JP2008157175A - Rotary pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the durability of a rotary pump and also suppress abnormal noise without imparting workability and assembling performance. <P>SOLUTION: In this rotary pump, a groove 13c extending over the whole periphery in a circumferential direction is formed on the peripheral surface 13b of an outer rotor 13, and a space is formed between the peripheral surface 13b of the outer rotor 13 and the inner peripheral surface 14d of a casing 14 by the groove 13c. By this space, even though the outer rotor 13 is displaced to cause unbalance in the space between the outer rotor 13 and the casing 14, portions in the space that are narrowed like a wedge shape are reduced. Thereby, a force by wedge action is reduced, the durability of the rotary pump is improved, and also abnormal noise can be suppressed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal gear type rotary pump that sucks and discharges fluid.

  Conventionally, Patent Document 1 discloses a trochoid pump that is an internal gear type rotary pump.

  This type of trochoidal pump includes an inner rotor that is connected to a drive shaft and has a plurality of external teeth on the outer peripheral side, an outer rotor that has a plurality of inner teeth on the inner peripheral side, The casing includes a casing that rotatably accommodates an inner rotor and an outer rotor that are meshed so that the teeth come into contact with each other.

  Then, by rotating the inner rotor and the outer rotor, the volume of the plurality of gaps formed between the inner teeth and the outer teeth is changed, and the fluid is sucked into the gaps through the suction port. The fluid is discharged from the part through the discharge port. For this reason, a pressure difference arises between the space | gap part connected to the suction port side and the space | gap part connected to the discharge port side.

  Furthermore, since the outer rotor is pressed against the casing by this pressure difference, the gap between the outer rotor and the casing is biased. On the other hand, as described above, since the internal teeth and the external teeth are in contact with each other, if such a deviation occurs, the contact load of a part of the contact portion between the internal teeth and the external teeth increases, and the internal teeth and the external teeth Becomes easy to wear and causes abnormal noise.

Therefore, in the trochoidal pump of Patent Document 1, at least one of the internal teeth and the external teeth is formed in a left-right asymmetric shape, the internal teeth and the external teeth are brought into contact with each other in the gap portion on the suction port side, and the discharge port side In the gap portion, the inner teeth and the outer teeth are arranged in a non-contact state, and the gap portions on the discharge port side are communicated with each other to reduce the pressure difference.
Japanese Unexamined Patent Publication No. 64-32083

  However, in the trochoidal pump of Patent Document 1, at least one of the inner teeth and the outer teeth is formed in a left-right asymmetric shape. Gets worse. Moreover, since the rotation direction which can exhibit the pump action of an inner rotor and an outer rotor is limited, the assembly | attachment property of a trochoid type pump also deteriorates.

  Further, according to the study of the present inventor, even if at least one of the internal teeth and the external teeth is formed in a left-right asymmetric shape as in Patent Document 1, the wear suppression effect and noise suppression effect of the internal teeth and external teeth It was found that could not be obtained sufficiently.

  The reason is that when the outer rotor is pressed against the casing as described above, a wedge-shaped gap as shown in FIG. 5 is formed in the gap between the outer circumferential surface of the outer rotor and the inner circumferential surface of the casing. Because it is done.

  FIG. 5 is a cross-sectional view perpendicular to the axial direction of the outer rotor 13. The gap narrowed in a wedge shape is in contact with the outer peripheral surface 13 b of the outer rotor 13 and the inner peripheral surface 14 d of the casing 14 indicated by an arc. It is formed in the vicinity of the part to do. FIG. 5 shows the outer diameter of the outer rotor 13 smaller than the actual diameter in order to clarify the gap that narrows in a wedge shape.

  And when the space between the relatively moving solid surfaces is narrowed in a wedge shape in the direction of movement, the phenomenon that the fluid is drawn into the wedge-shaped part due to the viscosity of the fluid to generate pressure, so-called wedge action occurs, The outer rotor is pressed against the inner rotor by a force having a factor different from the above-described pressure difference (hereinafter referred to as fluid force).

  This fluid force not only causes the internal and external teeth to wear and generates abnormal noise, but if air or the like enters the gap, the fluid force also fluctuates greatly, causing an impact load to be applied to the contact portion between the internal and external teeth. As a result, the internal and external teeth are worn and damaged, and a large impact sound is generated on the internal and external teeth.

  In view of the above points, an object of the present invention is to improve the durability of a rotary pump and to suppress the generation of abnormal noise without impairing workability and assembly.

  In order to achieve the above object, in the present invention, the inner rotor (12) having outer teeth (12a) formed on the outer peripheral side and the inner teeth (13a) meshed with the outer teeth (12a) are formed on the inner peripheral side. A formed outer rotor (13) and a casing (14) for rotatably accommodating the inner rotor (12) and the outer rotor (13) are provided, and the inner rotor (12) and the outer rotor (13) are rotated. Is a rotary pump that changes the volume of the gap (B) formed between the outer teeth (12a) and the inner teeth (13a) and sucks and discharges the fluid, and the outer rotor (13 ) Between the outer peripheral surface (13b) and the inner peripheral surface (14d) at least one of the outer peripheral surface (13b) and the inner peripheral surface (14d) of the casing (14) sliding with the outer peripheral surface (13b). Space Forming recesses (13c, 13d, 13e) and said rotary pump is formed.

  According to this, as described above, the outer rotor (13) is moved between the outer rotor (13) and the casing (14) by the pressure difference between the suction port side gap and the discharge port side gap. Even when the gap is displaced so as to be biased, the space formed by the recesses (13c, 13d, 13e) has a wedge shape in the gap between the outer peripheral surface (13b) and the inner peripheral surface (14d). The area | region used as a narrow shape can be reduced.

  As a result, the fluid force described above can be suppressed, so that the durability of the rotary pump can be improved and the occurrence of abnormal noise can also be suppressed.

  Further, since the recesses (13c, 13d, 13e) are formed on the outer peripheral surface (13b) or the inner peripheral surface (14d), the inner teeth (13a) or the outer teeth (12a) are formed in a left-right asymmetric shape. Therefore, workability can be improved. Moreover, since the rotation direction of an inner rotor (12) and an outer rotor (13) is not limited, the assembly property of a rotary pump is not impaired.

  Further, in the rotary pump having the above characteristics, in order to easily configure the recess, the recess may be configured by a groove (13c, 13d) formed on the outer peripheral surface (13b). Furthermore, the groove (13c) may be formed over the entire circumference along the circumferential direction of the outer rotor (13), or a plurality of grooves (13c) may be formed along the axial direction of the outer rotor (13). Good.

  In the rotary pump having the above characteristics, the concave portion may be constituted by a plurality of flat surfaces (13e) having the outer peripheral surface (13b) formed thereon, or by a groove formed on the inner peripheral surface (14d). It may be configured.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. In this embodiment, the rotary pump of the present invention is applied to a vehicle oil pump 10 that supplies lubricating oil to each moving part of a vehicle travel engine. The oil pump 10 is attached to a side surface of a cylinder block of a vehicle travel engine (not shown).

  The oil pump 10 is an internal gear type trochoid pump in which gears mesh with each other, and includes a drive shaft 11, an inner rotor 12, an outer rotor 13, and a casing 14, as shown in FIGS. Composed.

  1 is a schematic axial sectional view for explaining a schematic configuration of the oil pump 10 of the present embodiment, FIG. 2A is a sectional view taken along the line AA of FIG. 1, and FIG. FIG. 2A is a side view of FIG. 2A, and the middle plate 14 c of the casing 14 is omitted in order to clarify the outer peripheral surface 13 b of the outer rotor 13.

  First, the drive shaft 11 transmits the rotational driving force of the vehicle running engine to the inner rotor 12, and is connected to the connecting hole 12 b of the inner rotor 12. Specifically, the pin 15 is inserted into the key groove portion 11a formed in the drive shaft 11 and the key groove portion 12c formed in the connection hole 12b.

  A plurality of external teeth 12a are formed on the outer peripheral side of the inner rotor 12, and a plurality of internal teeth 13a are formed on the inner periphery of the outer rotor 13. The inner rotor 12 and the outer rotor 13 are connected to the outer teeth 12a and the inner teeth. In a state where the teeth 13a are engaged with each other, the teeth 13a are arranged in a housing space formed in the casing 14.

  In the present embodiment, six external teeth 12a are provided, and seven internal teeth 13a are provided, one more than the external teeth 12a. Of course, the number of external teeth 12a and internal teeth 13a may be appropriately changed according to the required discharge flow rate. Even in this case, the number of the inner teeth 13a may be one more than the number of the outer teeth 12a.

  Thus, when the external teeth 12a and the internal teeth 13a are engaged with each other and the external teeth 12a and the internal teeth 13a are brought into contact with each other, a plurality of gaps B are formed between the external teeth 12a and the internal teeth 13a. The Further, the plurality of gaps B are formed as independent spaces by the inner rotor 12, the outer rotor 13 and the casing 14.

  Further, when the outer teeth 12a and the inner teeth 13a are engaged with each other, the inner rotor 12 and the outer rotor 13 are arranged such that the rotation center X of the inner rotor 12 and the rotation center Y of the outer rotor 13 are eccentric. Thereby, when the inner rotor 12 and the outer rotor 13 rotate with the rotation of the drive shaft 11, the meshing amount of the outer teeth 12a and the inner teeth 13a continuously changes, and the volume of the gap B continuously changes. To do.

  Further, on the outer circumferential surface 13 b in the radial direction of the outer rotor 13, a groove portion 13 c constituting a recess is formed along the circumferential direction of the outer rotor 13 over the entire circumference.

  The casing 14 includes an upper plate 14 a and a lower plate 14 b that are disposed on both axial ends of the inner rotor 12 and the outer rotor 13, and a middle plate 14 c that is disposed on the radially outer peripheral side of the outer rotor 13 and the inner rotor 12. Have.

  Further, by combining these plates 14a to 14c and fixing them with fixing means such as screws, an accommodation space for rotatably accommodating the inner rotor 12 and the outer rotor 13 is formed.

  Accordingly, an inner peripheral surface 14d that slides with the outer peripheral surface 13b of the outer rotor 13 is formed on the radially inner peripheral side of the middle plate 14c, and a groove 13c is formed between the outer peripheral surface 13b of the outer rotor 13 and the middle plate 14c. Thus, a space for suppressing the aforementioned fluid force is formed.

  In the present embodiment, the lower plate 14b is provided with a suction port 14e for sucking oil and a discharge port 14f for discharging oil. Specifically, the suction port 14e is provided in a substantially arc shape so as to communicate with the gap B in a region where the volume increases by rotation of the drive shaft 11 in the direction of arrow C, and the discharge port 11e decreases in volume. It is provided in a substantially arc shape so as to communicate with the void portion B of the region.

  The inner rotor 12, the outer rotor 13 and the casing 14 are formed of a material having excellent wear resistance such as an iron-based sintered metal (for example, an iron-based sintered metal), for example, and the casing 14, the outer rotor 13 and the inner rotor 12 may be subjected to a surface treatment for reducing sliding resistance.

  Next, the operation of this embodiment in the above configuration will be described. First, when the drive shaft 11 is rotated in the direction of arrow C by the vehicle running engine, the rotational driving force is transmitted to the inner rotor 12. When the inner rotor 12 rotates, the outer rotor 13 also rotates in the direction of arrow C due to the meshing of the outer teeth 12a and the inner teeth 13a.

  By this rotation, the volume of each gap B increases and decreases while the inner rotor 12 and the outer rotor 13 make one rotation. Then, oil is sucked into the gap B in the area where the volume increases through the suction port 14e, and oil is discharged from the gap B in the area where the volume decreases through the discharge port 14f.

  Here, when the oil pump 10 operates as described above, the oil suction pressure acts on the gap B communicating with the suction port 14e, and the oil discharge pressure acts on the gap B communicating with the discharge port 14f. To do. For this reason, a pressure difference is generated between the gap B communicating with the suction port 14e and the gap B communicating with the discharge port 14f.

  Due to this pressure difference, the outer rotor 13 is pressed against the casing 14, the gap between the outer rotor 13 and the casing 14 is biased, and the gap near the contact portion between the outer rotor and the casing is narrowed in a wedge shape. Become. On the other hand, in this embodiment, the area | region used as the shape narrowed in a wedge shape can be reduced with the space formed of the groove part 13c.

  Thereby, since the fluid force mentioned above can be suppressed, the abrasion and damage of the external teeth 12a and the internal teeth 13a can be suppressed, and the impact sound generated in the external teeth 12a and the internal teeth 13a can also be suppressed. As a result, the durability of the rotary pump can be improved and the occurrence of abnormal noise can be suppressed.

(Second Embodiment)
In the first embodiment, the recess is formed by the groove 13c. However, in this embodiment, the recess is formed by a plurality of grooves 13d formed on the outer peripheral surface 13b of the outer rotor 13 as shown in FIG. Yes.

  3A is a cross-sectional view taken along the line AA of FIG. 1 in the present embodiment, and FIG. 3B is a side view of FIG. 3A, similarly to FIG. 2B. The middle plate 14c is omitted. As shown in FIG. 3, the grooves 13 d are formed so as to extend in parallel with the axial direction of the outer rotor 13 and are equally arranged in the circumferential direction.

  Even if the recess portion is formed by the groove portion 13d and a space for suppressing fluid force is formed as in the present embodiment, the gap between the outer peripheral surface 13b of the outer rotor 13 and the inner peripheral surface 14d of the casing 14 Among them, since the region that is narrowed in a wedge shape can be reduced, the same effect as in the first embodiment can be obtained.

(Third embodiment)
In the first embodiment, the recess is formed by the groove 13c, but in this embodiment, the recess is formed by a plurality of flat surfaces 13e formed on the outer peripheral surface 13b of the outer rotor 13, as shown in FIG. ing.

  4A is a cross-sectional view taken along the line AA of FIG. 1 in the present embodiment, and FIG. 4B is a side view of FIG. 4A, similarly to FIG. 2B. The middle plate 14c is omitted. As shown in FIG. 4, by forming the flat surface 13 e, it is possible to configure a recess that is recessed inward in the radial direction from the outermost radial direction of the outer rotor 13. The flat surface 13e is evenly arranged in the circumferential direction of the outer rotor 13.

  Even if the recess is formed by the flat surface 13e and the space for suppressing the fluid force is formed as in the present embodiment, the space between the outer peripheral surface 13b of the outer rotor 13 and the inner peripheral surface 14d of the casing 14 is not limited. Since the area | region which becomes a shape narrowed in a wedge shape among clearance gaps can be reduced, the effect similar to 1st Embodiment can be acquired.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be variously modified as follows.

  (1) In the above-described embodiment, the recess is formed by the grooves 13c and 13d or the flat surface 13e formed on the outer peripheral surface 13b of the outer rotor 13, but the groove is formed on the inner peripheral surface 14d of the middle plate 14c of the casing 14. Alternatively, the recess may be formed by forming a flat surface or the like. Furthermore, you may comprise a recessed part in both the outer peripheral surface 13b of the outer rotor 13, and the inner peripheral surface 14d of the middle plate 14c.

  Further, the force acting on the outer rotor 13 due to the pressure difference described above acts from the gap B side in the area where the volume decreases toward the gap B side in the area where the volume increases. For this reason, the site | part by which the outer rotor 13 is pressed on the casing 14 is specified. Therefore, when forming a recess in the inner peripheral surface 14d of the middle plate 14c, the recess may be formed only in the vicinity of a portion where the outer rotor 13 is pressed against the casing 14.

  (2) In the above-described embodiment, an example in which the rotary pump of the present invention is applied to an oil pump for a vehicle has been described, but the application of the rotary pump of the present invention is not limited to this. For example, the present invention can be applied to a fuel pump that pumps fuel from a vehicle fuel tank, a brake fluid pump that is used for brake fluid pressure control in an antilock brake device for a vehicle, and the like. Of course, the present invention can be applied to various uses without being limited to vehicles.

  (3) In the second embodiment described above, the groove 13d is formed so as to penetrate both side surfaces in the axial direction along the axial direction of the outer rotor 13, but may be formed so as not to penetrate. Further, the groove 13d may be formed to extend in a direction inclined with respect to the axial direction.

  (4) In the above-described embodiment, the casing 14 is constituted by the separate upper plate 14a, lower plate 14b, and middle plate 14c. For example, the upper plate 14a and the middle plate 14c or the middle plate 14c and the lower plate are formed. 14b may be configured as an integral structure. Further, the upper plate 14a and the middle plate 14c may be configured on the main body side such as a fuel pump.

  (5) Transmission of the driving force from the drive shaft 11 to the inner rotor 13 may be configured by Oldham couplings, splines, or the like.

It is a typical axial sectional view of the oil pump of a 1st embodiment. (A) is AA sectional drawing of FIG. 1, (b) is a side view of the principal part of (a). (A) is AA sectional drawing of FIG. 1, (b) is a side view of the principal part of (a). (A) is AA sectional drawing of FIG. 1, (b) is a side view of the principal part of (a). It is explanatory drawing explaining the clearance gap of the shape narrowed in a wedge shape.

Explanation of symbols

12 ... Inner rotor, 12a ... External teeth, 13 ... Outer rotor, 13a ... Internal teeth,
13b ... outer peripheral surface, 13c, 13c ... groove, 13e ... flat surface,
14 ... casing, 14d ... inner peripheral surface,

Claims (6)

An inner rotor (12) having outer teeth (12a) formed on the outer peripheral side;
An outer rotor (13) in which inner teeth (13a) meshed with the outer teeth (12a) are formed on the inner peripheral side;
A casing (14) that rotatably accommodates the inner rotor (12) and the outer rotor (13);
By rotating the inner rotor (12) and the outer rotor (13), the volume of the gap (B) formed between the outer teeth (12a) and the inner teeth (13a) is changed. A rotary pump for sucking and discharging fluid,
At least one of the outer peripheral surface (13b) of the outer rotor (13) and the inner peripheral surface (14d) of the casing (14) sliding with the outer peripheral surface (13b) includes the outer peripheral surface (13b) and the A concave pump (13c, 13d, 13e) that forms a space with the inner peripheral surface (14d) is formed. The rotary pump according to claim 1, wherein the concave portion is constituted by a groove (13c, 13d) formed in the outer peripheral surface (13b). The rotary pump according to claim 2, wherein the groove (13c) is formed over the entire circumference along the circumferential direction of the outer rotor (13). The rotary pump according to claim 2, wherein a plurality of the groove portions (13d) are formed along the axial direction of the outer rotor (13). The rotary pump according to claim 1, wherein the concave portion is constituted by a plurality of flat surfaces (13e) formed on the outer peripheral surface (13b). The rotary pump according to any one of claims 1 to 5, wherein the concave portion is constituted by a groove portion formed in the inner peripheral surface (14d).

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