Two-row phase difference pump

Abstract

To provide a two-row phase difference pump which can reduce a pulsation of discharge pressure to the minimum.SOLUTION: In a two-row phase difference pump which comprises gear pump mechanisms in two rows having a pair of gears which are engaged with each other, and in which shafts of the gear pump mechanisms are connected to each other via a connecting part, a pair of the gears are engaged with each other without causing backlash, the connecting part can connect the shafts to each other at any of a plurality of preset phase angles, and phase difference between the gear pump mechanisms becomes equal even if the shafts are connected by any of the phase angles.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a dual phase differential pump in which two gear pump mechanisms are connected with a phase difference. [Background technology]

[0002] One of the purposes of this type of dual phase differential pump is to reduce pulsation in the discharge pressure of the working fluid, and the shafts of the drive gears that make up each gear pump mechanism are connected via a spline connection structure.

[0003] Conventionally, as shown in Patent Document 1, the teeth of the gear portion of each drive gear and the teeth of the spline are machined without aligning them relative to each other, and the phase difference between the gear pump mechanisms varies from product to product depending on differences in gear sets and the meshing position of the spline connection during assembly.

[0004] The reason for processing the gear teeth and the spline teeth as they are without aligning them relative to one another is that the processing of the gear teeth and the spline are carried out separately, and processing that includes adjustments to keep their relative positions constant is difficult, and by appropriately determining the number of gear teeth and the number of spline teeth, it is possible to achieve pulsation smoothing that is comparable to that achieved by adjusting the relative positions, without adjusting the relative positions.

[0005] On the other hand, in order to reduce pressure pulsation, it is also known to reduce backlash, as shown in Patent Document 2.

[0006] However, the inventors have discovered that when the backlash is made substantially zero in order to further reduce pressure pulsation, it is difficult to sufficiently reduce pulsation unless the phase difference between the gear pump mechanisms is precisely adjusted.

[0007] In conventional structures where the positional relationship between the teeth of the gear portion and the teeth of the spline is determined by the circumstances of processing and varies from gear to gear, the phase difference between the gear pump mechanisms can be stabilized to a certain extent by selecting the meshing position of the male spline and female spline during assembly, but some variation cannot be prevented from occurring between products, making it difficult to stabilize quality. Moreover, a process is required to select the meshing position, which creates the problem of reduced assembly efficiency.

[0008] Furthermore, when backlash is essentially zero, unexpected loads are likely to act on the gear teeth. However, with conventional structures, thin parts are formed in the gear section, which can lead to unexpected deformation due to thermal expansion and the like, resulting in unexpected load concentrations, making it difficult to ensure sufficient strength. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 2611052 [Patent Document 2] JP 2001-173574 A Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made to solve the above-mentioned problems, and aims to provide a dual phase differential pump capable of reducing pulsation of the discharge pressure as much as possible. [Means for solving the problem]

[0011] That is, the dual phase differential pump according to the present invention is a dual phase differential pump including two gear pump mechanisms each having a pair of gears that mesh with each other, and the shafts of these gear pump mechanisms are connected to each other via a connecting portion, The pair of gears are configured to mesh without backlash, the connecting portion is configured to be able to connect the shafts at any of a plurality of predetermined phase angles, and the phase difference between the gear pump mechanisms is configured to be equal regardless of the phase angle at which the shafts are connected. Effect of the Invention

[0012] According to the above configuration, it is possible to prevent the variation in the phase difference between the gear pump mechanisms of each product and to keep it constant, which, together with the backlash-free structure, reduces the pulsation of the discharge pressure. In addition, since it does not matter how the shafts are connected to each other, it is possible to avoid an increase in the burden during assembly. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a vertical sectional view of a dual phase differential pump according to a first embodiment of the present invention. [Diagram 2] 4 is a view showing a drive gear and a male spline of a first gear pump mechanism in the embodiment as viewed from the axial direction. [Diagram 3] 5 is a view showing a drive gear and a female spline of a second gear pump mechanism in the embodiment as viewed from the axial direction. [Figure 4] 5 is a view seen in the axial direction showing a phase difference between a first gear pump mechanism and a second gear pump mechanism realized by spline engagement in the embodiment. [Diagram 5] 13 is a view showing a state in which drive gears according to a second embodiment of the present invention are connected to each other at a connecting portion, viewed from a direction perpendicular to the axial direction. [Figure 6] 4 is a view showing a coupling member in the embodiment as viewed from an axial direction. [Figure 7] 4 is a diagram showing each drive gear in the embodiment as viewed from an axial direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] First Embodiment Hereinafter, a dual phase differential pump 100 according to this embodiment will be described with reference to the drawings.

[0015] As shown in FIG. 1, this dual phase differential pump 100 has two sets of gear pump mechanisms 1 and 2 housed in a common casing 3 and axially connected so as to rotate synchronously with a predetermined phase difference.

[0016] In the following description, one direction in the axial direction will be referred to as the front side and the other direction as the rear side, with the front side gear pump mechanism being referred to as the first gear pump mechanism 1 and the rear side gear pump mechanism being referred to as the second gear pump mechanism 2. In each of the gear pump mechanisms 1 and 2, corresponding components will be given the same reference numerals, and when it is necessary to distinguish between them, those belonging to the first gear pump mechanism 1 will have (1) added after the reference numeral, and those belonging to the second gear pump mechanism 2 will have (2) added after the reference numeral.

[0017] Each part will be explained.

[0018] The casing 3 is composed of a block-shaped body 31, and a front cover 32 and a rear cover 33 attached to the front and rear end faces, respectively, of the body 31. Eyelet holes 34 are formed in each end face of the body 31, and the front cover 32 and rear cover 33 are configured to cover the openings of the eyelet holes 34.

[0019] The gear pump mechanisms 1 and 2 each include a pair of gears that mesh with each other, that is, a drive gear 4 and a driven gear 5. Each gear 4 and 5 is composed of a disk-shaped gear portion 41, 51 having a plurality of teeth 41a, 51a formed at an equal pitch on the outer periphery, and a shaft 42, 52 extending in both directions from the center of the gear portion 41, 51. The drive gear 4 and the driven gear 5 in each gear pump mechanism 1 and 2 are configured so that the backlash is substantially zero. In other words, the drive gear 4 and the driven gear 5 are configured so that one tooth 41a (51a) of one of the paired gear portions 41 (51) always comes into contact with two teeth 51a (41a) of the other gear 51 (41).

[0020] First gear pump mechanism 1 has gear portions 41(1), 51(1) housed in front-side socket 34 of body 31, and shafts 42(1), 52(1) extending from gear portions 41(1), 51(1) are engaged via bushings with bearing holes formed in the bottom surface of front-side socket 34 in body 31 and in front cover 32, respectively.

[0021] The second gear pump mechanism 2 has its gear portions 41(2), 51(2) housed in the rear-side socket 34 of the body 31, and each side of the shafts 42(2), 52(2) extending from the gear portions 41(2), 51(2) is engaged via bushings with bearing holes formed in the bottom surface of the rear-side socket 34 in the body 31 and in the rear cover 33, respectively.

[0022] In the drawing, reference numeral 7 denotes side plates attached to both side surfaces of these gear portions 41, 51, and reference numeral 8 denotes a gasket that seals against pressure and forms a confinement portion.

[0023] In the gear pump mechanisms 1 and 2 configured as described above, the drive shafts 42(1) and 42(2) are connected to each other via a connecting portion 6 and are configured to rotate synchronously with a predetermined phase difference γ.

[0024] This connecting portion 6 is capable of connecting drive shafts 42(1), 42(2) to each other at any of a plurality of predetermined phase angles, and is configured so that the phase difference between the gear pump mechanisms 1, 2 is equal regardless of the phase angle at which the drive shafts 42(1), 42(2) are connected to each other.

[0025] Let me explain in detail. Here, a spline connection structure is adopted as the connecting portion 6.

[0026] As shown in Figures 1 to 3, this spline connection structure is configured so that a male spline 61 provided on the peripheral surface of the tip end of the front drive shaft 42(1) and a female spline 62 provided on the inner peripheral surface of a through hole that passes through the rear drive shaft 42(2) along the central axis thereof are engaged with each other without any play.

[0027] The tip of an effective engagement range W1 of the male spline 61 with respect to the female spline 62 in the axial direction is set to be on the same level as or more rear than the rear side surface of the gear portion 41(2) of the second gear pump mechanism 2, and the base end of the engagement range W1 is set to be on the same level as or more front than the front side surface of the gear portion 41(2). In other words, when viewed from a direction perpendicular to the axial direction, the engagement range W1 of the male spline 61 with the female spline 62 is set to include the tooth width range W2 of the gear portion 41(2) of the second gear pump mechanism 2.

[0028] Next, the relationship between the number of teeth of the splines 61, 62 and the number of teeth of the gear portions 41(1) and 41(2), and the phase relationship between the teeth 61a and tooth grooves 62a of the splines 61, 62 and the teeth 41a(1) and 41a(2) of the gear portions 41(1) and 41(2) will be described with reference to FIGS. 2 to 4.

[0029] First, the relationship between the number of teeth of the splines 61, 62 and the number of teeth of the gear portions 41(1), 41(2) will be described.

[0030] When the number of teeth of the splines 61, 62 is m and the number of teeth of the gear portions 41(1), 41(2) is n, m is configured to be a divisor of n.

[0031] In this embodiment, the number of teeth n of the gear portions 41(1), 41(2) is 12, and the number of teeth m of the splines 61, 62 is also 12. The number of teeth of the splines 61, 62 may be any number that is a divisor of 12, which is the number of teeth of the gear portions 41(1), 41(2), and may be any number other than 12, such as 1, 2, 3, 4, or 6.

[0032] Next, the phase relationship between the teeth 61a and tooth grooves 62a of the splines 61, 62 and the teeth 41a(1), 41a(2) of the gear portions 41(1), 41(2) will be described.

[0033] As shown in FIG. 2, when any tooth 61a of the male spline 61 (any one will do) is set as a reference tooth (indicated by a black triangle in the figure), the absolute value of the angle difference between this reference tooth 61a and the tooth 41a(1) of the front drive gear 4(1) that is closest to this reference tooth 61a (indicated by a black circle in the figure) is defined as α.

[0034] Also, as shown in FIG. 3, when one of the tooth grooves 62a of the female spline 62 (any one will do) is set as a reference tooth groove (indicated by a white triangle in the figure), the absolute value of the angle difference between this reference tooth groove 62a and the tooth 41a(2) of the rear drive gear 4(2) that is closest to this reference tooth groove 62a is defined as β.

[0035] The difference between α and β at this time is configured to be a desired phase difference (absolute value) γ between the gear pump mechanisms 1 and 2. In this case, since the phase difference (absolute value) γ between the gear pump mechanisms 1 and 2 is ¼ of 30°, which is the angle between the gear teeth 41a, or 7.5°, it is configured so that, for example, α is 7.5° and β is 0°.

[0036] In such a configuration, the phase angle between drive shafts 42(1), 42(2) when connected is determined by which tooth 61a of male spline 61 is engaged with which tooth groove 62a of female spline 62, and drive shafts 42(1), 42(2) can be connected to each other at any of the number of spline teeth, i.e., 12 possible phase angles.

[0037] Therefore, as shown in FIG. 4, regardless of the phase angle at which the gear pump mechanisms 1 and 2 are connected, the phase difference γ between them is equal to 7.5°.

[0038] 3, the number of tooth grooves of the female spline 62 and the number of teeth of the gear 4(2) are equal, and the tooth grooves 62a of the female spline 62 and the teeth 41a(2) of the gear 4 are configured to be in the same phase, i.e., at the same angle. This makes the thickness of the gear 4 equal at each tooth bottom, and allows the thickness D at the tooth bottom of the gear 4 to be maximized, thereby achieving maximum strength.

[0039] <Second embodiment> In this embodiment, as shown in FIGS. 5 and 6, the connecting portion 6 utilizes a coupling member 64 interposed between the front drive shaft 42(1) and the rear drive shaft 42(2).

[0040] Specifically, the coupling member 64 is, for example, disk-shaped, and has on one end face a concave first engaged portion 641 that engages with a convex first engaging portion 651 formed on the end of the front drive shaft 42(1) without any backlash in the rotational direction, and has on the other end face a concave second engaged portion 642 that engages with a convex second engaging portion 652 formed on the end of the rear drive shaft 42(2) without any backlash in the rotational direction. The first engaging portion 651 and the first engaged portion 641 engage with each other, and the second engaging portion 652 and the second engaged portion 642 engage with each other, thereby forming a connecting portion.

[0041] Here, the engaging portions 651, 652 and the engaged portions 641, 642 form straight strips when viewed in the axial direction, and here, as shown in Fig. 6, the angles of the engaged portions 641, 642 provided on the coupling member 61 when viewed in the axial direction are made different, and the angle difference is set to be a desired phase difference γ between the gear pump mechanisms 1, 2. On the other hand, the relative angles of the engaging portions 651, 652 with respect to the gear portions 41(1), 41(2) when viewed in the axial direction are configured to match, as shown in Figs. 7(a) and (b).

[0042] According to the above configuration, there are two phase angles between drive shafts 42(1), 42(2) when they are connected, namely, 0° and 180°. Regardless of the phase angle at which drive shafts 42(1), 42(2) are connected, the phase difference between gear pump mechanisms 1, 2 is equal, resulting in the desired phase difference γ.

[0043] It is also possible to match the angles of the engaged parts of the coupling member as viewed in the axial direction, while varying the relative angles of the engaging parts of the drive shafts as viewed in the axial direction with respect to the gear parts, so that the angle difference becomes the desired phase difference between the gear pump mechanisms.

[0044] The recessed and projecting relationship between the engaging portion and the engaged portion may be reversed. Also, the engaging portion and the engaged portion are not limited to being in a straight band shape when viewed from the axial direction, but may be in a cross shape or may have a spline connection structure.

[0045] Additionally, in the above embodiment, the phase difference of each gear pump mechanism is set to 1 / 4 of the gear tooth angle, but it may be set to 1 / 2, or to a value greater than 0 and less than 1 / 2, such as 1 / 3.

[0046] In addition, although the drive shafts are connected to each other by a connecting portion in the above embodiment, the driven shafts may be connected to each other by a connecting portion. The spline connection structure may be configured so that its tip does not extend to the rear gear portion, but is connected at a shallower position.

[0047] Additionally, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0048] <Summary> The features of the above-mentioned configuration can be summarized as follows:

[0049] [1] A dual-phase differential pump 100 includes dual gear pump mechanisms 1 and 2 having a pair of gears 4 that mesh with each other, and shafts 42 of the gear pump mechanisms 1 and 2 are connected to each other via a connecting portion 6, The pair of gears 4 are configured to mesh with each other without backlash, The dual phase differential pump (100) is characterized in that the connecting portion (6) is configured to be able to connect the shafts (42) together at any of a plurality of predetermined phase angles, and is configured so that the phase difference between the gear pump mechanisms (1, 2) is equal regardless of the phase angle at which the shafts (42) are connected to each other.

[0050] With this configuration, it is possible to prevent the phase difference between the gear pump mechanisms 1 and 2 from varying from product to product and to keep it constant, which, together with the backlash-free structure, reduces pulsation in the discharge pressure. In addition, since it does not matter how the shafts 42 are connected to each other, it is also possible to avoid an increase in the burden of assembly.

[0051] [2] The connecting portion 6 is configured with a spline coupling structure in which a male spline 61 provided on one shaft 42 to be connected is engaged with a female spline 62 provided on the other shaft 42, The dual phase differential pump 100 according to [1] is characterized in that, when the number of teeth 41a, 51a of the gear portions 41, 51 is n, the number m of the teeth 41a, 51a of the spline coupling structure is configured to be a divisor of n.

[0052] With this configuration, the structure of [1] can be realized using a spline connection structure.

[0053] More specifically, if the angular difference between one reference tooth 41a, 51a on the male spline 61 and the tooth 41a, 51a of one gear closest to this tooth 41a, 51a is defined as α, and the angular difference between one reference tooth 41a, 51a on the female spline 62 and the tooth 41a, 51a of the other gear closest to this tooth 41a, 51a is defined as β, then the angular difference between α and β can be configured to become the phase difference γ between the gear pump mechanisms 1 and 2.

[0054] [3] The connecting portion 6 is configured with a spline coupling structure in which a male spline 61 provided on one of the shafts 42, 52 to be connected is engaged with a female spline 62 provided on the other shaft 42, 52, The dual phase differential pump 100 according to [1] or [2], wherein the gear 4 provided with the female spline 62 is configured so that the thickness of the gear 4 at each tooth bottom is equal.

[0055] With this configuration, the thickness of each gear 4 is equal, and the load is evenly distributed to each tooth 41a of the gear 4, so that sufficient strength can be ensured even if the backlash is substantially zero.

[0056] More specifically, as shown in FIG. 3, if the number of tooth grooves of the female spline 62 and the number of teeth of the gear 4(2) are equal and the tooth grooves 62a of the female spline 62 and the teeth 41a(2) of the gear 4 are configured to be in the same position, i.e., at the same angle, the thickness D at the tooth bottom of the gear 4 can be maximized, thereby achieving maximum strength.

[0057] [4] The dual phase differential pump 100 according to [2] or [3], wherein, when viewed from a direction perpendicular to the axis, the engagement range of the male spline 61 with the female spline 62 is set to encompass the tooth width range of the gear 4 (2) on which the female spline 62 is provided.

[0058] With such a configuration, not only is twisting difficult to occur and strength is improved, but also the phase difference between the gear pump structures 1 and 2 can be reduced.

[0059] [5] The dual phase differential pump 100 according to [1], wherein the connecting portion 6 includes a coupling member 61 provided between the shafts 42(1) and 42(2) to connect them.

[0060] In cases where it is difficult to provide a spline connection structure, the above-described structure using the coupling member 61 is effective.

[0061] [6] The dual phase differential pump 100 according to any one of [1] to [5], wherein a phase difference between the gear pump mechanisms 1 and 2 is set to ¼ of an inter-tooth angle of the gear 4.

[0062] This can reduce the pulsation of the discharge pressure more effectively than other phase differences. [Explanation of symbols]

[0063] 100···Double Phase Differential Pump 1, 2 Gear pump mechanism 6...Connection part 4, 5... gears 42, 52... Shaft 61 Male spline 62 Female spline D Gear thickness W1: Spline fitting range W2 Gear face width range 61 Coupling member

Claims

1. A two-stage phase difference pump comprising two gear pump mechanisms each having a pair of meshing gears, wherein the shafts of these gear pump mechanisms are connected via a connecting portion, the pair of gears are configured to mesh without backlash, and the connecting portion is configured to be connectable at any of a plurality of predetermined phase angles between the shafts, and regardless of the phase angle at which the shafts are connected, the phase difference between the gear pump mechanisms is equal. A two-stage phase difference pump characterized by being configured as such.

2. The connecting portion is configured with a spline coupling structure in which a male spline provided on one of the connected shafts fits into a female spline provided on the other shaft, When the number of teeth of the gear portion is n, the number of teeth m of the spline coupling structure is configured to be a divisor of n. The two-stage phase difference pump according to claim 1, characterized by being configured as such.

3. When the angular difference between one tooth serving as a reference in the male spline and the tooth of one gear closest to this tooth is α, and the angular difference between one tooth serving as a reference in the female spline and the tooth of the other gear closest to this tooth is β, the angular difference between α and β is configured to be the phase difference between the gear pump mechanisms. The two-stage phase difference pump according to claim 1 or 2, characterized by being configured as such.

4. The connecting portion is configured with a spline coupling structure in which a male spline provided on one of the connected shafts fits into a female spline provided on the other shaft, In the gear provided with the female spline, the thickness at the bottom of each tooth is configured to be equal. The two-stage phase difference pump according to claim 1, characterized by being configured as such.

5. The number of teeth of the female spline is equal to the number of teeth of the gear, and the tooth groove of the female spline and the tooth of the gear are configured to have the same angle. The two-stage phase difference pump according to claim 4, characterized by being configured as such.

6. The twin-phase difference pump according to claim 2, wherein a fitting range of the male spline with respect to the female spline is set so as to include a tooth width range of a gear provided with the female spline when viewed from a direction orthogonal to the axis.

7. The twin-phase difference pump according to claim 1, wherein the connecting portion includes a coupling member provided between the shafts to connect them.

8. The twin-phase difference pump according to claim 1, wherein a phase difference between the gear pump mechanisms is set to 1 / 4 of an angle between teeth of the gear.

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