JP3746399B2 - Gear pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gear pump that performs pumping action by rotation of a pair of gears that mesh with each other.
[0002]
[Background Art and Problems to be Solved by the Invention]
Conventionally, a gear pump has been used in various industrial fields as a small and light pump having a simple structure.
As a structure of this type of gear pump, a pair of side plates are fitted in a cavity inside a housing to define a gear chamber, and a pair of gears meshing with each other are accommodated inside the gear chamber, and a support shaft of each gear is accommodated. A type in which a suction chamber and a discharge chamber for the working fluid are formed inside the gear chamber with the meshing position of both gears interposed therebetween is generally supported by a support hole formed in each side plate.
[0003]
By the way, in the meshing portion of the gear of the gear pump, oil is trapped in a closed region formed by each side plate and each gear tooth to be meshed, so that a so-called confinement phenomenon occurs, and the trapped oil is accompanied by the rotation of the gear. When compressed, there is a problem that vibration and noise are generated as a result of extremely high pressure.
In response to this problem, the applicant of the present application has proposed a gear pump provided with a flow path that connects the closed region and the support hole (for example, Japanese Patent Laid-Open No. 11-13644). In this gear pump, as shown in FIG. 6, the discharge chamber 90 on the high pressure side and the suction chamber 91 on the low pressure side are partitioned by an engagement point 92 between the drive gear 96 and the driven gear 97. A pair of closed regions 93 and 94 (hatched in FIG. 6) are defined in the vicinity of both sides. A flow path closed area side inlet opening 95 is provided so as to communicate with the pair of closed areas 93 and 94, and the flow path has an outlet in a support hole serving as an outflow destination. In this gear pump, vibration and noise due to the confinement can be prevented, and lubrication to the support hole can be ensured. On the other hand, since this gear pump causes oil to flow out from the closed region of the gear chamber to the support hole through the flow path, there is a concern that a flow loss may occur.
[0004]
Accordingly, an object of the present invention is to solve the above technical problem and provide a gear pump that can prevent vibration and noise due to the confinement phenomenon of the gear pump and suppress flow loss.
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, a pair of side plates are fitted into a cavity inside a housing to define a gear chamber, and a pair of gears meshing with each other are accommodated in the gear chamber to support each gear. In the gear pump in which the shaft is supported via each side plate and the suction chamber and the discharge chamber for the working fluid are formed inside the gear chamber with the meshing point of both gears interposed therebetween, A pair of fluid reservoir holes having an inlet opening facing a closed region formed by both side plates and meshing gear teeth and having no outlet are formed independently of each other, and the inlet openings of the pair of fluid reservoir holes are Formed on only a predetermined portion of the gear side surface, and the predetermined portion is a portion of the gear side surface on which the side surfaces of the gear teeth forming the closed region face each other as the gear rotates. Ri, the inlet opening of the pair of fluid reservoir holes, to provide a gear pump, characterized in that are arranged on both sides of the line of action of the meshing of gears when viewed from the axial direction of the support shaft.
[0006]
According to this aspect, as the gear rotates, a part of the working fluid confined in the closed region can be accommodated in the fluid reservoir hole. As a result, the compressibility of the working fluid is suppressed, resulting in an increase in the confining pressure. Is suppressed.
By the way, with the rotation of the gear, the closed area and the discharge chamber may communicate (see FIG. 6). Assuming the case where the inlet opening 95 is provided in the closed region 93 that is in communication with the discharge chamber 90, in the conventional gear pump in which the flow path with the outflow destination is provided in the side plate, the closed region 93 is removed from the discharge chamber 90. Since the working fluid flows out to the outflow destination through the inlet opening 95 and the flow path, there is a concern about an increase in flow rate loss. On the other hand, since the outflow destination of the fluid reservoir hole is eliminated in the present invention, the flow loss can be suppressed.
[0007]
Here, the action line of meshing is a trajectory in which the meshing point between the two gears moves as the gear rotates. A pair of the above-described closed regions are defined on both sides of the line of action of meshing between both gears. The pair of closed regions may communicate with the suction chamber and the discharge chamber, respectively, as the meshing point moves along the meshing action line. In this state, as shown in FIG. 6, assuming that the above-described inlet opening 95 is formed across the action line L, the pair of closed regions 93 and 94 communicate with each other through the inlet opening 95. Therefore, the suction chamber 91 and the discharge chamber 90 communicate with each other, and as a result, there is a possibility that a flow rate loss may occur.
[0008]
On the other hand, according to this aspect, since the fluid reservoir hole avoids the line of action, the partition between the two closed regions can be maintained, thereby preventing communication between the suction chamber and the discharge chamber. It is possible to prevent the occurrence of flow loss caused by In addition, since the fluid reservoir holes are arranged corresponding to the respective closed regions, the confining pressure in each closed region can be reliably suppressed.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a front view showing a schematic configuration of a gear pump according to an embodiment of the present invention. 2 is a cross-sectional side view taken along the line II-II in FIG. 1, and hatching is omitted.
[0010]
In this gear pump, a housing 1 constituted by closing both sides of a main body cylinder 10 having an oval cross-sectional cavity 10a penetrating through a central portion thereof with a pair of cover plates 11 screwed in a manner covering the entire surface thereof. I have. Inside the housing 1, a gear chamber 14 is defined between a pair of side plates 12 made of, for example, aluminum alloy that are fitted from both sides of the cavity 10 a. A drive gear 3 and a driven gear 4 that are paired with each other are disposed in the gear chamber 14.
[0011]
The cavity 10 a of the housing 1 is sealed by an O-ring 19 interposed between the lid plate 11 and the main body cylinder 10, and the O-ring 19 is accommodated in an annular groove of the lid plate 11. In the cavity 10 a, a seal 13 accommodated in the accommodation groove of the side plate 12 is provided between the side plate 12 and the cover plate 11 that face each other.
[0012]
The support shafts 30 and 40 of the drive gear 3 and the driven gear 4 are respectively positioned on the axial centers of the semicircular portions on both sides of the gear chamber 14 having an oval cross section, and are laid in parallel to each other. That is, the support shafts 30 and 40 are supported at both ends by the support holes 31 and 41 formed in a pair on each side plate 12.
The support shaft 30 is supported by a pair of support holes 31, extends through the one cover plate 11, and is driven to rotate by a driving force from a power source such as a motor (not shown) transmitted to the extended end. The drive shaft is configured. Further, the drive gear 3 is mounted on the support shaft 30 so as to be integrally rotatable inside the gear chamber 14. An oil seal 17 is disposed at a portion where the support shaft 30 penetrates the cover plate 11.
[0013]
The support shaft 40 is supported by a pair of support holes 41 and constitutes a driven shaft having a shaft end in the support hole 41 of each side plate 12. The driven gear 4 is mounted on the support shaft 40 inside the gear chamber 14. When the driven gear 4 is mounted on the support shaft 40, the rotation around the axis may be restricted or the rotation around the axis may be allowed. The driven gear 4 meshes with the drive gear 3 within a range in the vicinity of the plane including the shaft centers of both the support shafts 30, 40, and (or with the support shaft 40) as the drive gear 3 driven by the support shaft 30 rotates. The rotation is driven (without rotation of the shaft 40).
[0014]
In FIG. 2, the rotation direction of the drive gear 3 and the driven gear 4 interlocked therewith is indicated by an arrow, and suction chambers 5 are provided on the rotation direction side on both sides of the meshing positions of the two gears 3 and 4. A discharge chamber 6 is formed on the side opposite to the rotation direction. The suction chamber 5 and the discharge chamber 6 are respectively connected to a suction destination and a discharge destination (not shown) outside the housing 1 via a suction port 15 and a discharge port 16 that open to corresponding positions of the main body cylinder 10. .
[0015]
In FIG. 3, a clearance groove 63 extending toward the suction chamber 5 and a clearance groove 64 extending toward the discharge chamber 6 from the meshing position of the gears 3 and 4 are formed on the gear side surface 12 a of the side plate 12. These escape grooves 63 and 64 prevent the so-called confinement in which the working fluid is confined in the closed region formed by the side plates 12 and the meshing gear teeth at the meshing position of the gears 3 and 4. belongs to. Both escape grooves 63, 64 are provided so as to avoid the meshing center position of both gears 3, 4, and a predetermined distance is secured between them. This is to prevent the relief chambers 63 and 64 from communicating with each other because the suction chamber 5 and the discharge chamber 6 are communicated with each other and cannot perform the pump function. The gear side surface 12a is formed with a communication groove 65 for communicating the support holes 31 and 41 with the suction chamber 5 respectively.
[0016]
On the other hand, referring to FIG. 1, on the non-gear side surface 12 b of the side plate 12, the space between the side plate 12 and the cover plate 11 facing each other with the seal 13 as a boundary is a low pressure communicating with the suction chamber 5. It is partitioned into a side space and a high-pressure side space communicating with the discharge chamber 6. As described above, the low-pressure working fluid and the high-pressure working fluid act as back pressure in the state partitioned by the seal 13 on the non-gear side surface 12b which is the back surface of the side plate 12, and this acts on the side plate 12. Since the load is applied according to the discharge pressure, the gap between the side plate 12 and both the gears 3 and 4 is maintained with high accuracy, so that the pump efficiency at high pressure can be maintained high.
[0017]
With such a configuration, the working fluid introduced into the suction chamber 5 through the suction port 15 is received between the teeth of the drive gear 3 and the driven gear 4 facing the suction chamber 5, and by rotation of both gears 3, 4, It is conveyed in a sealed state between each tooth and the inner peripheral surface of the main body cylinder 10 and sent out to the discharge chamber 6. The drive gear 3 and the driven gear 4 that have finished sending out to the discharge chamber 6 are directed toward the suction chamber 5 through the meshing positions of the two gears 3 and 4, and receive the working fluid in the suction chamber 5 again to discharge the discharge chamber. Acts to send to 6 side.
[0018]
During the operation of the gear pump performed as described above, in the vicinity of the meshing point of the drive gear 3 and the driven gear 4, an operation is performed in a closed region formed between the tooth bottom of one tooth and the tooth tip of the other tooth. There is a so-called confinement in which the fluid is trapped, and as a result, a very high pressure may be generated, causing vibration and noise.
In the present embodiment, a fluid reservoir hole 80 for receiving a part of the working fluid from the closed region is provided in the gear side surface 12a of the side plate 12 in order to prevent the closing. Thereby, in addition to the effect of preventing the closing by the above-described escape grooves 63 and 64, the prevention of the closing is further ensured.
[0019]
Details will be described below.
As shown in FIG. 1, a plurality of fluid reservoir holes 80 are provided, for example, a total of four fluid reservoir holes 80 in each pair of side plates 12.
The fluid reservoir hole 80 has an inlet opening 81 on the gear side surface 12a of the side plate 12, and is formed in parallel to the central axis 71 of the support hole 31 from there at a predetermined depth (parallel to the central axis 72 of the support hole 41). However, the fluid reservoir hole 80 is opened only by the inlet opening 81 and does not have an outlet at the back thereof. Further, the fluid reservoir holes 80 in the same side plate 12 do not communicate with each other. The fluid reservoir hole 80 may be configured by closing the outlet end of the through hole with a stopper or a lid.
[0020]
As shown in FIG. 3, a pair of inlet openings 81 on one gear side surface 12a is a closed region of both gears 3 and 4 and is an area isolated from both escape grooves 63 and 64, for example, both escape grooves. It is arranged at a substantially intermediate position between 63 and 64. The pair of inlet openings 81 and the escape grooves 63 and 64 are prevented from communicating with each other.
The pair of inlet openings 81 are arranged side by side along a line 73 connecting the rotation centers 71 and 72 of the two gears 3 and 4 when viewed from the axial direction of the support shaft 30, and are arranged on the drive gear 3 side. An inlet opening 81 and an inlet opening 81 on the driven gear 4 side are configured.
[0021]
The centers of the pair of inlet openings 81 are arranged at a predetermined distance from the meshing pitch point P0 toward the rotation centers 71 and 72 of the corresponding gears when viewed from the axial direction of the support shaft 30. . The predetermined distance is, for example, substantially half of the total tooth depth of the gears 3 and 4. As a result, the opening 81 on the drive gear side can be surely opened in a gap formed between the tooth bottom of the drive gear 3 and the tooth tip of the driven gear 4 approaching the drive gear 3 and forming a closed region.
[0022]
The inlet opening 81 is formed in a circular shape, for example. The diameter of this circle is made smaller than the tooth thickness of the gear tooth portion passing in front of the entrance opening 81, thereby preventing adjacent tooth spaces from communicating with each other via the entrance opening 81.
The pair of inlet openings 81 are disposed on both sides across the line of action L of meshing between the gears 3 and 4, and the pair of inlet openings 81 and the line of action L of the support shaft 30 (the support shaft 40 may be used). It avoids overlapping each other when viewed from the axial direction. As a result, the suction chamber 5 and the discharge chamber 6 are prevented from communicating with each other. This is because the closed region is composed of a pair, and in this pair of closed regions (see closed regions S3 and S4 in FIG. 4), the meshing point K of both gears 3 and 4 moves along the meshing action line L. Accordingly, the suction chamber 5 and the discharge chamber 6 may be communicated with each other. In this state, if even one inlet opening 81 overlaps the action line L, the inlet opening 81 and the pair of closed regions communicate with each other. As a result, the suction chamber 5 and the discharge chamber 6 may communicate with each other through the inlet opening 81.
[0023]
Next, the operation will be described.
FIG. 4 is an enlarged side view of the main part of the side plate for explaining the meshing of the drive gear and the driven gear. FIG. 5 is a schematic diagram showing a communication state between the closed region and the fluid reservoir hole.
First, the closed area will be described with reference to FIG.
[0024]
The closed region is partitioned as a pair on both sides of the meshing point K that is the contact point between the tooth surfaces of the gears 3 and 4. The pair of closed regions are a drive gear side closed region S3 defined by the tooth bottom of the drive gear 3 and a driven gear side closed region S4 defined by the tooth bottom of the driven gear 4. Since the meshing point K is located on the tooth surface 3b of the drive gear 3 on the traveling direction side of the gear teeth 3a (that is, the suction chamber 5 side), the closed region S4 on the driven gear side discharges from the meshing point K. The closed region S3 on the drive gear side near the chamber 6 is close to the suction chamber 5 with respect to the meshing point K.
[0025]
As the both gears 3 and 4 rotate, the meshing point K moves, and the locus thereof becomes the action line L described above. When viewed from the axial direction of the support shaft 30, the action line L passes through the pitch point P0 and is inclined at the gear tooth pressure angle with respect to the direction in which the gear tooth advances at the pitch point P0.
Hereinafter, with reference to FIG. 5, the mutual communication state of each closed region, the discharge chamber, the suction chamber, and each fluid reservoir hole will be described together with the rotation of the pair of gears. In FIG. 5, hatching is applied to a portion of the inlet opening that communicates with the closed region.
[0026]
First, reference is made to FIG. From the suction chamber 5, a closed region S3 on the drive gear side, an engagement point K, a closed region S4 on the driven gear side, and the discharge chamber 6 are arranged in this order. In this state, the suction chamber 5 and the discharge chamber 6 are partitioned only by the meshing point K, and the other portions communicate with each other.
Further, a part of the drive gear side inlet opening 81 opens in the drive gear side closing area S3, and a part of the driven gear side inlet opening 81 opens in the driven gear side closing area S4. As the meshing progresses, as shown in FIG. 5B, the closed area S3 on the drive gear side widens, and at the same time, the inlet opening 81 on the drive gear side is closed by the gear teeth 3a of the drive gear 3. Closed for S5. Further, the closed area S4 on the driven gear side is narrowed, and the inlet opening 81 on the driven gear side opens to the closed area S4 on the driven gear side as a whole, and a part of the working fluid in the closed area S4 is driven. It can be accommodated in the fluid reservoir hole 80 on the gear side.
[0027]
When the meshing further proceeds, the meshing point K closer to the suction chamber with respect to the closed region S5 on the drive gear side has moved closer to the suction chamber on the action line L as shown in FIG. On the other hand, a new meshing point K is generated on the discharge chamber side with respect to the closed region S5. Thereby, the suction chamber 5 and the discharge chamber 6 are partitioned into three parts by the two meshing points K. Between the two meshing points K, there are two closed areas S4 and S5, and the two closed areas S4 and S5 communicate with each other. This is because the tooth surface 3c on the side opposite to the traveling direction of the gear teeth 3a of the drive gear 3 and the tooth surface 4c on the traveling direction side of the gear teeth 4a of the driven gear 4 between the above-described closed regions S4 and S5. This is because a gap (backlash) usually occurs between the two.
[0028]
Further, as shown in FIGS. 5 (c) to 5 (d), as the tooth tip of the driven gear 4 approaches the tooth bottom of the drive gear 3, the closed region S5 on the drive gear side becomes narrower. At the same time, the inlet opening 81 on the drive gear side starts to open in the closed region S5 and eventually opens largely as a whole, and a part of the working fluid in the closed region S5 is accommodated in the fluid reservoir hole 80 on the drive gear side. can do. On the other hand, the closed area S4 on the driven gear side widens, and the inlet opening 81 on the driven gear side is gradually closed by the gear teeth 4a with respect to the closed area S4 on the driven gear side.
[0029]
As described above, according to the present embodiment, a part of the working fluid confined in the closed region can be accommodated in the fluid reservoir hole 80 as the gears 3 and 4 rotate, so that the compressibility of the working fluid is suppressed. As a result, an increase in the confining pressure is suppressed.
Further, the combination of the relief grooves 63 and 64 and the fluid reservoir hole 80 can reliably prevent generation of a high pressure due to confinement. As a result, it is possible to reliably prevent vibration and noise caused by the increase in the confining pressure.
[0030]
Incidentally, as shown in FIG. 4, the closed region and the discharge chamber 6 may communicate with each other as the gears 3 and 4 rotate. For example, the closed region S <b> 4 shown in FIG. 4 communicates with the discharge chamber 6. Assuming the case where the inlet opening 81 is provided in the closed region in communication with the discharge chamber 6, in the conventional gear pump in which the flow path with the outflow destination is provided in the side plate, the closed region and the flow channel are provided from the discharge chamber 6. Therefore, the working fluid flows out to the outflow destination, and there is a concern about an increase in flow rate loss. On the other hand, since the outflow destination of the fluid reservoir hole 80 is eliminated in the present invention, the flow loss can be suppressed.
[0031]
Further, since the inlet opening 81 of the fluid reservoir hole 80 avoids the action line L, it is possible to maintain a partition between the closed regions of the drive gear 3 side and the driven gear 4 side, and thereby the suction chamber 5 and the discharge chamber. As a result of preventing the communication of the chamber 6, it is possible to prevent the occurrence of a flow loss due to this communication. In addition, since the fluid reservoir holes 80 are arranged corresponding to the respective closed regions, the confining pressure in each closed region can be reliably suppressed.
[0032]
In addition, various design changes can be made without changing the gist of the present invention.
[0033]
【The invention's effect】
According to the first aspect of the present invention, since the compressibility of the working fluid is suppressed by accommodating a part of the confined working fluid in the fluid reservoir hole, the increase in the confining pressure is suppressed, Noise and vibration resulting from the increase in the confining pressure can be prevented, and as a result, the pump efficiency can be improved.
[0034]
Further, even when the discharge chamber communicates with the fluid reservoir hole through the closed region, the working fluid does not flow out of the fluid reservoir hole, so that the flow rate loss can be suppressed, and the pump efficiency can be prevented from being lowered. .
Further, since the fluid reservoir hole avoids the meshing line of action, it is possible to prevent the occurrence of flow loss due to the communication between the suction chamber and the discharge chamber. In addition, the confining pressure can be reliably suppressed as a whole by suppressing the confining pressure in each closed region.
[Brief description of the drawings]
FIG. 1 is a cross-sectional front view of a gear pump according to an embodiment of the present invention.
2 is a cross-sectional side view of the gear pump of FIG. 1, and is a cross-sectional view taken along the line II-II of FIG. 1, with hatching omitted.
3 is a side view of the side plate, taken along the line III-III in FIG.
FIG. 4 is an enlarged side view of a main part of a side plate for explaining meshing of a drive gear and a driven gear.
FIG. 5 is a schematic diagram showing an open state of a closed region and a fluid reservoir hole, and hatching is applied to a portion where the fluid reservoir hole is open.
FIG. 6 is an enlarged side view of a main part of a side plate for explaining a conventional gear pump and a gear pump of a comparative example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Housing 3 Drive gear 3a, 4a Gear tooth 4 Driven gear 5 Suction chamber 6 Discharge chamber 10a Cavity 12 Side plate 12a Gear side surface 14 Gear chamber 30, 40 Support shaft 80 Fluid reservoir hole 81 Inlet opening L Meshing action line K Meshing Points S3 to S6 Blocked area

Claims (1)

A pair of side plates are fitted into a cavity inside the housing to define a gear chamber, and a pair of gears that mesh with each other are accommodated in the gear chamber, and the support shafts of the gears are supported via the side plates. In the gear pump in which the suction chamber and the discharge chamber for the working fluid are formed inside the gear chamber with the meshing point of both gears interposed therebetween,
A pair of fluid reservoir holes having an inlet opening facing a closed region formed by both side plates and meshing gear teeth and having no outlet are formed on the side surface of each side plate on the gear side independently of each other. ,
The inlet openings of the pair of fluid reservoir holes are formed only in a predetermined portion of the side surface of the gear, and the predetermined portion faces the side surface of the gear tooth forming the closed region as the gear rotates. A part of the gear side surface,
A gear pump characterized in that the inlet openings of the pair of fluid reservoir holes are respectively arranged on both sides of the action line of meshing of both gears when viewed from the axial direction of the support shaft.

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