Fuel pump

Abstract

A fuel pump (10) has a pump unit (30) and a motor unit (40). The pump unit (30) increases the pressure of fuel suctioned in from a fuel suction port (252e) and discharges the resultant fuel from a pump discharge port (23p). The motor unit (40) is a drive source for the pump unit (30), and is provided with an armature (430) that constitutes a rotor (43). A housing part (20) coaxially houses the pump unit (30) and the motor unit (40). The fuel discharged from the pump discharge port (23p) passes around the armature (430) of the motor unit (40) and is discharged from a fuel discharge port (252e) in the housing part (20). One end side, in the axial direction of the armature (430), facing the pump unit (30) is covered by a cover member (50). Recessed-protruding shapes (55r, 55e, 54d, 54u) are formed on the front surface side and / or the rear surface side of the cover member (50).

Description

fuel pump

[0001] The present technology relates to a fuel pump that supplies fuel to an internal combustion engine. The fuel pump draws fuel from a fuel tank through a fuel suction port and discharges the pressurized fuel from a fuel discharge port to the internal combustion engine.

[0002] Technology related to the above-mentioned fuel pump is described in Japanese Patent No. 4158154. This fuel pump pumps fuel from a fuel tank to an internal combustion engine. The fuel pump includes a pump unit (not shown) and a motor unit 100 (see FIG. 7) that drives the pump unit. The motor unit 100 has an armature 102 that forms a rotor. The pump unit and motor unit 100 are coaxially housed in a cylindrical housing unit (not shown). The housing unit is configured to allow fuel discharged from the pump unit to pass around the armature 102 of the motor unit 100 and be discharged from a fuel discharge port (not shown).

[0003] Specifically, a pump unit (not shown in FIG. 7 ) is disposed below the motor unit 100. When the pump unit discharges fuel, the fuel flows upward from the pump unit and passes around the motor unit 100. One axial end (lower end) of the armature 102 of the motor unit 100 facing the pump unit is covered by a metal cover member 104. This prevents the fuel discharged from the discharge port of the pump unit from directly hitting the lower end side of the armature 102. As a result, the fuel is smoothly guided around the armature 102 by the cover member. Furthermore, since the lower end side of the armature 102 is covered by the cover member, the lower end side of the armature 102 becomes flat, thereby reducing the rotational resistance of the armature 102.

[0004] In the above fuel pump, the lower end side of the armature 102 is covered with a cover member so as to be flat, thereby reducing the rotational resistance of the armature 102. Therefore, even if the cover member is made of metal, the heat dissipation efficiency of the armature 102 cannot be increased significantly because the cover member is flat.

[0005] Therefore, there has been a need for a fuel pump that can improve the efficiency of dissipating heat generated by the armature while suppressing the rotational resistance of the armature of the motor.

[0006] According to one feature of the present disclosure, a fuel pump draws fuel from a fuel tank through a fuel suction port and discharges it from a fuel discharge port to supply it to an internal combustion engine. A pump section of the fuel pump pressurizes the fuel drawn through the fuel suction port and discharges it from a pump discharge port. A motor section is a drive source for the pump section and includes an armature constituting a rotor. A housing section coaxially houses the pump section and the motor section. Fuel discharged from the pump discharge port passes around the armature of the motor section and is discharged from the fuel discharge port of the housing section. One axial end of the armature facing the pump section is covered by a cover member. The cover member has an uneven shape formed on at least one of its front and back sides.

[0007] One axial end of the armature facing the pump section is covered by a cover member. Therefore, the cover member prevents fuel discharged from the pump discharge port from directly hitting the one axial end of the armature, and the fuel is smoothly guided around the armature. Also, by covering the one axial end of the armature with the cover member, that portion becomes relatively flat, thereby reducing the rotational resistance of the armature. Furthermore, the cover member has an uneven shape on at least one of its front and back sides. Therefore, the uneven shape can expand the surface area of ​​the cover member, improving the heat dissipation efficiency of the heat generated by the armature.

[0008] According to another feature of the present disclosure, the concave-convex shape of the cover member is formed on both the front and back sides. The height difference dimension of the concave-convex shape on the back side is set to a value larger than the height difference dimension of the concave-convex shape on the front side. In other words, fuel discharged from the pump discharge port directly hits the concave-convex shape on the front side of the cover member. The height difference dimension of the concave-convex shape on the front side of the cover member is smaller than the height difference dimension of the concave-convex shape on the back side. This configuration prevents the rotational resistance of the armature from increasing.

[0009] According to another feature of the present disclosure, the concave-convex shape includes an outer concave-convex shape formed on the cover member and an inner concave-convex shape formed radially inward of the outer concave-convex shape. The concave-convex height difference of the inner concave-convex shape is set to a value greater than the concave-convex height difference of the outer concave-convex shape. During rotation of the armature, the rotation speed is higher on the radially outer side than on the radially inner side. The concave-convex height difference of the outer concave-convex shape located on the radially outer side is smaller than the concave-convex height difference of the inner concave-convex shape located on the radially inner side. This configuration can suppress an increase in rotational resistance of the armature.

[0010] According to another feature of the present disclosure, the concave and convex shape of the cover member includes a plurality of radially arranged ridges, which improves fuel agitation during rotation of the armature and improves heat dissipation efficiency.

[0011] According to another feature of the present disclosure, the ridges are curved so as to be convex in the rotation direction of the armature, which allows fuel to easily flow from the center to the outside in the radial direction, further improving heat dissipation efficiency.

[0012] According to another feature of the present disclosure, the cover member includes a cover body that covers one axial end of the armature and a terminal that is connected to the coil of the armature. The cover body and the terminal are integrally formed from the same metal. This allows heat from the armature to be guided to the cover member (cover body) via the terminal, enabling efficient heat dissipation.

[0013] 1 is a longitudinal sectional view of a fuel pump according to a first embodiment of the present disclosure; FIG. 2 is a schematic plan view of a pump section of the fuel pump; FIG. 3 is a longitudinal sectional view of a rotor (armature) of a motor section of the fuel pump; FIG. 4 is a perspective view of a cover member covering a lower end surface of the armature; FIG. 5 is a longitudinal sectional view of the cover member (a sectional view taken along arrows VV in FIG. 4); FIG. 6 is a plan view of a modified example of the cover member; and FIG. 7 is a perspective view of an armature and cover member of a conventional fuel pump.

[0014] 1 to 6, a fuel pump 10 according to a first embodiment of the present disclosure will be described. The fuel pump 10 according to this embodiment is a pump device that draws fuel from a fuel tank (not shown) through a fuel suction port 252e and discharges the pressurized fuel from a fuel discharge port 23p to supply it to a vehicle engine (not shown). Here, the front, rear, left, right, and top and bottom shown in the drawings correspond to the front, rear, left, right, and top and bottom of the fuel pump 10.

[0015] 1, the fuel pump 10 includes a pump section 30 that pressurizes the fuel and a motor section 40 that rotates the pump section 30. The fuel pump 10 also includes a fuel suction port 252e and a fuel discharge port 23p. The pump section 30 and the motor section 40 are coaxially housed in a housing section 20. The housing section 20 includes a cylindrical housing main body 21, an upper cover section 23 that closes the upper end of the housing main body 21, and a pump case section 25 that is a lower cover section that closes the lower end of the housing main body 21.

[0016] As shown in FIG. 1 , the top cover 23 of the housing 20 has a fuel discharge port 23p formed at its center, which communicates with the internal space of the housing main body 21. Also, an upper bearing 23j that supports the upper end of the rotation center shaft 13 of the pump unit 30 and the motor unit 40 is provided at the center of the top cover 23. Furthermore, a connector 23c and a pressure regulation valve 23v are provided on the top cover 23 of the housing 20. A power cable (not shown) that supplies power to the motor unit 40 is connected to the connector 23c. The pressure regulation valve 23v regulates the pressure of the fuel discharged from the fuel discharge port 23p.

[0017] As shown in FIG. 1 , the pump case 25, which is the lower cover of the housing 20, is a component of the pump section 30. As shown in FIGS. 1 and 2 , the pump section 30 includes an upper case 251 constituting the upper side of the pump case 25, a lower case 252 constituting the lower side of the pump case 25, and a disc-shaped impeller 32 that rotates within the pump flow path of the pump case 25. The impeller 32 receives rotational force from the rotation center shaft 13 and rotates integrally with the rotation center shaft 13. As shown in FIG. 1 , the upper case 251 of the pump case 25 is provided with a lower bearing 251j that supports the lower end of the rotation center shaft 13. As shown in FIG. 2 , the upper case 251 is formed with a pump discharge port 251p that communicates with the pump flow path. Furthermore, as shown in FIGS. 1 and 2 , the lower case 252 of the pump case 25 is formed with a fuel suction port 252e that draws fuel and directs it to the pump flow path.

[0018] <Motor Unit 40> The motor unit 40 is a DC motor. As shown in FIG. 1, the motor unit 40 is composed of a planar arc-shaped permanent magnet 41 and a rotor 43. A plurality of pairs of the permanent magnets 41 are fixed to the inner wall surface of the housing main body 21 of the housing unit 20. The rotor 43 is fixed coaxially to the rotation center axis 13 and rotates around its axis radially inside the permanent magnets 41. As shown in FIG. 3, the rotor 43 includes an armature 430, a commutator 45 (segments) provided on the upper end side of the armature 430, and a cover member 50 that covers the lower end side of the armature 430.

[0019] As shown in FIG. 3 , the armature 430 includes a multi-pole coil core 431 and a resin coil bobbin 433. The multi-pole coil cores 431 are arranged at equal intervals in the circumferential direction. A coil 435 is wound around each coil core 431 via the coil bobbin 433. The commutator 45 supplies power supplied from the connector 23c to each coil 435 of the armature 430 in sequence via brushes (not shown) and segments of the commutator 45. The cover member 50 covers the lower end of the armature 430, thereby preventing fuel discharged from the pump discharge port 251p of the pump unit 30 from directly hitting the lower end of the armature 430, i.e., the unevenness of the coil bobbin 433 of the armature 430 or the connection terminals of the coil 435. This allows the cover member 50 to smoothly guide the fuel discharged from the pump unit 30 around the armature 430. Furthermore, by covering the lower end side of the armature 430 with the cover member 50, this portion becomes relatively flat, thereby reducing the rotational resistance of the armature 430.

[0020] <Specific Configuration of Cover Member 50> The cover member 50 is a press-formed product made of metal such as aluminum, and includes a cover main body 50m and a terminal portion 51 connected to the coil 435 of the armature 430, as shown in FIGS. 4 and 5 . The cover main body 50m includes a ring-shaped bottom plate 52, a truncated cone-shaped mountain portion 54 provided radially inward of the bottom plate 52, and a fence-like vertical wall portion 55 provided upright along the outer periphery of the bottom plate 52. As shown in FIG. 1 , the mountain portion 54 is formed in a truncated cone shape to avoid interference with the lower bearing portion 251j of the pump unit 30 (upper case 251), which protrudes upward. A circular opening 57 is formed in the center of the mountain portion 54, through which the rotation center shaft 13 passes.

[0021] 3 and 4, a plurality of terminal portions 51 are provided in the circumferential direction on the vertical wall portion 55 of the cover member 50 at positions corresponding to the connection terminals of the coils 435 of the armature 430. Furthermore, as shown in Fig. 4, a plurality of engaging claw portions 58 are provided in the circumferential direction on the vertical wall portion 55 at positions corresponding to the claw receiving portions (not shown) of the coil bobbin 433 of the armature 430. That is, the terminal portions 51 of the cover member 50 are connected to the connection terminals of the coils 435 of the armature 430, and further, the engaging claw portions 58 of the cover member 50 engage with the claw receiving portions of the coil bobbin 433 of the armature 430. With this structure, the cover member 50 is fixed to the armature 430 while covering the lower end portion of the armature 430.

[0022] As shown in Fig. 4, a first uneven shape 55r is formed around the entire outer circumferential surface (front surface side) of the vertical wall portion 55 of the cover member 50 in consideration of heat dissipation. A second uneven shape 55e is also formed around the entire inner circumferential surface (back surface side) of the vertical wall portion 55 in consideration of heat dissipation. Furthermore, a third uneven shape 54d is formed around the entire lower surface side (front surface side) of the mountain-shaped portion 54 of the cover member 50. A fourth uneven shape 54u is formed around the entire upper surface side (back surface side) of the mountain-shaped portion 54.

[0023] Fuel from the pump 30 shown in FIG. 1 flows along the outer peripheral surface of the vertical wall portion 55 located on the front side (upstream side) of the cover member 50 and the lower surface of the angled portion 54. The fuel then flows along the inner peripheral surface of the vertical wall portion 55 located on the back side (downstream side) of the cover member 50 and the upper surface of the angled portion 54. The height difference between the second uneven shape 55e and the fourth uneven shape 54u located on the back side of the cover member 50 is set to a value greater than the height difference between the first uneven shape 55r and the third uneven shape 54d located on the front side. In other words, fuel discharged from the pump discharge port 251p of the pump section 30 directly hits the front side of the cover member 50. The height difference between the uneven shapes 55r and 54d on the front side of the cover member 50 is relatively small. This structure prevents the rotational resistance of the armature 430 from becoming too large.

[0024] As shown in FIG. 4 , the vertical wall portion 55 of the cover member 50 is located radially outward from the mountain-shaped portion 54. On the back surface side of the cover member 50, the second uneven shape 55e of the vertical wall portion 55 is located radially outward from the fourth uneven shape 54u of the mountain-shaped portion 54. The unevenness height difference dimension of the second uneven shape 55e on the radially outer side is set to a value smaller than the unevenness height difference dimension of the fourth uneven shape 54u on the radially inner side. On the front surface side of the cover member 50, the first uneven shape 55r of the vertical wall portion 55 is located radially outward from the third uneven shape 54d of the mountain-shaped portion 54. The unevenness height difference dimension of the first uneven shape 55r on the radially outer side is set to a value smaller than the unevenness height difference dimension of the third uneven shape 54d on the radially inner side. In this way, the height difference between the concave-convex shapes 55r and 55e on the radially outer side, where the rotation speed is higher during rotation of the armature 430, is set smaller than the height difference between the concave-convex shapes 54d and 54u on the radially inner side, where the rotation speed is lower. This configuration prevents an increase in rotational resistance of the armature 430. In this embodiment, the height difference between the first concave-convex shape 55r, the second concave-convex shape 55e, the third concave-convex shape 54d, and the fourth concave-convex shape 54u can each be set to approximately 1 μm to 5 mm.

[0025] <Operation of Fuel Pump 10> When power is supplied to the motor unit 40 via the connector 23c, the armature 430 and the permanent magnet 41 act to rotate the armature 430 (clockwise), and the rotational force is transmitted to the impeller 32 of the pump unit 30 via the rotation center shaft 13. As a result, as shown in FIG. 2, the impeller 32 rotates within the pump flow path of the pump case 25. Fuel drawn in through the fuel suction port 252e of the pump unit 30 is pressurized and discharged into the housing unit 20 from the pump discharge port 251p. The fuel discharged from the pump discharge port 251p strikes the cover member 50 that covers the lower end side of the armature 430 and is guided around the armature 430. The fuel then passes through the gap between the armature 430 and the permanent magnet 41, is guided to the upper part of the housing unit 20, and is discharged from the fuel discharge port 23p. At this time, the pressure of the fuel discharged from the fuel discharge port 23p is adjusted by the pressure adjustment valve 23v.

[0026] Advantages of the Fuel Pump 10 of the Present Embodiment In the fuel pump 10 of the present embodiment, the lower end of the armature 430, which faces the pump section 30, is covered by the cover member 50. Therefore, the cover member 50 prevents fuel discharged from the pump discharge port 251p from directly hitting the lower end of the armature 430, and smoothly guides the fuel to the periphery of the armature 430. Furthermore, by covering the lower end of the armature 430 with the cover member 50, this portion becomes relatively flat, thereby reducing the rotational resistance of the armature 430. Furthermore, the cover member 50 is made of a heat-dissipating material (aluminum), and the front and back sides of the cover member 50 are provided with concave-convex shapes 55r, 55e, 54d, and 54u. Therefore, the surface area of ​​the cover member 50 can be expanded by the concave-convex shapes, thereby improving the heat dissipation efficiency of the armature 430.

[0027] Furthermore, the concave-convex shapes 55r, 55e, 54d, and 54u of the cover member 50 are formed on both the front and back sides. The concave-convex shapes 55e and 54u on the back side of the cover member 50 are configured so that the height difference between the concave-convex shapes 55r and 54d is greater than the height difference between the concave-convex shapes 55r and 54d on the front side. That is, fuel discharged from the pump discharge port 251p directly hits the front side of the cover member 50 and flows along the concave-convex shapes 55r and 54d on the front side of the cover member 50. The height difference between the concave-convex shapes 55r and 54d on the front side is smaller than the height difference between the concave-convex shapes 55e and 54u on the back side. This configuration prevents the rotational resistance of the armature from increasing.

[0028] The cover member 50 has a radially outer surface and a radially inner surface. The radially outer surface is, for example, the vertical wall portion 55 shown in FIG. 4 . The radially inner surface is located radially inward of the radially outer surface and is, for example, a mountain-shaped portion 54. The radially outer surface is formed with an outer uneven shape, for example, a first uneven shape 55r and a second uneven shape 55e. The radially inner surface is formed with an inner uneven shape, for example, a third uneven shape 54d and a fourth uneven shape 54u. The unevenness height difference of the inner uneven shape is set to be larger than the unevenness height difference of the outer uneven shape. In other words, the unevenness height difference of the outer uneven shape where the rotation speed increases during rotation of the armature 430 is smaller than the unevenness height difference of the inner uneven shape where the rotation speed decreases. This configuration prevents the armature from increasing in rotational resistance.

[0029] The present disclosure is not limited to the above-described embodiment, and modifications are possible within the scope of the present disclosure. For example, in the present embodiment, the concave-convex shapes 55r, 55e, 54d, and 54u of the cover member 50 are formed on both the front and back sides. However, the concave-convex shapes 55r, 55e, 54d, and 54u can be formed only on the back side of the cover member 50, or only on the front side of the cover member 50. Furthermore, in the present embodiment, the concave-convex shapes 55r, 55e, 54d, and 54u are formed on the angled portion 54 and the vertical wall portion 55 of the cover member 50. Additionally or alternatively, the concave-convex shapes can be formed on both the front and back sides of the bottom plate portion 52. In the above-described embodiment, the angled portion 54 is formed on the cover member 50 to avoid interference with the lower bearing portion 251j. Alternatively, the overall length of the fuel pump can be extended and the angled portion 54 can be eliminated, leaving only the bottom plate portion 52.

[0030] Alternatively, the concave-convex shape of the cover member 50 can be formed by a plurality of radially arranged ridges 60, as shown in FIG. 6 . Preferably, the ridges 60 are curved so that they are convex in the rotation direction (see the white arrows). The protrusion dimension of the ridges 60 is set, for example, to approximately 2 to 5 mm when formed on the front side of the cover member 50, and approximately 2 to 8 mm when formed on the back side. This improves fuel agitation during rotation of the armature 430. Furthermore, fuel flows more easily from the center to the radially outward direction. As a result, the heat dissipation efficiency of the armature 430 is improved.

[0031] Here, even when the protrusions 60 are formed on the cover member 50, it is possible to form the uneven shapes 55r, 55e, 54d, and 54u on both the front and back sides of the cover member 50. It is also possible to form the uneven shape 55r or the like on either the front or back side of the cover member 50. In this case, as described above, the uneven height difference of the inner uneven shapes 54d and 54u on the radially inner surface of the cover member 50 may be set to a dimension larger than the uneven height difference of the outer uneven shapes 55r and 55e on the radially outer surface. Furthermore, the uneven height difference of the front-side uneven shapes 55r and 54d on the front side of the cover member 50 may be set to a dimension smaller than the uneven height difference of the back-side uneven shapes 55e and 54u on the back side.

[0032] In the present embodiment, an example has been shown in which the cover member 50 is made of aluminum, but it is also possible to use brass, copper, steel plate, etc. Also, in the present embodiment, an example has been shown in which the uneven shapes 55r, 55e, 54d, 54u or the ridges 60 are formed by press-forming the cover member 50. However, it is also possible to form the uneven shapes 55r, 55e, 54d, 54u of the cover member 50 or the ridges 60 by forging, casting, cutting, or the like.

Claims

1. A fuel pump that draws fuel from a fuel tank through a fuel suction port and discharges the pressurized fuel from a fuel discharge port to supply it to an internal combustion engine, comprising: a pump section that pressurizes the fuel drawn through the fuel suction port and discharges it from a pump discharge port; a motor section that is the drive source of the pump section and has an armature that forms a rotor; a housing section that coaxially houses the pump section and the motor section and is configured to allow the fuel discharged from the pump discharge port to pass around the armature of the motor section and be discharged from the fuel discharge port; a cover member that covers one axial end side of the armature that faces the pump section; and a fuel pump having an uneven shape formed on at least one of the front and back sides of the cover member.

2. A fuel pump according to claim 1, wherein the uneven shape includes a front-side uneven shape formed on the front side of the cover member facing the motor section, and a back-side uneven shape formed on the back side of the cover member, and the unevenness height difference dimension of the back-side uneven shape is greater than the unevenness height difference dimension of the front-side uneven shape.

3. A fuel pump according to claim 1 or 2, wherein the uneven shape includes an outer uneven shape formed on the cover member and an inner uneven shape located radially inward of the outer uneven shape, and the unevenness height difference dimension of the inner uneven shape is greater than the unevenness height difference dimension of the outer uneven shape.

4. A fuel pump according to any one of claims 1 to 3, wherein the uneven shape includes a plurality of ridges arranged radially on the cover member.

5. A fuel pump according to claim 4, wherein the protrusion is curved so as to be convex in the direction of rotation of the armature.

6. A fuel pump according to any one of claims 1 to 5, wherein the cover member comprises a cover body portion covering one axial end of the armature and a terminal portion connected to the coil of the armature, and the cover body portion and the terminal portion are formed from the same metal part.

Images