Internal Gear Pump

Abstract

To provide an internal gear pump capable of suppressing reduction of volumetric efficiency by reducing leakage from a discharge port to a suction port.SOLUTION: A pump chamber T is defined and formed by internal teeth 5A of an internal tooth gear 5 and external teeth 6A of an external tooth gear 6. The pump chamber T increases a volume in a suction area space S by rotating both the gears 5 and 6 to suck a liquid from a suction port 10 and decreases the volume in a discharge area space P to discharge the liquid to a discharge port 12. One-side side faces of both the gears 5 and 6 are recessed in an axial direction to form annular recesses 5C and 6C. In the recesses 5C and 6C, a plurality of beams 5G and 6G are formed with a clearance in a circumferential direction. The beams 5G and 6G divide the annular recesses 5C and 6C in the circumferential direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an internal gear pump that accommodates an external gear eccentrically inside a ring-shaped internal gear and rotates both gears to suck in and discharge liquid. [Background technology]

[0002] This type of internal gear pump houses an external gear eccentrically inside a ring-shaped internal gear, and sucks in liquid through a suction port and discharges it from a discharge port by rotating both gears. The external gear has both sides recessed in the axial direction to form annular recesses, making it lightweight. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-122548 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in such conventional internal gear pumps, the annular recesses are sealed at the outer periphery of the recesses to prevent them from communicating with the suction port and discharge port formed in an arc shape in the pump housing. As a result, the outer periphery is thin and the sealing between the two ports and the recesses is not satisfactory, which could lead to increased leakage from the discharge port through the recesses to the suction port, reducing volumetric efficiency.

[0005] An object of the present invention is to provide an internal gear pump that can reduce leakage from the discharge port to the suction port and suppress a decrease in volumetric efficiency. [Means for solving the problem]

[0006] In order to achieve this object, the present invention takes the following measures: A ring-shaped internal gear having internal teeth is rotatably housed in an accommodation hole of a pump housing, and an external gear having external teeth that mesh internally with the internal teeth of the internal gear is eccentrically housed inside the internal gear, and an intake area space is formed between both gears in a region where the meshing gap between both teeth increases as both gears rotate, the intake area space being connected to an intake port that draws in liquid, and a discharge area space is formed between both gears in a region where the meshing gap between both teeth decreases as both gears rotate, the discharge area space being connected to an exhaust port that discharges liquid, and a pump chamber is defined by the internal teeth of the internal gear and the external teeth of the external gear, and the pump chamber is opened by the intake area space being opened by the rotation of both gears. The volume of the pump housing is increased in the discharge area space to draw in liquid from the suction port, and the volume of the discharge area space is decreased to discharge liquid to the discharge port. One side of each of the gears is recessed in the axial direction to form an annular recess, and a plurality of beams are formed in the recess with gaps in the circumferential direction, and each beam divides the annular recess in the circumferential direction. The gears have one side that faces the other side formed flat. The pump housing has one sliding surface where the one side of each of the gears slides together formed flat, and the suction port and the discharge port are opened in the other sliding surface where the other side of each of the gears slide together. The recesses in each of the gears are divided in the circumferential direction, 、 In the discharge area A part of the liquid discharged into the discharge port is introduced through the gap between the tip of the thin-walled portion forming the recess and one sliding surface of the pump housing. The pressure at the discharge port Low In the intake area, the intermediate pressure is A part of the liquid inside is discharged through the gap between the tip of the thin-walled part forming the recess and one sliding surface of the pump housing. The pressure in the intake port High The internal gear pump is characterized by its low intermediate pressure.

[0007] in this case ,before Both of the gears may be made of synthetic resin. Effect of the Invention

[0008] As described above in detail, the invention described in claim 1 defines a pump chamber by the internal teeth of the internal gear and the external teeth of the external gear, and the pump chamber increases in volume in the suction area space by the rotation of both gears to draw in liquid from the suction port and decreases in volume in the discharge area space to discharge liquid to the discharge port, and both gears are recessed in one side in the axial direction to form an annular recess, and the recess has multiple beams with gaps in the circumferential direction, and each beam divides the annular recess in the circumferential direction. Therefore, since both gears have multiple beams between the discharge port and the suction port, liquid leaking from the discharge port to the suction port is separated by the multiple beams. in This can suppress leakage into the suction port, and reduce leakage from the discharge port to the suction port, thereby suppressing a decrease in volumetric efficiency. In addition, both gears can be made lighter by forming recesses. In addition, both gears have multiple beams formed in the recesses, which can improve their strength.

[0009] In addition, in the invention described in claim 1, both gears have one side surface and the opposing other side surface formed flat, and the pump housing has one sliding contact surface on which the one side surfaces of both gears slide, and the suction port and discharge port are opened on the other sliding contact surface on which the other side surfaces of both gears slide. Therefore, the flat other side surfaces of both gears slide on the other sliding contact surface of the pump housing on which the suction port and discharge port are opened, so that the suction port and discharge port are not exposed to the recesses recessed into the one side surfaces of both gears, and leakage from the discharge port to the suction port can be further reduced, further suppressing a decrease in volumetric efficiency. Also, the recesses located in the discharge area space are more sensitive to pressure from the discharge port. Low The pressure in the recess located in the suction area is intermediate, and the pressure in the recess is higher than that of the suction port. High Therefore, the pressure of the recess located in the discharge area space and the pressure of the discharge port act in opposite directions on both gears in the axial direction, and the pressure of the recess located in the suction area space and the pressure of the suction port act in opposite directions on both gears in the axial direction, so that both gears can be well pressure balanced in the axial direction.

[0010] Also, Claim 2 In the invention described in the above, both gears are made of synthetic resin, which makes it possible to further reduce the weight of both gears. [Brief description of the drawings]

[0011] [Figure 1] 3 is a cross-sectional view taken along line AA in FIG. 2 of the internal gear pump showing one embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line BB in FIG. [Diagram 3] FIG. 2 is a cross-sectional view corresponding to FIG. 1 of another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In Fig. 1 and Fig. 2, 1 denotes a pump body, which forms a bottomed accommodation hole 2. 3 denotes a cover member, which is attached to the pump body 1 so as to close the opening of the accommodation hole 2. The pump body 1 and the cover member 3 are made of metal, and the pump body 1 and the cover member 3 together form a pump housing 4. 5 denotes a ring-shaped internal gear, which has eight internal teeth 5A, and is rotatably accommodated in the accommodation hole 2. 6 denotes an external gear, which has seven external teeth 6A that mesh internally with the internal teeth 5A, and is eccentrically accommodated inside the internal gear 5. Both gears 5 and 6 are molded products of synthetic resin. One side surface 5B in the axial direction of the internal gear 5 and one side surface 6B of the external gear 6 are capable of sliding against the bottom surface of the accommodation hole 2, and this bottom surface is formed flat as one sliding contact surface 4A of the pump housing 4.

[0013] Both gears 5, 6 have recesses 5C, 6C formed by axially recessing one side surface 5B, 6B. The recess 5C formed in the internal gear 5 is formed in an annular shape, with the outer circumference being slightly smaller in diameter than the outer circumference of the internal gear 5. The inner circumference of the recess 5C is shaped to follow the internal teeth 5A and is slightly larger than the internal teeth 5A. The axial depth of the recess 5C is slightly smaller than the width of the internal gear 5. The internal gear 5 has an outer peripheral thin portion 5D on the outer circumference of the recess 5C, an inner peripheral thin portion 5E on the inner circumference of the recess 5C, and a bottom thin portion 5F on the bottom surface of the recess 5C, with the thicknesses of the thin portions 5D, 5E, 5F being approximately the same.

[0014] 5G denotes beams formed in the recess 5C, and eight of them are provided at equal intervals in the circumferential direction. Each beam 5G is formed radially outward from the radial center of the internal gear 5, connecting between each tooth tip of the internal teeth 5A in the inner peripheral thin portion 5E and the outer peripheral thin portion 5D, dividing the recess 5C into eight in the circumferential direction. The axial width of each beam 5G is set to be approximately the same as the axial depth of the recess 5C, and the thickness is set to be approximately the same as the thickness of each thin portion 5D, 5E, 5F.

[0015] The recess 6C formed in the external gear 6 is formed in an annular shape, and the outer circumference is shaped to follow the external teeth 6A and is slightly smaller than the external teeth 6A. The inner circumference of the recess 6C is larger in diameter than the through hole 7 formed to penetrate the axial direction from the radial center. The axial depth of the recess 6C is slightly smaller than the width of the external gear 6. The external gear 6 has an outer peripheral thin wall portion 6D formed on the outer circumference of the recess 6C, a boss portion 6E formed on the inner circumference of the recess 6C, and a bottom thin wall portion 6F formed on the bottom surface of the recess 6C. The through hole 7 is approximately D-shaped in vertical section, and a drive shaft 8 with a vertical section of a tip end approximately D-shaped is fitted into the through hole 7. The drive shaft 8 is sealed with a seal member 9 arranged in the pump body 1, and drives the external gear 6 to rotate.

[0016] 6G denotes beams formed in the recess 6C, and seven of them are provided at equal intervals in the circumferential direction. Each beam 6G is formed radially outward from the radial center of the external gear 6, connecting between the boss portion 6E and each tooth tip of the external teeth 6A in the outer peripheral thin portion 6D, and dividing the recess 6C into seven in the circumferential direction. The axial width of each beam 6G is set to be approximately the same as the axial depth of the recess 6C, and the thickness is set to be approximately the same as the thickness of each thin portion 6D, 6F.

[0017] The gears 5 and 6 have flat sides 5H and 6H facing the side surfaces 5B and 6B. The side surfaces 5H and 6H of the gears 5 and 6 are in sliding contact with the side surface of the cover member 3 that closes the opening of the receiving hole 2, and this side surface is the other sliding surface 4B of the pump housing 4, and is formed flat. S is an intake area space, and P is a discharge area space, which are provided between the gears 5 and 6, respectively. The intake area space S is formed in an area where the meshing gap between the teeth 5A and 6A increases as the gears 5 and 6 rotate. The discharge area space P is formed in an area where the meshing gap between the teeth 5A and 6A decreases as the gears 5 and 6 rotate. T is a pump chamber, which is divided into multiple spaces by the internal teeth 5A of the internal gear 5 and the external teeth 6A of the external gear 6, and the volume of the intake area space S increases as the gears 5 and 6 rotate, while the volume of the discharge area space P decreases.

[0018] Reference numeral 10 denotes a suction port communicating with the suction area space S, which opens into a semicircular recess formed in the other sliding surface 4B of the pump housing 4. Reference numeral 11 denotes a suction flow passage connected to the suction port 10, which is formed in the cover member 3 and passes the liquid suctioned from the low pressure side. Reference numeral 12 denotes a discharge port communicating with the discharge area space P, which is formed into a semicircular recess in the other sliding surface 4B of the pump housing 4 and opens at a position symmetrical in the radial direction to the suction port 10. Reference numeral 13 denotes a discharge flow passage connected to the discharge port 12, which is formed in the cover member 3 and passes the liquid discharged to the load side.

[0019] In the discharge area space P, each of the eight circumferentially divided recesses 5C introduces a small amount of liquid to be discharged to the discharge port 12 into the interior through the gap between the tip of the inner thin portion 5E and one sliding contact surface 4A of the pump housing 4, and in the suction area space S, a portion of the liquid inside is discharged to the suction port 10 through the gap between the tip of the inner thin portion 5E and one sliding contact surface 4A of the pump housing 4. For this reason, each of the eight circumferentially divided recesses 5C has an intermediate pressure in the discharge area space P that is slightly lower than the pressure of the discharge port 12, and an intermediate pressure in the suction area space S that is slightly higher than the pressure of the suction port 10.

[0020] In the discharge area space P, each of the seven recessed portions 6C divided in the circumferential direction introduces a small amount of liquid to be discharged to the discharge port 12 into the interior through the gap between the tip of the outer circumferential thin portion 6D and one sliding contact surface 4A of the pump housing 4, and in the suction area space S, each of the seven recessed portions 6C divided in the circumferential direction has an intermediate pressure slightly lower than the pressure of the discharge port 12 in the discharge area space P, and an intermediate pressure slightly higher than the pressure of the suction port 10 in the suction area space S.

[0021] Next, the operation of this configuration will be described. When the external gear 6 is rotated by the drive shaft 8, the internal gear 5, which is inscribed in mesh with the external gear 6, is rotated, and liquid flows from the low pressure side through the suction passage 11, is sucked into the suction area space S through the suction port 10, is transported to the discharge area space P, and is discharged through the discharge passage 13 from the discharge port 12.

[0022] At this time, a part (a small amount) of the liquid flowing from the discharge area space P through the discharge port 12 is introduced into the recess 5C located in the discharge area space P through the gap between the tip of the inner thin portion 5E of the internal gear 5 and one sliding contact surface 4A of the pump housing 4, and is also introduced into the recess 6C located in the discharge area space P through the gap between the tip of the outer thin portion 6D of the external gear 6 and one sliding contact surface 4A of the pump housing 4. Therefore, the recesses 5C and 6C located in the discharge area space P have an intermediate pressure that is slightly lower than the pressure of the discharge port 12.

[0023] Also, a part (a small amount) of the liquid in recess 5C located in the suction area space S is led out from the suction area space S to the suction port 10 through the gap between the tip of inner thin portion 5E and one sliding contact surface 4A of the pump housing 4. Also, a part (a small amount) of the liquid in recess 6C located in the suction area space S is led out to the suction port 10 through the gap between the tip of outer thin portion 6D and one sliding contact surface 4A of the pump housing 4. Therefore, the recesses 5C and 6C located in the suction area space S have an intermediate pressure that is slightly higher than the pressure of the suction port 10.

[0024] In this operation, the internal teeth 5A of the internal gear 5 and the external teeth 6A of the external gear 6 define a pump chamber T, and the pump chamber T increases the volume in the suction area space S by the rotation of both gears 5 and 6 to suck in liquid from the suction port 10, and decreases the volume in the discharge area space P to discharge liquid to the discharge port 12. The gears 5 and 6 have one side surface 5B and 6B recessed in the axial direction to form annular recesses 5C and 6C, and the recesses 5C and 6C have gaps in the circumferential direction to form multiple beams 5G and 6G, and each beam 5G and 6G divides the annular recesses 5C and 6C in the circumferential direction. Therefore, since both gears 5 and 6 have multiple beams 5G and 6G between the discharge port 12 and the suction port 10, liquid leaking from the discharge port 12 to the suction port 10 is caused to leak through the multiple beams 5G and 6G. in This can suppress leakage into the suction port 10, and reduce leakage from the discharge port 12 to the suction port 10, thereby suppressing a decrease in volumetric efficiency. In addition, the gears 5, 6 are formed with recesses 5C, 6C to reduce their weight. In addition, the gears 5, 6 are formed with a plurality of beams 5G, 6G in the recesses 5C, 6C, thereby improving their strength.

[0025] In addition, the gears 5, 6 have flat side surfaces 5H, 6H facing the side surfaces 5B, 6B, and the pump housing 4 has flat first sliding contact surface 4A where the side surfaces 5B, 6B of the gears 5, 6 slide, and the suction port 10 and the discharge port 12 are opened in the second sliding contact surface 4B where the side surfaces 5H, 6H of the gears 5, 6 slide. Therefore, the flat second side surfaces 5H, 6H of the gears 5, 6 slide against the second sliding contact surface 4B of the pump housing 4 where the suction port 10 and the discharge port 12 are opened, and the suction port 10 and the discharge port 12 are not exposed to the recesses 5C, 6C recessed in the side surfaces 5B, 6B of the gears 5, 6, and leakage from the discharge port 12 to the suction port 10 can be further reduced, and a decrease in volumetric efficiency can be further suppressed. 。

[0026] In addition, both gears 5 and 6 are made of synthetic resin, which allows the weight of both gears 5 and 6 to be further reduced.

[0027] Further, the recesses 5C, 6C located in the discharge area space P have an intermediate pressure slightly lower than the pressure of the discharge port 12, and the recesses 5C, 6C located in the suction area space S have an intermediate pressure slightly higher than the pressure of the suction port 10. As a result, the pressures of the recesses 5C, 6C located in the discharge area space P and the pressure of the discharge port 12 act in opposing axial directions on both gears 5, 6, and the pressures of the recesses 5C, 6C located in the suction area space S and the pressure of the suction port 10 act in opposing axial directions on both gears 5, 6, so that the gears 5, 6 can be well pressure balanced in the axial direction.

[0028] FIG. 3 shows another embodiment of the present invention. The same parts as those in the first embodiment are given the same reference numerals and their explanation is omitted, and only the different parts will be explained. Eight beams 14 are formed in the recess 5C of the internal gear 5 at equal intervals in the circumferential direction, connecting between each tooth bottom of the internal teeth 5A in the inner peripheral thin portion 5E and the outer peripheral thin portion 5D, dividing the recess 5C into eight in the circumferential direction. Seven beams 15 are formed in the recess 6C of the external gear 6 at equal intervals in the circumferential direction, connecting between the boss portion 6E and each tooth bottom of the external teeth 6A in the outer peripheral thin portion 6D, dividing the recess 6C into seven in the circumferential direction. The drive shaft 16 that rotates and drives the external gear 6 has a vertical cross section at its tip that is approximately two-face shaped. The through hole 17 into which the drive shaft 16 is fitted has a vertical cross section that is approximately two-face shaped.

[0029] The operation is substantially the same as in the first embodiment, in that the external gear 6 is rotationally driven by the drive shaft 16 , and liquid is sucked in through the suction port 10 and discharged from the discharge port 12 .

[0030] At this time, the recesses 5C, 6C located in the discharge area space P are at an intermediate pressure slightly lower than the pressure of the discharge port 12. Moreover, the recesses 5C, 6C located in the suction area space S are at an intermediate pressure slightly higher than the pressure of the suction port 10. Therefore, the pressures of the recesses 5C, 6C located in the discharge area space P and the pressure of the discharge port 12 act in opposing directions on both gears 5, 6, and the pressures of the recesses 5C, 6C located in the suction area space S and the pressure of the suction port 10 act in opposing directions on both gears 5, 6, so that the gears 5, 6 can be well pressure balanced in the axial direction.

[0031] In this operation, a plurality of beams 14, 15 are formed in the recesses 5C, 6C with gaps in the circumferential direction, and each beam 14, 15 divides the annular recesses 5C, 6C in the circumferential direction. Therefore, since both gears 5, 6 have a plurality of beams 14, 15 between the discharge port 12 and the suction port 10, liquid leaking from the discharge port 12 to the suction port 10 is guided by the plurality of beams 14, 15. in This can suppress leakage into the suction port 10, and reduce leakage from the discharge port 12 to the suction port 10, thereby suppressing a decrease in volumetric efficiency. In addition, the gears 5, 6 are formed with recesses 5C, 6C to reduce their weight. In addition, the gears 5, 6 are formed with a plurality of beams 14, 15 in the recesses 5C, 6C, thereby improving their strength.

[0032] Furthermore, substantially similar to the first embodiment, the suction port 10 and the discharge port 12 are opened on the other sliding contact surface 4B (shown in FIG. 2) of the pump housing 4 with which the flat other side surfaces 5H, 6H (shown in FIG. 2) of both gears 5, 6 slide. Therefore, the suction port 10 and the discharge port 12 are not exposed to the recesses 5C, 6C recessed into the one side surfaces 5B, 6B (shown in FIG. 2) of both gears 5, 6, so that leakage from the discharge port 12 to the suction port 10 can be further reduced and a decrease in volumetric efficiency can be further suppressed. .Ma In addition, since both gears 5, 6 are made of synthetic resin, the weight of both gears 5, 6 can be further reduced.

[0033] In the above-mentioned embodiments, the beams 5G, 6G are connected to the tooth tips of the internal teeth 5A and the external teeth 6A, and the beams 14, 15 are connected to the tooth bottoms of the internal teeth 5A and the external teeth 6A, but the beams may be connected to both the tooth tips and the tooth bottoms of the internal teeth and the external teeth. The pump housing 4 is composed of the pump body 1 and the cover member 3, but the pump housing may be composed of three members: a first member that penetrates and forms an accommodation hole that accommodates both gears, a second member that is attached to one side of the first member and with which one side of both gears slide, and a third member that is attached to the other side of the first member and with which the other side of both gears slide. The through holes 7, 17 that fit the drive shafts 8, 16 that rotate the external gear 6 are formed to be approximately D-shaped or approximately two-faced in vertical section, but it goes without saying that the through holes may be formed to be spline-shaped in vertical section. [Explanation of symbols]

[0034] 2: Storage hole 4: Pump housing 4A: One slide contact surface 4B: Other sliding surface 5: Internal gear 5A: Internal teeth 5B, 6B: One side 5C, 6C: Concave 5G, 6G, 14, 15: Beam 5H, 6H: Other side 6: External gear 6A: External teeth 10: Intake port 12: Discharge port S: Suction area space P:Discharge area space T: Pump room

Claims

1. A ring-shaped internal gear having internal teeth is rotatably accommodated in an accommodation hole of a pump housing, and an external gear having external teeth that internally mesh with the internal teeth of the internal gear is eccentrically accommodated inside the internal gear, and an suction area space is formed between both gears in a region where the meshing gap between both teeth increases as both gears rotate, and the suction area space is formed in communication with a suction port that draws in liquid, and a discharge area space is formed in communication with a discharge port that discharges liquid to a region where the meshing gap between both teeth decreases as both gears rotate, and a pump chamber is defined by the internal teeth of the internal gear and the external teeth of the external gear, and the pump chamber is provided such that the volume of the suction area space increases as both gears rotate to draw in liquid from the suction port and the volume of the discharge area space decreases to discharge liquid to the discharge port, and one side of both gears is recessed in the axial direction to form an annular recess, a pump housing having a plurality of beams formed with gaps in the circumferential direction, each beam dividing an annular recess in the circumferential direction, one side surface of each of the gears being flat and opposing the other side surface of the gears, a pump housing having a flat sliding surface on which one side surfaces of the gears slide and an intake port and a discharge port being opened in the other sliding surface on which the other side surfaces of the gears slide, and each of the circumferentially divided recesses of the gears introduces, in a discharge area space, a portion of the liquid discharged to the discharge port through the gap between the tip of the thin-walled portion forming the recess and the one sliding surface of the pump housing, thereby creating an intermediate pressure lower than the pressure of the discharge port, and, in a suction area space, a portion of the liquid inside is discharged through the gap between the tip of the thin-walled portion forming the recess and the one sliding surface of the pump housing, thereby creating an intermediate pressure higher than the pressure of the suction port.

2. 2. The internal gear pump according to claim 1, wherein both of said gears are made of synthetic resin.

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