JP6526371B1 - Internal gear pump - Google Patents

Abstract

The internal gear pump (1) includes a pinion gear (3), a ring gear (4), a crescent (54), and a housing (5) having a sliding surface (51) on which the outer peripheral surface (41) of the ring gear slides. The high pressure oil supply unit (8) having an inlet (81) opening to the sliding surface and supplying high pressure hydraulic oil, and the distance between the outer peripheral surface of the ring gear and the sliding surface is increased; And a recess (9) provided on the moving surface. The inlet is located in the pressurizing area, and the recess is located in the high pressure area.

Description

  The technology disclosed herein relates to an internal gear pump.

  Patent Document 1 describes an internal gear pump provided with an external gear drive gear and an internal gear driven gear. The internal gear pump of Patent Document 1 forms a pocket on the circumferential surface of the pump housing on the opposite side of the meshing point where the drive gear and the driven gear mesh with each other. The pocket is in communication with the discharge port of the internal gear pump. When the internal gear pump is operating, a portion of the high pressure hydraulic fluid 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 is sealed by contact between the tip of the driven gear and the tip of the drive gear. The high pressure hydraulic fluid discharged from the pocket pushes the driven gear so as to press the driven gear tip onto the drive gear tip. The hydraulic oil in the crescent-shaped space is prevented from leaking between the tip of the driven gear and the tip of the drive gear.

  Patent Document 2 also describes an internal gear pump that suppresses the leakage of hydraulic oil in the housing. In the internal gear pump of Patent Document 2, an oil groove is 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. Hydraulic fluid is prevented from leaking between the inner teeth of the outer rotor and the outer teeth of the inner rotor.

  In the internal gear pump described in Patent Document 3, two pressure balance grooves are provided 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. The two pressure balance grooves are respectively connected to the discharge port. When the internal gear pump is in operation, 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 in a floating state relative to the housing, seizure of the ring gear is suppressed.

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

  As described in Patent Document 1 and Patent Document 2, when the 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 operates at a low rotational speed It is possible to suppress the leakage of hydraulic fluid from between the external teeth and the internal teeth in the pressure increase region where the engagement between the external teeth of the pinion gear and the internal teeth of the ring gear is separated. In addition to this, in the internal gear pump of the above configuration, the suction port is opened from the high pressure region of the hydraulic oil because the gap between the outer circumferential surface of the ring gear and the inner circumferential surface of the housing is small even in the high pressure region. Leakage to the low pressure region can be suppressed.

  However, the inventor noticed that when the internal gear pump having the above-mentioned configuration is operated at a high rotation speed, the leakage of hydraulic oil in the housing increases.

  The technology disclosed herein suppresses the leakage of hydraulic fluid in the housing of the internal gear pump.

  As described above, when the ring gear is pushed from the outer periphery of the pressure-rising region toward the rotation center of the ring gear by supplying high-pressure hydraulic oil between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing, 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 smaller. 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” refers to the outer circumferential surface of the ring gear and the inner circumferential surface of the housing by the hydraulic oil being dragged into a narrow gap between the outer circumferential surface of the ring gear and the inner circumferential surface of the housing as the ring gear rotates. It refers to the phenomenon that the pressure of the oil film between the surface and the surface increases.

  When the internal gear pump is operating at a low speed, the wedge effect is low, so that the gap between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing is small in the high pressure region, and the hydraulic oil leaks less.

  However, when the internal gear pump is operating at a high rotation speed, the wedge effect of the gap between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing is enhanced, and the ring gear is rotated from the outer periphery of the high pressure region to the center of rotation of the ring gear. The present inventor found that it was pushed and moved toward the When the ring gear is pushed and moved toward the rotational center of the ring gear from the outer periphery of the high pressure region by the wedge effect, the gap between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing becomes large in the high pressure region, and the outer periphery of the ring gear Not only does leakage of hydraulic oil from the gap between the surface and the inner circumferential surface of the housing increases, but also leakage of hydraulic oil from between the external teeth of the pinion gear and the internal teeth of the ring gear also in the pressure increase region. I will.

  Since the inventor of the present application has obtained the above-mentioned findings, in order to reduce the wedge effect, the distance between the outer peripheral surface of the ring gear and the inner peripheral surface of the housing is partially extended. Then, by providing a recess at a specific position on the inner peripheral surface of the housing, it is confirmed that the leakage of hydraulic oil is suppressed within the housing of the internal gear pump during operation at a high rotational speed, and is disclosed herein. We came to complete the technology.

  Specifically, in the internal gear pump disclosed herein, a pinion gear having an external tooth, a ring gear having an internal surface that engages with the external tooth on an inner circumferential surface, and a location where the meshing between the pinion gear and the ring gear is separated A housing provided with a crescent on which the outer teeth and the inner teeth contact each other, and a sliding surface on which the outer peripheral surface of the ring gear slides, wherein the pinion gear and the ring gear are rotatably accommodated. A high pressure oil supply portion 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 the outer peripheral surface of the ring gear And a recess provided on the sliding surface such that the distance between the sliding surface and the sliding surface is increased.

The space in the housing is divided into three areas: a low pressure area where the suction port opens, a high pressure area where the discharge port opens, and a pressure area where the crescent is disposed, and the inlet is The recessed portion is located in the high pressure region while being apart from the introduction port .

  According to this configuration, the pinion gear and the ring gear rotate in the direction from the low pressure area to the high pressure area through the pressure increase area.

  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 introduction port located in the pressure increase region. The high pressure hydraulic oil causes the ring gear to be pushed and moved from the outer periphery of the pressure raising region toward the rotational center of the ring gear, and the internal teeth of the ring gear are pressed against the crescent. In the pressure increase region, leakage of hydraulic fluid from between the internal gear of the ring gear and the crescent is suppressed. Further, in the high pressure region, leakage of hydraulic oil from between the outer peripheral surface of the ring gear and the sliding surface of the housing is suppressed.

  Since the ring gear is pushed toward the rotational center of the ring gear from the outer periphery of the pressurizing region, a wedge effect is generated between the outer peripheral surface of the ring gear and the housing sliding surface in the high pressure region. A recess is provided on the sliding surface of the high pressure region. The recess partially 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 and moved from the outer periphery of the high pressure region toward the rotational center of the ring gear when the internal gear pump is operating at a high rotational speed. As a result, in the high pressure region, leakage of hydraulic oil is suppressed through the gap between the outer peripheral surface of the ring gear and the sliding surface of the housing. In addition, in the pressure increase region, leakage of hydraulic fluid from between the internal teeth of the ring gear and the crescent is suppressed.

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

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

  Furthermore, as described above, heat generation in the housing can be suppressed by preventing leakage of the hydraulic oil in the housing. This can also suppress 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 not be connected to the discharge port.

  The recess functions to reduce the wedge effect by increasing the distance between the outer peripheral surface of the ring gear and the sliding surface of the housing as described above. The recess does not need to have the function of introducing high pressure hydraulic oil into the housing.

  Also, if high pressure hydraulic oil is introduced into the housing through the recess, the ring gear is pushed from the outer periphery of the high pressure region toward the center of rotation of the ring gear by the high pressure hydraulic oil introduced from the recess. In the high pressure region, leakage of hydraulic fluid may be promoted through the gap between the outer peripheral surface of the ring gear and the sliding surface of the housing. In addition, in the pressure increase region, there is a risk that hydraulic oil may be leaked from between the inner teeth of the ring gear and the crescent.

  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-rising region and the reduction of the wedge effect by the recess positioned in the high-pressure region And preventing seizure of the ring gear.

  The high-pressure oil supply unit may include an oil passage connecting the discharge port and the inlet, and a throttle provided in the oil passage and reducing the pressure of the hydraulic fluid.

  If the pressure of the hydraulic fluid introduced into the housing through the inlet is too high, the force by which the ring gear tip is pressed against the crescent becomes too strong. Wear of ring gear teeth 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.

  In addition, by combining the adjustment of the pressure of the hydraulic oil introduced into the housing and the reduction of the wedge effect by the recess, the leakage of the hydraulic oil in the housing is suppressed, and the ring gear and the housing To ensure the lubricity between the balance.

  A lubricating coating may be formed on the outer peripheral surface of the ring gear.

  In this way, seizure between the ring gear and the housing is suppressed. The conventional internal gear pump has a relatively low processing accuracy and no lubricating coating is formed on the outer peripheral surface of the ring gear. Therefore, as described in Patent Document 3, the hydraulic oil is housed through the two balance grooves as described in Patent Document 3. By introducing it inside, it was necessary to suppress the seizure between the ring gear and the housing.

  On the other hand, the ring gear can be used without introducing hydraulic oil into the housing through the two balance grooves by forming the lubricating coating on the outer peripheral surface of the ring gear as described above while the processing accuracy is now increased. Seizing between the housing and the housing can be suppressed.

The concave portion may be provided at a position separated by an angle of 10 to 40 in the circumferential direction with respect to a meshing point at which the pinion gear and the ring gear mesh with each other.

  According to the internal gear pump, the leakage of hydraulic oil in the housing can be suppressed.

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

  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 configuration 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 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, for the shaft 2, the pinion gear 3 and the ring gear 4, hatching indicating end surfaces is omitted in FIG.

  The shaft 2 extends in the left-right direction in FIG. The shaft 2 is connected to a motor 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 disposed eccentric to the shaft 2. An inner tooth 41 is 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, a part of the external teeth 31 of the pinion gear 3 mesh with a part of the internal teeth 41 of the ring gear 4. Although not shown in the drawings, the outer circumferential surface 42 of the ring gear 4 is provided with a lubricating coating. The lubricant coating may be made of, for example, a material containing an inorganic material and a fluorine-based resin.

  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 accommodated in the gear housing 5. The gear housing 5 has a sliding surface 51 on which the outer circumferential surface 42 of the ring gear 4 slides. The outer peripheral surface 42 of the ring gear 4 has a circular cross-sectional shape. The sliding surface 51 of the gear housing 5 also has a circular cross-sectional shape. The sliding surface 51 is eccentric 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 for housing the pinion gear 3 and the ring gear 4. The space 50 is open on the left side of the drawing of FIG. The first side (right side in FIG. 1) 32 of the pinion gear 3 and the first side (right side in FIG. 1) 43 of the ring gear 4 slide on the side 52 of the gear housing 5 respectively.

  The front cover 6 is disposed adjacent to the gear housing 5. The front cover 6 has a side surface 61 in contact with the gear housing 5 and closing the space 50. The second side surface (left side surface in FIG. 1) 33 of the pinion gear 3 and the second side surface (left side surface in FIG. 1) 44 of the ring gear 4 respectively slide on the side surface 61 of the front cover 6. A support hole 62 through which the shaft 2 passes is formed through 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 disposed 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 one another. The front cover 6, the gear housing 5 and the rear cover 7 constitute a housing 10 of the internal gear pump 1.

  In the front cover 6 and the gear housing 5, a suction port 11 for drawing hydraulic fluid is formed in the space 50, in other words, in the housing 10. The inlet of the suction port 11 opens at the outer peripheral surface of the front cover 6 as shown in FIG. The outlet of the suction port 11 opens to the side surface 61 of the front cover 6 and the side surface 52 of the gear housing 5 respectively. The outlet of the suction port 11 also extends circumferentially along the rotational direction of the shaft 2 as shown in FIG.

  In the front cover 6, the gear housing 5, and the rear cover 7, a discharge port 12 for discharging the hydraulic oil from the inside of the housing 10 is formed. The outlet of the discharge port 12 is open at 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 as illustrated in FIG. 1 or may be different although not shown. .

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

  The gear housing 5 is provided with a crescent 54. The crescent 54 is disposed at a position where the meshing between the pinion gear 3 and the ring gear 4 is separated. The crescent 54 separates a high pressure area and a low pressure area to be described later.

  The crescent 54 extends in the circumferential direction over a predetermined angular range along the rotational direction of the shaft 2. More specifically, the crescent 54 has two arc surfaces of a first arc surface 541 and a second arc surface 542, and the first arc surface 541 and the second arc surface 542 are each a side surface 52 of the gear housing 5. (See also Figure 3). The crescent 54 has a crescent shape when viewed along the axial direction of the shaft 2 as shown in FIG. The tips of the external teeth 31 of the pinion gear 3 abut on the first arc surface 541 of the crescent 54. The tips of the internal teeth 41 of the ring gear 4 abut on the second arc surface 542 of the crescent 54.

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

  Next, the operation of the internal gear pump 1 will be briefly described. When the shaft 2 is rotated by the prime mover in the direction of the white arrow in FIG. 2, the pinion gear 3 and the ring gear 4 rotate in the direction from the low pressure area to the high pressure area through the pressurizing area.

  In the low pressure region in the housing 10, as the external teeth 31 of the engaged pinion gear 3 and the internal teeth 41 of the ring gear 4 separate, working oil is sucked between the external teeth 31 and the internal teeth 41 from the suction port 11. Be The sucked hydraulic oil is conveyed from the low pressure region to the high pressure region through the pressure increase region as the pinion gear 3 and the ring gear 4 rotate.

  In the high pressure area in the housing 10, the outer teeth 31 of the pinion gear 3 and the inner teeth 41 of the ring gear 4 which are separated come closer and mesh with each other. As a result, the hydraulic oil is discharged from between the external teeth 31 and the internal teeth 41 through the discharge port 12.

(Configuration to suppress leakage of hydraulic oil in housing)
The internal gear pump 1 is provided with a high pressure oil supply unit 8 for supplying 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 moves the ring gear 4 from the outer periphery of the pressure-rising region toward the rotation center O of the ring gear 4 by the high-pressure hydraulic oil to suppress the hydraulic oil from leaking in the housing 10. The high pressure oil supply unit 8 has an inlet 81 opened to the sliding surface 51, an oil passage 82 connecting the discharge port 12 and the inlet 81, and a throttle 83 provided in the oil passage 82.

  The inlet 81 is located in the pressure increase area, as shown in FIG. More specifically, the inlet 81 is radially opposed to the crescent 54. The inlet 81 introduces a part of the high-pressure hydraulic fluid discharged from the discharge port 12 into the housing 10 as described later. In order to prevent the high pressure hydraulic oil introduced into the housing 10 from flowing into the low pressure region, the inlet 81 is preferably in the region from the middle position of the pressure rising region to the high pressure side in the pressure rising region. The inlet 81 is provided at a position separated by an angle φ of 10 to 40 ° in the circumferential direction from the line connecting the end point of the second arc surface 542 of the crescent 54 and the rotation center O in the high pressure side area. preferable. Further, in order to effectively press the tip of the ring gear 4 against the crescent 54 by the high-pressure hydraulic oil introduced from the introduction port 81, the introduction port 81 is preferably provided to face the crescent 54.

  As illustrated in FIG. 3, the inlet 81 is provided at a central position or a substantially central position in the axial direction of the shaft 2 on the sliding surface 51. 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 specific shape.

  The oil passage 82 is provided in the gear housing 5 in the configuration example of FIG. 3. The oil passage 82 connects the discharge port 12 opened to the side surface 52 of the gear housing 5 and the introduction port 81. 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 virtually shown by a dashed dotted line in FIG. Good. Further, the oil passage may connect the discharge port 12 provided in the gear housing 5 and the introduction port 81 and 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 restrictor 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 depressurized by the throttle 83. The pressure of the hydraulic fluid introduced into the gear housing 5 through the inlet 81 is lower than the pressure of the hydraulic fluid discharged from the discharge port 12. The pressure of the hydraulic fluid introduced into the gear housing 5 can be adjusted by changing the structure of the throttle 83.

  As described above, during the operation of the internal gear pump 1, a portion of the hydraulic oil discharged from the discharge port 12 passes through the oil passage 82 and the inlet port 81 to the outer peripheral surface of the ring gear 4 and the sliding surface of the gear housing 5. Introduced between 51 and The high pressure hydraulic oil causes the ring gear 4 to be pushed from the outer periphery of the pressure increase region toward the rotation center O and moved. As a result, since the tip of the ring gear 4 is pressed against the crescent 54, leakage of hydraulic fluid through the gap between the tip of the ring gear 4 and the crescent 54 is suppressed in the pressure-rising region. In addition, in the high pressure region, leakage of the hydraulic oil through the space 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 lowered by providing the oil passage 82 with the throttle 83, it is possible to suppress that the tooth tip of the ring gear 4 is strongly pressed against the crescent 54. It is suppressed that the tooth tip of ring gear 4 wears.

  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 is also used as a lubricating oil between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5. Function. Thereby, the seizure between the ring gear 4 and the gear housing 5 is suppressed. Further, as described above, since the leak in the housing 10 is suppressed, the heat generation in 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. The concave portion 9 is recessed outward in the radial direction from the sliding surface 51, as shown in an enlarged manner in FIG. In FIG. 5, the size of the gap between the outer circumferential 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 space between the outer circumferential surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5 is partially enlarged by the recess 9 (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. 4. 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 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 any as long as it 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. The recess 9 may be constituted by, for example, a plurality of holes recessed from the sliding surface 51, although not shown. Alternatively, the recess 9 may be configured by arranging a plurality of short grooves in the axial direction of the shaft 2. The groove-shaped recess 9 as shown in FIG. 4 has the advantage of easy processing.

  Further, as shown in FIG. 4, only one concave portion 9 may be provided. Although not shown, a plurality of recesses 9 may be provided in the circumferential direction of the sliding surface 51.

  The recessed part 9 is provided in the high voltage | pressure area | region, as shown in FIG. As described above, the ring gear 4 is moved from the outer periphery of the pressure-rising region toward the rotation center O by the high-pressure hydraulic oil introduced from the inlet 81 of the high-pressure oil supply unit 8. 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 smaller in the high pressure region, a wedge effect is produced (see the arrow in FIG. 5). The recess 9 is preferably provided in the vicinity of a portion where the wedge effect is large in the high pressure region where the wedge effect is generated. More specifically, as shown in FIG. 2, the recess 9 may be provided at a position separated by an angle θ of 10 to 40 ° in the circumferential direction with respect to the meshing point A of the pinion gear 3 and the ring gear 4. When the angle θ is too large (that is, when the recess 9 is away from the meshing point A between the pinion gear 3 and the ring gear 4), the wedge effect is located far away from the location where the effect is large. Becomes weak. If 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 working oil is passed through the gap between the outer peripheral surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5 Can 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 the gears 3 and 4 rotate together. Here, the center point of the movement range is taken as the meshing point A (see FIG. 2).

  Unlike the high pressure oil supply unit 8, the recess 9 has no 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 distance between the outer circumferential surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5 is partially widened, thereby reducing the wedge effect. Since the wedge effect is reduced, it is suppressed that the ring gear 4 is pushed and moved from the outer periphery of the high pressure region toward the rotation center O when the rotation speed of the internal gear pump 1 is high. As a result, in the high pressure region, leakage of the hydraulic oil is suppressed 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, leakage of hydraulic fluid from between the internal teeth 41 of the ring gear 4 and the crescent 54 is also suppressed in the pressure increase region. Since the wedge effect is inherently low when the internal gear pump 1 is operating at a low rotational speed, the working oil is transmitted 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 in the pressure increase region, leakage of hydraulic oil from between the internal teeth 41 of the ring gear 4 and the crescent 54 is also suppressed.

  As described above, the recess 9 is not connected to the discharge port 12 and has no function of introducing high-pressure hydraulic oil. Here, if 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 region toward the rotation center O by the high-pressure hydraulic oil. In the high pressure region, the 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. In addition, in the pressure increase region, there is a possibility that the hydraulic oil may be leaked from between the internal teeth 41 of the ring gear 4 and the crescent 54. By disconnecting the recess 9 with the discharge port 12, it is possible to suppress the leakage of hydraulic oil in the housing 10 of the internal gear pump 1.

  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. Therefore, high pressure hydraulic oil is provided in the housing from each of a plurality of inlets provided on the sliding surface. In order to prevent the burn-in between the ring gear and the housing, a configuration had to be adopted.

  On the other hand, the internal gear pump 1 forms a lubricating coating on the outer peripheral surface 42 of the ring gear 4 while the processing accuracy is relatively high. 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 the plurality of inlets.

  Therefore, the internal gear pump 1 introduces high pressure hydraulic oil into the housing 10 by providing the inlet 81 of the high pressure oil supply unit 8 in the pressure increase region, while high pressure hydraulic oil is introduced in the high pressure region. The recessed part 9 which is not introduce | transduced is provided. The combination of the high pressure oil supply portion 8 and the recess 9 makes it possible to suppress the leakage of the hydraulic oil in the housing 10 while suppressing the seizure between the ring gear 4 and the gear housing 5. The internal gear pump 1 is highly reliable and highly efficient.

  A lubricating coating may be formed on the sliding surface 51 of the gear housing 5 or may be formed on both the outer circumferential 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 unit. The high pressure oil supply unit 80 shown in FIG. 6 has an inlet 810, an oil passage 820, and a throttle 830. The inlet 810 is different in shape from the inlet 81 shown in FIG. 3 and has a groove shape. The inlet 810 is open to the sliding surface 51 and extends in the axial direction of the shaft 2. The inlet 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 inlet 810 in the same manner as the oil passage 82 described above. 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 at the side surface 61 of the front cover 6 and is connected to the opening of the inlet 810. Further, the throttle 830 is provided in the middle of the oil passage 820.

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

  The oil passage may be formed by a concave groove extending in the radial direction as well as being recessed from the joint surface of the front cover 6 with the gear housing 5 as indicated by an alternate long and short dash line in FIG. Further, although not shown, the oil passage and the throttle may be provided in the gear housing 5.

  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 operating 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 causes the ring gear 4 to move from the outer periphery of the pressure raising region toward the rotation center O. It is preferable not to move by pushing.

  Although the internal gear pump 1 illustrated here is configured as a stationary type in which the crescent 54 does not move, a movable crescent may be provided. In addition, the technology disclosed herein can also be applied to internal gear pumps that do not have a crescent. In the internal gear pump not equipped with a crescent, the combination of the high-pressure oil supply portion 8 and the recess 9 described above suppresses the burn-in between the ring gear 4 and the gear housing 5 and prevents the tip of the ring gear 4 and the pinion gear 3 It is possible to suppress the leakage of hydraulic oil with the tip of the tooth and the leakage of hydraulic oil between the outer circumferential surface 42 of the ring gear 4 and the sliding surface 51 of the gear housing 5.

  However, in the internal gear pump of the type in which the suction port or the discharge port is opened to the sliding surface, the wedge effect does not occur originally. Even if the technology disclosed herein is applied to this type of internal gear pump, its effect can not be expected.

Reference Signs List 1 internal gear pump 10 housing 3 pinion gear 31 outer teeth 4 ring gear 41 inner teeth 42 outer circumferential surface 5 gear housing 51 sliding surface 54 crescent 6 front cover 7 rear cover 8 high pressure oil supply unit 80 high pressure oil supply unit 81 introduction port 810 introduction port 82 Oil passage 820 Oil passage 83 Throttle 830 Throttle 9 Recess

Claims (6)

A pinion gear having external teeth,
A ring gear having an inner circumferential surface provided with an inner tooth engaging with the outer tooth;
A crescent which is provided at a location where the engagement between the pinion gear and the ring gear is separated, and in which each of the outer teeth and the inner teeth abut;
A housing having a sliding surface on which the outer peripheral surface of the ring gear slides, and rotatably accommodating the pinion gear and the ring gear;
A high pressure oil supply unit 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 a recessed portion provided on the sliding surface such that a distance between an outer peripheral surface of the ring gear and the sliding surface is increased,
The space in the housing is divided into three regions: a low pressure region in which the suction port opens, a high pressure region in which the discharge port opens, and a pressure increasing region in which the crescent is disposed.
The inlet is located in the boosting region,
The internal gear pump, wherein the recess is separated from the inlet and is located in the high pressure region. In the internal gear pump according to claim 1,
The internal gear pump, wherein the recess has a groove shape. In the internal gear pump according to claim 1 or 2,
The internal gear pump, wherein the recess is not connected to the discharge port. In 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 inlet;
A throttle provided in the oil passage and reducing the pressure of the hydraulic fluid;
Internal gear pump that has. In 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. In the internal gear pump according to any one of claims 1 to 5,
The internal gear pump, wherein the recess is provided at a position separated by an angle of 10 to 40 in a circumferential direction with respect to a meshing point at which the pinion gear and the ring gear mesh with each other.

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