JP2012207638A - Internal gear pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal gear pump that can reduce generation of gear rattling sound.SOLUTION: In an electrically driven oil pump including a center housing 2 having a pump element housing part 24, an outer rotor 21 freely rotatably housed in the pump element housing part 24 and having an inner tooth on the inner peripheral side, a pump rotor 22 freely rotatably provided on the inner peripheral side of the outer rotor 21 and having an outer tooth engaged with the inner tooth on an outer peripheral side and a rotor driving shaft 32 connected to the pump rotor 22 and rotating and driving the pump rotor 22, the chip clearance CLt1 in a confinement part 52 having the maximum volume among a plurality of volume chambers formed between the inner tooth and the outer tooth after pump assembly is made to be smaller than a chip clearance CLt0 before the pump assembly.

Description

  The present invention relates to an internal gear pump.

  Conventionally, trochoid internal gear pumps are often used as oil pumps mounted on automobile transmissions and the like. The internal gear pump is formed between the inner teeth of the outer rotor and the outer teeth of the pump rotor by rotating the outer rotor having the inner teeth meshing with the outer teeth of the pump rotor by rotating the pump rotor by the drive shaft. The volume of a plurality of volume chambers is continuously changed to suck and discharge oil. Here, both rotors contact and rotate on the rotation direction side at the meshing portion having the smallest volume in each volume chamber. At that time, a predetermined backlash is set on the side opposite to the rotation direction at the meshing portion, and both rotors are smoothly rotated (see Patent Document 1).

JP 2008-151065 A

The outer rotor of the internal gear pump is rotatably supported on the outer periphery of the pump housing, and a predetermined gap is set between the inner periphery of the pump housing and the outer periphery of the outer rotor. For this reason, when the pump is driven, the outer rotor moves in the radial direction by an amount corresponding to the gap, so that both rotors come into contact with each other on the backlash side and unpleasant rattling noise is generated.
An object of the present invention is to provide an internal gear pump that can reduce the occurrence of rattling noise.

  In order to achieve the above object, the internal gear pump of the present invention includes both an internal gear of the outer rotor and an external gear of the pump rotor after the pump assembly of the confining portion having a substantially maximum volume among the plurality of volume chambers. The confinement gap between the crests was set smaller than the confinement gap before the pump was assembled.

  Therefore, in the present invention, generation of rattling noise can be reduced.

1 is a front view of an electric oil pump according to a first embodiment. It is a side view of the electric oil pump of Example 1. It is S3-S3 sectional drawing of FIG. It is S4-S4 sectional drawing of FIG. The eccentric amount of the pump rotor and the outer rotor before the pump is assembled, the tip clearance, and the outer diameter of the outer rotor. It is a figure which shows the tip clearance before a pump assembly | attachment. FIG. 4 is a view of the S7-S7 cross section of FIG. 3 viewed from the Y direction. It is a figure which shows the eccentric amount of a pump cover and a pump element accommodating part, and a pump element accommodating part internal diameter. It is a figure which shows the clearance of the outer rotor outer diameter after a pump assembly | attachment, and a pump element accommodating part internal diameter. It is a figure which shows the tip clearance after pump assembly | attachment. It is a figure which shows the backlash amount of the meshing part after a pump assembly | attachment.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the internal gear pump of this invention is demonstrated based on the Example shown on drawing.
[Example 1]
1 is a front view of an electric oil pump according to a first embodiment to which the internal gear pump of the present invention is applied, FIG. 2 is a side view of the electric oil pump according to the first embodiment, and FIG. 3 is a sectional view taken along line S3-S3 in FIG. 4 is a cross-sectional view taken along line S4-S4 of FIG.
[Overall structure]
The electric oil pump according to the first embodiment is a pump mounted for an automatic transmission of a vehicle having an idle stop function. This automatic transmission is a belt-type continuously variable transmission, and is separately provided with a main pump driven by an engine. When the engine is stopped by the idle stop control, the hydraulic pressure by the main pump cannot be secured, and if the hydraulic pressure decreases due to a frictional engagement element in the belt-type continuously variable transmission or a leak from the pulley, the hydraulic pressure required for restarting Since it takes time to secure the operability, drivability is reduced. Therefore, in addition to the main pump, an electric oil pump that can discharge hydraulic pressure regardless of the operating state of the engine is equipped, and by ensuring the hydraulic pressure corresponding to the leakage from the frictional engagement elements and pulleys, the engine can be restarted and restarted. Improved drivability.

  The electric oil pump according to the first embodiment includes a pump rotor 22 having external gears (hereinafter abbreviated as external teeth) and an outer rotor 21 having internal gears (hereinafter abbreviated as internal teeth). The pump element includes a motor element including a motor rotor 33 connected to the pump rotor 22 and the stator 3. These pump element and motor element are accommodated in one center housing 2. The center housing (housing) 2 has openings at both ends toward the outer side in the axial direction, and a pump element housing portion (outer rotor housing portion) 24 for rotatably housing the outer rotor 21 is formed on one opening inner periphery. A cylindrical pump housing portion 2a is formed, and a motor housing portion 2b is formed in the inner periphery of the other opening for fixing and supporting the stator 3 and housing the motor rotor 33 and the like, and further outside in the axial direction from the motor housing portion 2b. Is formed with a bracket 2c for attachment to the automatic transmission. Further, in the center housing 2, a cylindrical support portion 2d that rotatably supports the rotor drive shaft 32, and this cylindrical support portion 2d is connected to the outer periphery of the center housing 2, and the pump housing portion 2a and the motor housing portion. A partition wall is defined between 2b. A seal member that supports the rotor drive shaft 32 on the inner periphery of the cylindrical support portion 2d and seals between the rotor drive shaft 32 and the inner periphery of the cylindrical support portion 2d at the end on the motor housing portion 2b side. 31 is provided.

  The pump cover 1 has a discharge port 11 extending in a cylindrical shape communicating with the discharge port 26 of the pump element, and a suction port 12 communicating with the suction port 27 of the pump element. A seal ring groove 11a to which a seal ring 11b is attached is formed on the outer periphery of the distal end of the discharge port 11. The pump cover 1 is formed with bolt holes 13 at three locations in the circumferential direction, and is fastened and fixed by bolts 14 to the bolt holes 23 formed in the center housing 2. The motor cover 4 that closes the motor housing portion 2b includes a closing portion 41 that closes the motor housing portion 2b, and a cylindrical standing portion 42 that is erected from the closing portion 41 and inserted into the inner wall of the motor housing portion 2b. And a flange portion 43 that contacts the bracket 2c and presses the seal member 16. Bolt holes 25 and bolt holes 44 through which the bolts 5 pass are formed in the bracket 2c and the flange portion 43. Thereby, the inside of the motor housing portion 2b is configured as a drying chamber, and the inside of the pump housing portion 2a and the outer periphery of the pump are configured as wet chambers.

The pump element includes a pump rotor 22 having an external number of teeth Nr = 6 and an outer rotor 21 having an internal number of teeth of 7. The pump rotor 22 has a connecting hole 22a having a two-sided width at the center, and is fitted to the two-sided width formed at the pump side end of the rotor drive shaft 32. Thus, the relative position in the rotational direction between the rotor drive shaft 32 and the pump rotor 22 is determined and power is transmitted.
The motor element includes a motor rotor 33 having a magnetic pole number Nm = 4 and a stator 3 having a slot number Ns = 6. That is, the coil 35 is wound around each of the six teeth formed on the stator core 34 of the stator 3 to form slots. The motor rotor 33 is a cylindrical member having a substantially U-shaped cross section, and four permanent magnets are attached to the outer periphery of the cylinder so that N poles and S poles are alternately arranged. A connecting hole having a two-sided width is formed at the center of the support surface that closes the cylinder of the motor rotor 33, and is fitted to the two-sided width formed at the motor side end of the rotor drive shaft 32. Thereby, the relative position in the rotation direction between the rotor drive shaft 32 and the motor rotor 33 is determined and power transmission is performed. The positional relationship based on the rotation angles of the pump rotor 22, the rotor drive shaft 32, and the motor rotor 33 will be described later.

  The automatic transmission housing 100 is formed with an electric oil pump accommodating portion for accommodating the electric oil pump. Specifically, a discharge oil passage 103 for supplying hydraulic pressure to a control valve unit (not shown), a suction oil passage opening 102 communicating with the suction port 12 in a state where a pump element of the electric oil pump is accommodated, a suction oil A pump support opening 101 having a larger diameter than the path opening 102 and having substantially the same diameter as the outer periphery of the motor housing portion 2b of the center housing 2, and a tapered surface 101a formed at the outer opening edge of the housing 100 of the pump support opening 101 And have. The discharge oil passage 103 is substantially the same as the outer diameter of the discharge port 11, and is fitted and supported by insertion. The suction oil passage opening 102 is a cylindrical space formed at a position surrounding the discharge oil passage 103, and communicates with an oil suction opening that opens in an oil pan (not shown). Further, the pump support opening 101 is fitted between the outer periphery of the motor housing portion 2b to support the electric oil pump in the radial direction. Further, the taper surface 101a holds the seal ring 15 between the outer periphery of the motor housing portion 2b. The electric oil pump is fastened and fixed to the side wall of the housing 100 by bolts 5.

The operation of the electric oil pump according to the first embodiment will be described with reference to FIG.
When the rotor drive shaft 32 is rotated clockwise in FIG. 4, the pump rotor 22 provided integrally with the rotor drive shaft 32 is rotated, and the outer rotor 21 having the inner teeth meshing with the external teeth of the pump rotor 22 is also rotated clockwise. By rotating, oil is sucked from the suction port 27 into the suction-side volume chamber R1 whose volume increases and becomes negative pressure. The suction-side volume chamber R1 is changed to a discharge-side volume chamber R2 in which the volume decreases and the internal pressure increases as the pump rotor 22 and the outer rotor 21 rotate, and the oil sucked from the discharge-side volume chamber R2 Is discharged to the discharge port 26.
Such a pumping action is continuously performed by the rotation of the pump rotor 22 and the outer rotor 21, and the oil is continuously pumped. The differential pressure generated between the volume chambers R1 and R2 becomes remarkable due to the liquid sealing effect in which the sealing performance of the volume chambers R1 and R2 is enhanced by the sucked oil, and a pump action is obtained.

[Parameter setting methods for reducing rattling noise]
In the oil pump of the first embodiment, the parameters of the outer rotor 21, the pump rotor 22, the pump cover 1, and the pump element accommodating portion 24 are set as follows with the aim of reducing the occurrence of rattling noise.
As shown in FIGS. 5 and 6, the eccentric amount between the center of the pump rotor 22 and the center of the outer rotor 21 before assembly of the pump is X0, and the tip clearance (between both crests of the inner teeth of the outer rotor 21 and the outer teeth of the pump rotor 22). CLt0 and outer rotor outer diameter φD0, the eccentric amount between the center P1 of the bearing part and the center P2 of the pump element accommodating part 24 as shown in FIG. 7, X1 and the inner diameter of the pump element accommodating part (volume inner diameter) Is φD1.
At this time, as shown in FIG. 8, the clearance (gap) CLd between the outer diameter φD0 of the outer rotor after assembly of the pump and the inner diameter φD1 of the pump element accommodating portion is
CLd = φD1-φD0
It becomes.
Further, as shown in FIG. 9, the tip clearance CLt1 after the pump assembly of the confinement part 52 that has the largest volume among the plurality of volume chambers is as follows.
CLt1 = CLt0 / 2-(X0-X1) + CLd / 2
It becomes.
The tip clearance CLt1 is preferably defined by a gap between the crest portions 21a and 21b of the inner teeth of the outer rotor 21 and the outer teeth of the pump rotor 22, but backlash Y> 0 described later It is assumed that the clearance between both teeth having a slight phase difference in the rotation direction from both tooth crests 21a and 21b is included in the tip clearance CLt1.

Here, as shown in FIG. 10, when the outer rotor 21 moves within the clearance CLd in a direction in which the backlash amount is reduced in the direction in which the backlash amount becomes Y in the meshing portion 51 where the volume of the plurality of volume chambers is almost the minimum. Each parameter (CLt0, X0, φD0, X1, φD1) is set so that Y> 0 is always satisfied.
Note that when the tip clearance CLt1 of the confining portion 52 becomes larger than an appropriate value, the amount of oil leakage from the discharge side volume chamber R2 to the suction side volume chamber R1 increases, and the pump efficiency decreases. Therefore, in order to avoid this, each parameter is set so that the tip clearance CLt1 after assembling the pump becomes an appropriate value.
For this reason, in Example 1, the eccentric amount X1 after the pump assembly is set between the outer rotor 21 and the pump rotor 22 before the pump assembly so that the tip clearance CLt0 before the pump assembly becomes larger than the tip clearance CLt1 after the pump assembly. Each parameter (CLt0, X0, φD0, X1, φD1) is set to be smaller than the eccentric amount X0 and the backlash amount Y is larger than the clearance CLd between the pump element housing inner diameter φD1 and the outer rotor outer diameter φD0. ) Is set.

Next, the operation will be described.
[Tooth noise reduction effect]
In a conventional internal gear pump, when the pump is driven, the outer teeth of the pump rotor and the inner teeth of the outer rotor rotate while contacting each other at the meshing portion on the rotational direction side. At this time, a predetermined backlash is set on the side opposite to the rotation direction at the meshing portion, and both rotors are smoothly rotated.
Here, the outer rotor is rotatably supported in the pump element accommodating portion of the pump accommodating portion, and a predetermined gap is set between the inner periphery of the pump element accommodating portion and the outer periphery of the outer rotor. For this reason, when the pump is driven, the outer rotor moves in the radial direction by the amount of the gap, so that both rotors come into contact with each other on the backlash side, and the noise may be hindered by the generation of rattling noise. .

On the other hand, in the electric oil pump of the first embodiment, the eccentric amount X1 between the outer rotor 21 and the pump rotor 22 after assembling the pump is set smaller than the eccentric amount X0 between the outer rotor 21 and the pump rotor 22 before assembling the pump, Outer rotor 21, pump rotor 22, pump cover 1 and pump element so that tip clearance CLt1 after pump assembly of confining portion 52 having the largest volume among a plurality of volume chambers is smaller than tip clearance CLt0 before pump assembly Each parameter (CLt0, X0, φD0, X1, φD1) of the accommodating part 24 was set.
For this reason, the backlash amount Y in the meshing portion 51 can be increased as compared with the conventional internal gear pump that is set so that the tip clearance is the same before and after the pump is assembled. This backlash amount Y functions as an absorption margin to avoid contact on the backlash side of both rotors 21 and 22 when the outer rotor 21 moves in the direction of reducing the backlash, so a larger backlash amount Y than the conventional product is set. As a result, it is possible to avoid contact between the rotors 21 and 22 on the backlash side, and to reduce the occurrence of rattling noise.

In addition, since the tip clearance CLt1 after the pump assembly is smaller than the tip clearance CLt0 before the pump assembly, an increase in the amount of oil leak from the discharge side volume chamber R2 to the suction side volume chamber R1 is prevented, and the pump efficiency is reduced. Can be suppressed.
Further, in the first embodiment, the backlash amount Y between the pump rotor 22 and the outer rotor 21 in the meshing portion 51 is made larger than the clearance CLd between the outer diameter φD0 of the outer rotor and the inner diameter φD1 of the pump element accommodating portion. Contact on the side can be avoided and generation of rattling noise can be suppressed.
In contrast to the oil pump driven by the engine, the electric oil pump operates even when the engine is stopped, such as idle stop control, and therefore requires higher silent performance. By adopting the electric oil pump of the first embodiment having the above-described effect of reducing rattling noise, high silent performance can be realized in a silent environment when the engine is stopped.

Next, the effect will be described.
The electric oil pump according to the first embodiment has the following effects.
(1) Center housing 2 having a pump element accommodating portion 24, an outer rotor 21 rotatably accommodated in the pump element accommodating portion 24 and having inner teeth on the inner peripheral side, and rotatably provided on the inner peripheral side of the outer rotor 21 An electric oil pump comprising a pump rotor 22 having external teeth meshing with internal teeth on the outer peripheral side, and a rotor drive shaft 32 connected to the pump rotor 22 and rotationally driving the pump rotor 22, The tip clearance CLt1 after the pump assembly of the confinement part 52 having the maximum volume among the plurality of volume chambers formed between the teeth and the external teeth was set smaller than the tip clearance CLt0 before the pump assembly.
Therefore, it can suppress that both rotors 21 and 22 contact on the backlash side, and generation | occurrence | production of a rattling sound can be reduced. Further, it is possible to suppress a decrease in pump efficiency accompanying an increase in the amount of oil leak.

(2) Since the eccentric amount X1 between the outer rotor 21 and the pump rotor 22 after the pump assembly is set smaller than the eccentric amount X0 between the outer rotor 21 and the pump rotor 22 before the pump assembly, the tip clearance CLt1 after the pump assembly It can be made smaller than the tip clearance CLt0 before assembly.
(3) The backlash amount Y between the inner teeth and the outer teeth of the meshing portion 51 that has the smallest volume among the plurality of volume chambers is greater than the clearance CLd between the pump element housing portion inner diameter φD1 and the outer rotor outer diameter φD0. Since it is set to be large, it is possible to avoid contact between the rotors 21 and 22 on the backlash side, and to prevent the occurrence of rattling noise.

(Other examples)
As mentioned above, although the internal gear pump of this invention was demonstrated based on the Example, the specific structure of this invention is not limited to the structure of an Example.
For example, although the example applied to the automatic transmission is shown in the embodiment, it may be another fluid pressure operating device, may be used for cooling a heating element as an electric water pump, or for other hydraulic actuators It can also be applied as a pump. Moreover, it may not be electric.

2 Center housing (housing)
21 Outer rotor
22 Pump rotor
24 Pump element housing (outer rotor housing)
32 Rotor drive shaft (drive shaft)
51 Meshing part
52 Containment

Claims (3)

A housing having an outer rotor accommodating portion;
An outer rotor that is rotatably accommodated in the outer rotor accommodating portion and has an internal gear on the inner peripheral side;
A pump rotor that is rotatably provided on the inner peripheral side of the outer rotor and has an external gear that meshes with the internal gear on the outer peripheral side;
A drive shaft connected to the pump rotor and rotationally driving the pump rotor;
An internal gear pump comprising:
Between the tooth crests of the internal gear and the external gear after the pump assembly of the confining portion having a substantially maximum volume among the plurality of volume chambers formed between the internal gear and the external gear. The internal gear pump is characterized in that the confining gap is set smaller than the confining gap before the pump is assembled. The internal gear pump according to claim 1,
An internal gear pump, wherein an eccentric amount between the outer rotor and the pump rotor after the pump is assembled is set smaller than an eccentric amount between the outer rotor and the pump rotor before the pump is assembled. The internal gear pump according to claim 1 or 2,
The backlash amount between the internal gear and the external gear of the meshing portion where the volume is substantially minimum among the plurality of volume chambers is set to be larger than the gap between the inner diameter of the outer rotor housing portion and the outer diameter of the outer rotor. An internal gear pump characterized by a large setting.

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