JP2003278670A - Electric oil pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress load of force in the direction of axial length to a shaft regarding an electric oil pump. <P>SOLUTION: The oil pump 10 is provided with a pump housing 11 equipped with a suction port 16, a discharge port 17 of oil and a bearing port 18, and one end 31b side is equipped with an inner rotor 19 which extends in the pump housing 11 and forcibly feeds the oil by rotating in the pump housing 11, and another end 31a side is equipped with a shaft 31 which extends outside the pump housing 11 through the bearing port 18 and connected to a motor 30. The pump housing 11 is equipped with a recessed part 21 opposing to the one end 31b and a communicating groove 22 communicating a recessed part 21 and the suction port 16. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric oil pump. 2. Description of the Related Art As a conventional electric oil pump of this type, a device disclosed in Japanese Patent Application Laid-Open No. H11-173278 is known. The device includes a pump housing having an oil suction port, a discharge port, and a drive-side connection port, and a drive gear capable of pumping oil in the pump housing by extending and rotating one end of the pump housing. And a shaft having the other end extending out of the housing through the drive-side connection port and connected to an electric power source. In this device, the shaft and the drive gear rotate integrally by an electric power source, and as a result, the oil is sucked in by operating the drive gear and the driven gear disposed in the pump housing so as to interlock with the drive gear. Pumping from mouth to outlet. However, this device has the following disadvantages. Generally, in the pump housing, the oil pressure particularly on the discharge port side becomes high. this is,
This is caused by the influence of a device to which the electric oil pump sends oil. Therefore, when the oil in the pump housing extends near one end of the shaft, the oil pressure applies a force so as to press the shaft toward the other end (in the axial direction). Thus, for example, the drive gear may be pressed against the housing near the drive-side connection port. Therefore, there is a problem that the resistance is applied to the rotation of the shaft, that is, the driving of the pump, due to the sliding resistance between the drive gear and the housing. SUMMARY OF THE INVENTION [0004] It is a technical object of the present invention to provide a motor-driven oil pump which suppresses a load on a shaft in the axial direction. [0005] In order to solve the above-mentioned technical problems, technical measures taken in the present invention include a pump housing having an oil intake port, an oil discharge port, and a drive side connection port. A drive rotor capable of pumping oil in the pump housing by one end extending into the pump housing and rotating, and the other end extending out of the pump housing via the drive side connection port. And a shaft connected to an electric power source, wherein the pump housing includes a concave portion facing the one end and a communication portion communicating the concave portion with the suction port. That is. [0006] In this configuration, the oil located in the concave portion facing the one end of the shaft in the pump housing can move to the suction port through the communication portion. Note that the suction port side is a portion where the oil pressure is low in the pump housing. Therefore, an increase in the oil pressure of the oil located in the recess is suppressed. Therefore, the load on the shaft in the axial length direction (from one end to the other end) is suppressed. FIG. 1 is a longitudinal sectional view of an oil pump 10 (electric oil pump). The oil pump 10 is, for example, an electric pump that is disposed in an engine (not shown) of a vehicle and that pumps oil from an oil pan (not shown) to a lubricating portion of the engine. Oil pump 10
When viewed from a general rule, the exterior is formed by a pump housing 11 (pump housing) made of metal such as aluminum and a motor housing 12 made of resin. The pump housing 11 includes a lid member 11 a and a bearing member 11 b disposed between the lid member 11 a and the motor housing 12. The lid member 11a, the bearing member 11b, and the motor housing 12 are integrally assembled with bolts 13. An O-ring 14 is provided between the lid member 11a and the bearing member 11b, and between the motor housing 12 and the bearing member 11b.
Are arranged. The lid member 11a is open in the direction of the motor housing 12 (left direction in FIG. 1), and a bearing member 11b is disposed so as to cover the opening. The space in the lid member 11a, that is, the lid member 11a and the bearing member 11b
An oil chamber 15 is formed between the two. The lid member 11a has a suction port 16 (shown in FIGS. 1 and 3) (suction port) for sucking oil into the oil chamber 15 and a discharge port 17 (shown in FIGS. 1 and 3) (discharge port) for discharging oil. ) Is formed. The oil chamber 15 is roughly viewed as a suction-side oil chamber 15a, an inter-rotor oil chamber 15a.
b, a discharge-side oil chamber 15c. The suction-side oil chamber 15a and the discharge-side oil chamber 15c are connected to a suction port 16 and a discharge port 17, respectively. The inter-rotor oil chamber 15b is formed by gaps between respective teeth between an inner rotor 19 (described later) and an outer rotor 20 (described later). The pump housing 11 including the oil chamber 15, the suction port 16, the discharge port 17 and the like will be described later in detail. The bearing port 1 is located substantially at the center of the bearing member 11b.
8 (drive side connection port) is formed. The bearing port 18 is provided with a metal shaft 31 (shaft) connected to the motor 30 (electric power source). In other words, the shaft 31 extends inside and outside the pump housing 11 via the bearing port 18. The bearing port 18 also performs the bearing function of the shaft 31 and supports the shaft 31 so as to be rotatable around its axis. The motor housing 12 covers the motor 30 while securing a predetermined gap.
It is open in the direction of the pump side housing 11, and the opening is linked to the bearing port 18. The motor 30 includes a shaft 31, a back yoke 32, a magnet 33, a coil 34, and the like. The back yoke 32 is a cylindrical magnetic body, and is fixed to an end 31 a (the other end) of the shaft 31 in the motor housing 12. As an assembling method, the cylindrical inner diameter portion of the back yoke 32
The shaft 31 is assembled by press fitting. Further, a magnet 33 is fixed on the outer periphery of the back yoke 32. The magnets 33 are arranged so that the excitation layers are arranged alternately (alternately N-poles and S-poles) side by side in the circumferential direction (hereinafter, circumferential direction) of the cross-section circle of the shaft 31. The back yoke 32 allows the magnet 3
The magnetic properties of 3 and the like are good. In the present embodiment, the back yoke 32 is separate from the shaft 31, but the back yoke 32 may be integrally formed, and the magnet 33 of the shaft 31 may be fixed to the back yoke 32. . In this case, with a simpler configuration,
The magnet 33 has good magnetic properties. A metal core 35 is fixed inside the motor housing 12. When viewed from the magnet 33, the core 35 is positioned at a predetermined distance outward in the radial direction (hereinafter, radial direction) of the cross-section circle of the shaft 31.
They are arranged side by side in the circumferential direction. A coil 34 is wound around each core 35 in a plurality of layers.
The oil pump 1 is connected to each coil 34 via a terminal 36.
0 controller (not shown) is connected. Then, the excitation layer of each coil 34 is switched by the controller controlling the energization of the coil 34. As a result, the magnet 33, the back yoke 32, and the shaft 31 are integrally rotated in the circumferential direction. As shown in FIGS. 1 and 2, a metal inner rotor 19 (drive rotor) is fixed to an end 31b (one end) of the shaft 31 in the housing 11. The inner rotor 19 has four teeth, and the shaft 31 is press-fitted into the inner diameter portion 19a of the inner rotor 19.
Fixed to 1. Note that the end portion 31b is inserted through the inner diameter portion 19a of the inner rotor 19, and extends a small amount into a recess 21 (recess) (described later) formed in the housing 11. Therefore, the corner portion of the inner diameter portion 19a on the lid member 11a side and the corner portion of the end portion 31b are chamfered, but the engagement margin between the shaft 31 and the inner diameter portion 19a is sufficiently ensured. The shaft 31 of the inner rotor 19
Has been stable. The shaft 31 and the inner rotor 19 are configured to rotate integrally in the circumferential direction. An outer rotor 20 is provided around the inner rotor 19. This inner rotor 1
9 and the outer rotor 20 are trochoid type rotors.
The outer rotor 20 has five teeth, and the inner rotor 1
The rotation of the rotor 9 causes the teeth of both rotors to mesh with each other, so that the rotor rotates with respect to the pump housing 11. Here, the center of rotation of the outer rotor 20 is eccentric with respect to the center of rotation of the inner rotor 19 (the shaft 31). As shown in FIGS. 1 and 3, the lid member 11a
In addition to the suction port 16 and the discharge port 17 described above, a concave portion 21 (concave portion) is provided on the inside of the. The concave portion 21 is provided for the lid member 11.
1A is formed so as to be depressed rightward in FIG. 1, and as described above, the extension of the end portion 31b is allowed inside.
That is, the concave portion 21 faces the end portion 31b. Furthermore,
A communication groove 22 (communication portion) that connects the concave portion 21 and the suction port 16 is formed in the lid member 11a. This communication groove 22
Thereby, the oil can move in the concave portion 21 and the suction port 16. In the present embodiment, the communication groove 22
Has a shape in which the inner side surface of the lid member 11a is notched, but may have a hole shape communicating the recess 21 with the communication groove 22. As shown in FIG. 1, a rubber oil seal 23 is disposed on the motor 30 side (left side in FIG. 1) of the bearing port 18 of the bearing member 11b. The oil seal 23 is
It is press-fitted to the shaft 31 to prevent oil from penetrating from the oil chamber 15 to the motor 30 side. A cutout 24 is formed in a part of the bearing port 18 on the oil chamber 15 side. The oil in the oil chamber 15 is
Through the shaft 31, the portion of the shaft 31 that is supported by the bearing port 18 can be penetrated. Therefore, the shaft 3
Good lubricity for the one bearing port 18 is ensured. Further, a communication hole 25 from the oil seal 23 to the suction-side oil chamber 15a is formed in the bearing member 11b. The oil accumulated in the oil seal 23 via the communication hole 25 can move into the suction-side oil chamber 15a. As shown in FIG. 1, a mounting plate 26 for a hydraulic device (not shown) or the like is formed integrally with the lid member 11a. The mounting plate 26 has three mounting holes 26a. And the mounting hole 26
By fitting a bolt or the like (not shown) to a, the oil pump 10 is fixed to a hydraulic device or the like. Next, the operation of the oil pump 10 will be briefly described. As described above, when the energization of the coil 34 is controlled by the oil pump controller,
The motor 30 is driven. Then, the shaft 31 rotates, whereby the inner rotor 19 and the outer rotor 20 rotate in the pump housing 11. As a result, the oil flows from the suction port 16 to the discharge port 17 as described below, and the function of the pump is realized. As described above, the oil chamber 15 in the housing 11 is roughly composed of a suction-side oil chamber 15a, an inter-rotor oil chamber 15b, and a discharge-side oil chamber 15c. The volume of the inter-rotor oil chamber 15b is
It changes with the rotation of both rotors. Oil chamber 1 between rotors
5b is in contact with the suction side oil chamber 15a,
The rotation of both rotors changes the direction in which the volume of the oil chamber 15b between the rotors increases. Then, a negative pressure is generated in the inside due to the increase in the volume, and the negative pressure causes oil to be sucked from the suction side oil chamber 15a into the inter-rotor oil chamber 15b, and the inside is filled with the oil. By further rotation, the inter-rotor oil chamber 15b is moved to the discharge side oil chamber 1
5c. As the volume of the inter-rotor oil chamber 15b decreases, oil can move from the inter-rotor oil chamber 15b to the discharge-side oil chamber 15c. Here, the communication groove 22 in the above operation is used.
The operation of will be described. The oil in the oil chamber 15
The pressure is fed so as to discharge from the discharge port 7, but the discharge amount is restricted by a hydraulic device or the like connected to the end of the discharge port 17.
Therefore, the oil pressure in the oil chamber 15 becomes high especially on the discharge port 17 side. Therefore, the oil on the discharge port 17 side is
Inner rotor 19, outer rotor 20, and lid member 11
a penetrates to the concave portion 21 through the gap with “a”. The oil in the concave portion 21 flows through the communication groove 22 to the suction port 16.
Can move to the side. Here, the suction port 16 side is a portion where oil is sucked by the oil pump 10,
The oil pressure inside is relatively low.
Therefore, an increase in the oil pressure of the oil accumulated in the concave portion 21 is suppressed. Therefore, the load of the force on the shaft 31 from the end 31b to the end 31a (axial direction) due to the oil pressure is suppressed. If the shaft 31 is pressed toward the motor 30, the sliding resistance between the inner rotor 19 and the bearing member 11 b increases, and there is a possibility that the driving of the oil pump 10 is loaded. However, in this embodiment, such a resistance is not loaded,
The smooth drive of the oil pump 10 is ensured. According to the present invention, the oil located in the concave portion facing the one end of the shaft in the pump housing can move to the suction port through the communicating portion. Therefore, an increase in the oil pressure of the oil located in the recess is suppressed. Therefore, the load on the shaft in the axial length direction (from one end to the other end) is suppressed, and the drive rotor is not pressed against the pump housing integrally with the shaft. As a result, smooth driving of the electric oil pump is ensured.

[Brief description of the drawings] FIG. 1 is a longitudinal sectional view of an oil pump according to the present invention. FIG. 2 is a view taken in the direction of arrow A in FIG. FIG. 3 is a view taken in the direction of arrow B in FIG. 1; [Explanation of symbols] 11 Pump housing 16 Inlet 17 Discharge port 18 Bearing port (drive side connection port) 19 Inner rotor (drive rotor) 21 recess 22 Communication groove (communication part) 31 shaft 30 motor (electric drive source) 31a The other end 31b one end

Claims (1)

Claims: 1. A pump housing having an oil suction port, a discharge port, and a drive-side connection port, and one end extending into the pump housing and rotating to rotate the oil in the pump housing. A shaft extending from the pump housing through the drive-side connection port and connected to an electric power source, the pump housing being opposed to the one end. An electric oil pump, comprising: a recess that communicates with the recess; and a communication portion that communicates the recess with the suction port.