Electric pump

Abstract

This electric pump (1) comprises a motor part (15), a pump part (10), and a housing (20). The housing (20) has a body part (30) and a cover part (40). The cover part (40) has a flange part (41), a cylindrical part (45) that is formed concentrically with the flange part (41) and that protrudes in the axial direction from the flange part (41), a suction port (51), and a discharge port (52). One of the suction port (51) and the discharge port (52) is formed within the cylindrical part (45), while the other of the suction port (51) and the discharge port (52) is formed in the flange part (41). At least a part of the outer peripheral surface of the flange part (41) is formed to a smaller diameter compared to the outer peripheral surface (30a) of the body part (30).

Description

Electric pump

[0001] The present invention relates to an electric pump.

[0002] Japanese Unexamined Patent Application Publication No. 2014-082918 discloses an electric pump including a pump element composed of a pump rotor and an outer rotor housed in a center housing, and a motor element composed of a motor rotor and a stator connected to the pump rotor. A pump cover is attached to the center housing. The pump cover is formed in a cylindrical shape protruding from the surface and has a discharge port communicating with the discharge port of the pump element and a suction port formed side by side with the discharge port and communicating with the suction port of the pump element. The electric pump is housed in an electric pump housing portion of the center housing, and oil flows into the space between the electric pump and the electric pump housing portion.

[0003] In the electric pump described in Patent Document 1, oil is sucked through the suction port from the space between the electric pump housing portion and the pump cover. From the viewpoint of suction performance, it is preferable that the volume of the space between the electric pump housing portion and the pump cover is larger. In order to increase the volume of the space between the electric pump housing portion and the pump cover, it may be considered to increase the depth of the bottom surface of the electric pump housing portion to increase the gap between the electric pump housing portion and the pump cover. In that case, since it is necessary to increase the axial length of the discharge port to ensure the insertion length of the discharge port into the discharge oil passage, the electric pump becomes larger.

[0004] An object of the present invention is to miniaturize the electric pump.

[0005] According to one aspect of the present invention, an electric pump comprises a motor unit for driving a drive shaft, a pump unit connected to the drive shaft for discharging liquid, and a housing for housing the motor unit and the pump unit, wherein the housing has a main body and a cover unit attached to the main body and covering the pump unit, the cover unit has an annular flange unit attached to the main body, a cylindrical unit formed concentrically with the flange unit and projecting axially from the flange unit, a suction port for guiding liquid to the pump unit, and a discharge port for guiding liquid discharged from the pump unit, one of the suction port and the discharge port is formed within the cylindrical unit, the other of the suction port and the discharge port is formed within the flange unit, and the outer circumferential surface of the flange unit is formed to be smaller in diameter at least in part compared to the outer circumferential surface of the main body of the housing.

[0006] This is a perspective view of an electric pump according to an embodiment of the present invention. This is a perspective view of the pump section of an electric pump according to an embodiment of the present invention. This is a side view of an electric pump according to an embodiment of the present invention, showing the electric pump mounted in the mounting hole. This is a side view of an electric pump according to a modified example 3 of the embodiment of the present invention, showing the electric pump mounted in the mounting hole.

[0007] Hereinafter, an electric pump 1 according to an embodiment of the present invention will be described with reference to the drawings. The electric pump 1 is, for example, mounted on a vehicle and discharges a coolant (liquid) to cool equipment mounted on the vehicle, or discharges oil (liquid) to lubricate gears mounted on the vehicle. The electric pump 1 may also be used as a fluid pressure supply source that discharges a working fluid (liquid) to drive equipment. Furthermore, the electric pump 1 may be mounted on industrial machinery other than vehicles.

[0008] Figure 1 is a perspective view of the electric pump 1, and Figure 2 is a perspective view of the pump section 10 of the electric pump 1.

[0009] As shown in Figures 1 and 2, the electric pump 1 comprises a motor unit 15 (see Figure 1) that drives a drive shaft (not shown), a pump unit 10 connected to the drive shaft that discharges liquid, a control unit 17 (see Figure 1) that controls the motor unit 15, and a housing 20 that houses the motor unit 15, the pump unit 10, and the control unit 17.

[0010] The motor unit 15 has an annular stator (not shown) and a motor rotor (not shown) arranged radially inward of the stator. The motor rotor rotates around the drive shaft due to the interaction between the magnetization state of the stator core and the permanent magnets (not shown) of the motor rotor. A known configuration can be used for the motor unit 15, so a detailed explanation is omitted.

[0011] The pump section 10 is an internal gear pump having an inner rotor (not shown) to which a shaft is connected, and an outer rotor (not shown) positioned outside the inner rotor. Since a known configuration can be used for the pump section 10, a detailed explanation is omitted. In this embodiment, the pump section is an internal gear pump, but other pumps such as vane pumps may also be used.

[0012] The control unit 17 controls the current supplied to the stator of the motor unit 15, and includes a circuit board (not shown) and electronic components such as a magnetic sensor (not shown) mounted on the circuit board. Since a known configuration can be used for the control unit 17, a detailed explanation is omitted.

[0013] When the drive shaft is rotated by the motor unit 15, the inner rotor and outer rotor of the pump unit 10 rotate. As the inner rotor and outer rotor rotate, the volume of the pump chamber (not shown) repeatedly expands and contracts. In the expanded region (suction region) where the pump chamber expands, liquid is drawn in through the suction port 51 of the housing 20, and in the contracted region (discharge region) where the pump chamber contracts, liquid is discharged and led to the outside through the discharge port 52 of the housing 20.

[0014] As shown in Figures 1 and 2, the housing 20 has a main body 30 that houses the pump unit 10, the motor unit 15, and the control unit 17, and a cover unit 40 that is attached to the main body 30 and covers the pump unit 10. The main body 30 and the cover unit 40 are arranged side by side in the axial direction of the drive shaft. A pair of mounting flanges 35 (see Figure 1) for attaching the electric pump 1 to the mounting body 100 are formed on the outer circumferential surface of the end of the main body 30. The mounting flanges 35 are fixed to the mounting body 100 by bolts 70 (see Figure 3).

[0015] The main body 30 has a through hole (not shown) through which the drive shaft is inserted, and a pump housing recess (not shown) that houses the pump unit 10. The inner rotor and outer rotor of the pump unit 10 are housed inside the pump housing recess. An annular sealing member 61 (see Figures 1 and 3), such as an O-ring, is provided on the outer circumferential surface 30a of the main body 30. A detailed explanation of the specific configuration of the pump housing recess is omitted as a known configuration can be adopted.

[0016] As shown in Figure 2, the cover portion 40 is provided to close the pump housing recess in which the inner rotor and outer rotor are housed. The cover portion 40 is attached to the end face 30b of the main body portion 30 by bolts 50 as fastening members. The cover portion 40 has an annular flange portion 41 attached to the end face 30b of the main body portion 30, a cylindrical portion 45 formed projecting axially from the flange portion 41, a suction port 51 for guiding liquid from the outside into the pump chamber of the pump portion 10, and a discharge port 52 for guiding liquid discharged from the pump chamber to the outside. The axial direction of the flange portion 41 is the same as the axial direction of the drive shaft, and hereafter, the axial direction of both will simply be referred to as the "axial direction".

[0017] The outer diameter of the outer circumferential surface 41a of the flange portion 41 is formed to be smaller than the outer diameter of the outer circumferential surface 30a of the main body portion 30 of the housing 20. In this embodiment, the outer diameter of the outer circumferential surface 41a of the flange portion 41 is formed to be smaller than the outer diameter of the outer circumferential surface 30a of the main body portion 30 over its entire circumference. More specifically, the outermost diameter of the outer circumferential surface 41a of the flange portion 41 is formed to be smaller than the outer diameter of the outer circumferential surface 30a of the main body portion 30 over its entire circumference. However, it is sufficient that at least a portion of it is formed to be smaller than the outer circumferential surface 30a of the main body portion 30. In other words, a portion of the outer circumferential surface 41a of the flange portion 41 may have the same outer diameter as the outer circumferential surface 30a of the main body portion 30. Also, in this embodiment, the outer diameter of the outer circumferential surface 41a of the flange portion 41 is the same in the axial direction, but the outer circumferential surface 41a of the flange portion 41 may be formed to gradually decrease in diameter from the main body portion 30 of the housing 20. A cylindrical portion 45 is continuously formed on the flange portion 41. The discharge port 52 is formed on the flange portion 41. In this embodiment, the discharge port 52 is formed opening on the outer circumferential surface 41a of the flange portion 41. Specifically, the discharge port 52 is formed across the outer circumferential surface 41a and the back surface of the flange portion 41 and is demarcated by the end face 30b of the main body portion 30. In addition, multiple through holes (not shown) through which bolts 50 are inserted are formed on the flange portion 41, corresponding to the fastening holes (not shown) of the main body portion 30 of the housing 20.

[0018] The cylindrical portion 45 is formed concentrically with the flange portion 41. An intake port 51 is formed inside the cylindrical portion 45, corresponding to the intake area. An annular sealing member 60, such as an O-ring, is provided on the outer circumferential surface of the cylindrical portion 45.

[0019] Figure 3 is a side view showing the electric pump 1 attached to the mounting body 100, with the mounting body 100 shown in cross-section. The mounting body 100 is the case of equipment that utilizes the liquid discharged from the electric pump 1, and the equipment is, for example, a transmission or a transaxle device. The mounting body 100 has fastening holes (not shown) formed corresponding to the insertion holes of the mounting flange 35 of the housing 20 of the electric pump 1, into which bolts 70 are fastened, a mounting hole 71 that accommodates the main body portion 30 of the housing 20, a suction passage 72 formed on the bottom surface 71a of the mounting hole 71 into which the cylindrical portion 45 of the cover portion 40 of the housing 20 is inserted, and a discharge passage 73 formed on the side surface of the mounting hole 71. The suction passage 72 is a passage that guides liquid from the mounting body 100 to the pump portion 10 of the electric pump 1, and the discharge passage 73 is a passage that guides liquid discharged from the pump portion 10 of the electric pump 1 to the mounting body 100.

[0020] When attaching the electric pump 1 to the mounting body 100, the main body portion 30 of the housing 20 of the electric pump 1 is fitted into the mounting hole 71 of the mounting body 100, and the cylindrical portion 45 of the cover portion 40 of the housing 20 is inserted into the suction passage 72 of the mounting body 100 while the mounting flange 35 of the housing 20 is brought into contact with the end face of the mounting body 100. Then, the bolt 70 is inserted through the insertion hole of the mounting flange 35 and fastened into the fastening hole of the mounting body 100. As a result, the mounting flange 35 is pressed against the end face of the mounting body 100, and the electric pump 1 is attached to the mounting body 100. At this time, in this embodiment, there is a small gap between the bottom surface 71a of the mounting hole 71 and the end face 41b of the flange portion 41 of the electric pump 1. Alternatively, the electric pump 1 may be attached so that the end face 41b of the flange portion 41 of the electric pump 1 is in contact with the bottom surface 71a of the mounting hole 71.

[0021] As shown in Figure 3, the outer circumferential surface 41a of the flange portion 41 is formed to be smaller in diameter than the outer circumferential surface 30a of the main body portion 30. As a result, when the electric pump 1 is attached to the mounting body 100, a gap is formed between the inner circumferential surface of the mounting hole 71 in which the electric pump 1 is housed and the outer circumferential surface 41a of the flange portion 41. Therefore, even if the gap between the bottom surface 71a of the mounting hole 71 and the end surface 41b of the flange portion 41 is small, the gap formed between the inner circumferential surface of the mounting hole 71 and the outer circumferential surface 41a of the flange portion 41 can be used as a space 4 connecting the discharge port 52 and the discharge passage 73, and the liquid discharged from the discharge port 52 is guided to the discharge passage 73 through space 4. As a result, the liquid discharged from the discharge port 52 can be smoothly supplied to the discharge passage 73.

[0022] Thus, in the electric pump 1, the outer circumferential surface 41a of the flange portion 41 is formed to be smaller in diameter at least in part compared to the outer circumferential surface 30a of the main body portion 30. Therefore, even if the gap between the bottom surface 71a of the mounting hole 71 and the end surface 41b of the flange portion 41 is small, the volume of the space 4 through which the discharge port 52 communicates can be secured. Furthermore, since it is not necessary to increase the depth of the mounting hole 71 in order to secure the volume of the space 4, the length of the cylindrical portion 45 in which the suction port 51 is formed does not need to be increased, and the electric pump 1 can be made smaller. In this embodiment, since the flange portion 41 is formed to be smaller in diameter all around, the volume of the space 4 communicating with the discharge port 52 can be increased, and liquid can be supplied and discharged smoothly.

[0023] Furthermore, in the electric pump 1, since the discharge port 52 is formed to open onto the outer circumferential surface 41a of the flange portion 41, the discharge port 52 is in direct communication with the inner circumferential surface of the mounting hole 71 and the outer circumferential surface 41a of the flange portion 41. Therefore, even if the gap between the bottom surface 71a of the mounting hole 71 and the end surface 41b of the flange portion 41 is small, the liquid can be smoothly supplied to the discharge passage 73.

[0024] According to the above embodiment, the following effects are achieved.

[0025] In the electric pump 1, the outer circumferential surface 41a of the flange portion 41 of the cover portion 40 is formed to be smaller in diameter, at least in part, compared to the outer circumferential surface 30a of the main body portion 30. As a result, a gap is formed between the inner circumferential surface of the mounting hole 71 in which the electric pump 1 is housed and the outer circumferential surface 41a of the flange portion 41. Therefore, even if the gap between the bottom surface 71a of the mounting hole 71 and the end surface 41b of the flange portion 41 is small, the volume of the space 4 through which the discharge port 52 communicates can be secured. Consequently, there is no need to increase the depth of the mounting hole 71, and therefore there is no need to increase the length of the cylindrical portion 45 in which the suction port 51 is formed, making the electric pump 1 more compact.

[0026] Next, modifications of this embodiment will be described. The following modifications are also within the scope of the present invention, and it is possible to combine the configurations shown in the modifications with the configurations described in the above embodiments, or to combine the configurations described in the following different modifications.

[0027] <Modification 1> In the above embodiment, a suction port 51 is formed on the inside of the cylindrical portion 45, and a discharge port 52 is formed on the flange portion 41. However, it is not limited to this, and a discharge port 52 having the same shape as the suction port 51 in the above embodiment may be formed on the inside of the cylindrical portion 45, and a suction port 51 having the same shape as the discharge port 52 in the above embodiment may be formed on the flange portion 41. In this case, the positions of the suction passage 72 and the discharge passage 73 of the mounted body 100 are swapped. In other words, one of the suction port 51 and the discharge port 52 may be formed on the inside of the cylindrical portion 45, and the other of the suction port 51 and the discharge port 52 may be formed on the flange portion 41. Even with this configuration, the same effects as the above embodiment are achieved.

[0028] <Modification 2> In the electric pump 1 of the above embodiment, the discharge port 52 opens to the outer peripheral surface 41a of the flange portion 41. However, the discharge port 52 may also open to the end surface 41b of the flange portion 41. This configuration also provides the same effects as the above embodiment. In this case, the gap between the bottom surface 71a of the mounting hole 71 and the end surface 41b of the flange portion 41 needs to be made somewhat large.

[0029] <Modification 3> In the electric pump 1 of the above embodiment, the outermost diameter of the outer peripheral surface 41a of the flange portion 41 is formed to be smaller in diameter over its entire circumference compared to the outer peripheral surface 30a of the main body portion 30. However, as shown in the electric pump 2 of Figure 4, the outer peripheral surface 41a of the flange portion 41 may be formed such that the outermost diameter that contacts the main body portion 30 of the housing 20 is the same as the main body portion 30, and the diameter gradually decreases from the main body portion 30 of the housing 20. In this configuration, the contact area between the flange portion 41 and the main body portion 30 can be secured while securing the volume of the space 4 through which the mounting hole 71 and the discharge port 52 communicate.

[0030] The configuration, operation, and effects of the embodiments of the present invention will be described below.

[0031] The electric pumps 1 and 2 each include a motor unit 15 that drives a drive shaft, a pump unit 10 connected to the drive shaft that discharges liquid, and a housing 20 that houses the motor unit 15 and the pump unit 10. The housing 20 has a main body 30 and a cover 40 attached to the main body 30 that covers the pump unit 10. The cover 40 has an annular flange 41 attached to the main body 30, a cylindrical 45 formed concentrically with the flange 41 and projecting axially from the flange 41, a suction port 51 that guides liquid to the pump unit 10, and a discharge port 52 that guides liquid discharged from the pump unit 10. One of the suction port 51 and the discharge port 52 is formed within the cylindrical part, and the other of the suction port 51 and the discharge port 52 is formed in the flange 41. The outer circumferential surface 41a of the flange 41 is formed to be smaller in diameter, at least in part, compared to the outer circumferential surface 30a of the main body 30 of the housing 20.

[0032] In this configuration, the flange portion 41 of the cover portion 40 of the electric pump 1 is formed to be smaller in diameter, at least in part, compared to the main body portion 30. As a result, a gap is formed between the inner circumferential surface of the mounting hole 71 in which the electric pump 1 is housed and the outer circumferential surface 41a of the flange portion 41. Therefore, even if the gap between the bottom surface 71a of the mounting hole 71 and the flange portion 41 is small, the volume of the space 4 through which the discharge port 52 communicates can be secured. Consequently, there is no need to increase the depth of the mounting hole 71, and therefore there is no need to increase the length of the cylindrical portion 45 in which the discharge port 52 is formed, allowing the electric pump 1 to be miniaturized.

[0033] In addition, in the electric pumps 1 and 2, the other of the suction port 51 and discharge port 52 is formed to open onto the outer circumferential surface 41a of the flange portion 41.

[0034] In this configuration, the discharge port 52 is in direct communication with the inner circumferential surface of the mounting hole 71 and the outer circumferential surface 41a of the flange portion 41. Therefore, even if the distance between the bottom surface 71a of the mounting hole 71 and the flange portion 41 is reduced, the liquid can be supplied smoothly.

[0035] Furthermore, in the electric pump 1, the outer circumferential surface 41a of the flange portion 41 is formed to be smaller in diameter over its entire circumference compared to the outer circumferential surface 30a of the main body portion 30 of the housing 20.

[0036] In this configuration, since the flange portion 41 is formed with a small diameter around its entire circumference, the volume of the space 4 communicating with the discharge port 52 can be increased, allowing for smoother liquid supply.

[0037] Furthermore, in the electric pump 2, the outer circumferential surface 41a of the flange portion 41 is formed to gradually decrease in diameter from the main body portion 30 of the housing 20.

[0038] In this configuration, it is possible to secure the contact area between the flange portion 41 and the main body portion 30 while also securing the volume of the space 4 through which the discharge port 52 communicates.

[0039] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0040] This application claims priority under Japanese Patent Application No. 2025-012342, filed with the Japan Patent Office on 28 January 2025, and all contents of that application are incorporated herein by reference.

Claims

1. An electric pump comprising: a motor unit for driving a drive shaft; a pump unit connected to the drive shaft for discharging liquid; and a housing for housing the motor unit and the pump unit, wherein the housing has a main body portion and a cover portion attached to the main body portion and covering the pump unit, the cover portion has an annular flange portion attached to the main body portion, a cylindrical portion formed concentrically with the flange portion and projecting axially from the flange portion, a suction port for guiding liquid to the pump unit, and a discharge port for guiding liquid discharged from the pump unit, one of the suction port and the discharge port being formed within the cylindrical portion, the other of the suction port and the discharge port being formed in the flange portion, and the outer circumferential surface of the flange portion being formed to be smaller in diameter in at least a portion of the outer circumferential surface of the main body portion of the housing.

2. An electric pump according to claim 1, wherein the other of the suction port and the discharge port is formed to open to the outer circumferential surface of the flange portion.

3. An electric pump according to claim 1, wherein the outer circumferential surface of the flange portion is formed to be smaller in diameter over its entire circumference compared to the outer circumferential surface of the main body portion of the housing.

4. An electric pump according to claim 2, wherein the outer circumferential surface of the flange portion is formed to gradually decrease in diameter from the main body portion of the housing.

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