Gear pump or gear motor

Abstract

To suppress the increase of a high-pitched sound in the driving sound of a gear pump.SOLUTION: A toothed wheel pump or a toothed wheel motor includes a driving toothed wheel (2) and a driven toothed wheel (3) that mesh with each other, a toothed wheel (G) indicates any toothed wheel (G) of the driving toothed wheel (2) and the driven toothed wheel (3), or each of the driving toothed wheel (2) and the driven toothed wheel (3), and a volume of at least one G2 among a plurality of grooves (G2) of the toothed wheel (G) is different from a volume of another G2.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to gear pumps or gear motors. [Background technology]

[0002] Patent Document 1 discloses a gear pump or gear motor. The gear pump or gear motor described in Patent Document 1 includes a casing with an internal space, and a drive gear and a driven gear disposed in the internal space. The casing has a suction passage through which fluid is drawn and a discharge passage through which the fluid is discharged. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-223122 Summary of the Invention [Problem to be solved by the invention]

[0004] In the gear pump described in Patent Document 1, the working fluid in the space surrounded by the tooth surfaces of the drive gear and the driven gear is transferred to the discharge passage side by the rotation of the gears, pressurized to a high pressure, and sent to the hydraulic equipment through the discharge passage and piping. However, the driving noise of the gear pump can become loud and high-pitched, especially in the high-speed rotation range.

[0005] An object of the present disclosure is to prevent the high-pitched driving noise of a gear pump from increasing. [Means for solving the problem]

[0006] A first aspect relates to a gear pump or gear motor, which includes a drive gear (2) and a driven gear (3) that mesh with each other, and a gear (G) refers to either the drive gear (2) or the driven gear (3), or each of the drive gear (2) and the driven gear (3), and at least one of a plurality of tooth spaces (G2) of the gear (G) has a volume different from the volumes of the other tooth spaces (G2).

[0007] In the first aspect, it is possible to prevent high frequency components of the driving sound of the gear pump from concentrating on a specific sound, and therefore it is possible to prevent high-pitched sounds from becoming louder.

[0008] In the second aspect, in the first aspect, the volumes of the adjacent tooth spaces (G2) of the gear (G) are different from each other.

[0009] In the second mode, the sounds of the high frequency components corresponding to the adjacent tooth spaces (G2) can be made different from each other.

[0010] In a third aspect, in the first aspect, the volumes of all the tooth spaces (G2) of the gear (G) are different from one another.

[0011] In the third aspect, the high frequency components of the drive noise generated each time the tooth groove (G2) passes through the meshing region (14) can be effectively dispersed differently for each tooth groove (G2), thereby effectively preventing the high-pitched sound from becoming louder.

[0012] A fourth aspect is any one of the first to third aspects, wherein the plurality of tooth grooves (G2) include a first tooth groove (G21) and a second tooth groove (G22), the first tooth groove (G21) includes a first recess (G61) at the bottom of the first tooth groove (G21), the second tooth groove (G22) includes a second recess (G62) at the bottom of the second tooth groove (G22), and the shape of the first recess (G61) and the shape of the second recess (G62) are different from each other.

[0013] In the fourth aspect, by making the shape of the first recess (G61) and the shape of the second recess (G62) different from each other, the volume of the first tooth groove (G21) and the volume of the second tooth groove (G22) can be made different from each other. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic cross-sectional view of a gear pump or gear motor according to an embodiment. [Figure 2] FIG. 2 is a plan view of the gear. [Figure 3] FIG. 3 is a side view of the gear. [Figure 4] FIG. 4 is a cross-sectional view of the gear shown in FIG. 3 taken along line IV-IV. [Figure 5] FIG. 5 is a graph showing the test results. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below, and various modifications are possible within the scope of the technical concept of the present disclosure. Since the drawings are intended to conceptually explain the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary to facilitate understanding.

[0016] Exemplary embodiments will now be described in detail with reference to the accompanying drawings.

[0017] A gear pump or gear motor 1 according to an embodiment of the present invention will be described with reference to Figure 1. Figure 1 is a cross-sectional view of the gear pump or gear motor 1. Hereinafter, the gear pump or gear motor 1 will be referred to as the gear pump 1. The gear pump 1 draws in and pressurizes fluid (e.g., hydraulic oil) supplied from a tank that stores the fluid, and then discharges the fluid to supply it to hydraulic equipment.

[0018] -Overall structure- 1, the gear pump 1 includes a drive gear 2 and a driven gear 3 that mesh with each other, a drive shaft 4 and a driven shaft 5 that support the drive gear 2 and the driven gear 3, respectively, and a casing 6 that houses the drive gear 2, the driven gear 3, the drive shaft 4, and the driven shaft 5. The gear pump 1 of this embodiment sucks in and pressurizes a fluid supplied from a tank that stores the fluid, and then discharges the fluid to supply it to hydraulic equipment.

[0019] Hereinafter, the direction parallel to the axis (4A) of the drive shaft (4) and the axis (5A) of the driven shaft (5) may be referred to as the first direction (A). Of the directions perpendicular to the first direction (A), the direction parallel to the arrangement direction of the drive gear (2) and the driven gear (3) may be referred to as the second direction (B). The direction perpendicular to the first direction (A) and the second direction (B) may be referred to as the third direction (C) (see Figure 2).

[0020] The casing (6) has a main body (7) and a cover (9) fixed to the main body (7). The cover (9) is disposed on one side (A1) of the casing (6) in the first direction (A). An internal space (10) of the casing (6) is formed across the internal space of the main body (7) and the internal space of the cover (9).

[0021] A drive gear 2, a drive shaft 4 that is integral with or fixed to the drive gear 2, a driven gear 3, and a driven shaft 5 that is integral with or fixed to the driven gear 3 are arranged in the internal space 10 of the casing 6. The axis 4A of the drive shaft 4 and the axis 5A of the driven shaft 5 are arranged parallel to each other.

[0022] The drive shaft (4) extends along its axis (4A) so as to pass through the center of the drive gear (2). The drive shaft (4) rotates around its axis (4A) together with the drive gear (2). The driven shaft (5) extends along its axis (5A) so as to pass through the center of the driven gear (3). The driven shaft (5) rotates around its axis (5A) together with the driven gear (3).

[0023] The drive gear (2) and the driven gear (3) are meshed with each other. When the drive gear (2) rotates, power is transmitted from the drive gear (2) to the driven gear (3) at the meshing point between the drive gear (2) and the driven gear (3), causing the drive gear (2) and the driven gear (3) to rotate together.

[0024] As shown in FIGS. 1 and 2, the drive gear (2) and the driven gear (3) are each configured as a spur gear and are disposed in an internal space (10) formed inside the casing (6).

[0025] The drive shaft (4) has a first drive shaft (4a) located on one side (A1) in the first direction (A) with respect to the drive gear (2) and a second drive shaft (4b) located on the other side (A2) in the first direction (A) with respect to the drive gear (2). A driving means (e.g., a prime mover) is connected to the second drive shaft (4b). The driven shaft (5) has a first driven shaft (5a) located on one side (A1) in the first direction (A) with respect to the driven gear (3) and a second driven shaft (5b) located on the other side (A2) in the first direction (A) with respect to the drive gear (2).

[0026] In the gear pump 1, the drive gear 2 and the driven gear 3 are housed in the internal space 10 in a state of meshing with each other, with their teeth in sliding contact with the inner circumferential surface of the internal space 10. As a result, the drive gear 2 and the driven gear 3 rotate while meshing with each other in the internal space 10 of the casing 6. When rotating, the drive gear 2 and the driven gear 3 each come in sliding contact with the inner circumferential surface of the internal space 10 of the casing 6, dividing the internal space 10 into a low-pressure region and a high-pressure region.

[0027] The gear pump (1) has a drive bearing (11) that rotatably supports the drive shaft (4) and a driven bearing (12) that rotatably supports the driven shaft (5). The drive bearing (11) has a first drive bearing (11a) that rotatably supports the first drive shaft (4a) and a second drive bearing (11b) that rotatably supports the second drive shaft (4b). The driven bearing (12) has a first driven bearing (12a) that rotatably supports the first driven shaft (5a) and a second driven bearing (12b) that rotatably supports the second driven shaft (5b). Each of the first drive bearing (11a), the second drive bearing (11b), the first driven bearing (12a), and the second driven bearing (12b) includes, for example, a slide bearing.

[0028] An oil seal (13) is provided between the casing (6) and the drive shaft (4) in the internal space (10) of the casing (6). The oil seal (13) is made of, for example, rubber. The oil seal (13) is located on the other side (A2) of the second drive bearing (11b) in the first direction (A).

[0029] The gear pump (1) includes a pair of side plates (20) and a pair of sealing members (30). The pair of side plates (20) are arranged to sandwich the drive gear (2) and the driven gear (3) from both sides in the first direction (A). Each of the pair of side plates (20) is arranged to face the drive gear (2) and the driven gear (3). Each of the pair of side plates (20) is arranged to be sandwiched between the drive gear (2) and the driven gear (3) and the casing (6). A drive shaft (4) and a driven shaft (5) are inserted through each of the pair of side plates (20).

[0030] One side plate (20A) of the pair of side plates (20) is disposed on one side (A1) in the first direction (A) relative to the drive gear (2) and the driven gear (3). The other side plate (20B) of the pair of side plates (20) is disposed on the other side (A2) in the first direction (A) relative to the drive gear (2) and the driven gear (3). One seal member (30A) of the pair of seal members (30) is attached to the side plate (20A). The other seal member (30B) of the pair of seal members (30) is attached to the side plate (20B).

[0031] As shown in Fig. 2, in the gear pump 1, a suction passage 7a communicating with a low-pressure region of the internal space 10 and a discharge passage 7b communicating with a high-pressure region of the internal space 10 are formed in the casing 6. The suction passage 7a and the discharge passage 7b are spaced apart from each other along the third direction C. The pressure of the fluid flowing through the discharge passage 7b is greater than the pressure of the fluid flowing through the suction passage 7a.

[0032] The gears (2, 3) include a plurality of teeth (G1). The plurality of teeth (G1) are aligned along the rotation direction (R1, R2) of the gears (2, 3). The plurality of teeth (G1) rotate around the axes (4A, 5A). A gap (G2), which is a tooth space, is formed between adjacent teeth (G1). The rotation direction (R1) of the drive gear (2) and the rotation direction (R2) of the driven gear (3) are opposite to each other.

[0033] The rotational locus of the teeth (G1) of the gears (2, 3) includes a suction passage (7a), a discharge passage (7b), an engagement region (14), and a rotational locus region (15).

[0034] The meshing region (14) indicates the region where the drive gear (2) and the driven gear (3) mesh with each other.

[0035] The rotation locus region (15) is a region located between the suction passage (7a) and the discharge passage (7b) of the locus of the teeth (G1) formed during rotation of the gears (2, 3). In the rotation locus region (15), a process for increasing the pressure of the fluid in the tooth gaps (G2) is performed during rotation of the gears (2, 3).

[0036] The suction passage (7a), the discharge passage (7b), the meshing region (14), and the rotational locus region (15) are arranged in the following order along the rotational direction (R) of the gears (2, 3): suction passage (7a), rotational locus region (15), discharge passage (7b), and meshing region (14). The rotational direction (R) indicates the direction in which the gears (2, 3) (the teeth (G1) of the gears (2, 3)) rotate when the gear pump (1) is operating. The operation of the gear pump (1) means that the rotation of the gears (2, 3) causes a process of sending fluid to a hydraulic device through the suction passage (7a), the rotational locus region (15), and the discharge passage (7b).

[0037] When the teeth G1 of the gears 2 and 3 rotate within the rotation locus region 15, the tips G3 of the gears 2 and 3 come into sliding contact with the wall surface 10a of the internal space 10. As a result, the tooth gap G2 is closed.

[0038] The side plate (20) has a facing surface (21). The facing surface (21) is the outer surface of the side plate (20) that faces the gears (2, 3). In the gear pump (1), a pipe extending from a tank that stores a fluid is connected to the suction passage (7a) of the casing (6). A pipe leading to a hydraulic device is connected to the discharge passage (7b).

[0039] - Gear pump operation - When the drive shaft (4) of the drive gear (2) is rotated by a driving means (e.g., a prime mover), not shown, the driven gear (3) meshed with the drive gear (2) rotates in the rotational direction (R) together with the drive gear (2). As a result, the fluid in the space surrounded by the inner circumferential surface of the internal space (10) and the tooth grooves (G2) is transferred in the rotational direction (R) to the discharge passage (7b) side by the rotation of the gears (2, 3). As a result, the discharge passage (7b) side becomes the high-pressure side and the suction passage (7a) side becomes the low-pressure side, with the meshing region (14) as the boundary.

[0040] As the fluid is transferred to the discharge passage (7b), the fluid in the tank is sucked into the low-pressure internal space (10) through the piping and the suction passage (7a). The fluid in the space enclosed by the inner circumferential surface of the internal space (10) and the tooth grooves (G2) is transferred in the rotation direction (R) from the suction passage (7a) by the rotation of the gears (2, 3), is pressurized to a high pressure as it passes through the rotation locus region (15), and is then supplied to the discharge passage (7b). The fluid supplied to the discharge passage (7b) is then supplied to hydraulic equipment through the piping.

[0041] -Gear structure- The structure of the gear (G) will be described. The gear (G) represents either the drive gear (2) or the driven gear (3), or both the drive gear (2) and the driven gear (3). In other words, the gear (G) can be any of a configuration showing only the drive gear (2), a configuration showing only the driven gear (3), or a configuration showing both the drive gear (2) and the driven gear (3).

[0042] When the gear (G) refers to the drive gear (2), the rotation direction (R) of the gear (G) refers to the rotation direction (R1). When the gear (G) refers to the driven gear (3), the rotation direction (R) of the gear (G) refers to the rotation direction (R2). When the gear (G) refers to each of the drive gear (2) and the driven gear (3), the rotation direction (R) of the gear (G) refers to the rotation direction (R1) for the drive gear (2) and the rotation direction (R2) for the driven gear (3). When the gear (G) refers to the drive gear (2), the rotation axis (GA) refers to the drive axis (4). When the gear (G) refers to the driven gear (3), the rotation axis (GA) refers to the driven axis (5). When the gear (G) refers to each of the drive gear (2) and the driven gear (3), the rotation axis (GA) refers to the drive axis (4) for the drive gear (2) and the driven axis (5) for the driven gear (3). The rotating shaft (GA) is rotatably supported. The rotating shaft (GA) rotates around the axis. When the gear (G) represents the driving gear (2), the axis of the rotating shaft (GA) represents the axis (4A), and when the gear (G) represents the driven gear (3), the axis of the rotating shaft (GA) represents the axis (5A). When the gear (G) represents each of the driving gear (2) and the driven gear (3), the axis of the rotating shaft (GA) represents the axis (4A) for the driving gear (2) and the axis (5A) for the driven gear (3).

[0043] As shown in FIGS. 3 and 4, the gear G includes a plurality of teeth G1 extending radially from the rotation axis GA and tooth spaces G2 located between adjacent teeth G1. The tooth spaces G2 are arranged in an annular shape. The tooth spaces G2 are arranged along the rotation direction R. The tooth spaces G2 of the gear G are all different in volume. In this embodiment, the gear G represents the drive gear 2 and the driven gear 3, and the tooth spaces G2 of the drive gear 2 and the driven gear 3 are all different in volume. The volume of the tooth spaces G2 is the volume of the area defined by the space surrounded by adjacent teeth G1, the pair of side plates 20, and the wall surface 10a (see FIGS. 1 to 4). The volume of the tooth space (G2) is the volume of the tooth space (G2) when the gear (G) is located in the rotation locus region (15) (see FIG. 2).

[0044] As shown in FIGS. 3 and 4, each of the tooth grooves G2 includes a main body portion G5 located between adjacent teeth G1. The main body portions G5 have the same shape and therefore the same volume. One of the tooth grooves G2 (the eleventh tooth groove G211) is connected to the main body portion G5 but does not include a recess G6, whereas the other tooth grooves G2 (the first tooth groove G21 to the tenth tooth groove G210) include a recess G6. The recess G6 is formed at the bottom of the tooth groove G2. The recess G6 has a shape in which the bottom of the tooth groove G2 is recessed toward the axial center of the rotation axis GA. The bottom of the tooth groove G2 indicates the boundary between adjacent teeth G1. In this embodiment, the first tooth groove (G21) to the tenth tooth groove (G210) include the first recess (G61) to the tenth recess (G610), respectively. The first recess (G61) to the tenth recess (G610) are formed at the bottoms of the first tooth groove (G21) to the tenth tooth groove (G210), respectively.

[0045] The shapes of the plurality of recesses (G6) are different from one another. As a result, the volumes of the plurality of recesses (G6) are different from one another. The fact that the shapes of the plurality of recesses (G6) are different from one another means that at least one of the vertical width (L1), horizontal width (L2), and depth (L3) of the plurality of recesses (G6) is different from one another, and therefore the volumes of the plurality of recesses (G6) are different from one another.

[0046] In the first tooth groove (G21) to the tenth tooth groove (G210), the volume of the tooth groove (G2) indicates the sum of the volume of the main body portion (G5) and the volume of the recess (G6). In the eleventh tooth groove (G211), the volume of the tooth groove (G2) indicates only the volume of the main body portion (G5).

[0047] -Test Results- Figure 5 shows data obtained through testing by the inventors of the present application. Figure 5 shows the relationship between the rotation angle of the tooth space (G2) of the gear (G) and the pressure of the fluid in the tooth space (G2) (tooth space pressure).

[0048] FIG. 5 compares the gradient of the change in tooth gap pressure and the timing at which the change in tooth gap pressure begins for the eleventh tooth gap (G211) with a small volume due to the absence of a recess (G6) (no recess volume) and the first tooth gap (G21) with a large volume due to the presence of a first recess (G61) (large recess volume) over the rotation angle range of −60° to 180°. As shown in FIG. 5, the inventors of the present application confirmed that the gradient of the change in tooth gap pressure is gentler for the first tooth gap (G21) with a large volume (large recess volume) than for the eleventh tooth gap (G211) with a small volume (no recess volume). Furthermore, the timing at which the change in tooth gap pressure begins (the timing at which pressure rises or falls) is delayed. In other words, the inventors of the present application confirmed that when the volume of the tooth gap (G2) differs, variations in the gradient of the change in tooth gap pressure occur, and variations in the timing at which the change in tooth gap pressure begins also occur. Furthermore, the gear pump 1 generates driving noise due to changes in tooth gap pressure each time the tooth gap G2 passes through the meshing region 14. However, by using gears G including tooth gaps G2 with different volumes as described above, variations in the gradient of the change in tooth gap pressure and variations in the timing at which the tooth gap pressure starts to change occur, which in turn causes variations in the fundamental frequency of the driving noise, and the inventors have confirmed that this results in dispersion of the high-frequency components contained in the driving noise. Furthermore, in the high-speed rotation range of the gear pump 1, the driving noise of the gear pump 1 can produce a high-pitched tone containing high-frequency components. However, the inventors have confirmed that by using gears G including tooth gaps G2 with different volumes to disperse the high-frequency components of the driving noise generated each time the tooth gap G2 passes through the meshing region 14, a driving noise with less high-pitched noise can be generated. Furthermore, the inventors of the present application have confirmed that when a gear (G) including a tooth groove (G2) with a fixed volume is used, the high-frequency components of the drive noise generated each time the tooth groove (G2) passes through the meshing region (14) become a specific sound without being dispersed, and that the specific high-frequency components of the sound are generated periodically each time the tooth groove (G2) passes through the meshing region (14), resulting in a high-pitched, loud, and unpleasant drive noise.

[0049] -effect- As described above, one of the tooth grooves (G2) of the gear (G) does not include a recess (G6) at its bottom, while the other tooth grooves (G2) include a recess (G6) at their bottom, and the shapes of the recesses (G6) of the other tooth grooves (G2) are different from one another. This causes all of the tooth grooves (G2) of the gear (G) to have different volumes. This allows the fundamental frequency of the drive noise of the gear pump (1) generated each time the tooth groove (G2) passes through the meshing region (14) to be different for each drive noise. As a result, the high-frequency components of the drive noise generated each time the tooth groove (G2) passes through the meshing region (14) can be effectively dispersed by varying the frequency for each tooth groove (G2) so as not to be concentrated in a specific sound, thereby effectively preventing the high-pitched sound from becoming louder.

[0050] -Variation- All of the tooth grooves G2 of the gear G may include a recess G6 at their bottoms, and the shapes of the recesses G6 of all of the tooth grooves G2 may be different from one another. For example, the gear G shown in FIG. 4 may be modified so that a recess G6 having a volume different from the volumes of the first recess G61 to the tenth recess G610 is formed at the bottom of the eleventh tooth groove G211. In this way, the volumes of all of the tooth grooves G2 of the gear G are different from one another. This allows the high-frequency components of the drive noise generated each time the tooth groove G2 passes through the meshing region 14 to be effectively dispersed differently for each tooth groove G2, thereby effectively preventing the high-pitched sound from becoming louder.

[0051] The volume of at least one of the tooth grooves G2 of the gear G may be different from the volumes of the other tooth grooves G2. For example, the gear G shown in FIG. 4 may be modified so that one of the tooth grooves G2 of the gear G is designated as the first tooth groove G21 and the other tooth grooves G2 are designated as the eleventh tooth groove G211. This makes it possible to make the high-frequency sound component corresponding to the first tooth groove G21 (the high-frequency sound component of the drive sound generated when the first tooth groove G21 passes through the meshing region 14) different from the high-frequency sound component corresponding to the eleventh tooth groove G211 (the high-frequency sound component of the drive sound generated when the eleventh tooth groove G211 passes through the meshing region 14).

[0052] The volumes of adjacent tooth grooves G2 of the gear G may be different from each other. For example, the gear G shown in FIG. 4 may be modified by arranging the first tooth grooves G21 and the second tooth grooves G22 alternately, so that tooth grooves G21, G22 with different volumes are arranged alternately. This makes it possible to make the high-frequency sound components corresponding to the adjacent tooth grooves G2 (the high-frequency sound components corresponding to the first tooth groove G21 and the high-frequency sound components corresponding to the second tooth groove G22) different from each other.

[0053] Although the embodiments and modifications have been described above, it will be understood that various modifications in form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments, modifications, and other embodiments may be combined or substituted as appropriate as long as the functionality of the subject matter of the present disclosure is not impaired. [Industrial Applicability]

[0054] As described above, the present disclosure is useful for gear pumps or gear motors. [Explanation of symbols]

[0055] 1 Gear pump or gear motor 2 Drive gear 3 Driven gear G gear G2 Tooth groove G21 1st tooth space G22 2nd tooth space G61 1st recess G62 2nd recess

Claims

1. The gear mechanism comprises a driving gear (2) and a driven gear (3) that mesh with each other, A gear (G) indicates either the gear (G) of the drive gear (2) or the driven gear (3), or each of the drive gear (2) and the driven gear (3), A gear pump or gear motor, wherein the volume of at least one tooth gap (G2) among the plurality of tooth gaps (G2) of the gear (G) is different from the volumes of the other tooth gaps (G2).

2. 2. The gear pump or gear motor according to claim 1, wherein the volumes of the adjacent tooth spaces (G2) of the gear (G) are different from each other.

3. 2. A gear pump or gear motor according to claim 1, wherein the volumes of all the tooth spaces (G2) of the gear (G) are different from each other.

4. The plurality of tooth grooves (G2) include a first tooth groove (G21) and a second tooth groove (G22), The first tooth groove (G21) includes a first recess (G61) at the bottom of the first tooth groove (G21), The second tooth groove (G22) includes a second recess (G62) at the bottom of the second tooth groove (G22), 4. The gear pump or gear motor according to claim 1, wherein the first recess (G61) and the second recess (G62) have different shapes.

Images