycles and automobiles. This type of non-positive displacement pump is installed inside a fuel tank. A non-positive displacement pump includes a disk-shaped impeller and a pump case formed to completely cover the impeller. Among non-positive displacement pumps, a so-called Westco pump has a plurality of blades arranged circumferentially around the outer periphery of the impeller. A plurality of through-flow passages are formed between each blade, penetrating the impeller in its thickness direction. The pump case accommodates the impeller for rotation. The pump case also has flow passage grooves formed in locations corresponding to the blades and through-flow passages, and an intake port and an exhaust port formed on either side of the impeller.

[0003] With this configuration, when the non-positive displacement pump is driven to rotate the impeller, fuel flows into the impeller's through-flow passage through the suction port in the pump case. The fuel that has entered the through-flow passage is compressed as the impeller rotates and is sent to the discharge port through the flow channel groove. The fuel is then discharged from the discharge port. As the impeller continues to rotate, fuel flows back into the through-flow passage from which it was discharged through the suction port.

[0004] When the impeller rotates, the pressure difference between the suction port side and the discharge port side creates a pressure difference that causes the impeller to tilt slightly relative to the rotation axis. At this time, the impeller is pressed against the inner surface of the pump case facing the impeller along the rotation axis, the inner surface closest to the suction port. This increases the sliding resistance between the pump case and the impeller, resulting in reduced pump performance. For this reason, various technologies have been disclosed to reduce the sliding resistance between the pump case and the impeller.

[0005] For example, a technique has been disclosed in which recesses (concave portions) are formed on the inner surfaces of the impeller or pump case (see, for example, Patent Document 1). This reduces the contact area between the pump case and the impeller, thereby reducing the sliding resistance between the pump case and the impeller. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 7-151091 Summary of the Invention [Problem to be solved by the invention]

[0007] However, some impellers for non-positive displacement pumps have blades or through-flow passages formed radially inward from the outer periphery of the impeller. In such cases, if the impeller tilts, the outer periphery of the impeller is pressed strongly against the pump case. For this reason, there is a problem in that simply forming recesses as in the above-mentioned conventional technology is not enough to sufficiently reduce sliding resistance. In the Westco pump of the above-mentioned prior art, the flow channel is formed in a location corresponding to the outer periphery of the impeller, so it was not anticipated that the outer periphery of the impeller would be pressed against the pump case.

[0008] Therefore, the present invention provides a non-positive displacement pump in which blade portions and through-flow passages are formed radially inward from the outer peripheral surface of the impeller, which can reduce the sliding resistance between the pump case and the impeller and improve pump performance. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, in a first aspect of the present invention, a non-positive displacement pump includes a disk-shaped impeller and a pump case formed to cover the entire impeller and accommodating the impeller so as to be rotatable around a radial center of the impeller as a rotation center, the impeller having a plurality of blade portions formed radially inward from an outer peripheral surface of the impeller and arranged side by side in a circumferential direction, and a plurality of through-flow passages formed between the blade portions adjacent in the circumferential direction and communicating an impeller first end face and an impeller second end face on both sides in a thickness direction of the impeller, and the pump case has a portion facing the impeller first end face. the pump case has a first wall portion having a case first end face facing the impeller second end face; a second wall portion having a case second end face facing the impeller second end face; an intake port formed in the first wall portion, penetrating the first wall portion and communicating with the through passage, through which liquid is drawn into the pump case; and a discharge port formed in the second wall portion, penetrating the second wall portion and communicating with the through passage, through which the liquid is discharged to the outside of the pump case. An outer recess that is annular when viewed from the rotational axis direction is formed on the case first end face, radially outward of the blade portion and the through passage, and at a position that overlaps with the outer peripheral surface of the impeller in the rotational axis direction.

[0010] With this configuration, the outer recess can reduce the contact area between the pump case and the impeller. In a non-positive displacement pump in which the blades and through-flow passages are formed radially inward of the outer periphery of the impeller, the outer recess prevents the outer periphery of the impeller from being pressed against the pump case even when the impeller tilts as it rotates, thereby further reducing the sliding resistance between the pump case and the impeller and improving pump performance. The outer recess increases the allowable range of tilt angle when the impeller rotates. This makes it easier for liquid (fuel) to flow into the gap between the pump case and impeller that occurs when the impeller tilts. This forms a film between the pump case and impeller, reliably reducing the sliding resistance between the pump case and impeller.

[0011] In a second aspect of the present invention, in the non-positive displacement pump of the first aspect, an annular inner recess may be formed in the first end face of the case, radially inward from the blade portion and the through passage, as viewed from the direction of the rotation axis.

[0012] With this configuration, the contact area between the pump case and the impeller can be further reduced by the inner recess, thereby further reducing the sliding resistance between the pump case and the impeller.

[0013] In a third aspect of the present invention, in the non-positive displacement pump of the first or second aspect, a shaft mounting hole is formed in the radial center of the impeller, penetrating the impeller in the thickness direction and into which an input shaft for rotating the impeller is attached, and the inner recess may be connected to the shaft mounting hole.

[0014] This configuration allows liquid to easily flow into the inner recess through the shaft mounting hole. This makes it easier for the inner recess to form a film between the pump case and the impeller. By enlarging the inner recess so that it communicates with the shaft mounting hole, the pressure-receiving area of ​​the inner recess of the impeller also increases. The shaft mounting hole makes it possible to equalize the pressure of the liquid on both sides of the impeller in the thickness direction. This reduces the pressing force of the impeller against the pump case on the suction port side, further reducing the sliding resistance between the pump case and the impeller.

[0015] In a fourth aspect of the present invention, in the non-positive displacement pump of any one of the first to third aspects, a flow path groove is formed in the first case end face, between the suction port and a point opposite the discharge port in the rotational axis direction, so as to extend along the circumferential direction and communicate with the through flow path, and an outer seal surface is formed in the first case end face between the outer recess and the flow path groove, so as to prevent leakage of the liquid from the flow path groove to the outer recess, and the size of the gap between the outer seal surface and the impeller may be smaller than the size of the gap between the bottom surface of the outer recess and the impeller.

[0016] This configuration can prevent liquid from leaking from the flow channel into the outer recess, thereby improving the drive efficiency of the non-positive displacement pump.

[0017] In a fifth aspect of the present invention, in the non-positive displacement pump of the second or third aspect, a flow path groove is formed in the first case end face, between the suction port and a point opposite the discharge port in the direction of the rotation axis, so as to extend along the circumferential direction and communicate with the through flow path, and an inner seal surface is formed in the first case end face between the inner recess and the flow path groove, so as to prevent leakage of the liquid from the flow path groove to the inner recess, and the size of the gap between the inner seal surface and the impeller may be smaller than the size of the gap between the bottom surface of the inner recess and the impeller.

[0018] This configuration can prevent liquid from leaking from the flow channel into the inner recess, thereby improving the drive efficiency of the non-positive displacement pump.

[0019] In a sixth aspect of the present invention, in the non-positive displacement pump of any one of the first to fifth aspects, a gap may be formed between the outer peripheral surface of the impeller and the pump case, and the gap may be connected to the outer recess.

[0020] The gap between the outer circumferential surface of the impeller and the pump case is likely to be filled with liquid leaking from the discharge port side of the impeller. In other words, liquid with a higher pressure than the suction port side is likely to flow into the outer recess side through the gap between the outer circumferential surface of the impeller and the pump case. This increases the pressure of the liquid on the suction port side of the impeller, reducing the force pressing the impeller against the pump case. This further reduces the sliding resistance between the pump case and the impeller.

[0021] In a seventh aspect of the present invention, a non-positive displacement pump includes a disk-shaped impeller and a pump case formed to cover the entire impeller and accommodating the impeller so as to be rotatable around a radial center of the impeller as a rotation center, the impeller having a plurality of blade portions formed in a row in a circumferential direction radially inward from an outer peripheral surface of the impeller, and a plurality of through-flow passages formed between adjacent blade portions in the circumferential direction and communicating an impeller first end face and an impeller second end face on both sides in a thickness direction of the impeller, the pump case having a first wall portion having a case first end face opposite the impeller first end face, The pump case has a second wall portion having a case second end face opposite to the impeller second end face, an intake port formed in the first wall portion, penetrating the first wall portion and communicating with the through passage, through which liquid is drawn into the pump case, and an outlet port formed in the second wall portion, penetrating the second wall portion and communicating with the through passage, through which the liquid is discharged outside the pump case, and an annular outer recess is formed on the case first end face, radially outward of the blade portion and the through passage, at a position that overlaps with the outer peripheral surface of the impeller in the direction of the rotational axis, and the outer recess is arranged at least in the vicinity of the outlet port.

[0022] With this configuration, in a non-positive displacement pump in which the blades and through-flow passages are formed radially inward of the outer periphery of the impeller, even if the impeller tilts as it rotates, the outer recess can prevent the outer periphery of the impeller from being pressed against the pump case, thereby reducing the sliding resistance between the pump case and the impeller and improving pump performance. The outer recess increases the allowable range of tilt angle when the impeller rotates. This makes it easier for liquid to flow into the gap between the pump case and the impeller that occurs when the impeller tilts. This forms a film between the pump case and the impeller, reliably reducing the sliding resistance between the pump case and the impeller. [Effects of the Invention]

[0023] According to the present invention, in a non-positive displacement pump in which blade portions and through-flow passages are formed radially inward from the outer peripheral surface of the impeller, the sliding resistance between the pump case and the impeller can be reduced, thereby improving pump performance. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a perspective view of a liquid supply device according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view taken along the axial direction of a liquid supply device according to an embodiment of the present invention. [Figure 3] FIG. 2 is a perspective view of an impeller according to an embodiment of the present invention. [Figure 4] FIG. 2 is an enlarged axial cross-sectional view of a pump portion according to an embodiment of the present invention. [Figure 5] FIG. 2 is a plan view of the bracket body according to the embodiment of the present invention, viewed from the inlet side. [Figure 6] FIG. 2 is a plan view of the inlet according to the embodiment of the present invention, viewed from the bracket main body side. [Figure 7] FIG. 10 is a cross-sectional view taken along the axial direction of a liquid supply device according to a modified example of the embodiment of the present invention. [Figure 8] FIG. 8 is an enlarged view of part VIII in FIG. 7. [Figure 9] FIG. 10 is a plan view of an inlet according to a modified example of the embodiment of the present invention, as viewed from the bracket main body side. DETAILED DESCRIPTION OF THE INVENTION

[0025] Next, an embodiment of the present invention will be described with reference to the drawings.

[0026] <Liquid supply device> Fig. 1 is a perspective view of the liquid supply device 1. Fig. 2 is a cross-sectional view of the liquid supply device 1 taken along the axial direction. The liquid supply device 1 is used as a fuel pump for vehicles such as motorcycles, four-wheeled vehicles, etc. The liquid supply device 1 is a so-called in-tank fuel pump that is disposed inside a fuel tank (not shown).

[0027] As shown in Figures 1 and 2, the liquid supply device 1 includes a cylindrical metal housing 2, a motor unit 3, and a pump unit 4 that are fitted onto the inner circumferential surface of the housing 2 and are arranged side by side in the axial direction of the housing 2. The rotation axis of the motor unit 3 coincides with the axial direction of the housing 2. The housing 2, motor unit 3, and pump unit 4 are arranged coaxially.

[0028] The liquid supply device 1 is used with the pump section 4 facing downward in the direction of gravity. For this reason, in the following description, the motor section 3 side may be referred to as the upper side and the pump section 4 side as the lower side. In addition, in the following description, the axial direction of the housing 2, motor section 3, and pump section 4 will be simply referred to as the axial direction, the radial direction of the housing 2, motor section 3, and pump section 4 will be simply referred to as the radial direction, and the circumferential direction of the housing 2, motor section 3, and pump section 4 will be simply referred to as the circumferential direction.

[0029] <Housing> The housing 2 is integrally molded with a motor fitting portion 11 into which the motor portion 3 is fitted, and a pump fitting portion 12 which is formed with a smaller diameter than the motor fitting portion 11 via a step and into which the pump portion 4 is fitted. An inner flange portion 12a is bent and extended radially inward from the lower end of the pump fitting portion 12 of the housing 2. The inner flange portion 12a determines the axial positioning of the housing 2 and the pump portion 4.

[0030] <Motor section> A brushed motor, for example, is used as the motor unit 3. The motor unit 3 mainly comprises a cylindrical yoke 5, a permanent magnet 8 provided on the inner peripheral surface of the yoke 5, an armature 6 rotatably provided within the yoke 5, a cylindrical outlet cover 7 with a bottom that closes the upper opening 5a of the yoke 5, and brushes 25 housed in the outlet cover 7. The outer peripheral surface of the yoke 5 is fitted into the inner peripheral surface of the housing 2.

[0031] The yoke 5 serves as a magnetic path through which the magnetic flux of the permanent magnet 8 passes. The upper opening 5a of the yoke 5 is fitted to the outer peripheral surface of the outlet cover 7. A minute gap is formed between the inner peripheral surface of the permanent magnet 8 and the radially outer ends of the teeth 17 (described later) of the armature core 15 and the resin molded portion 22.

[0032] The armature 6 mainly comprises a shaft 14, an armature core 15 fitted and fixed to the outer peripheral surface of the shaft 14, and a commutator 16 fitted and fixed to the outer peripheral surface of the shaft 14 closer to the outlet cover 7 than the armature core 15. The armature core 15 has a plurality of teeth 17 extending radially outward. A winding (not shown) is wound around these teeth 17. An end of the winding is connected to a commutator 16.

[0033] The commutator 16 is a so-called disk-type commutator having a disc-shaped resin commutator body 18. A plurality of segments 19 are arranged in the circumferential direction on one surface 18a of the commutator body 18 opposite to the armature core 15. One end of a winding (not shown) is connected to each segment 19.

[0034] The armature 6 formed in this manner is mostly covered with a resin molded portion 22. The resin molded portion 22 is formed in a cylindrical shape. The resin molded portion 22 extends from the pump portion 4 side of the armature core 15 to the axial center of the commutator body 18. Only the radial outer ends (outer peripheral surfaces) of the teeth 17 of the armature core 15 are exposed. The windings (not shown) are covered with the resin molded portion 22.

[0035] The outlet cover 7 has an opening 7a on the armature core 15 side. The upper opening 5a of the yoke 5 is fitted into the outer peripheral surface of this opening 7a side. Furthermore, the outer peripheral surface of the upper opening 5a of the yoke 5 is covered by a motor fitting portion 11. The upper opening edge 11a of the motor fitting portion 11 is crimped radially inward from above the outlet cover 7. A cylindrical bearing portion 23 is integrally formed in the radial center of the bottom portion 7b of the outlet cover 7, protruding toward the armature core 15. An upper end portion 14a of the shaft 14 is rotatably supported by this cylindrical bearing portion 23.

[0036] Brush holders 24 are integrally molded on both sides of the cylindrical bearing portion 23 at the bottom portion 7b of the outlet cover 7. The brush holders 24 are formed in a box shape with an opening on the commutator 16 side. Brushes 25 are housed in the brush holders 24 so that they can slide axially. Coil springs 26 are housed in the brush holders 24 in a compressed and deformed state. The brushes 25 are urged toward the commutator 16 by the coil springs 26. The tips of the brushes 25 protrude from the brush holders 24 and are in sliding contact with the segments 19.

[0037] A terminal 27 is provided on the bottom 7b of the outlet cover 7, penetrating the bottom 7b in the vertical direction. The brush 25 is connected to the terminal 27 via a pigtail (not shown). An external power supply (not shown) is connected to the terminal 27. This supplies external power to the winding (not shown) via the terminal 27, the pigtail (not shown), the brush 25, and the segments 19. Furthermore, an upwardly protruding discharge port 28 is integrally formed on the bottom portion 7b of the outlet cover 7. The discharge port 28 is a location from which the fuel pumped up by the liquid supply device 1 is discharged, and is connected to a fuel flow path (not shown).

[0038] <Pump section> The pump section 4 is a non-positive displacement pump having an impeller 40. The pump section 4 is composed of the impeller 40 and a pump case 41 formed to cover the entire impeller 40. The pump case 41 is fitted into the pump fitting section 12 of the housing 2.

[0039] <Impeller> FIG. 3 is a perspective view of the impeller 40. As shown in FIG. 2 and 3, the impeller 40 is a disc-shaped member made of a resin material. A shaft mounting hole 61 is formed in the radial center of the impeller 40, penetrating the impeller 40 in the thickness direction. The lower end portion 14b of the shaft 14 is inserted into the shaft mounting hole 61 for mounting.

[0040] Here, the lower end 14b of the shaft 14 has a D-shaped cross section along the radial direction. The shaft mounting hole 61 of the impeller 40 is D-shaped when viewed in the axial direction so as to correspond to the cross section of the lower end 14b of the shaft 14. By inserting the lower end 14b of the shaft 14 into such a shaft mounting hole 61, the shaft 14 and the impeller 40 rotate integrally but are unable to rotate relative to each other.

[0041] The impeller 40 is formed with a plurality of blades 62 having an L-shaped cross section along the axial direction, radially inward of the outer peripheral surface 40a. The blades 62 are arranged at equal intervals in the circumferential direction so that they face in the same circumferential direction. A through-flow passage 63 is formed between adjacent blades 62 in the circumferential direction. The through-flow passage 63 penetrates the impeller 40 so as to communicate with both end faces 40b, 40c (upper end face 40b, lower end face 40c) in the thickness direction.

[0042] <Pump case> FIG. 4 is an enlarged cross-sectional view of the pump section 4 taken along the axial direction. As shown in Figures 2 and 4, the pump case 41, which covers the entire impeller 40, is composed of a bracket 45 arranged on the motor section 3 side and an inlet (an example of the first wall section in the claims) 42 arranged below the bracket 45. The bracket 45 includes a bracket main body (an example of a second wall portion in the claims) 43 disposed on the upper end surface 40b (an example of the second impeller end surface in the claims) of both end surfaces 40b, 40c of the impeller 40, and a cylindrical portion 44 extending downward from the outer periphery of the bracket main body 43. The bracket main body 43 is formed in a disk shape so as to cover the upper end surface 40b of the impeller 40. The outer diameter of the bracket main body 43 is set to be slightly smaller than the outer diameter of the yoke 5.

[0043] FIG. 5 is a plan view of the bracket body 43 as seen from the inlet 42 side (below). 4 and 5, an insertion hole 46, through which the lower end portion 14b of the shaft 14 can be inserted, is formed in the radial center of the bracket body 43. The shaft 14 is rotatably supported in this insertion hole 46 via a sliding bearing 59.

[0044] A recess 47 that is annular when viewed from the axial direction is formed on the upper surface 43a of the bracket main body 43 so as to surround the insertion hole 46. The portion of the upper surface 43a of the bracket main body 43 that is outer than the recess 47 serves as a contact surface 43b against which the yoke 5 abuts. Sufficient space is ensured for the contact surface 43b. Therefore, even when the lower end of the yoke 5 abuts against the contact surface 43b, buckling deformation of the contact surface 43b and the yoke 5 is suppressed.

[0045] Furthermore, an outlet port 48 that penetrates the bracket body 43 in the up-down direction is formed in the upper surface 43a of the bracket body 43 near the outer periphery of the recess 47. A recess 48a that widens the opening of the outlet port 48 is formed in the lower surface 43c of the bracket body 43 around the periphery of the outlet port 48. The recess 48a is formed so as to widen toward the lower surface 43c of the bracket body 43.

[0046] The lower surface 43c of the bracket main body 43 is a first sliding contact surface (an example of a case second end surface in the claims) 43d that comes into sliding contact with the upper end surface 40b of the impeller 40. A bracket recess 43e is formed in the radial center of the first sliding contact surface 43d. The bracket recess 43e is formed in an annular shape when viewed in the axial direction so as to surround the periphery of the insertion hole 46. The bracket recess 43e is in communication with the insertion hole 46. The bracket recess 43e also communicates with the shaft mounting hole 61 of the impeller 40 that comes into sliding contact with the first sliding contact surface 43d.

[0047] A first flow passage groove 64 is formed in the first sliding contact surface 43d at a position facing the through flow passage 63 of the impeller 40 in the axial direction. The first flow passage groove 64 is formed in an arc shape (C-shape) when viewed in the axial direction. The first flow passage groove 64 is disposed at a predetermined distance in the radial direction from the bracket recess 43e. One circumferential end of the first flow passage groove 64 communicates with the discharge port 48 (recess 48a). A tapered portion 64a is formed at the other circumferential end of the first flow passage groove 64 so as to taper when viewed in the axial direction.

[0048] The cylindrical portion 44 is formed integrally with the bracket body 43. The cylindrical portion 44 has an outer diameter slightly larger than that of the bracket body 43 and surrounds the impeller 40. The cylindrical portion 44 aligns the radial center of the impeller 40 with the axial center A of the shaft 14. The axial thickness of the cylindrical portion 44 is the same as or slightly greater than the plate thickness of the impeller 40. This allows predetermined clearances to be formed between the impeller 40 and the bracket body 43, and between the impeller 40 and the inlet 42. This allows the impeller 40 to slide smoothly with the bracket body 43 and the inlet 42, respectively. In addition, a predetermined gap C (an example of a gap in the claims) is formed between the inner peripheral surface 44a of the cylindrical portion 44 and the outer peripheral surface 40a of the impeller 40. Hereinafter, this gap C will be referred to as the outer peripheral gap C.

[0049] FIG. 6 is a plan view of the inlet 42 as seen from the bracket main body 43 side (above). 4 and 6, pump case 41 is formed to cover the entire impeller 40 by bracket main body 43, which is integrally formed with cylindrical portion 44, and inlet 42. A lower surface 43c of bracket main body 43 and an upper surface 42a of inlet 42 form a storage section 60 that stores impeller 40. The inlet 42 is formed in a disk shape. The outer diameter of the inlet 42 is set to be substantially the same as the outer diameter of the cylindrical portion 44.

[0050] A cylindrical intake port 53 is formed on the lower surface 42b of the inlet 42, protruding downward on the outer periphery. The inner circumferential surface of the intake port 53 is tapered so that the inner diameter gradually increases from bottom to top. A lower chamfered flat 53a is formed on the inner circumferential edge of the lower end of the intake port 53. An upper chamfered flat 53b is formed on the inner circumferential edge of the upper end of the intake port 53. The size of the lower chamfered flat 53a is larger than the size of the upper chamfered flat 53b.

[0051] Furthermore, a step 49 is formed on the outer circumferential edge of the lower surface 42b of the inlet 42. The step 49 is formed by reducing the diameter of the lower surface 42b side of the inlet 42. The step 49 is formed at a position overlapping the inner flange portion 12a of the housing 2 when viewed in the axial direction.

[0052] The upper surface 42a of the inlet 42 is a second sliding contact surface (an example of a case first end surface in the claims) 42c that is in sliding contact with the lower end surface 40c (an example of an impeller first end surface in the claims) of the impeller 40, one of the two end surfaces 40b, 40c. A bearing accommodating recess 54 is formed in the radial center of the second sliding contact surface 42c. The lower end portion 14b of the shaft 14 is inserted into the bearing accommodating recess 54. A thrust bearing 55 is accommodated in the bearing accommodating recess 54. The lower end portion 14b of the shaft 14 is rotatably supported by the inlet 42 while abutting against the thrust bearing 55. The thrust bearing 55 bears the thrust load of the shaft 14.

[0053] A stepped recess 71 having an inner diameter larger than the inner diameter of the bearing accommodating recess 54 is formed in the opening 54a of the bearing accommodating recess 54. The depth of the stepped recess 71 is sufficiently shallower than the depth of the bearing accommodating recess 54. Furthermore, an inner recess 72 having a circular shape when viewed from the axial direction is formed in the second sliding contact surface 42c so as to surround the periphery of the stepped recess 71. The inner recess 72 has a rectangular cross section along the radial and axial directions.

[0054] The inner recess 72 communicates with the stepped recess 71. That is, the inner recess 72, the stepped recess 71, and the bearing accommodating recess 54 communicate with one another. These recesses 72, 71, and 54 also communicate with the shaft mounting hole 61 of the impeller 40 placed on the second sliding contact surface 42c. The depth of the inner recess 72 is shallower than the depth of the stepped recess 71. The inner diameter of the inner recess 72 is larger than the inner diameter of the bracket recess 43e.

[0055] A second flow passage groove (an example of a flow passage groove in the claims) 65 is formed on the second sliding contact surface 42c at a position facing the through flow passage 63 of the impeller 40 in the axial direction and at a position facing the first flow passage groove 64 of the bracket body 43. The second flow passage groove 65 is formed in an arc shape (C-shape) when viewed in the axial direction. The second flow passage groove 65 is disposed at a predetermined distance in the radial direction from the inner recess 72. One circumferential end of the second flow passage groove 65 communicates with the suction port 53. A tapered portion 65a is formed at the other circumferential end of the second flow passage groove 65 so as to be tapered when viewed in the axial direction.

[0056] Here, the intake ports 53 communicating with one circumferential end of the second flow passage groove 65 and the tapered portions 65a formed at the other circumferential end of the second flow passage groove 65, and the discharge ports 48 communicating with one circumferential end of the first flow passage groove 64 and the tapered portions 64a formed at the other circumferential end of the first flow passage groove 64 are arranged alternately. That is, the discharge ports 48 are opposed to the tapered portions 65a of the second flow passage groove 65 in the axial direction. The intake ports 53 are opposed to the tapered portions 64a of the first flow passage groove 64 in the axial direction.

[0057] Further, a vent hole 68 is formed in the second flow passage groove 65, slightly closer to the suction port 53 than the center between the suction port 53 and the tapered portion 65a, so as to penetrate in the thickness direction of the inlet 42. The vent hole 68 is a hole for discharging vapor (air bubbles) generated inside the pump case 41.

[0058] An outer recess 73 having a circular shape as viewed from the axial direction is formed on the second sliding contact surface 42c radially outward of the second flow path groove 65. The outer recess 73 has a rectangular cross section along the radial and axial directions. The outer recess 73 is formed at a position overlapping with the outer peripheral surface 40a of the impeller 40 in the axial direction. In other words, the outer peripheral surface 40a of the impeller 40 is disposed at the location where the outer recess 73 is formed as viewed from the axial direction. Therefore, even when the impeller 40 is stored in the storage portion 60 of the pump case 41, the outer recess 73 and the outer peripheral gap C are in communication.

[0059] Returning to FIG. 2 , a square ring 50 serving as a sealing member is attached to a stepped portion 49 formed on the underside 42b of the inlet 42. The square ring 50 is a member having a rectangular cross section and made of a material with excellent oil resistance, such as fluororubber. The outer diameter of the square ring 50 is set slightly smaller than the outer diameter of the inlet 42. Therefore, the outer peripheral surfaces of the bracket main body 43, the cylindrical portion 44, and the inlet 42 are fitted into the pump fitting portion 12 of the housing 2. A small gap is formed between the outer peripheral surface of the square ring 50 and the inner peripheral surface of the pump fitting portion 12 of the housing 2.

[0060] When assembling the liquid supply device 1, the motor unit 3 and the pump unit 4 are housed in the housing 2, and the square ring 50 is brought into contact with the inner flange 12a of the housing 2. Then, with the square ring 50 slightly compressed by the step 49 of the inlet 42 and the inner flange 12a, the upper opening edge 11a of the motor fitting portion 11 is crimped radially inward from above the outlet cover 7.

[0061] As a result, the pump section 4 is fitted into the pump fitting section 12 of the housing 2. Furthermore, the motor section 3 is fitted into the motor fitting section 11 of the housing 2. The motor section 3 and the pump section 4 are then positioned relative to the housing 2, and the housing 2, motor section 3, and pump section 4 are integrated together. Furthermore, the square ring 50 ensures sealing between the housing 2 and the pump section 4. This completes the assembly of the liquid supply device 1.

[0062] <Operation of the liquid supply device> Next, the operation of the liquid supplying apparatus 1 will be described. When the liquid supply device 1 is driven to rotate the shaft 14 of the motor unit 3, the impeller 40 rotates integrally with the shaft 14. As a result, fuel is sucked into the pump case 41 through the suction port 53. The sucked fuel enters the through-flow passage 63 of the impeller 40. The fuel then enters the first flow passage groove 64 of the bracket body 43 and the second flow passage groove 65 of the inlet 42. A swirling flow is then generated between the impeller 40 and the pump case 41. This swirling flow increases the pressure of the fuel in the through-flow passage 63 as it moves toward the discharge port 48.

[0063] The pressurized fuel is discharged into the yoke 5 of the motor unit 3 through the discharge port 48. In other words, the pressure of the fuel at the discharge port 48 is greater than the pressure of the fuel at the suction port 53. Therefore, a force acts at the discharge port 48 to press the impeller 40 against the inlet 42 (see arrow F in FIG. 4). As a result, the impeller 40 tilts around the shaft 14 within the housing portion 60 of the pump case 41 (see arrow Y in FIG. 4).

[0064] Here, an outer recess 73 is formed on the second sliding contact surface 42c of the inlet 42. The outer peripheral surface 40a of the impeller 40 is disposed at the location where the outer recess 73 is formed when viewed from the axial direction. Therefore, when the impeller 40 tilts, the outer peripheral edge of the impeller 40 fits into the outer recess 73. Therefore, the outer peripheral edge of the impeller 40 is not pressed against the second sliding contact surface 42c of the inlet 42.

[0065] Furthermore, because the outer recess 73 prevents the impeller 40 from coming into contact with the inlet 42, the inclination of the impeller 40 becomes slightly greater compared to when the outer recess 73 is not formed. As a result, a gap is generated between the second sliding contact surface 42c of the inlet 42 and the first sliding contact surface 43d of the bracket main body 43 and the impeller 40. Fuel flows into this gap, and an oil film is likely to form between the second sliding contact surface 42c of the inlet 42 and the first sliding contact surface 43d of the bracket main body 43 and the lower end surface 40c of the impeller 40.

[0066] The impeller 40 is accommodated in the accommodation portion 60 of the pump case 41 so that a predetermined clearance is formed between the impeller 40 and the bracket body 43, and between the impeller 40 and the inlet 42. For this reason, a small amount of fuel discharged from the discharge port 48 leaks between the first sliding contact surface 43d of the bracket body 43 and the upper end surface 40b of the impeller 40. A portion of this leaked fuel flows into the outer peripheral gap C. Since the outer peripheral gap C is in communication with the outer recess 73, the fuel flows into the outer recess 73 via the outer peripheral gap C.

[0067] In other words, by arranging the blade portion 62 and the through flow passage 63 radially inward of the outer peripheral surface 40a of the impeller 40, the outer peripheral gap C formed between the inner peripheral surface 44a of the cylindrical portion 44 in the pump case 41 and the outer peripheral surface 40a of the impeller 40 can function as a flow passage that flows fuel on the bracket main body 43 side toward the inlet 42 side. As a result, the pressure of the fuel between the second sliding contact surface 42c of the inlet 42 and the lower end surface 40c of the impeller 40 increases, and the pressing force of the impeller 40 against the inlet 42 decreases.

[0068] Furthermore, an inner recess 72 is formed on the second sliding contact surface 42c of the inlet 42. Therefore, the contact area between the second sliding contact surface 42c of the inlet 42 and the lower end surface 40c of the impeller 40 is reduced. The inner recess 72 is in communication with the shaft mounting hole 61 of the impeller 40 via the stepped recess 71 and the bearing housing recess 54. Therefore, a portion of the fuel discharged from the discharge port 48 via the shaft mounting hole 61 and a portion of the fuel drawn into the pump case 41 from the suction port 53 flow into and fill the recesses 72, 71, 54.

[0069] Because the shaft mounting hole 61 is also in communication with the bracket recess 43e of the bracket 45, the bracket recess 43e, the shaft mounting hole 61, the inner recess 72, the stepped recess 71, and the bearing accommodating recess 54 are all at the same pressure as the fuel filling them. This reduces the differential pressure between both sides of the impeller 40 in the thickness direction. The stepped recess 71 and the bearing accommodating recess 54 are formed so that the inner recess 72 is in communication with the shaft mounting hole 61, and this increases the pressure-receiving area on the inlet 42 side of the impeller 40. Moreover, the inner diameter of the inner recess 72 is larger than the inner diameter of the bracket recess 43e. This further increases the pressure-receiving area of ​​the inner recess 72 of the impeller 40.

[0070] The fuel that has passed through the first flow passage groove 64 of the bracket body 43 and the second flow passage groove 65 of the inlet 42 and is discharged from the discharge port 48 is pumped through a minute gap between the permanent magnet 8 and the resin molded portion 22 (the radially outer end of the teeth 17 of the armature core 15) and is then pumped to the discharge port 28. Thereafter, the fuel is pumped through the discharge port 28 to an engine or the like (not shown).

[0071] Here, the size of the gap between the first sliding contact surface 43d of the bracket main body 43 and the upper end surface 40b of the impeller 40 is smaller than the size of the gap between the first flow path groove 64 formed in the bracket main body 43 or the bottom surface of the bracket recess 43e and the upper end surface 40b of the impeller 40. Therefore, the first sliding contact surface 43d functions as a bracket-side sealing surface 43f that suppresses leakage of fuel from the first flow path groove 64.

[0072] On the other hand, the size of the gap between the second sliding contact surface 42c of the inlet 42 and the lower end surface 40c of the impeller 40 is smaller than the size of the gap between the bottom surfaces of the second flow path groove 65, the inner recess 72, and the outer recess 73 formed in the inlet 42 and the lower end surface 40c of the impeller 40. Therefore, the second sliding contact surface 42c functions as an inlet-side sealing surface 42d that suppresses leakage of fuel from the second flow path groove 65. The inlet-side seal surface 42d, between the inner recess 72 and the second flow passage groove 65, forms an inner seal surface 74 that suppresses leakage of fuel from the second flow passage groove 65 to the inner recess 72. The inlet-side seal surface 42d, between the outer recess 73 and the second flow passage groove 65, forms an outer seal surface 75 that suppresses leakage of fuel from the second flow passage groove 65 to the outer recess 73.

[0073] In this way, in the above-described liquid supply device 1, the blade portion 62 and the through-flow passage 63 are formed radially inward of the outer peripheral surface 40a of the impeller 40. In such liquid supply device 1, an outer recess 73 is formed in the second sliding contact surface 42c of the inlet 42. The outer recess 73 is formed at a position overlapping with the outer peripheral surface 40a of the impeller 40 in the axial direction.

[0074] With this configuration, the contact area between the inlet 42 and the impeller 40 can be reduced, and the sliding resistance between the inlet 42 and the impeller 40 can be reduced. Even if the impeller 40 tilts as it rotates, the outer circumferential edge of the impeller 40 can be prevented from being pressed against the second sliding contact surface 42c of the inlet 42. This further reduces the sliding resistance between the inlet 42 and the impeller 40, and improves the pump performance of the liquid supply device 1. Furthermore, the outer recess 73 increases the allowable range of tilt angle when the impeller 40 rotates. This makes it easier for fuel to flow into the gap between the inlet 42 and the impeller 40 that occurs when the impeller 40 tilts. This allows an oil film to be formed between the inlet 42 and the impeller 40, ensuring a reduction in sliding resistance between the inlet 42 and the impeller 40.

[0075] An inner recess 72 is formed on the second sliding contact surface 42c of the inlet 42. This allows the contact area between the inlet 42 and the impeller 40 to be further reduced, and the sliding resistance between the inlet 42 and the impeller 40 to be further reduced. The inner recess 72 is in communication with the shaft mounting hole 61 of the impeller 40. This makes it easier for fuel to flow into the inner recess 72 via the shaft mounting hole 61. This makes it easier for an oil film to form between the inlet 42 and the impeller 40 due to the inner recess 72. The pressure difference between both sides of the impeller 40 in the thickness direction can be reduced via the shaft mounting hole 61. This reduces the pressing force of the impeller 40 against the inlet 42, further reducing the sliding resistance between the inlet 42 and the impeller 40.

[0076] Since the stepped recess 71 and the bearing accommodating recess 54 are formed so that the inner recess 72 is in communication with the shaft mounting hole 61, the pressure-receiving area on the inlet 42 side of the impeller 40 is also increased. Moreover, the inner diameter of the inner recess 72 is larger than the inner diameter of the bracket recess 43e. This further increases the pressure-receiving area of ​​the inner recess 72 of the impeller 40. This ensures that the pressure between the inlet 42 and the impeller 40 can be increased. As a result, the sliding resistance between the inlet 42 and the impeller 40 can be further reduced.

[0077] The second sliding contact surface 42c of the inlet 42 functions as an inlet-side seal surface 42d that suppresses leakage of fuel from the second flow path groove 65. Of the inlet-side seal surface 42d, the portion between the inner recess 72 and the second flow path groove 65 serves as an inner seal surface 74 that suppresses leakage of fuel from the second flow path groove 65 to the inner recess 72. Of the inlet-side seal surface 42d, the portion between the outer recess 73 and the second flow path groove 65 serves as an outer seal surface 75 that suppresses leakage of fuel from the second flow path groove 65 to the outer recess 73. This improves the drive efficiency of the liquid supply device 1.

[0078] The outer recess 73 is connected to the outer peripheral gap C. Here, the outer peripheral gap C is likely to be filled with fuel leaking from the discharge port 48 side of the impeller 40. In other words, fuel with a higher pressure than the fuel on the suction port 53 side is likely to flow into the outer recess 73 side through the outer peripheral gap C. This increases the pressure of the oil film on the suction port 53 side of the impeller 40. As a result, the pressing force of the impeller 40 against the inlet 42 can be reduced. Therefore, the sliding resistance between the inlet 42 and the impeller 40 can be further reduced.

[0079] Since the sliding resistance between the inlet 42 and the impeller 40 can be reduced and the pump performance of the liquid supply device 1 can be improved, it will be possible to contribute to Goal 7 of the United Nations-led Sustainable Development Goals (SDGs), "Ensure access to affordable, reliable, sustainable and modern energy for all," and Goal 9, "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

[0080] [Variations] The present invention is not limited to the above-described embodiment, and includes various modifications to the above-described embodiment without departing from the spirit of the present invention.

[0081] For example, in the above embodiment, the inner recess 72 and the outer recess 73 formed on the second sliding contact surface 42c of the inlet 42 are described as having rectangular cross sections along the radial and axial directions. However, this is not limited to this, and the shapes of the inner recess 72 and the outer recess 73 can be determined arbitrarily. For example, the inner recess 72 and the outer recess 73 may be formed in a stepped shape with multiple recesses of different depths. For example, the inner recess 72 and the outer recess 73 may be formed in a tapered inclined shape. This tapered shape will be described in detail below.

[0082] Fig. 7 is a cross-sectional view taken along the axial direction of liquid supplying device 1 in a modified example. Fig. 8 is an enlarged view of part VIII in Fig. 7. Fig. 9 is a plan view of the inlet in the modified example as seen from the bracket main body side (above). 7 and 8, liquid supply device 1 may employ a brushless motor instead of a brushed motor as motor unit 3. That is, motor unit 3 may include a cylindrical stator 81 fitted to the inner circumferential surface of motor fitting portion 11, and a rotor 82 rotatably provided radially inside stator 81.

[0083] The stator 81 includes a cylindrical stator core 83 and a plurality of windings 84 wound around the stator core 83. The outer peripheral surface of the stator core 83 is fitted into the inner peripheral surface of the motor fitting portion 11. The windings 84 are connected to terminals 27 provided on the outlet cover 7. External power is selectively supplied to predetermined windings 84 among the plurality of windings 84 via the terminals 27. The rotor 82 includes a cylindrical rotor core 85 fitted onto the shaft 14 and a permanent magnet 86 fixed to the outer peripheral surface of the rotor core 85.

[0084] In the pump section 4 of the modified example, the inner recess 172 formed on the second sliding contact surface 42c of the inlet 42 is tapered so as to gradually become deeper toward the inside in the radial direction. In other words, the depth of the inner recess 172 is shallower on the outside in the radial direction. Therefore, at the radially outer side of the inner recess 172, the size of the gap between the bottom surface of the inner recess 172 and the lower end surface 40c of the impeller 40 is small, similar to the size of the gap between the second sliding surface 42c of the inlet 42 and the lower end surface 40c of the impeller 40.

[0085] As a result, the radially outer side of the inner recess 172 functions as the inner seal surface 74. Therefore, even if the inner recess 172 is formed closer to the second flow path groove 65 than the inner recess 72 of the above-described embodiment, it is possible to sufficiently suppress leakage of fuel from the second flow path groove 65 to the inner recess 172. Therefore, the radial width of the inner recess 172 in the modified example can be made larger than the radial width of the inner recess 72 of the above-described embodiment (see also FIG. 6 above).

[0086] The outer recess 173 formed on the second sliding contact surface 42c of the inlet 42 is tapered so that its depth gradually increases toward the radially inner side. In other words, the depth of the outer recess 173 is shallower on the radially inner side.

[0087] Therefore, at the radially inner side of the outer recess 173, the size of the gap between the bottom surface of the outer recess 173 and the lower end surface 40c of the impeller 40 is small, similar to the size of the gap between the second sliding contact surface 42c of the inlet 42 and the lower end surface 40c of the impeller 40. As a result, the radially inner side of the outer recess 173 functions as the outer seal surface 75. Therefore, even if the outer recess 173 is formed closer to the second flow passage groove 65 than the outer recess 73 in the above-mentioned embodiment, leakage of fuel from the second flow passage groove 65 to the outer recess 173 can be sufficiently suppressed. Therefore, the radial width of the outer recess 173 in the modified example can be made larger than the radial width of the outer recess 73 in the above-mentioned embodiment (see also FIG. 6 above).

[0088] Therefore, the above-described modified example achieves the same effects as the previously described embodiment. In addition, the radial widths of the inner recess 172 and the outer recess 173 can be made larger than the radial widths of the inner recess 72 and the outer recess 73 in the previously described embodiment, while still satisfying the functions of the inner seal surface 74 and the outer seal surface 75. This further reduces the contact area between the inlet 42 and the impeller 40, and further reduces the sliding resistance between the inlet 42 and the impeller 40.

[0089] Additionally, in the above-described embodiment, the inner recess 72 and the outer recess 73 are described as being formed in an annular shape when viewed in the axial direction. However, this is not limiting, and the inner recess 72 and the outer recess 73 do not have to be completely annular when viewed in the axial direction. In particular, the outer recess 73 only needs to be formed radially outward of the blades 62 and through-flow passages 63 of the impeller 40 and in a position that overlaps with the outer peripheral surface 40a of the impeller 40 in the axial direction.

[0090] The outer recess 73 does not have to be formed in an annular shape. In other words, it is sufficient if the outer recess 73, 173 can prevent the outer peripheral edge of the impeller 40 from being pressed against the inlet 42 even when the impeller 40 tilts as the impeller 40 rotates. Furthermore, it is sufficient if the outer recess 73, 173 can increase the allowable angle range of the tilt when the impeller 40 rotates.

[0091] For example, the outer recesses 73, 173 may be disposed at a position overlapping the outer peripheral surface 40a of the impeller 40 in the axial direction and near the discharge port 48. The vicinity of the discharge port 48 refers to the location facing the discharge port 48 in the axial direction and its surroundings. This is because the tilted impeller 40 is pressed against the location of the second sliding contact surface 42c of the inlet 42 facing the discharge port 48 in the axial direction and its surroundings. This configuration provides the same effects as the above-described embodiment.

[0092] In the above embodiment, the liquid supply device 1 is described as being used as a non-positive displacement pump, for example, a fuel pump for vehicles such as motorcycles and four-wheeled vehicles. However, the present invention is not limited to this, and the configuration of the pump unit 4 described above can be applied to various non-positive displacement pumps. The configuration of the pump unit 4 described above can be applied to various liquids instead of fuel.

[0093] In the above embodiment, a description has been given of a case where, for example, a brushed motor is used as the motor unit 3. However, this is not limited to this, and it is also possible to use, for example, a brushless motor as the motor unit 3.

[0094] In the above embodiment, the pump case 41 is described as being composed of the bracket 45 and the inlet 42. However, this is not limiting, and the pump case 41 only needs to have the housing portion 60 that houses the impeller 40 so that it can rotate freely, and does not have to be composed of the bracket 45 and the inlet 42 separately. For example, the cylindrical portion 44 of the bracket 45 may be integrally formed with the inlet 42. [Explanation of symbols]

[0095] 1...liquid supply device, 2...housing, 3...motor section, 4...pump section, 5...yoke, 5a...upper opening, 6...armature, 7...outlet cover, 7a...opening, 7b...bottom, 8...permanent magnet, 11...motor fitting section, 11a...upper opening edge, 12...pump fitting section, 12a...inner flange section, 14...shaft, 14a...upper end, 14b...lower end, 15...armature core, 16...commutator, 17...teeth, 18...commutator body, 18a... One surface, 19...segment, 22...resin molded portion, 23...bearing cylindrical portion, 24...brush holder, 25...brush, 26...coil spring, 27...terminal, 28...discharge port, 40...impeller, 40a...outer peripheral surface, 40b...upper end surface (impeller second end surface), 40c...lower end surface (impeller first end surface), 41...pump case, 42...inlet (pump case, first wall portion), 42a...upper surface, 42b...lower surface, 42c...second sliding surface (case first end surface), 42d... Inlet side seal surface, 43... bracket main body (second wall portion), 43a... upper surface, 43b... abutment surface, 43c... lower surface, 43d... first sliding contact surface (second end surface of case), 43e... bracket recess, 43f... bracket side seal surface, 44... cylindrical portion, 44a... inner peripheral surface, 45... bracket (pump case), 46... insertion hole, 47... recess, 48... discharge port, 48a... recess, 49... step portion, 50... square ring, 53... suction port, 53a... lower chamfered portion, 53b... upper flat surface Recess, 54...bearing accommodation recess, 54a...opening, 55...thrust bearing, 59...slide bearing, 60...accommodation portion, 61...shaft mounting hole, 62...vane portion, 63...through passage, 64...first passage groove, 64a...tapered portion, 65...second passage groove (passage groove), 65a...tapered portion, 68...vent hole, 71...step recess, 72...inner recess, 73...outer recess, 74...inner seal surface, 75...outer seal surface, 172...inner recess, 173...outer recess, A...axis center, C...periphery gap (gap)

Claims

1. A disc-shaped impeller; a pump case formed to cover the entire impeller and accommodating the impeller so as to be rotatable around a radial center of the impeller as a rotation center; Equipped with The impeller is a plurality of blade portions formed radially inward from an outer peripheral surface of the impeller and arranged in a circumferential direction; a plurality of through-flow passages formed between the blade portions adjacent in the circumferential direction and communicating the first impeller end surface and the second impeller end surface on both sides in the thickness direction of the impeller; and The pump case includes: a first wall portion having a case first end surface facing the impeller first end surface; a second wall portion having a case second end surface facing the impeller second end surface; a suction port formed in the first wall portion, penetrating the first wall portion and communicating with the through-flow passage, through which liquid is drawn into the pump case; a discharge port formed in the second wall portion, penetrating the second wall portion and communicating with the through-flow passage, through which the liquid is discharged to the outside of the pump case; and an outer recess having an annular shape as viewed from the rotation axis direction is formed on the first end surface of the case at a position radially outward of the blade portion and the through-flow passage and overlapping with the outer peripheral surface of the impeller in the rotation axis direction; A non-positive displacement pump.

2. an annular inner recess portion is formed in the first end surface of the case radially inward of the blade portion and the through-flow passage when viewed from the rotation axis direction; 2. The non-positive displacement pump according to claim 1.

3. a shaft mounting hole is formed at the radial center of the impeller, the shaft mounting hole penetrating the impeller in the thickness direction and into which an input shaft for rotating the impeller is mounted; The inner recess communicates with the shaft mounting hole.

3. The non-positive displacement pump according to claim 2.

4. a flow path groove is formed in the first end surface of the case, extending along a circumferential direction from the suction port to a location facing the discharge port in a rotational axis direction, so as to communicate with the through flow path; an outer seal surface is formed on the first end surface of the case between the outer recess and the flow path groove, the outer seal surface preventing the liquid from leaking from the flow path groove to the outer recess; a size of a gap between the outer seal surface and the impeller is smaller than a size of a gap between a bottom surface of the outer recess and the impeller; 2. The non-positive displacement pump according to claim 1.

5. a flow path groove is formed in the first end surface of the case, extending along a circumferential direction from the suction port to a location facing the discharge port in a rotational axis direction, so as to communicate with the through flow path; an inner seal surface is formed on the first end surface of the case between the inner recess and the flow path groove, the inner seal surface preventing the liquid from leaking from the flow path groove to the inner recess; a size of a gap between the inner seal surface and the impeller is smaller than a size of a gap between a bottom surface of the inner recess and the impeller; 3. The non-positive displacement pump according to claim 2.

6. a gap is formed between the outer circumferential surface of the impeller and the pump case, The gap and the outer recess are in communication with each other.

2. The non-positive displacement pump according to claim 1.

7. A disc-shaped impeller; a pump case formed to cover the entire impeller and accommodating the impeller so as to be rotatable around a radial center of the impeller as a rotation center; Equipped with The impeller is a plurality of blade portions formed radially inward from an outer peripheral surface of the impeller and arranged in a circumferential direction; a plurality of through-flow passages formed between the blade portions adjacent in the circumferential direction and communicating the first impeller end surface and the second impeller end surface on both sides in the thickness direction of the impeller; and The pump case includes: a first wall portion having a case first end surface facing the impeller first end surface; a second wall portion having a case second end surface facing the impeller second end surface; a suction port formed in the first wall portion, penetrating the first wall portion and communicating with the through-flow passage, through which liquid is drawn into the pump case; a discharge port formed in the second wall portion, penetrating the second wall portion and communicating with the through-flow passage, through which the liquid is discharged to the outside of the pump case; and an outer recess portion having an annular shape as viewed from the rotation axis direction is formed in the first end surface of the case at a position radially outward of the blade portion and the through passage and overlapping with the outer peripheral surface of the impeller in the rotation axis direction, The outer recess is disposed at least near the discharge port. A non-positive displacement pump.

Images