WO2020110180A1

WO2020110180A1 - Internal gear pump

Info

Publication number: WO2020110180A1
Application number: PCT/JP2018/043438
Authority: WO
Inventors: 啓吉田
Original assignee: 住友精密工業株式会社
Priority date: 2018-11-26
Filing date: 2018-11-26
Publication date: 2020-06-04
Also published as: EP3828415A1; JP6526371B1; JPWO2020110180A1; CN112639290A; EP3828415B1; CN112639290B; EP3828415A4

Abstract

An internal gear pump (1) is provided with: a pinion gear (3); a ring gear (4); a crescent (54); a housing (5) with a slide surface (51) on which an outer peripheral surface (41) of the ring gear slides; a high-pressure oil supply portion (8) which has an inlet (81) opening on the slide surface and supplies a high-pressure operating oil; and a recess (9) provided in the slide surface so as to increase the interval between the outer peripheral surface of the ring gear and the slide surface. The inlet is located in a pressure-increasing region, and the recess is located in a high-pressure region.

Description

Internal gear pump

The technology disclosed here relates to internal gear pumps.

Patent Document 1 describes an internal gear pump including a drive gear having external teeth and a driven gear having internal teeth. The internal gear pump of Patent Document 1 has a pocket formed on the circumferential surface of the pump housing on the side opposite to the meshing point where the drive gear and the driven gear mesh with each other. The pocket communicates with the discharge port of the internal gear pump. When the internal gear pump is operating, a part of the high-pressure hydraulic oil discharged from the discharge port is introduced between the driven gear and the housing through the pocket.

A crescent-shaped space is formed between the driven gear and the drive gear, which seals when the tooth tips of the driven gear and the tooth tips of the drive gear come into contact with each other. The high-pressure hydraulic fluid discharged from the pocket pushes the driven gear so that the tooth tip of the driven gear is pressed against the tooth tip of the drive gear. The hydraulic oil in the crescent-shaped space is suppressed from leaking between the tooth tips of the driven gear and the tooth tips of the drive gear.

Patent Document 2 also describes an internal gear pump that suppresses leakage of hydraulic oil inside the housing. The internal gear pump of Patent Document 2 has an oil groove formed on the inner peripheral surface of the housing. The oil groove is connected to the discharge port and extends in the circumferential direction to a position corresponding to the crescent-shaped space. During operation of the internal gear pump, high-pressure hydraulic oil introduced into the housing through the oil groove pushes the outer rotor. The hydraulic oil is suppressed from leaking between the inner teeth of the outer rotor and the outer teeth of the inner rotor.

The internal gear pump described in Patent Document 3 has two pressure balance grooves on the inner peripheral surface of the housing. The two pressure balance grooves are provided at intervals in the circumferential direction in a high pressure region where the discharge port opens. Each of the two pressure balance grooves is connected to the discharge port. When the internal gear pump is operating, high-pressure hydraulic oil is supplied between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing through each of the two pressure balance grooves. Since the ring gear rotates with respect to the housing in a floating state, seizure of the ring gear is suppressed.

Japanese Utility Model Publication No. 61-179385 Japanese Patent Laid-Open No. 7-151066 Japanese Utility Model Publication No. 62-158181

As described in Patent Document 1 and Patent Document 2, an internal gear pump that supplies high-pressure hydraulic oil between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing is operated at a low rotational speed. In the pressure increasing region where the outer teeth of the pinion gear and the inner teeth of the ring gear are disengaged from each other, it is possible to prevent the hydraulic oil from leaking between the outer teeth and the inner teeth. In addition to this, in the internal gear pump configured as described above, the gap between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing becomes small even in the high pressure region, so that the suction port opens from the high pressure region of the hydraulic oil. Leakage to the low pressure region can be suppressed.

However, the inventor of the present application has noticed that when the internal gear pump having the above-described configuration operates at a high rotation speed, the amount of hydraulic oil leaking inside the housing increases.

The technology disclosed here suppresses leakage of hydraulic oil in the housing of the internal gear pump.

By supplying high-pressure hydraulic oil between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing, when the ring gear is pushed and moves from the outer periphery of the boost region toward the center of rotation of the ring gear, as described above. In addition, in the high pressure region, the gap between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing becomes small. During operation of the internal gear pump, a so-called "wedge effect" occurs in the gap between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing as the ring gear rotates. The "wedge effect" means that as the ring gear rotates, the hydraulic oil is dragged into the narrow gap between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing, and the outer peripheral surface of the ring gear and the inner peripheral surface of the housing. A phenomenon in which the pressure of the oil film between the surfaces increases.

When the internal gear pump is operating at low speed, the wedge effect is low, so in the high pressure range, the gap between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing is small, and there is little leakage of hydraulic oil.

However, when the internal gear pump is operating at a high rotational speed, the wedge effect of the gap between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing increases, and the ring gear moves from the outer periphery of the high pressure region to the center of rotation of the ring gear. The inventor of the present application has found that they are pushed and moved toward. When the ring gear is pushed and moves from the outer circumference of the high pressure area toward the center of rotation of the ring gear due to the wedge effect, the gap between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing increases in the high pressure area, and the outer circumference of the ring gear increases. Not only increases the leakage of hydraulic oil from the gap between the inner surface of the housing and the inner peripheral surface of the housing, but also increases the leakage of hydraulic oil between the outer teeth of the pinion gear and the inner teeth of the ring gear even in the boost region. I will end up.

Based on the above knowledge, the inventor of the present application decided to partially widen the distance between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing in order to reduce the wedge effect. Then, it is confirmed that by providing a concave portion at a specific position on the inner peripheral surface of the housing, leakage of hydraulic oil is suppressed in the housing of the internal gear pump that is operating at a high rotational speed, and disclosed herein. The technology was completed.

Specifically, the internal gear pump disclosed herein has a pinion gear having external teeth, a ring gear having internal teeth meshing with the external teeth provided on an inner peripheral surface thereof, and a pinion gear and the ring gear that are meshed with each other. A housing provided and having a crescent against which each of the outer teeth and the inner teeth abuts, and a sliding surface on which the outer peripheral surface of the ring gear slides, and a housing that rotatably accommodates the pinion gear and the ring gear, A high-pressure oil supply part having an inlet opening to the sliding surface and supplying high-pressure hydraulic oil between the outer peripheral surface of the ring gear and the sliding surface through the inlet, and an outer peripheral surface of the ring gear And a recess provided in the sliding surface so that the distance between the sliding surface and the sliding surface widens.

Then, the space in the housing is divided into three regions of a low pressure region where the suction port is open, a high pressure region where the discharge port is open, and a pressure rise region where the crescent is disposed, and the introduction port is Located in the boost region, the recess is located in the high pressure region.

According to this configuration, the pinion gear and the ring gear rotate in the direction from the low pressure region to the high pressure region via the boost region.

During operation of the internal gear pump, high-pressure hydraulic oil is introduced between the outer peripheral surface of the ring gear and the sliding surface of the housing from the inlet located in the boost region. The high-pressure hydraulic oil pushes and moves the ring gear from the outer periphery of the pressurizing region toward the center of rotation of the ring gear, and the inner teeth of the ring gear are pressed against the crescent. In the pressure rising region, hydraulic oil is suppressed from leaking between the inner teeth of the ring gear and the crescent. Further, in the high pressure region, hydraulic oil is suppressed from leaking from between the outer peripheral surface of the ring gear and the sliding surface of the housing.

ㆍSince the ring gear is pushed from the outer circumference of the boost region toward the center of rotation of the ring gear, a wedge effect is created between the outer peripheral surface of the ring gear and the sliding surface of the housing in the high pressure region. A recess is provided on the sliding surface in the high-pressure region. The recess partly widens the distance between the outer peripheral surface of the ring gear and the sliding surface of the housing. The recess reduces the wedge effect.

Since the wedge effect is reduced, the ring gear is suppressed from being pushed from the outer periphery of the high pressure region toward the center of rotation of the ring gear when the internal gear pump is operating at a high rotation speed. As a result, in the high pressure region, hydraulic oil is suppressed from leaking through the gap between the outer peripheral surface of the ring gear and the sliding surface of the housing. In addition, in the boost region, leakage of hydraulic oil from between the inner teeth of the ring gear and the crescent is suppressed.

Note that when the internal gear pump is operating at a low rotational speed, the wedge effect does not increase, so in the high pressure region, hydraulic oil is suppressed from leaking through the gap between the outer peripheral surface of the ring gear and the sliding surface of the housing. .. In addition, in the boost region, leakage of hydraulic oil from between the inner teeth of the ring gear and the crescent is suppressed.

Also, the hydraulic oil introduced between the outer peripheral surface of the ring gear and the sliding surface of the housing through the inlet also functions as lubricating oil between the ring gear and the housing. The seizure between the ring gear and the housing is suppressed.

Further, as described above, by preventing the hydraulic oil from leaking inside the housing, it is possible to suppress heat generation inside the housing. This also prevents seizure between the ring gear and the housing.

The recess may have a groove shape.

　The groove-shaped recess can effectively reduce the wedge effect. Further, the groove-shaped recess can be easily formed on the sliding surface of the housing.

The recess may be unconnected to the discharge port.

As described above, the concave portion has the function of reducing the wedge effect by widening the gap between the outer peripheral surface of the ring gear and the sliding surface of the housing. The recess does not require the function of introducing high-pressure hydraulic oil into the housing.

Further, if the high pressure hydraulic oil is introduced into the housing through the recess, the high pressure hydraulic oil introduced from the recess pushes the ring gear from the outer periphery of the high pressure area toward the center of rotation of the ring gear. In the high pressure region, there is a risk that hydraulic fluid may be promoted to leak through the gap between the outer peripheral surface of the ring gear and the sliding surface of the housing. Further, in the pressure increasing region, there is a risk that the hydraulic oil may be promoted to leak from between the inner teeth of the ring gear and the crescent.

By suppressing the leakage of hydraulic oil in the housing by combining the introduction of high-pressure hydraulic oil from the inlet located in the pressure-increasing region and the reduction of the wedge effect by the recesses located in the high-pressure region, , As well as preventing the seizure of the ring gear.

The high-pressure oil supply unit may have an oil passage that connects the discharge port and the introduction port, and a throttle that is provided in the oil passage and that reduces the pressure of the hydraulic oil.

If the pressure of the hydraulic oil introduced into the housing through the inlet is too high, the force at which the tooth tips of the ring gear are pressed against the crescent becomes too strong. Wear of the teeth of the ring gear is likely to progress. Therefore, the pressure of the hydraulic oil introduced into the housing may be adjusted by providing a throttle in the oil passage.

Further, by adjusting the pressure of the hydraulic oil introduced into the housing and reducing the wedge effect by the recess, the leakage of the hydraulic oil in the housing is suppressed, and the ring gear and the housing are prevented from leaking. There is a balance between ensuring lubricity between them.

The outer peripheral surface of the ring gear may be provided with a lubricating coating.

By doing this, seizure between the ring gear and the housing is suppressed. Since the conventional internal gear pump has relatively low processing accuracy and the lubrication coating is not formed on the outer peripheral surface of the ring gear, as described in Patent Document 3, the hydraulic oil is supplied to the housing through two balance grooves. It was necessary to suppress seizure between the ring gear and the housing by introducing it inside.

On the other hand, now that the machining accuracy is high and the lubrication coating is formed on the outer peripheral surface of the ring gear as described above, the ring gear can be introduced without introducing hydraulic oil into the housing through the two balance grooves. It is possible to suppress the seizure between the housing and the housing.

According to the internal gear pump, it is possible to suppress the leakage of hydraulic oil in the housing.

FIG. 1 is a sectional view of an internal gear pump. FIG. 2 is an end view taken along the line II-II of FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2 and a view seen from the direction A. FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2 and a view seen from the direction B. FIG. 5 is an enlarged cross-sectional view showing an enlarged vicinity of a meshing portion of the pinion gear and the ring gear during operation of the internal gear pump. FIG. 6 is a cross-sectional view showing the configuration of a high-pressure oil supply unit different from that in FIG. 3 and a view seen from the direction C.

Hereinafter, an embodiment of the internal gear pump 1 will be described with reference to the drawings. The following description is an example of the internal gear pump 1.

(Overall structure of internal gear pump)
FIG. 1 is a cross-sectional view of the internal gear pump 1. FIG. 2 is an end view taken along the line II-II of FIG. The internal gear pump 1 includes a shaft 2, a pinion gear 3, a ring gear 4, a gear housing 5, a front cover 6, and a rear cover 7. In FIG. 2, the shaft 2, the pinion gear 3, and the ring gear 4 are not illustrated with hatching showing end faces for easy understanding.

The shaft 2 extends in the left-right direction on the paper surface of FIG. The shaft 2 is connected to a prime mover (not shown). The prime mover is, for example, an electric motor.

The pinion gear 3 is fixed to the shaft 2. The pinion gear 3 and the shaft 2 are coaxial. The pinion gear 3 rotates with the shaft 2. The pinion gear 3 has external teeth 31.

The ring gear 4 meshes with the pinion gear 3. The ring gear 4 is arranged eccentrically with respect to the shaft 2. Inner teeth 41 are formed on the inner peripheral surface of the ring gear 4. In the region on the right side of the paper surface of FIG. 2, part of the outer teeth 31 of the pinion gear 3 meshes with part of the inner teeth 41 of the ring gear 4. Although not shown in the drawing, the outer peripheral surface 42 of the ring gear 4 is provided with a lubricating coating. The lubricating coating may be made of, for example, a material containing an inorganic material and a fluororesin.

The gear housing 5 accommodates the pinion gear 3 and the ring gear 4. A through hole 53 is formed in the gear housing 5. The shaft 2 is located in the through hole 53.

The pinion gear 3 and the ring gear 4 are rotatably housed in a gear housing 5. The gear housing 5 has a sliding surface 51 on which the outer peripheral surface 42 of the ring gear 4 slides. The outer peripheral surface 42 of the ring gear 4 has a circular cross section. The sliding surface 51 of the gear housing 5 also has a circular cross section. The sliding surface 51 is eccentric with respect to the shaft 2.

The gear housing 5 has a side surface 52 orthogonal to the sliding surface 51. The sliding surface 51 and the side surface 52 form a space 50 that houses the pinion gear 3 and the ring gear 4. The space 50 is open to the left side of the paper surface of FIG. The first side surface (right side surface in FIG. 1) 32 of the pinion gear 3 and the first side surface (right side surface in FIG. 1) 43 of the ring gear 4 slide on the side surface 52 of the gear housing 5, respectively.

The front cover 6 is arranged adjacent to the gear housing 5. The front cover 6 has a side surface 61 that is in contact with the gear housing 5 and closes the space 50. The second side surface 33 of the pinion gear 3 (left side surface in FIG. 1) and the second side surface 44 of the ring gear 4 (left side surface in FIG. 1) slide on the side surface 61 of the front cover 6. A support hole 62 through which the shaft 2 passes is formed to penetrate the front cover 6. The shaft 2 is supported by the front cover 6 via a bearing 63 and bearing

members

64, 64.

The rear cover 7 is arranged on the opposite side of the front cover 6 with the gear housing 5 interposed therebetween. The front cover 6, the gear housing 5, and the rear cover 7 are integrated by being fixed to each other. The front cover 6, the gear housing 5, and the rear cover 7 form a housing 10 of the internal gear pump 1.

The front cover 6 and the gear housing 5 are formed with a suction port 11 for sucking hydraulic oil inside the space 50, in other words, inside the housing 10. The inlet of the suction port 11 is open on the outer peripheral surface of the front cover 6, as shown in FIG. The outlet of the suction port 11 is open on each of the side surface 61 of the front cover 6 and the side surface 52 of the gear housing 5. The outlet of the suction port 11 also extends in the circumferential direction along the rotational direction of the shaft 2, as shown in FIG.

The front cover 6, the gear housing 5, and the rear cover 7 are formed with a discharge port 12 for discharging hydraulic oil from the inside of the housing 10. The outlet of the discharge port 12 is open to the outer peripheral surface of the rear cover 7, as shown in FIG. The direction of the inlet of the suction port 11 and the direction of the outlet of the discharge port 12 may be the same direction as illustrated in FIG. 1, or may be different directions although not shown. ..

The inlet of the discharge port 12 is open on each of the side surface 61 of the front cover 6 and the side surface 52 of the gear housing 5. As shown in FIG. 2, the inlet of the discharge port 12 also extends in the circumferential direction along the rotation direction of the shaft 2 on the side opposite to the suction port 11 across the shaft 2.

The gear housing 5 is provided with a crescent 54. The crescent 54 is arranged at a position where the pinion gear 3 and the ring gear 4 are out of mesh with each other. The crescent 54 separates a high pressure region and a low pressure region described below.

The crescent 54 extends in the circumferential direction over a predetermined angle range along the rotation direction of the shaft 2. More specifically, the crescent 54 has two arc surfaces, a first arc surface 541 and a second arc surface 542, and the first arc surface 541 and the second arc surface 542 are respectively the side surface 52 of the gear housing 5. (See also Fig. 3). As shown in FIG. 2, the crescent 54 has a crescent shape when viewed along the axial direction of the shaft 2. The tooth tips of the outer teeth 31 of the pinion gear 3 come into contact with the first arc surface 541 of the crescent 54. The tooth tips of the inner teeth 41 of the ring gear 4 contact the second arc surface 542 of the crescent 54.

Here, in the housing 10, in the circumferential direction around the rotation center O of the ring gear 4, a low pressure region where the suction port 11 opens, a pressure increasing region where the crescent 54 is arranged, and a high pressure region where the discharge port 12 opens. The area can be divided into three areas.

Next, the operation of the internal gear pump 1 will be briefly explained. When the motor 2 rotates the shaft 2 in the direction of the white arrow in FIG. 2, the pinion gear 3 and the ring gear 4 respectively rotate in the direction from the low pressure region to the high pressure region to the high pressure region.

In the low-pressure region in the housing 10, as the outer teeth 31 of the pinion gear 3 and the inner teeth 41 of the ring gear 4 that are meshed with each other are separated, hydraulic oil is sucked from the suction port 11 between the outer teeth 31 and the inner teeth 41. Be done. The sucked hydraulic oil is carried from the low pressure region to the high pressure region through the pressure increasing region as the pinion gear 3 and the ring gear 4 rotate.

In the high pressure region inside the housing 10, the outer teeth 31 of the pinion gear 3 and the inner teeth 41 of the ring gear 4 that have been separated from each other gradually approach each other and mesh with each other. As a result, hydraulic fluid is discharged from between the outer teeth 31 and the inner teeth 41 through the discharge port 12.

(Structure that suppresses leakage of hydraulic oil in the housing)
The internal gear pump 1 includes a high-pressure oil supply unit 8 that supplies high-pressure hydraulic oil between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5. FIG. 3 illustrates the configuration of the high pressure oil supply unit 8. FIG. 3 corresponds to the III-III cross section of FIG.

The high-pressure oil supply unit 8 presses the ring gear 4 from the outer periphery of the pressure increasing region toward the rotation center O of the ring gear 4 by the high-pressure hydraulic oil, and suppresses the hydraulic oil from leaking inside the housing 10. The high-pressure oil supply unit 8 has an introduction port 81 that opens to the sliding surface 51, an oil passage 82 that connects the discharge port 12 and the introduction port 81, and a throttle 83 provided in the oil passage 82.

The inlet 81 is located in the boost area as shown in FIG. More specifically, the introduction port 81 faces the crescent 54 in the radial direction. The introduction port 81 introduces a part of the high-pressure hydraulic oil discharged from the discharge port 12 into the housing 10, as described later. In order to suppress the high-pressure hydraulic oil introduced into the housing 10 from flowing into the low-pressure region, the introduction port 81 is preferably a region on the high-pressure side from the intermediate position of the pressure-increasing region in the pressure-increasing region. It is further preferable that the introduction port 81 is provided at a position apart from the line connecting the end point of the second arc surface 542 of the crescent 54 and the rotation center O in the region on the high pressure side in the circumferential direction by an angle φ of 10 to 40°. preferable. Further, in order to effectively press the tooth tips of the ring gear 4 against the crescent 54 by the high pressure hydraulic oil introduced from the inlet 81, the inlet 81 is preferably provided facing the crescent 54.

As illustrated in FIG. 3, the introduction port 81 is provided on the sliding surface 51 at a central position or a substantially central position in the axial direction of the shaft 2. The opening shape of the inlet 81 is circular in the configuration example of FIG. 3. The opening shape of the introduction port 81 is not limited to a particular shape.

The oil passage 82 is provided in the gear housing 5 in the configuration example of FIG. The oil passage 82 connects the discharge port 12 opening to the side surface 52 of the gear housing 5 and the inlet 81. It should be noted that the oil passage may be provided in the front cover 6 and the gear housing 5 so as to connect the discharge port 12 provided in the front cover 6 and the introduction port 81, as indicated by a dashed line in FIG. Good. The oil passage may connect the discharge port 12 provided in the gear housing 5 and the introduction port 81, and may connect the discharge port 12 provided in the front cover 6 and the introduction port 81.

The throttle 83 is configured to reduce the cross-sectional area of the oil passage 82. The diaphragm 83 may be an orifice or a choke. The hydraulic oil flowing in the oil passage 82 from the discharge port 12 toward the inlet 81 is decompressed by the throttle 83. The pressure of the hydraulic oil introduced into the gear housing 5 through the introduction port 81 is lower than the pressure of the hydraulic oil discharged from the discharge port 12. The pressure of the hydraulic oil introduced into the gear housing 5 can be adjusted by changing the structure of the throttle 83.

As described above, during operation of the internal gear pump 1, a part of the hydraulic oil discharged from the discharge port 12 passes through the oil passage 82 and the inlet 81, and the outer peripheral surface of the ring gear 4 and the sliding surface of the gear housing 5. It is introduced between 51 and 51. The high-pressure hydraulic oil pushes and moves the ring gear 4 from the outer periphery of the pressurizing region toward the rotation center O. As a result, the tooth tips of the ring gear 4 are pressed against the crescent 54, so that the hydraulic oil is prevented from leaking between the tooth tips of the ring gear 4 and the crescent 54 in the pressure increasing region. Further, in the high pressure region, the leakage of hydraulic oil between the outer peripheral surface of the ring gear 4 and the sliding surface 51 of the gear housing 5 is also suppressed. By suppressing the leak in the housing 10, the efficiency of the internal gear pump 1 is improved.

Here, since the pressure of the hydraulic oil introduced into the housing 10 is reduced by providing the throttle 83 in the oil passage 82, the tooth tips of the ring gear 4 are suppressed from being strongly pressed against the crescent 54. Wear of the tooth tips of the ring gear 4 is suppressed.

Further, the hydraulic oil introduced between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5 also serves as lubricating oil between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5. Function. As a result, seizure between the ring gear 4 and the gear housing 5 is suppressed. Further, as described above, since the leakage inside the housing 10 is suppressed, the heat generation inside the housing 10 can be suppressed. This also suppresses seizure between the ring gear 4 and the gear housing 5.

The internal gear pump 1 also has a recess 9. FIG. 4 illustrates the configuration of the recess 9. FIG. 4 corresponds to the IV-IV cross section of FIG.

The recess 9 is provided on the sliding surface 51 of the gear housing 5. As shown in an enlarged view in FIG. 5, the recess 9 is recessed radially outward from the sliding surface 51. In FIG. 5, the size of the gap between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5 is exaggerated in order to facilitate understanding. The recess 9 partially widens the distance between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5 (see L in FIG. 5 ).

The recess 9 has a groove shape extending in the axial direction of the shaft 2 in the configuration example of FIG. The depth of the recess 9 may be, for example, about 1 to several millimeters.

The shape of the recess 9 is not limited to the groove shape. As will be described later, the recess 9 may have a function of reducing the wedge effect generated between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5. The recess 9 may be one that partially widens the distance between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5. Although not shown, the recess 9 may be formed by a plurality of holes recessed from the sliding surface 51, for example. In addition, the recess 9 may be configured by arranging a plurality of grooves having a short length in the axial direction of the shaft 2. The groove-shaped recess 9 as shown in FIG. 4 has an advantage that it is easy to process.

Also, only one recess 9 may be provided, as shown in FIG. Although illustration is omitted, a plurality of recesses 9 may be provided in the circumferential direction of the sliding surface 51.

The recess 9 is provided in the high pressure area as shown in FIG. As described above, the high pressure hydraulic oil introduced from the inlet 81 of the high pressure oil supply unit 8 pushes and moves the ring gear 4 from the outer periphery of the boost region toward the rotation center O. Since the gap between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5 becomes small in the high pressure region, a wedge effect occurs (see the arrow in FIG. 5). The recess 9 is preferably provided in the high pressure region where the wedge effect is generated, in the vicinity of a portion where the wedge effect is significantly generated. More specifically, as shown in FIG. 2, the recess 9 may be provided at a position separated from the meshing point A between the pinion gear 3 and the ring gear 4 by an angle θ of 10 to 40° in the circumferential direction. If the angle θ is too large (that is, the recessed portion 9 moves away from the meshing point A between the pinion gear 3 and the ring gear 4), the position is far from the place where the wedge effect is largely generated, and thus the function of reducing the wedge effect described later. Becomes weak. When the angle θ is too small (that is, when the recess 9 approaches the meshing point A between the pinion gear 3 and the ring gear 4), the operating oil passes through the gap between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5. May be encouraged to leak.

The position of the meshing point A between the pinion gear 3 and the ring gear 4 moves in the circumferential direction within a certain range because both

gears

3 and 4 rotate together. Here, the center point of the moving range is the meshing point A (see FIG. 2).

Unlike the high-pressure oil supply unit 8, the recess 9 does not have a function of introducing high-pressure hydraulic oil into the gear housing 5. The recess 9 is not connected to the discharge port 12.

By providing the recess 9 on the sliding surface 51 in the high pressure region, the gap between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5 is partially widened, so that the wedge effect is reduced. Since the wedge effect is reduced, the ring gear 4 is suppressed from being pushed toward the rotation center O from the outer periphery of the high pressure region when the rotation speed of the internal gear pump 1 is high. As a result, in the high pressure region, the hydraulic oil is suppressed from leaking through the gap between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5. At the same time, in the boost region, the hydraulic oil is also prevented from leaking from between the inner teeth 41 of the ring gear 4 and the crescent 54. When the internal gear pump 1 is operated at a low rotational speed, the wedge effect is originally low, so that the hydraulic oil flows through the gap between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5 in the high pressure region. Leakage is suppressed, and at the same time, the hydraulic oil is also prevented from leaking between the internal teeth 41 of the ring gear 4 and the crescent 54 in the pressure increasing region.

As described above, the recess 9 is not connected to the discharge port 12 and does not have the function of introducing high-pressure hydraulic oil. If the high-pressure hydraulic oil is introduced into the housing 10 through the recess 9, the ring gear 4 is pushed from the outer periphery of the high-pressure area toward the rotation center O by the high-pressure hydraulic oil. In the high pressure region, there is a possibility that hydraulic oil may be promoted to leak through the gap between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5. Further, in the boost region, there is a risk that the hydraulic fluid may be promoted to leak from between the internal teeth 41 of the ring gear 4 and the crescent 54. By disconnecting the recess 9 from the discharge port 12, it is possible to suppress the leakage of hydraulic oil in the housing 10 of the internal gear pump 1.

Since the conventional internal gear pump has relatively low processing accuracy and no lubricating coating is formed on the outer peripheral surface of the ring gear, high-pressure hydraulic oil is introduced into the housing from each of the multiple inlets provided on the sliding surface. Therefore, it has been necessary to adopt a configuration that suppresses seizure between the ring gear and the housing.

On the other hand, the machining accuracy is now relatively high, and the internal gear pump 1 has a lubricating coating on the outer peripheral surface 42 of the ring gear 4. The internal gear pump 1 can suppress seizure between the ring gear 4 and the gear housing 5 without adopting a configuration in which the hydraulic oil is introduced into the housing through a plurality of inlets.

Therefore, the internal gear pump 1 introduces the high pressure hydraulic oil into the housing 10 by providing the introduction port 81 of the high pressure oil supply unit 8 in the pressure increasing region, while the high pressure hydraulic oil is introduced in the high pressure region. A recess 9 that is not introduced is provided. The combination of the high-pressure oil supply part 8 and the recess 9 makes it possible to suppress the seizure between the ring gear 4 and the gear housing 5 while suppressing the leakage of the hydraulic oil in the housing 10. The internal gear pump 1 has high reliability and high efficiency.

A lubricating coating may be formed on the sliding surface 51 of the gear housing 5, or a lubricating coating may be formed on both the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5.

FIG. 6 shows a modification of the high pressure oil supply section. The high-pressure oil supply unit 80 shown in FIG. 6 has an introduction port 810, an oil passage 820, and a throttle 830. The inlet 810 is different from the inlet 81 shown in FIG. 3 in shape, and has a groove shape. The introduction port 810 is open to the sliding surface 51 and extends in the axial direction of the shaft 2. The introduction port 810 also opens in the contact surface of the gear housing 5 with the side surface 61 of the front cover 6.

The oil passage 820 is provided in the front cover 6 in the configuration example of FIG. The oil passage 820 connects the discharge port 12 and the introduction port 810 similarly to the oil passage 82. In the configuration example of FIG. 6, the oil passage 820 extends in the axial direction of the shaft 2. The oil passage 820 opens on the side surface 61 of the front cover 6 and is connected to the opening of the introduction port 810. The throttle 830 is provided in the middle of the oil passage 820.

Like the high-pressure oil supply unit 8 described above, the high-pressure oil supply unit 80 having this configuration can also introduce high-pressure hydraulic oil into the housing 10 in the pressure rising region. Accordingly, it is possible to suppress the leakage of the hydraulic oil between the tooth tips of the ring gear 4 and the crescent 54 and the leakage of the hydraulic oil between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5. it can.

The oil passage may be formed by a groove that extends from the joint surface of the front cover 6 with the gear housing 5 and extends in the radial direction, as shown by the alternate long and short dash line in FIG. Although illustration is omitted, the oil passage and the throttle may be provided in the gear housing 5.

Note that the recess 9 is not connected to the discharge port 12. However, the recess 9 may be connected to the discharge port 12. However, in this case, the ring gear 4 is moved from the outer periphery of the boost region toward the rotation center O by the hydraulic oil introduced between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5 through the recess 9. It is preferable that it is pushed and does not move.

The internal gear pump 1 illustrated here is a fixed type in which the crescent 54 does not move, but a movable crescent may be provided. The technology disclosed herein can also be applied to an internal gear pump that does not have a crescent. In the internal gear pump that does not include a crescent, the combination of the high-pressure oil supply unit 8 and the recess 9 described above suppresses seizure between the ring gear 4 and the gear housing 5, and at the same time, prevents the seizure between the ring gear 4 and the pinion gear 3. Leakage of hydraulic oil between the tooth tip and leakage of hydraulic oil between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5 can be suppressed.

However, the internal gear pump in which the suction port or the discharge port is open on the sliding surface does not originally have a wedge effect. Even if the technology disclosed herein is applied to this type of internal gear pump, the effect cannot be expected.

1 Internal Gear Pump 10 Housing 3 Pinion Gear 31 External Teeth 4 Ring Gear 41 Inner Teeth 42 Outer Surface 5 Gear Housing 51 Sliding Surface 54 Crescent 6 Front Cover 7 Rear Cover 8 High Pressure Oil Supply Section 80 High Pressure Oil Supply Section 81 Inlet 810 Inlet 82 Oil passage 820 Oil passage 83 Throttle 830 Throttle 9 Recess

Claims

A pinion gear having external teeth,
A ring gear in which inner teeth meshing with the outer teeth are provided on the inner peripheral surface,
A crescent provided at a location where the pinion gear and the ring gear are apart from each other, and the external teeth and the internal teeth are in contact with each other, and
A housing that has a sliding surface on which the outer peripheral surface of the ring gear slides, and rotatably accommodates the pinion gear and the ring gear;
A high-pressure oil supply unit that has an inlet opening to the sliding surface and that supplies high-pressure hydraulic oil between the outer peripheral surface of the ring gear and the sliding surface through the inlet.
A recess provided in the sliding surface so that a space between the outer peripheral surface of the ring gear and the sliding surface is widened,
The space in the housing is divided into three regions, a low pressure region where the suction port opens, a high pressure region where the discharge port opens, and a pressure rising region where the crescent is arranged,
The inlet is located in the pressure increasing region,
The internal gear pump, wherein the recess is located in the high pressure region.
The internal gear pump according to claim 1,
The internal gear pump in which the recess has a groove shape.
The internal gear pump according to claim 1 or 2,
The internal gear pump, wherein the recess is not connected to the discharge port.
The internal gear pump according to any one of claims 1 to 3,
The high-pressure oil supply unit,
An oil passage connecting the discharge port and the introduction port,
A throttle provided in the oil passage and configured to reduce the pressure of the hydraulic oil,
Internal gear pump having.
The internal gear pump according to any one of claims 1 to 4,
An internal gear pump in which a lubricating coating is formed on the outer peripheral surface of the ring gear.