JP2012057561A - Internal gear oil pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil pump in which the discharging amount is not lowered while preventing the seizure of the outer periphery of an outer gear.SOLUTION: An internal gear oil pump has the pump housing 2 having the cylindrical gear chamber 7, the pump cover, and the inner gear 4 and the outer gear 5 accommodated in the gear chamber 7, includes to the sucking port 9 to and the discharging port 10 in the gear chamber 7, the pump housing 2 and/or the pump cover has the sucking passage 11 communicating to the sucking port 9, the oil pump has the oil introducing opening at a part in the depth direction of the inner peripheral face of the gear chamber 7, the oil introducing opening is connected to the sucking passage 11 via the oil introducing passage 14.

Description

  The present invention relates to an internal gear type oil pump that sucks oil by an inner gear and an outer gear and then discharges the oil.

  The internal gear type oil pump is a pump that conveys oil by increasing or decreasing the volume of a pump chamber formed between an inner gear connected to a drive shaft and an outer gear driven by the inner gear. Due to its simple structure, low noise and high efficiency, the internal gear type oil pump is used as an automobile part. For example, it is used as an oil pump for generating hydraulic pressure for an automatic transmission or an oil pump used for engine lubrication.

  When an oil pump is used for operating hydraulic equipment, a high pressure of 1 MPa or more may be required as a generated pressure. In the internal gear type oil pump, the area of the pump chamber formed between the tooth surfaces of the inner gear and the outer gear is reduced, so that oil is discharged from the pump chamber to the discharge passage through the discharge port. Therefore, the discharge pressure is the same in the pump chamber on the discharge path and the discharge port.

  When a high pressure of 1 MPa or more is generated as the discharge pressure, a high pressure equivalent to the discharge pressure is applied to the tooth surfaces of the inner gear and the outer gear forming the pump chamber. In that case, since pressure toward the outer diameter direction of the discharge port is applied to the outer gear tooth surface, the outer gear is pressed against the inner peripheral surface of the gear chamber formed in the pump housing, and seizure may occur on the outer periphery of the outer gear. is there. As a countermeasure against seizure, a technique is known in which a concave groove is provided on the inner peripheral surface of the gear chamber on the discharge port side, and discharge pressure in the discharge port is introduced to the outer periphery of the outer gear (see Patent Document 1 below). By creating a concave groove on the inner peripheral surface on the discharge port side, seizure is suppressed because the pressure that pushes the outer gear tooth surface toward the outer periphery of the outer rotor and the pressure that pushes the outer gear outer periphery toward the inner periphery of the outer gear can be balanced. Is done.

Japanese Patent Laid-Open No. 2004-28005

  However, in the oil pump described in Patent Document 1, a recess is provided on the inner periphery of the gear chamber of the pump housing, and the recess and the discharge port communicate with each other. In this case, the oil carried by the pump chamber moves from the discharge port to the recess. The oil leaks from the gap between the pump housing and the rotor. Therefore, there has been a problem that the discharge amount of the pump is reduced.

  An object of the present invention is to provide an oil pump that prevents seizure on the outer periphery of an outer gear and does not reduce the discharge amount.

In order to solve the above problems, in the present invention, an internal gear oil pump,
A pump housing having a gear chamber, a pump cover, an inner gear and an outer gear accommodated in the gear chamber, the gear chamber including a suction port and a discharge port;
The pump housing and / or the pump cover has a suction passage communicating with the suction port, and includes an oil introduction port in a part of the inner circumferential surface of the gear chamber in the depth direction,
Here, the oil introduction port is an internal gear oil pump that is connected to the suction passage through the oil introduction passage.

  In the internal gear type oil pump of the present invention, the oil introduction port is connected to the suction path, so the amount of oil introduced does not affect the amount of oil carried by the gear, and the discharge amount does not decrease. Since the oil introduction port is connected to the suction path, a sufficient amount of oil is introduced to the outer periphery of the outer gear. The oil introduced to the outer periphery of the outer gear generates a hydraulic pressure by a wedge action and prevents seizure of the outer gear outer periphery.

  The ratio of the height of the oil inlet to the depth of the gear chamber is preferably 10% or more and 50% or less.

  The gear chamber has a cylindrical shape with a depth corresponding to the thickness of the gear. When the ratio of the height of the oil inlet to the depth of the gear chamber is 50% or more, the area of the peripheral surface of the gear chamber is reduced. Since the area supporting the outer periphery of the gear becomes small, the outer periphery of the gear may bite into the oil introduction port. If the bite occurs, the corner portion of the oil introduction port may be peeled off and the outer peripheral portion of the gear may be worn away. If it is less than 10%, the amount of oil supplied is not sufficient, and there is a possibility that seizure of the outer periphery of the gear occurs.

  It is preferable that the oil introduction port is provided on the inner peripheral surface of the gear chamber corresponding to the suction port.

  Oil can be sufficiently introduced by installing an oil inlet on the circumferential surface of the gear chamber corresponding to the suction port at the maximum. If the oil introduction port is installed on the gear chamber collecting surface beyond the gear chamber corresponding to the intake port, the distance between the oil introduction port and the high-pressure discharge port will be close, and oil will flow back to the oil introduction port, resulting in a decrease in the discharge amount. May happen.

  It is preferable that the oil introduction port is provided on an end surface of the pump housing.

  By forming the oil introduction port on the end face of the pump housing, the pump housing can be easily manufactured.

  The oil inlet is preferably connected to the suction port.

  Since the oil introduction port is connected to the suction port, the pump housing can be easily manufactured.

  It is preferable that the angle between the end portion of the oil inlet in front of the gear rotation direction and the inner peripheral surface of the gear chamber is less than 30 degrees.

  Smooth oil can be introduced by setting the angle between the end portion of the oil inlet in front of the gear rotation direction and the inner peripheral surface of the gear chamber to 30 degrees or less. If it exceeds 30 degrees, the oil flow at the end becomes unstable, and there is a possibility that sufficient oil cannot be introduced.

  The present invention provides an oil pump in which the discharge amount does not decrease while preventing seizure of the outer periphery of the outer gear.

It is a front view of the pump housing of this invention which combined the gear. It is arrow XX of the oil pump which combined the pump cover with the pump housing of FIG. It is a front view of the pump housing of FIG. FIG. 4 is a YY view of the pump housing of FIG. 3. It is the front view which combined the gear with the pump housing of invention 2 used in the example. FIG. 6 is an arrow XX of an oil pump in which a pump cover is combined with the pump housing of FIG. 5. It is a front view of the pump housing of FIG. FIG. 8 is a YY view of the pump housing of FIG. 7. It is the front view which combined the gear with the pump housing of the comparative product 1 used in the Example. FIG. 10 is an arrow XX of an oil pump in which a pump cover is combined with the pump housing of FIG. 9. FIG. 10 is a front view of the pump housing of FIG. 9. It is a front view of the pump housing of the invention 5 used in the Example. It is a front view of the pump housing of the invention product 6 used in the Example. It is a front view of the pump housing of invention 7 used in the example.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. As shown in FIG. 2, the oil pump 1 includes a pump housing 2, a pump cover 3, an inner gear 4, an outer gear 5, and a drive shaft 6. As shown in FIG. 1, the inner gear 4 and the outer gear 5 are combined with their centers shifted from each other by the amount of eccentricity and housed in a gear chamber 7 formed in the pump housing 2. The drive shaft 6 is fitted into the inner diameter of the inner gear 2. The pump housing 2 and the pump cover 3 are positioned and joined by pins or the like. Here, each part which comprises the oil pump is demonstrated in detail.

[Pump housing]
The pump housing 2 is manufactured from cast iron or aluminum alloy. As shown in FIG. 3, a cylindrical gear chamber 7 is formed on one end face of the pump housing. A shaft hole into which the drive shaft is inserted, a suction port 9 that is an oil inlet, and a discharge port 10 that is an oil outlet are formed on the bottom surface of the gear chamber.
As shown in FIG. 2 or FIG. 4, a suction path 11 and a discharge path 12 are connected to the suction port 9 and the discharge port 10. In the case of a high-pressure oil pump having a discharge pressure exceeding 1 MPa, the suction passage 11 and the discharge passage 12 are often not exposed to the bottom surface of the gear chamber 7. This is because when the discharge passage 12 is exposed on the bottom surface 20 of the gear chamber, the discharge pressure is applied to the side surface of the gear, so that the gear tilts or is pressed against one side surface, causing seizure or a decrease in the discharge amount. This is because it occurs.
The shapes of the suction port 9 and the discharge port 10 shown in FIG. 3 are designed according to the gear tooth profile. In the gear chamber 7, a crescent-shaped protrusion called a crescent may be formed depending on the tooth shape of the gear. This embodiment is also effective for an oil pump in which a crescent is formed.

[Pump cover]
The pump cover 3 is made of cast iron or aluminum alloy in the same manner as the pump housing 2.
In the case of a high-pressure oil pump, in order to make the pressure applied to the gear uniform as shown in FIG. 2, a suction port or a discharge port may be formed on the end surface of the pump cover in the same manner as the pump housing 2. . A suction path or a discharge path connected to the suction port or the discharge port is connected to the pump cover.

[Oil inlet]
As shown in FIGS. 2 to 4, an oil introduction port 13 for introducing oil to the outer periphery of the gear is formed on the inner peripheral surface of the gear chamber 7. The oil introduction port 13 is connected to the suction passage 11 through an oil introduction passage 14.
As shown in FIG. 4, the ratio (H / D) of the height H of the oil inlet to the depth D of the gear chamber is preferably 10% or more and 50% or less. If it is 50% or more, the area of the gear chamber peripheral surface is reduced. In that case, since the area supporting the gear outer periphery becomes small, the gear outer periphery may bite into the oil introduction port 13. When the bite occurs, the end portion of the oil inlet 13 causes peeling wear or uneven wear occurs on the outer periphery of the gear. If the ratio of the height H of the oil inlet to the depth D of the gear chamber (H / D) is less than 10%, the amount of oil supplied is not sufficient, and there is a risk of seizure of the outer periphery of the gear.
The oil inlet 13 is formed on the peripheral surface of the gear chamber corresponding to the suction port 9. The peripheral surface of the gear chamber corresponding to the suction port 9 is a section between the intersection of the straight line extending both ends of the suction port 9 and the side surface of the gear chamber. If both ends of the oil inlet 13 are close to the discharge port 10, oil may leak from the discharge port 10 to the oil inlet 13. Therefore, it is preferable to set both ends of the oil introduction port 13 to the gear chamber circumferential surface corresponding to the suction port 9.
When the angle between the end 18 of the oil inlet at the front of the gear rotation direction and the inner peripheral surface of the gear chamber is 5 degrees or more and 30 degrees or less, the oil is smoothly introduced to the outer periphery of the gear, and the end of the oil inlet The trouble due to flow separation or the like is eliminated at the portion 18. Further, a shallow groove of about 0.5 mm from the end may be extended forward in the gear rotation direction. Also in this case, the extended tip is set so as not to exceed the tip of the suction port 9.

[Oil introduction path]
As shown in FIG. 2, when the oil introduction port 13 is formed at a position in contact with the pump housing end surface 15 on the circumferential surface of the gear chamber, the oil introduction passage 14 connecting the oil introduction port 13 and the suction passage 11 is formed on the pump housing end surface 15. It is formed.
When the oil introduction path 14 is formed in the pump housing end surface 15, the cross-sectional area of the oil introduction path 14 can be increased, and the oil introduction port 13 and the oil introduction path 14 can be linearly arranged, so that it is efficient. Oil can be introduced into the outer gear profile.
In addition, when the oil introduction port 13 is formed at a position where the gear chamber circumferential surface and the pump housing end surface 15 intersect, the oil introduction port 14 may be formed on the pump cover end surface 16. If the oil introduction path 14 is formed in the pump cover end face 16, the oil introduction path can be easily formed.
As shown in FIG. 5 to FIG. 8, when the oil introduction port 13 is formed in the middle of the inner peripheral surface of the gear chamber 7 or on the bottom surface 20 of the gear chamber, the oil passes through the suction passage 11 from the bottom surface 20 of the gear chamber. The introduction path 14 may be formed. With this configuration, the pump housing can be easily manufactured.

[Inner gear / outer gear]
The gear 17 for the internal gear type oil pump is made of sintered metal. The gear 17 includes an inner gear 4 having external teeth and an outer gear 5 having internal teeth. As the tooth profile of each gear, a trochoid tooth profile, a cycloid tooth profile, or the like is used, but it is not particularly limited. Particularly, in the case of the gear 17 in which the number of teeth of the outer gear 5 is one more than the number of teeth of the inner gear 4, there is no other member that supports the tooth surface between the tooth surfaces of the inner gear 4 and the outer gear 5. 5 is easily pressed against the inner peripheral surface of the gear chamber 7 by the pressure applied to the tooth surface, and the outer periphery of the outer gear 5 is easily seized. Therefore, when this embodiment is applied, the effect of preventing seizure on the outer periphery of the outer gear 5 is high.

<Example 1>
An oil pump was produced under the following conditions, and the characteristics were evaluated.

(Invention 1)
Rotor dimensions: φ60mm × 10mm
Theoretical discharge amount: 8.5cc
Tooth profile of gear: Trochoid tooth profile Number of teeth of each gear (inner gear / outer gear): 9/10
Material of each gear: Iron-based sintered metal Pump housing material: Cast iron Pump cover material: Cast iron As shown in FIG. 4, an oil inlet 13 was formed at a position where the gear chamber peripheral surface and the pump housing end surface 15 intersect. As shown in FIG. 2, the oil introduction path 14 is formed on the pump housing end face 15. The depth D of the gear chamber is 10 mm. The height H of the oil inlet 13 was 5 mm (H / D = 50%). The lateral width of the oil introduction path 14 was the same as that of the suction path 11. The angle θ between the oil introduction port end 18 in the front of the rotor rotation direction and the inner peripheral surface of the gear chamber was 20 degrees.

(Invention 2)
As shown in FIG. 8, the oil introduction port 13 of the same size of the product 1 was formed so as to contact the gear chamber bottom surface 20. In this pump housing, the gear chamber bottom surface 20 is not formed on the suction passage 11. The oil introduction path 14 was formed so as to be connected to the suction path 11 (FIG. 6). Other configurations are the same as those of Invention 1.

(Comparative product 1)
Except that the oil introduction port 13 and the oil introduction passage 14 are not formed, it is the same as the product 1 of the invention.

An evaluation test was performed on the above pump.
Evaluation conditions are
Discharge pressure (MPa): 0.5, 1.8, 2.5
Oil temperature (° C): 100
Rotational speed (rpm): 5000
Oil used: ATF
Test time: 10 hours, and it was evaluated whether there was a scratch of 1 mm or more on the outer periphery of the outer gear, that is, whether burn-in occurred.

From the above evaluation results, seizure did not occur in Invention 1 and Invention 2 even at a high pressure of 1.8 MPa or more. It can be seen that the invention product 1 had no flaws even at 2.5 MPa, and the oil was efficiently introduced.
<Example 2>

(Invention 3)
Except for the height H of the oil inlet 13 being 1 mm (H / D = 10%), it is the same as the product 1 of the invention.

(Invention 4)
Except for the height H of the oil inlet 13 being 7 mm (H / D = 70%), it is the same as the product 1 of the invention.

(Invention 5)
Except for the height H of the oil inlet 13 being 10 mm (H / D = 100%), it is the same as the product 1 of the invention.

An evaluation test was performed on the inventive product 1, the inventive product 3, the inventive product 4, the comparative product 1 and the comparative product 2.
Evaluation conditions are
Discharge pressure (MPa): 1.8, 2.5
Oil temperature (° C): 100
Rotational speed (rpm): 5000
Oil used: ATF
Test time: 10 hours, and it was evaluated whether there was a scratch of 1 mm or more on the outer periphery of the outer gear, that is, whether burn-in occurred.

From the above evaluation results, seizure did not occur in Invention 1, Invention 3, Invention 4, and Invention 5 even at a high pressure of 1.8 MPa or more. It can be seen that Invention 1 and Invention 3 had no flaws even at 2.5 MPa, and the oil was introduced efficiently.
<Example 3>

(Invention 6)
The width of the oil inlet 13 was formed in the entire area of the gear chamber peripheral surface corresponding to the suction port 9. Other configurations are the same as those of Invention 1.

(Invention 7)
The oil introduction port end 18 in the front of the gear rotation direction is formed in the front of the gear rotation direction beyond the intersection of the straight line extending from the end of the suction port 9 and the side surface of the gear chamber. Other configurations are the same as those of Invention 1.

(Invention 8)
The oil introduction port end 19 at the rear of the gear rotation direction is formed at the rear of the gear rotation direction beyond the intersection of the straight line extending from the end of the suction port 9 and the side surface of the gear chamber. Other configurations are the same as those of Invention 1.

An evaluation experiment was conducted on the pump.
Evaluation conditions are
Discharge pressure (MPa): 1.8, 2.5
Oil temperature (° C): 100
Rotational speed (rpm): 5000
Oil used: ATF
The volumetric efficiency and seizure were evaluated.

  From the above evaluation results, it was found that although the inventive products 4, 5 and 6 did not cause seizure, the inventive product 4 has higher volumetric efficiency than the comparative product 2 and the comparative product 3.

  The internal gear pump of the present invention can be suitably used as an oil pump for lubricating a car engine or an automatic transmission (AT).

DESCRIPTION OF SYMBOLS 1 Oil pump 2 Pump housing 3 Pump cover 4 Inner gear 5 Outer gear 6 Drive shaft 7 Gear chamber 9 Suction port 10 Discharge port 11 Suction path 12 Discharge path 13 Oil introduction port 14 Oil introduction path 15 Pump housing end surface 16 Pump cover end surface 17 Gear 18 Oil introduction port end 19 in the gear rotation direction front Oil introduction port end 20 in the gear rotation direction rear Gear chamber bottom surface D Gear chamber depth H Oil introduction port height

Claims (6)

An internal gear oil pump,
A pump housing (2) having a cylindrical gear chamber (7);
A pump cover (3);
An inner gear (4) and an outer gear (5) accommodated in the gear chamber (7);
The gear chamber (7) includes a suction port (9) and a discharge port (10),
The pump housing (2) and / or the pump cover (3) has a suction passage (11) communicating with the suction port (9),
An oil inlet (13) is provided in a part of the inner circumferential surface of the gear chamber (7) in the depth direction,
Here, the oil introduction port is an internal gear type oil pump that is connected to the suction passage (11) through an oil introduction passage (14).   2. The internal gear oil pump according to claim 1, wherein a ratio of a height (H) of the oil introduction port to a depth (D) of the gear chamber is 10% or more and 50% or less.   The internal gear oil pump according to claim 1 or 2, wherein the oil introduction port (13) is provided on an inner peripheral surface of the gear chamber (7) corresponding to the suction port (9).   The internal gear type oil pump according to any one of claims 1 to 3, wherein the oil introduction port (13) is provided on an end surface (15) of the pump housing.   The internal gear type oil pump according to any one of claims 1 to 3, wherein the oil introduction port (13) is connected to the suction port (9).   The internal gear according to any one of claims 1 to 4, wherein an angle between an end portion (18) of the oil introduction port forward in the gear rotation direction and an inner peripheral surface of the gear chamber (7) is less than 30 degrees. Oil pump.

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