JP4367006B2 - Electric liquid pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a small and compact electric liquid pump in which a liquid pump is driven by an electric motor, for example, as a supply source of hydraulic oil for a clutch of an automatic transmission in an automobile or a cooling oil for an electric motor of a hybrid car. The present invention relates to an electric liquid pump of this type that is suitable for use.
[0002]
[Prior art]
As such an electric liquid pump, a magnet of a sensorless brushless DC motor is coupled to an outer end portion of a rotating shaft rotatably supported by a pump housing of a hydraulic pump, and integrated with a core and a coil of the sensorless brushless DC motor. A molded housing with a bottomed cylindrical resin is connected to the pump housing with a seal member through a sealing member to form a chamber in the motor housing to accommodate the magnet. The hydraulic oil discharged into the discharge chamber flows into the chamber described above through the gap between the outer periphery of the rotary shaft and the pump housing, and is formed in the pump housing from the chamber through the passage formed in the pump housing. The sensorless brushless DC motor is cooled by returning to the suction chamber Some (for example, see Patent Document 1).
[0003]
According to the technique of this Patent Document 1, the support portion of the rotating shaft with respect to the pump housing is lubricated by the hydraulic oil, and the cooling effect for the sensorless brushless DC motor is high, but this hydraulic oil has a fine effect caused by the operation of the hydraulic pump. Since magnetic foreign matter such as iron powder is included and gradually increases over time, this magnetic foreign matter adheres to and accumulates on the magnet of a sensorless brushless DC motor to reduce the motor drive torque, and in some cases stops the motor Sometimes
[0004]
As means for solving such a problem, as shown in FIG. 4, an inner rotor 4 a of the trochoid pump 4 and a rotor 8 b of the sensorless brushless DC motor 8 are provided at both ends of the rotating shaft 5 rotatably supported by the pump body 1. The motor housing 7 in which the annular stator 8a of the sensorless brushless DC motor 8 is molded and the bottomed cylindrical space 9 is formed inside the stator 8a is fixed, and the rotor 8b of the sensorless brushless DC motor 8 is somewhat It is fixed to the pump body 1 so as to be coaxially positioned in the cylindrical space 9 with a gap, and the concave portion formed on the end surface of the pump body 1 facing the cylindrical space 9 contacts the outer peripheral surface of the rotary shaft 5. An oil seal 6 that seals between the trochoid pump 4 side and the cylindrical space 9 is provided so that a gap between the discharge chamber 3 and the rotary shaft 5 and the pump body 1 is provided. Thus, it is considered that the working oil for lubrication flows into the bottom of the recess provided with the oil seal 6 and then returns to the suction chamber 2 from the bottom through the return passage 2a formed in the pump body 1. It is done. In this way, the hydraulic oil from the discharge chamber 3 containing magnetic foreign matter does not enter the cylindrical space 9, so that the magnetic foreign matter is prevented from adhering and accumulating on the magnet, and the motor driving torque is reduced or the motor is stopped. Can be prevented. The technique shown in FIG. 4 is shown as a comparative example and is not a known technique, and there is no document describing such a structure.
[0005]
[Patent Document 1]
JP 2002-317772 (paragraph [0005], FIG. 1).
[0006]
[Problems to be solved by the invention]
However, in the technique shown in FIG. 4, the lip portion of the oil seal 6 is brought into contact with the outer periphery of the rotating shaft 5 to generate a loss torque due to friction, so that the motor torque necessary to obtain a desired pump output increases. As a result, the amount of energy consumption increases and the size, weight and heat generation of the motor also increase. The object of the present invention is to solve each of these problems.
[0007]
[Means for solving the problems, actions and effects thereof]
To this end, the electric liquid pump according to the present invention has a pump operating part at one end of a rotating shaft rotatably supported by a bearing hole of a pump body having a pump operating part and having a suction chamber and a discharge chamber formed therein. A motor in which a rotor is fixed, a rotor of a brushless DC motor having a magnet is fixed to the other end of the rotating shaft, and a bottomed cylindrical space is formed inside an annular stator made up of a core and a coil of the brushless DC motor The housing is fixed to the pump body so that the rotor is positioned in the cylindrical space with a slight gap, and the hydraulic oil discharged from the pump operating part to the discharge chamber passes through the gap between the bearing hole and the rotating shaft. In an electric liquid pump configured to flow into the cylindrical space and then return to the suction chamber from the cylindrical space through a return passage formed in the pump body, the pump facing the cylindrical space A recess that surrounds the rotating shaft is formed on the end surface of the body so that the hydraulic oil that has passed through the gap between the bearing hole and the rotating shaft flows into the concave and the return passage communicates with the bottom of the concave so that The pump body is provided with a partition member that partitions the inside of the recess from the cylindrical space with a slight gap between the pump body and the rotary shaft. It is.
[0008]
According to the present invention as described above, the hydraulic oil containing the magnetic foreign matter from the discharge chamber lubricated between the bearing hole and the rotary shaft and flowing into the recess is immediately returned to the suction chamber of the pump operating portion from the return passage. Therefore, only a small amount of hydraulic oil enters the cylindrical space. Accordingly, since the increasing speed of the amount of magnetic foreign matter contained in the hydraulic oil in the cylindrical space is greatly reduced, the driving torque of the brushless DC motor caused by such magnetic foreign matter adhering to and accumulating on the rotor magnet. Decrease, and the life of the motor is extended by improving the durability against magnetic foreign matter. Moreover, since a seal member that contacts the outer peripheral surface of the rotating shaft and seals between the pump operating part side and the cylindrical space is unnecessary, such a sealing member contacts the outer periphery of the rotating shaft and generates a loss torque due to friction. It does not occur, the motor torque required to obtain the desired pump output is reduced, energy consumption is reduced, and the size, weight and heat generation of the motor are also reduced. In addition, since the pump body is provided with a partition member that partitions the inside of the concave portion from the cylindrical space with a slight gap between the rotary shaft and the hydraulic oil including magnetic foreign matters entering the cylindrical space from the concave portion, Since it further decreases, the decrease in the driving torque of the brushless DC motor due to the adhesion and accumulation of magnetic foreign matter on the rotor magnet is reduced, and the durability against magnetic foreign matter can be further improved.
[0010]
In the electric liquid pump described in the previous section , a partition cover made of a nonmagnetic material may be provided between the pump body and the motor housing so as to cover the rotor in a liquid-tight manner with a slight gap therebetween and located in the cylindrical space. preferable. If it does in this way, the leakage to the exterior of the hydraulic fluid through the motor housing which molded the stator of the brushless DC motor can be reduced.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the embodiment shown in FIGS. 1 to 3, the description of the electric fluid pump according to the present invention. The electric liquid pump of this embodiment mainly includes a pump unit 10, a motor unit 20 that rotationally drives the pump unit 10, and a driver unit 30 that controls the operation of the motor unit 20.
[0012]
As shown mainly in FIG. 1, the pump unit 10 includes a pump body 11 having a circular storage recess 11a formed on one side, and a side surface of the pump body 11 in which the storage recess 11a is formed via an annular seal member 18a. The pump body 11 is formed with a bearing hole 11b that is eccentric with the housing recess 11a. The pump operating portion 15 made of a trochoid pump provided in the housing recess 11a is composed of an outer toothed inner rotor (pump rotor) 15a and an inner toothed outer rotor 15b meshing with the outer rotor 15b. The inner rotor 15a is press-fitted and fixed coaxially to one end of the rotating shaft 16 rotatably supported by the bearing hole 11b.
[0013]
As shown mainly in FIG. 1, a large number of pump working chambers 15c whose volume increases and decreases with rotation are formed between the teeth of the rotors 15a and 15b meshing with each other, and serve as both sides of the pump working chamber 15c. Suction chambers 13 and 13a are formed on the inner surface of the pump cover 12 and the bottom surface of the housing recess 11a along the range where the volume of the pump working chamber 15c increases, and along the range where the volume of the pump working chamber 15c decreases. Discharge chambers 14 and 14a are formed. The pump cover 12 is formed with a suction port 13 b communicating with the suction chamber 13 and a discharge port 14 b communicating with the discharge chamber 14.
[0014]
As shown in FIGS. 1 to 3 , the pump body 11 on the side opposite to the housing recess 11a of the pump operating portion 15 is formed with a cylindrical portion 11c coaxially with the bearing hole 11b, and the inner rotor 15a is fixed to one end portion. The other end portion of the rotating shaft 16 is projected from the end surface of the cylindrical portion 11c. A circular recess 17 is formed on the end surface of the cylindrical portion 11c of the pump body 11 so as to be coaxial with the bearing hole 11b so as to surround the rotating shaft 16, and a bottom portion of the suction body 13a is formed by a return passage 17a formed in the pump body 11. It is communicated to. The pump body 11 has a notch 14c that communicates the discharge chamber 14a with the bearing hole 11b. Furthermore, the dimensions of the recess 17 may be, for example, a depth of 2 mm and a diameter of the shaft diameter of the rotating shaft 16 +2 mm (when the shaft diameter of the rotating shaft 16 is about 10 mm).
[0015]
The sensorless brushless DC motor 22 of the motor unit 20 includes a stator 23 and a rotor 24. As shown in FIGS. 1 to 3 , the rotor 24 has a magnet 24b integrally fixed to the outer periphery of a cylindrical back yoke 24a, and the other end of the rotary shaft 16 protruding from the cylindrical portion 11c of the pump body 11. It is press-fitted and fixed coaxially. The stator 23 of the sensorless brushless DC motor 22 has an annular shape made up of a core 23a and a coil 23b of a laminated iron plate, is integrally molded in a resin motor housing 21, and has a bottomed cylindrical shape on the inner side of the stator 23. A space 25 is formed.
[0016]
In this embodiment, a partition cover 19 is provided between the pump body 11 and the motor housing 21. The partition cover 19 is made of a nonmagnetic material plate such as stainless steel, and is covered with the rotor 24 with a slight gap, and the opening half is fitted to the cylinder portion 11c of the pump body 11. Yes. The partition cover 19 is housed in the cylindrical space 25 of the motor housing 21, and a flange extending outward from the opening edge of the partition cover 19 is between the pump cover 12 and the motor housing 21 that are integrally connected to each other. It is designed to be clamped and fixed. Between the flange of the partition cover 19 and the pump body 11, an annular seal member 18 b that seals the internal space of the partition cover 19 in which the rotor 24 is accommodated from the outside is provided. As described above, the rotor 24 is coaxially positioned within the cylindrical space 25 with a slight gap, and the rotor 24 is coaxially and liquid-tightly spaced within the cylindrical space 25. A covering partition cover 19 is positioned. Note that there may be no gap between the cylindrical space 25 and the partition cover 19.
[0017]
On the side surface of the motor housing 21 that is opposite to the cylindrical space 25, an accommodation recess 26 is formed that accommodates a driver unit 30 that attaches a number of components to the substrate 31 and controls the operation of the motor unit 20. The housing recess 26 is covered with a cover 35 in a liquid-tight manner.
[0018]
When a current controlled by the driver unit 30 is applied to the coil 23b of the stator 23 of the sensorless brushless DC motor 22 to generate a rotating magnetic field, the rotor 24 is rotated, and the inner rotor 15a of the pump operating unit 15 is rotated via the rotating shaft 16. Driven by rotation. As a result, the hydraulic oil sucked into the pump working chamber 15c of the trochoid pump 15 from the suction port 13b through the suction chamber 13 is discharged from the discharge port 14b through the discharge chamber 14. Part of the hydraulic oil discharged from the pump working chamber 15c enters the recess 17 through the notch 14c and between the bearing hole 11b of the pump body 11 and the rotary shaft 16 to lubricate and cool the shaft support. The hydraulic oil in the recess 17 rotates in a vortex with the rotation of the rotary shaft 16, while the hydraulic oil flowing into the recess 17 from between the bearing hole 11 b and the rotary shaft 16 accompanies the operation of the pump operating portion 15. The amount of magnetic foreign matter such as fine iron powder gradually increases as time passes, but since the gap between the bearing hole 11b and the rotating shaft 16 is small (for example, 30 μm in diameter), the amount of inflow is small and vigorous. First, it spreads in the radial direction along the bottom of the recess 17, and most of it is returned to the suction chamber 13 a from the return passage 17 a communicating with the bottom of the recess 17 before being diffused throughout the recess 17. Accordingly, it takes time for the hydraulic oil containing the magnetic foreign material flowing into the recess 17 to be diffused between the rotor 24 which is a part of the cylindrical space 25 and the partition cover 19, and the cylindrical shape inside the partition cover 19. The increasing speed of the amount of magnetic foreign matter contained in the hydraulic oil in the space 25 is greatly reduced. Accordingly, the reduction in the driving torque of the brushless DC motor 22 due to the magnetic foreign matter adhering to and accumulating on the magnet 24b of the rotor 24 is reduced, the durability against the magnetic foreign matter is improved, and the motor life is extended.
[0019]
In the above-described embodiment, the hydraulic oil passing between the rotary shafts 16 of the bearing holes 11b is once allowed to flow into the recesses 17 and most of them are recessed before being diffused into the cylindrical space 25. A return passage 17 a communicated with the bottom of 17 is returned to the suction chamber 13 a of the pump operating unit 15. Accordingly, in order to prevent hydraulic oil containing magnetic foreign matter from flowing into the cylindrical space 25 inside the partition cover 19, the hydraulic oil abuts on the outer peripheral surface of the rotary shaft 16 and between the pump operating portion 15 side and the cylindrical space 9. A sealing member for sealing is unnecessary, and such a sealing member does not abut on the outer periphery of the rotating shaft 16 to generate a loss torque due to friction. Thus, the motor torque required to obtain the desired pump output is reduced, energy consumption is reduced, and the size, weight and heat generation of the motor are also reduced.
[0020]
In the above-described embodiment, the partition cover 19 located in the cylindrical space 25 is provided between the pump body 11 and the motor housing 21 so as to cover the rotor 24 coaxially and liquid-tightly with a slight gap. In this way, leakage of hydraulic oil through the stator 23 to the outside can be eliminated. However, the present invention is not limited to this, and can be implemented without using such a partition cover 19 depending on the application or by taking a means for eliminating leakage of hydraulic fluid through the stator 23. It is. By doing so, since the heat transfer coefficient is improved when the hydraulic oil contacts the stator 23, the cooling efficiency of the stator 23 can be increased.
[0021]
In the present embodiment , a partition member 17 b is further provided in the recess 17 formed in the pump body 11 .
[0022]
As shown in FIG. 3, the partition wall member 17 b is an annular sheet metal product having an L-shaped cross-section. The cylindrical outer peripheral portion is press-fitted and fixed to the inner peripheral surface of the concave portion 17, and protrudes inward from the upper edge of the outer peripheral portion. A slight gap is provided between the front end of the flange portion and the outer periphery of the rotating shaft 16.
[0023]
As described above, a small amount of hydraulic oil including magnetic foreign matter flowing into the recess 17 from between the bearing hole 11 b and the rotary shaft 16 spreads in the radial direction along the bottom of the recess 17, but this diffuses into the recess 17. diffuse into the space between the rotor 24 and the partition cover 19 after which is time consuming since it is made through some gap between the outer periphery of the distal end of the inward flange portion of the partition wall member 17b rotating shaft 16 The rate of increase in the amount of magnetic foreign matter contained in the hydraulic oil in the space between the rotor 24 and the partition cover 19 is also greatly reduced. Accordingly, the reduction in the driving torque of the brushless DC motor 22 due to such magnetic foreign matter adhering to and accumulating on the magnet 24b of the rotor 24 is further reduced, and the durability against magnetic foreign matter can be further improved.
[0024]
In this embodiment , the partition wall member 17b has an L-shaped cross-sectional shape and is press-fitted and fixed to the inner peripheral surface of the recess 17. However, the partition wall member 17b has a slight gap between the rotation shaft 16 and the interior of the recess 17. What is necessary is just to partition from the inside of the cylindrical space 25, for example, it is screwed to the end surface of the pump body 11 so as to cover the upper side of the outer peripheral portion of the concave portion 17 as a disk shape provided with a hole through which the rotating shaft 16 passes. It may be fixed by.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing the overall structure of an embodiment of an electric liquid pump according to the present invention.
2 is a partially enlarged sectional view showing a recess formed in an end surface of the pump body according to the embodiment shown in FIG.
FIG. 3 is a partially enlarged cross-sectional view showing a main part of the electric liquid pump according to the embodiment of the present invention.
FIG. 4 is a partially enlarged sectional view showing a comparative example of this type of electric liquid pump.

Claims (2)

A brushless DC motor having a magnet, having a pump rotor fixed to one end of a rotary shaft rotatably supported in a bearing hole of a pump body having a pump operating portion and formed with a suction chamber and a discharge chamber. A rotor is fixed to the other end of the rotating shaft, and the rotor has a gap between the rotor and a motor housing in which a cylindrical space with a bottom is formed inside an annular stator formed of a core and a coil of the brushless DC motor. The hydraulic fluid is fixed to the pump body so as to be positioned in the cylindrical space, and the hydraulic oil discharged from the pump operating portion to the discharge chamber passes through a gap between the bearing hole and the rotary shaft. In the electric liquid pump configured to flow into the space and then return to the suction chamber through a return passage formed in the pump body from the cylindrical space. Forming a recess surrounding the rotating shaft on the end surface of the pump body, allowing hydraulic oil that has passed through the gap between the bearing hole and the rotating shaft to flow into the recess, and returning the return passage to the bottom of the recess. A partition wall configured to recirculate the hydraulic oil in the concave portion to the suction chamber and to partition the concave portion from the cylindrical space with a small gap between the pump body and the rotating shaft. An electric liquid pump characterized in that a member is provided . 2. The electric liquid pump according to claim 1 , wherein the partition is made of a nonmagnetic material and is located in the cylindrical space so as to be liquid-tightly covered with a slight gap between the pump body and the motor housing. An electric liquid pump provided with a cover.

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