Gear pump

Abstract

To reduce manufacturing costs of a gear pump.SOLUTION: A gear pump 100 includes: a drive gear 1 having a first rotary shaft 3 connected to a power source; a driven gear 2 which is rotatably supported by a second rotary shaft 4 and meshes with the drive gear 1 to be rotated by the drive gear 1; a body 10 which houses the drive gear 1 and the driven gear 2; and a cover 30 which covers an opening of the body 10. The first rotary shaft 3 is rotatably supported by the body 10 and the cover 30 and the second rotary shaft 4 is formed integrally with one of the body 10 and the cover 30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gear pump. [Background technology]

[0002] Patent Document 1 discloses a gear pump in which a pair of gears rotate while meshing with each other to discharge a fluid. The gear pump includes a body having a pair of gear chambers in which the pair of gears are respectively installed, and a pair of housings disposed on either side of the body and rotatably supporting the rotation shafts of the pair of gears. The body and housing are positioned with a positioning pin and fastened together with a bolt as a fastening member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2010 / 013354A1 Summary of the Invention [Problem to be solved by the invention]

[0004] In the gear pump described in Patent Document 1, the body, housing, positioning pin, and rotation shaft of the pair of gears are each provided separately, which results in a large number of parts and may increase the manufacturing cost of the gear pump.

[0005] The present invention has been made in view of the above problems, and has an object to reduce the manufacturing cost of gear pumps. [Means for solving the problem]

[0006] The present invention is a gear pump comprising a drive gear having a first rotating shaft connected to a power source, a driven gear rotatably supported on a second rotating shaft and meshing with the drive gear so as to be rotated by the drive gear, a body that houses the drive gear and driven gear, and a cover that covers an opening of the body, wherein the first rotating shaft is rotatably supported by the body and the cover, and the second rotating shaft is formed integrally with one of the body and the cover.

[0007] In this invention, since the second rotating shaft of the driven gear is formed integrally with the body or the cover, the number of parts of the gear pump can be reduced compared to a configuration in which the second rotating shaft is separate from the body and the cover, and the durability of the driven gear can be improved.

[0008] The present invention is also characterized in that the second rotary shaft positions the cover relative to the body by fitting into the other of the body and the cover.

[0009] In this invention, the second rotation shaft of the driven gear positions the cover relative to the body. In other words, in the gear pump, the second rotation shaft of the driven gear also serves as a positioning member that positions the cover relative to the body. Therefore, because the second rotation shaft has two functions: positioning the cover relative to the body and serving as the rotation shaft of the driven gear, it is possible to reduce the number of positioning members and the number of parts in the gear pump.

[0010] The present invention also provides a gear pump, further comprising a plurality of fastening members for fixing the body and the cover, one of the fastening members being provided to pass through the second rotation shaft.

[0011] In this invention, the body and cover can be fastened together by fastening members at the position where the second rotation shaft is provided, i.e., at the center of the driven gear, so the body and cover can be fixed in a more balanced manner around the entire circumference of the driven gear than in a configuration in which fastening members are provided only on the outer periphery of the driven gear, and therefore the number of fastening members can be reduced compared to a configuration in which fastening members are provided only on the outer periphery of the driven gear. [Effects of the Invention]

[0012] According to the present invention, the manufacturing cost of the gear pump can be reduced. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view of a gear pump according to an embodiment of the present invention. [Figure 2] FIG. 2 is a front view of the gear pump as seen from the direction of arrow II in FIG. [Figure 3] FIG. 2 is a cross-sectional view taken along line III-III in FIG. [Figure 4] 1 is a cross-sectional view of a gear pump according to a first modified example of the embodiment of the present invention, and corresponds to FIG. [Figure 5] FIG. 3 is a front view of a gear pump according to a first modified example of the embodiment of the present invention, corresponding to FIG. 2. [Figure 6] 1. FIG. 4 is a cross-sectional view of a gear pump according to a second modified example of the embodiment of the present invention, corresponding to FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] A gear pump 100 according to an embodiment of the present invention will now be described with reference to the drawings. The gear pump 100 is mounted on hydraulic machinery such as a forklift or a hydraulic excavator, and discharges hydraulic oil as a working fluid to drive actuators and other components of the hydraulic machinery. The gear pump 100 may also discharge fluids other than hydraulic oil, such as water. The use of the gear pump 100 is not limited to driving actuators and other components, and it can also be used for cooling or lubricating equipment.

[0015] Fig. 1 is a cross-sectional view of gear pump 100, and Fig. 2 is a front view of gear pump 100 as seen in the direction of arrow II in Fig. 1. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1, showing a cross section including a pair of gears, namely, drive gear 1 and driven gear 2. In Figs. 1 to 3, the positions of suction port 25 and discharge port 27, which are not visible in the drawings and will be described later, are indicated by dotted lines.

[0016] As shown in FIG. 1, the gear pump 100 includes a drive gear 1 having a first rotating shaft 3 connected to a power source (not shown), a driven gear 2 rotatably supported on a second rotating shaft 4 and meshing with the drive gear 1 so as to be rotated by the drive gear 1, a body 10 that houses the drive gear 1 and the driven gear 2, a cover 30 that covers an opening 10a of the body 10, bolts 40 as multiple fastening members that secure the body 10 and the cover 30, and a positioning pin 45 that is provided between the body 10 and the cover 30 and that positions the cover 30 relative to the body 10.

[0017] The gear pump 100 discharges hydraulic oil as a result of the rotation of a drive gear 1 and a driven gear 2. When the first rotating shaft 3 is rotated by the power of a power source, the drive gear 1 rotates, and the driven gear 2 meshing with the drive gear 1 also rotates. In the gear pump 100 of this embodiment, the second rotating shaft 4 of the driven gear 2 is formed integrally with the body 10, as will be described later. The driven gear 2 is rotatably supported on the second rotating shaft 4 via a bushing 50. The first rotating shaft 3 and the second rotating shaft 4 are arranged to extend parallel to each other. Note that, hereinafter, the axial direction of the first rotating shaft 3 and the second rotating shaft 4 will also be simply referred to as the "axial direction."

[0018] In this embodiment, the body 10 is formed by casting using a metal such as iron. As shown in Fig. 1, the body 10 has a gear chamber 21 having an opening 10a and accommodating the drive gear 1 and the driven gear 2, an intake port 25 (see Figs. 1 to 3) that sucks in hydraulic oil and directs it to the low-pressure side of the gear chamber 21, and a discharge port 27 (see Figs. 1 to 3) that directs hydraulic oil discharged from the high-pressure side of the gear chamber 21. The body 10 is formed in a substantially rectangular parallelepiped shape, and a cover 30 is attached to the body 10.

[0019] 1 and 3, the gear chamber 21 is formed into an elliptical shape in a cross section including the drive gear 1 and the driven gear 2 (see FIG. 3), and the teeth 1a of the drive gear 1 and the teeth 2a of the driven gear 2 are in sliding contact with the inner peripheral surface 21a, respectively. The body 10 is subjected to the pressure of the hydraulic oil in the gear chamber 21, but because it is formed by casting using a metal such as iron and has high strength, damage to the body 10 is prevented.

[0020] As shown in FIG. 1, the bottom 21b of the gear chamber 21 is formed with an accommodation hole 21c for accommodating one end of the first rotating shaft 3 of the drive gear 1, and a second rotating shaft 4 of the driven gear 2. The second rotating shaft 4 protrudes from the bottom 21b, is inserted into the gear chamber 21, and is formed to protrude from the opening 10a toward the cover 30 (to the right in FIG. 1) through the gear chamber 21. The second rotating shaft 4 is formed integrally and continuously with the bottom 21b. In other words, the second rotating shaft 4 forms a part of the body 10. In addition, the cover 30 is formed with a through hole 30a coaxial with the accommodation hole 21c, through which the first rotating shaft 3 of the drive gear 1 is inserted, and a accommodation hole 30b coaxial with the second rotating shaft 4 for accommodating the end of the second rotating shaft 4 of the driven gear 2. The first rotating shaft 3 is provided between the accommodation hole 21c and the through hole 30a and is rotatably supported by the body 10 and the cover 30 via a bearing 61. The second rotating shaft 4 is fitted into the accommodation hole 30b. As a result, the second rotating shaft 4, together with a positioning pin 45, as will be described later, positions the cover 30 relative to the body 10. A seal member 38 is provided between the outer peripheral surface of the first rotating shaft 3 and the inner peripheral surface of the through hole 30a.

[0021] As shown in Figures 1 to 3, suction port 25 and discharge port 27 are formed in body 10 in symmetrical shapes. As shown in Figures 2 and 3, suction port 25 has an opening 25a that opens to side surface 10b of body 10 and a passage 25b (see Figure 3) that connects opening 25a to gear chamber 21. Similarly, discharge port 27 has an opening 27a that opens to side surface 10c of body 10 opposite side surface 10b and a passage 27b (see Figure 3) that connects opening 27a to gear chamber 21. Suction port 25 has a piping (not shown) or the like connected to opening 25a to draw in hydraulic oil from the outside, and discharge port 27 has a piping (not shown) or the like connected to opening 27a to supply hydraulic oil to the outside. 3, the passage 25b of the suction port 25 is formed by a passage extending from the opening 25a perpendicular to the axial direction of the first rotating shaft 3 and the second rotating shaft 4, and a passage (not shown) that opens into the gear chamber 21 and extends in the axial direction. The same applies to the passage 27b of the discharge port 27.

[0022] The body 10 is formed with a plurality of insertion holes 15 through which bolts 40 are inserted. As shown in FIG. 2, in the gear pump 100 of this embodiment, the body 10 and the cover 30 are fixed together with four bolts 40. As shown in FIGS. 2 and 3, the four bolts 40 are provided at the four corners of the body 10, respectively, and are fastened from the body 10 side (the left side in FIG. 1). The insertion holes 15 are each formed to penetrate the body 10. No female thread is formed on the inner peripheral surface of the insertion holes 15, and the bolts 40 are inserted into the insertion holes 15 without being threadedly coupled to the insertion holes 15. The male threads 40a of the bolts 40 may be formed only at the tip of the shaft portion, or may be formed along the entire shaft portion.

[0023] In this embodiment, the cover 30 is made of aluminum and is formed into a shape by die casting. As shown in Fig. 1, the cover 30 has a main body 35 and an attachment portion 31 formed by partially protruding radially from the main body 35.

[0024] The main body 35 is formed with an annular fitting portion 36 that protrudes from the main body 35 toward the mounting target and fits into a recess in the mounting target. When mounting the gear pump 100 to the mounting target, the fitting portion 36 is fitted into the recess in the mounting target, thereby aligning the gear pump 100 (cover 30) with the mounting target. Then, with the two aligned, bolts (not shown) are inserted into notches 35a (see FIG. 2) in the main body 35 and fastened to the mounting target, thereby fixing the two together. The mounting portion 31 is formed in a shape corresponding to the body 10. The mounting portion 31 is formed with a plurality of fastening holes 37 (see FIG. 1) into which bolts 40 are inserted and fastened. The fastening holes 37 are each formed to penetrate the mounting portion 31. An internal thread 37a is formed on the inner peripheral surface of the fastening hole 37, and each bolt 40 is threadedly coupled to the fastening hole 37.

[0025] As shown in FIG. 1 , the positioning pin 45 is inserted into pin holes 46 and 47 formed in the mounting portion 31 of the body 10 and the cover 30, respectively. When the positioning pin 45 is fitted into the pin holes 46 and 47 and the second rotating shaft 4 of the driven gear 2 is fitted into the receiving hole 30b of the cover 30, relative movement between the body 10 and the cover 30 is restricted, thereby positioning the cover 30 relative to the body 10. In other words, the second rotating shaft 4 also serves as a positioning member that positions the cover 30 relative to the body 10 and has two functions: positioning the cover 30 relative to the body 10 and serving as the rotating shaft of the driven gear 2. In other words, the second rotating shaft 4 forms one of the multiple positioning pins 45 that position the cover 30 relative to the body 10. This allows for fewer positioning pins 45, thereby reducing the number of parts in the gear pump 100. Furthermore, the manufacturing cost of the gear pump 100 can be reduced because the time and effort required for machining the pin holes 46 and 47 and inserting the positioning pins 45 is also reduced. Only one positioning pin 45 may be provided, or multiple positioning pins 45 may be provided spaced apart in the circumferential direction. Furthermore, the positioning pin 45 is not necessarily required as long as the cover 30 can be positioned relative to the body 10 by the second rotating shaft 4. With the cover 30 positioned relative to the body 10 by the positioning pin 45 and the second rotating shaft 4, the bolt 40 is attached, thereby fixing the cover 30 to the body 10.

[0026] In this gear pump 100, the drive gear 1 and the driven gear 2 are rotated in the direction of the arrows shown in Fig. 3 by the power of the drive source while meshing with each other. When the drive gear 1 and the driven gear 2 rotate, the hydraulic oil is guided from the suction port 25 to the low-pressure side (left side in Fig. 3) of the gear chamber 21, is guided between adjacent teeth 1 a of the drive gear 1 and between adjacent teeth 2 a of the driven gear 2, moves along the inner circumferential surface 21 a of the gear chamber 21, is guided to the high-pressure side (right side in Fig. 3) of the gear chamber 21, and is discharged through the discharge port 27.

[0027] In the gear pump 100, as described above, the second rotating shaft 4 of the driven gear 2 is formed integrally with the body 10. This allows the number of parts of the gear pump 100 to be reduced. Furthermore, when the second rotating shaft 4 is formed separately from the body 10, the mounting accuracy of the driven gear 2 to the body 10 (in other words, the inclination of the driven gear 2 with respect to the body 10) depends on the machining accuracy of the body 10 and the machining accuracy and mounting accuracy of the cover 30. In contrast, when the second rotating shaft 4 is formed integrally with the body 10, the mounting accuracy of the driven gear 2 to the body 10 depends only on the machining accuracy of the body 10, and not on the machining accuracy and mounting accuracy of the cover 30. Therefore, by forming the second rotating shaft 4 integrally with the body 10, the mounting accuracy of the driven gear 2 to the body 10 is improved, and the accuracy of the parallelism between the second rotating shaft 4 and the first rotating shaft 3 is improved. This improves the meshing state between the drive gear 1 and the driven gear 2 and the sliding contact state between the driven gear 2 and the inner surface 21a of the gear chamber 21, preventing wear on the driven gear 2 and improving the durability of the gear pump 100.

[0028] Furthermore, in the gear pump 100, one end of the second rotating shaft 4 of the driven gear 2 is formed integrally (as a single member) with the body 10, which increases the durability of the driven gear 2 compared to a configuration in which the second rotating shaft 4 is separate from the body 10, and reduces deflection of the second rotating shaft 4 due to the reaction force of the meshing of the drive gear 1 and driven gear 2.

[0029] Specifically, in conventional configurations in which the first and second rotating shafts are formed separately from the body and cover, the first and second rotating shafts are rotatably supported by the body or cover, respectively. Therefore, the sliding clearance can cause the first and second rotating shafts to tilt, changing the meshing state between the drive gear and driven gear, potentially resulting in uneven wear of the drive gear and driven gear and loss of power transmission. In contrast, in the gear pump 100, the second rotating shaft 4 is integral with the body 10, preventing tilting of the second rotating shaft 4 and increasing the durability of the driven gear 2, as described above.

[0030] Furthermore, even if the first rotating shaft were formed integrally with the body or cover, the drive gear and the first rotating shaft would be separate entities, and poor coaxial accuracy between them could result in the drive gear tilting. If the drive gear tilts, problems could arise, such as uneven wear of the drive gear and driven gear and loss of power transmission. Furthermore, poor coaxial accuracy could result in vibrations occurring in the first rotating shaft, housing, etc. In contrast, in the gear pump 100, the drive gear 1 is formed integrally with the first rotating shaft 3, which serves as the gear shaft, thereby improving the coaxial accuracy between the two. Furthermore, because the drive gear 1 is connected to other rotating parts via the first rotating shaft 3, it is less likely to tilt than the driven gear 2. Therefore, by providing the first rotating shaft 3, which is the gear shaft of the drive gear 1, on the drive gear 1 side and the second rotating shaft 4, which is the gear shaft of the driven gear 2, on the body 10 side, it is possible to reduce the inclination of the drive gear 1 and the driven gear 2, thereby efficiently suppressing power transmission loss, uneven wear, vibration, etc. Furthermore, because uneven wear of the drive gear 1 and the driven gear 2 can be suppressed, leakage of the working fluid can be reduced and the efficiency of the gear pump 100 can be improved.

[0031] According to the present embodiment described above, the following effects are achieved.

[0032] In the gear pump 100, the second rotating shaft 4 of the driven gear 2 is formed integrally with the body 10, which reduces the number of parts in the gear pump 100 compared to a configuration in which the second rotating shaft 4 is separate from the body 10. Furthermore, the durability of the driven gear 2 can be improved.

[0033] In the gear pump 100, the second rotating shaft 4 of the driven gear 2 also serves as a positioning member that positions the cover 30 relative to the body 10. Therefore, the second rotating shaft 4 has two functions: to position the cover 30 relative to the body 10 and to serve as the rotating shaft of the driven gear 2. This makes it possible to reduce the number of positioning pins 45 and the number of parts in the gear pump 100. This allows for a reduction in the manufacturing cost of the gear pump.

[0034] Next, modified examples of this embodiment will be described. The following modified examples are also within the scope of the present invention, and it is possible to combine the configurations shown in the modified examples with the configurations described in the above embodiment, or to combine the configurations described in the different modified examples below.

[0035] <Variation 1> In the above embodiment, the multiple bolts 40 that secure the body 10 and the cover 30 are provided so as to be positioned at the four corners of the body 10. In other words, the bolts 40 are provided so as not to interfere with the second rotating shaft 4 of the driven gear 2. However, this is not limiting, and as shown in FIGS. 4 and 5, one of the bolts 40 may be provided so as to penetrate the second rotating shaft 4 and extend between the body 10 and the cover 30. In this configuration, as shown in FIG. 5, the bolt 40 is provided at each of the two corners of the body 10 on the side of the axis O1 of the first rotating shaft 3, and one bolt 40 is provided on the side of the axis O2 of the second rotating shaft 4 so as to overlap the axis O2.

[0036] In the gear pump 100, as shown in Fig. 3, the pressure of the hydraulic oil conveyed by the drive gear 1 and the pressure of the hydraulic oil conveyed by the driven gear 2 (in other words, the pressure inside the gear chamber 21) are balanced on the bisector of the distance between the drive gear 1 and the driven gear 2 (the dashed-dotted line B shown in Fig. 3). Therefore, by providing the bolt 40 on the axis O2 of the second rotating shaft 4, the body 10 and the cover 30 can be fixed by the bolt 40 inside the gear chamber 21 near the point where the pressures inside the gear chamber 21 are balanced. This makes it possible to efficiently fix the body 10 and the cover 30 with a small number of bolts 40. This allows the number of bolts 40 to be reduced, thereby reducing the manufacturing cost of the gear pump 100. In other words, because the body 10 and cover 30 can be fastened by the bolts 40 at the position where the second rotating shaft 4 is provided, i.e., at the center of the driven gear 2, the body 10 and cover 30 can be fixed in a more balanced manner around the entire circumference of the driven gear 2 than in a configuration in which the bolts 40 are provided only on the outer periphery of the driven gear 2. This allows for fewer bolts 40 than in a configuration in which the bolts 40 are provided only on the outer periphery of the driven gear 2. Furthermore, the body 10 can be formed into a substantially triangular prism shape along the positions where the bolts 40 are provided, thereby partially reducing the radial outward protrusion of the body 10 and cover 30. This allows for the gear pump 100 to be made more compact.

[0037] <Variation 2> In the gear pump 100 of the above embodiment, the second rotary shaft 4 of the driven gear 2 is formed integrally with the body 10. However, as shown in FIG. 6 , the second rotary shaft 4 of the driven gear 2 may be formed integrally with the cover 30. In this configuration, a receiving hole 121d for receiving one end of the second rotary shaft 4 is formed coaxially with the second rotary shaft 4 in the bottom 21b of the gear chamber 21. The second rotary shaft 4 is fitted into the receiving hole 121d, and thereby, the second rotary shaft 4 is fitted into the body 10 to position the cover 30 relative to the body 10, and together with the positioning pin 45, the second rotary shaft 4 is positioned relative to the body 10. In addition, one of the bolts 40 is provided between the body 10 and the second rotary shaft 4 of the cover 30. In other words, the second rotary shaft 4 may be formed integrally with either the body 10 or the cover 30, and may be fitted into the other of the body 10 or the cover 30 to position the cover 30 relative to the body 10. Even with this configuration, the same effects as those of the above embodiment can be achieved.

[0038] <Variation 3> In the gear pump 100 of the above embodiment, the cover 30 is positioned relative to the body 10 by fitting the second rotating shaft 4 into the cover 30. However, it is not essential that the second rotating shaft 4 be fitted into the cover 30, and the cover 30 may be positioned relative to the body 10 only by the positioning pin 45.

[0039] The configuration, operation, and effects of the embodiment of the present invention will be described below.

[0040] The gear pump 100 comprises a drive gear 1 having a first rotating shaft 3 connected to a power source, a driven gear 2 rotatably supported on a second rotating shaft 4 and meshing with the drive gear 1 so as to be rotated by the drive gear 1, a body 10 in which the drive gear 1 and driven gear 2 are housed, and a cover 30 that covers an opening 10a of the body 10, wherein the first rotating shaft 3 is rotatably supported by the body 10 and the cover 30, and the second rotating shaft 4 is formed integrally with one of the body 10 and the cover 30.

[0041] In this configuration, the second rotating shaft 4 of the driven gear 2 is formed integrally with the body 10 or the cover 30, which reduces the number of parts in the gear pump 100 compared to a configuration in which the second rotating shaft 4 is separate from the body 10 and the cover 30. In addition, the durability of the driven gear 2 can be improved.

[0042] In the gear pump 100 , the second rotary shaft 4 is fitted into the other of the body 10 and the cover 30 , thereby positioning the cover 30 relative to the body 10 .

[0043] In this configuration, the second rotation shaft 4 of the driven gear 2 positions the cover 30 relative to the body 10. In other words, in the gear pump 100, the second rotation shaft 4 of the driven gear 2 also serves as a positioning member that positions the cover 30 relative to the body 10. Therefore, since the second rotation shaft 4 has two functions, that is, to position the cover 30 relative to the body 10 and to serve as the rotation shaft of the driven gear 2, it is possible to reduce the number of positioning members (positioning pins 45), and the number of parts of the gear pump 100 can also be reduced.

[0044] The gear pump 100 further includes a plurality of bolts 40 as fastening members for fixing the body 10 and the cover 30 together, one of the bolts 40 being provided so as to pass through the second rotary shaft 4 .

[0045] In this configuration, the body 10 and the cover 30 can be fastened by the bolts 40 at the position where the second rotating shaft 4 is provided, that is, at the center of the driven gear 2, so the body 10 and the cover 30 can be fixed in a more balanced manner around the entire circumference of the driven gear 2 than in a configuration in which the bolts 40 are provided only on the outer periphery of the driven gear 2. Therefore, the number of bolts 40 can be reduced compared to a configuration in which the bolts 40 are provided only on the outer periphery of the driven gear 2.

[0046] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments. [Explanation of symbols]

[0047] 1 drive gear, 2... driven gear, 3... first rotating shaft, 4... second rotating shaft, 10... body, 10a... opening, 30... cover, 40... bolt (fastening member), 100... gear pump

Claims

1. a drive gear having a first rotation shaft connected to a power source; a driven gear that is rotatably supported on a second rotation shaft, and that meshes with the drive gear and is rotated by the drive gear; a body in which the drive gear and the driven gear are housed; a cover that covers the opening of the body, the first rotation shaft is rotatably supported by the body and the cover, The gear pump is characterized in that the second rotation shaft is formed integrally with one of the body and the cover.

2. 2. The gear pump according to claim 1, The gear pump according to claim 1, wherein the second rotating shaft is fitted to the other of the body and the cover to position the cover relative to the body.

3. 3. The gear pump according to claim 2, a plurality of fastening members for fastening the body and the cover together; A gear pump, characterized in that one of the fastening members is provided to penetrate the second rotating shaft.

Images