JP3561413B2 - Gear pump - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a gear pump for discharging a liquid such as oil and water.
[0002]
[Prior art]
For example, in a circumscribed or inscribed hydraulic gear pump having a constant discharge amount, as shown in FIG. 9, a pair of involute gears 3, 4 mesh with each other, so that an oil trap G is formed at the meshing portion. The compression and expansion of the oil occurs in the oil confining portion G, causing noise and vibration, and pulsation of the discharge pressure. In order to avoid the adverse effects caused by the oil confinement, a relief portion is provided in the casing for communicating the discharge path and the suction path with the oil confinement section G (see "Hydraulic Technology Handbook" published by Nikkan Kogyo Shimbun).
[0003]
[Problems to be solved by the invention]
By the way, oil flowing out from the inner peripheral surface of the casing and between the gear teeth of the driving gear and the driven gear in the gear axis direction may leak from the divided surface of the casing, and reduce the pump volumetric efficiency. In order to prevent such oil leakage, a technology has been developed in which a side plate is provided between the side surfaces of both gears and the casing, and a back pressure is applied to the side plates to press the side surfaces of both gears.
[0004]
When such a side plate is provided, if a relief portion communicating with the oil confining portion is formed in the casing on the same side as the side plate, a high-pressure applying portion for applying back pressure to the side plate is partitioned from the periphery by a seal member. It becomes difficult to do.
Although it is possible to form the sealing member for the partition into a very special shape to avoid interference, another problem occurs in that the back pressure applied to the side plate becomes too high.
[0005]
The present invention has been made to solve such various problems, and a side plate is arranged on a side opposite to a side on which a high-pressure side relief portion communicating with a liquid confining portion is formed for a pair of gears. It is another object of the present invention to provide a gear pump in which a seal member for partitioning a high-pressure applying portion from a periphery between a side plate and a casing can be formed without being affected by a relief portion.
[0006]
[Means for Solving the Problems]
A first specific means for solving the problem in the present invention is to form a cavity C in which a suction passage 8 and a discharge passage 6 communicate with each other in a casing K, and a driving gear 3 meshing with the driving gear 3 and The dynamic gear 4 is disposed, the side plate 10 is disposed between one side surface of the two gears 3 and 4 and the inner surface of the casing K, and the side plate 10 is discharged between the side plate 10 and the inner surface of the casing K by the discharge pressure. A high-pressure applying portion H that urges the gears 3 and 4 is formed, and a seal member 11 that divides the high-pressure applying portion H from its periphery is provided. The high pressure side relief portion 1c that connects the passage 6 with the liquid confining portions G of the gears 3 and 4 is formed.
[0007]
Thereby, the side plate 10 is urged to one side surface of the pair of gears 3 and 4 by the discharge pressure to prevent the liquid from leaking while allowing the trapped liquid to escape from the liquid trapping portion G of the gears 3 and 4. Prevents compression of liquids.
According to a second specific means for solving the problem in the present invention, in addition to the first specific means, the seal member 11 surrounds the shaft portions 3a, 4a of both gears 3, 4 and the suction passage 8. It has an inner seal portion 11b and an outer seal portion 11a which surrounds the high pressure applying portion H together with the inner seal portion 11b and has both ends connected to the inner seal portion 11b. It has a concave portion 11e which is narrowed toward the gear meshing start end portion in the middle of the portion surrounding 3a and 4a.
[0008]
Thereby, the seal member 11 reliably surrounds and forms the high-pressure applying portion H, and secures the size of the high-pressure applying portion H with the concave portion 11e.
A third specific means for solving the problem in the present invention is that, in addition to the second specific means, the concave portion 11e of the inner seal portion 11b and the high-pressure side relief portion 1c of the casing K are arranged in the gear axis direction. That is, they overlap at the projection position.
[0009]
Thereby, even if the high-pressure side relief portion 1c is formed, the concave portion 11e of the inner seal portion 11b is formed to a required size, and is not restricted by the presence of the high-pressure side relief portion 1c. H is not excessively increased, and the force for pressing the side plate 10 is prevented from becoming excessive.
A fourth specific means for solving the problem in the present invention is that, in addition to any one of the first to third specific means, the casing K or the side plate 10 is provided with a suction passage 8 and a liquid in both gears 3 and 4. That is, a low-pressure side relief portion 10g communicating with the closing portion G is formed.
[0010]
As a result, the liquid confining portions G of both gears 3 and 4 are opened on the low pressure side to prevent negative pressure of the liquid.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 8, a gear pump P has a casing K formed of a casing body K1 and a cover member K2, which can be divided into two parts, and has a cavity C in which the discharge path 6 and the suction path 8 communicate with each other. A drive side gear 3 and a driven side gear 4 meshing with each other are provided in the cavity C.
[0012]
The drive side gear 3 and the driven side gear 4 are formed in involute teeth, and the shaft portions 3a, 4a of both gears 3, 4 are rotatably supported by the casing body K1 and the cover member K2 via the bush 5, The shaft portion 3a of the drive side gear 3 projects from the casing K, and is driven to rotate by a power source such as an engine.
The discharge passage 6 is open to the cavity C so as to face the meshing start end portion S of the gears 3 and 4, and the suction passage 8 is opened to the cavity C so as to face the meshing end portion E of the gears 3 and 4. A pair of laterally elongated grooves 1a for collecting oil leaking in the vicinity of the shafts 3a and 4a, and a concave portion 1b connecting the pair of grooves 1a and the suction passage 8 are provided on the casing body K1 facing the cavity C. It is formed on the back surface.
[0013]
The lid member K2 can open one side surface (side surface of the cavity C) of the driving gear 3 and the driven gear 4 and has a recess 2a facing the discharge passage 6 of the casing body K1, and communicates with the suction passage 8. The suction pipe 9 is brazed (or welded), and the shaft portions 3a, 4a of the gears 3, 4 are rotatably supported via the bush 5. In the end surface of the cover member K2 on the casing body K1 side, a closed loop-shaped first groove (outer groove) 2b surrounding the recess 2a (part of the discharge path 6) and the suction path 8, and the inside of the first groove 2b. And a closed loop-shaped second groove (inner groove) 2c surrounding the suction passage 8 and the shaft portions 3a, 4a and communicating with the recess 2a, respectively, and the first and second grooves 2b, 2b on the suction passage 8 side. The second groove 2c is connected to form a single groove, and a third groove 2d is formed inside the second groove 2c to communicate the recesses of the shafts 3a, 4a and the suction passage 8.
[0014]
By forming the grooves 2b, 2c, and 2d, the cover member K2 includes a first protrusion 2e and a pair of second protrusions 2f located between the first groove 2b, the recess 2a, and the second groove 2c. A third convex portion 2h is formed inside the second groove portion 2c so as to surround the suction passage 8 and the bush 5.
On the side of the cover member K2 in the cavity C, a side plate 10 is provided on one side surface of the drive side gear 3 and the driven side gear 4, and a surface of the side plate 10 on the side of the cover member K2 is an end surface of the casing body K1. Are arranged substantially flush with each other.
[0015]
The side plate 10 has a pair of holes 10a through which the shafts 3a and 4a of both gears 3 and 4 are inserted, a first notch 10c that does not close the discharge passage 6 of the casing body K1, and a casing body. A second notch 10d for preventing the suction passage 8 of K1 from being closed, a pair of flat notches 10e formed at a position closer to the suction passage 8 on the outer peripheral portion, and a meshing end portion of the two gears 3, 4; A long hole (low-pressure side relief portion) 10g facing E is formed.
[0016]
A seal member 11 that fits into the first and second grooves 2b and 2c and contacts the side plate 10 is provided on an end surface of the cover member K2. The seal member 11 has a closed loop-shaped outer seal portion 11a fitted into the first groove portion 2b, and a closed loop-shaped inner seal portion 11b fitted into the second groove portion 2c. The portions 11a and 11b are connected to form a connection portion 11c, and a groove portion 11d is formed in the connection portion 11c so as to communicate between the inner and outer seal portions 11a and 11b in the circumferential direction.
[0017]
The inner seal portion 11b surrounds the suction passage 8 and the shaft portions 3a and 4a of the gears 3 and 4 as a low-pressure side seal, and the outer seal portion 11a surrounds the inner seal portion 11b. 11b, a high-pressure side seal having a high-pressure application portion H communicating with the discharge path 6 is formed.
That is, the seal member 11 regulates the flow of oil between the casing body K1 and the side plate 10 and the lid member K2, and surrounds the suction passage 8 and the shaft portions 3a and 4a to define an annular shape. It has an inner seal portion 11b and an annular outer seal portion 11a which surrounds the high pressure applying portion H together with the inner seal portion 11b and is partitioned from the outside thereof, and both ends of which are connected to the inner seal portion 11b.
[0018]
The high-pressure applying section H is formed along the outer periphery of the side plate 10 except for the vicinity of the suction passage 8. In the high-pressure applying section H, the high-pressure oil in the discharge path 6 and the recess 2a acts between the side plate 10 and the inner surface of the cover member K2 (the inner surface of the cavity C), and the discharge pressure is reduced. A force for urging (pressing) the side plate 10 toward the gears 3 and 4 is generated.
[0019]
The side plate 10 is pressed against the side surfaces of the gears 3 and 4 by this urging force, thereby restricting oil leakage from the side surfaces of the gears 3 and 4 as much as possible, thereby increasing the pump efficiency.
An intermediate portion of a portion surrounding the shaft portions 3a and 4a of the gears 3 and 4 of the inner seal portion 11b is a concave portion (a portion protruding when viewed from the high-pressure application portion H side) 11e which is narrowed toward the gear engagement start end portion S. Has become. The concave portion 11e is a portion in which the pressure receiving area of the side plate 10 changes depending on the size of the constricted area, and is a portion where the pressure receiving area can be adjusted.
[0020]
A high pressure side relief portion 1c that connects the discharge path 6 and the oil confining portions G of the two gears 3 and 4 is formed in a rear portion of the casing body K1. This high-pressure side relief portion 1c is paired with the long hole 10g of the side plate 10, and as shown in FIG. 8, the meshing portion of the pair of gears 3, 4 from the meshing start end portion S to the meshing end portion E. When the oil confinement portion G is formed between the oil confinement portions G, the high pressure side relief portion 1c communicates with the engagement start end portion S side of the oil confinement portion G, and the high pressure oil can be released by opening the oil confinement portion G during compression. Has become.
[0021]
The high-pressure side relief portion 1c is opposed to the engagement start end portion S and overlaps with the concave portion 11e of the seal member 11 at the projection position in the gear axis center direction. It is possible to increase the amount of depression in the recess 11e of the seal member 11 and form a long hole that does not interfere with the same in the side plate 10 as in the case of the low-pressure escape long hole 10g, but the amount of depression in the recess 11e is large. When this happens, the back pressure applied to the side plate 10 becomes too large, and the sliding friction resistance with the gears 3 and 4 becomes excessive, which is not preferable.
[0022]
As described above, when the high-pressure side relief portion 1c is formed in the deep portion of the casing main body K1, the amount of depression of the concave portion 11e can be appropriately set, and the biasing force to the side plate 10 can be set to an optimal size.
In the gear pump P described above, when the drive side gear 3 is driven to rotate clockwise in FIG. 6, the driven side gear 4 is driven to rotate counterclockwise, so that the cover member K2 and the suction passage 8 of the casing body K1 The oil that has entered the cavity C in the main body K1 is carried by the gear teeth of the gears 3 and 4 along the inner peripheral surface of the casing main body 1K, sent out to the discharge path 6, and discharged as high-pressure oil.
[0023]
Along with this, a part of the high-pressure oil in the discharge passage 6 enters the high-pressure applying portion H of the seal member 11 and presses the side plate 10 against the side surfaces of the gears 3 and 4, and the side plate 10 Reduce oil leaks. Part of the oil conveyed by the gear teeth of the gears 3 and 4 also communicates with the high-pressure application section H via the flat notch 10e.
In the meshing portion of the gears 3 and 4, an oil trap portion G is generated from the mesh start end portion S to the mesh end portion E, and the volume of the oil trap portion G is reduced and then expanded as the gears 3 and 4 rotate. When the oil is compressed due to the volume reduction, the oil confining portion G communicates with the high pressure side relief portion 1c at the engagement start end portion S side to release the high pressure oil to eliminate the compression, and to reduce the oil negative pressure accompanying the volume expansion. At times, the oil confining portion G communicates with the long hole 10g on the side of the engagement end portion E to introduce the low-pressure oil and release the negative pressure.
[0024]
FIG. 10 shows a second embodiment, in which a suction passage 8 and a discharge passage 6 are formed in a casing body K1 and a pipe 9 is inserted into the casing body K1 and brazed (or welded). The member K2 has a recess 2e facing the suction passage 8.
FIG. 11 shows a third embodiment, in which the gear pump P is a double gear pump, and an intermediate casing body K3 is arranged between a casing body K1 and a cover member K2 of the second embodiment. The drive side gear 3 and the driven side gear 4 arranged in K1 and the drive side gear 3 and the driven side gear 4 arranged in the intermediate casing main body K3 are concentrically connected to each other.
[0025]
In this case, the side plate 10 and the seal member 11 are arranged between the casing main body K1 and the intermediate casing main body K3 and between the intermediate casing main body K3 and the lid member K2. Although the pipes 9 are connected to both the casing body K1 and the intermediate casing body K3, both the casing body K1 and the intermediate casing body K3 can be separated from one pipe 9 using the cover member K2 of the first embodiment. The oil may be supplied to the suction path 8.
[0026]
The present invention is not limited to the above embodiment, and can be variously modified. For example, oil is exemplified, but it may be used for other liquids such as water and chemicals, or may be a multiple pump having two or more pumps. Instead of the long hole 10g for opening the engagement end portion E, the inner surface of the casing body K1 A low-pressure side relief groove may be formed in the recess (the concave portion 1b has a low-pressure side relief groove function).
[0027]
The casing main body K1, the cover member K2, the intermediate casing main body K3 and the like are usually formed of an aluminum alloy or the like, but may be a casting of another metal. Although they are integrally formed, they may be machined after casting.
[0028]
【The invention's effect】
According to the present invention described in detail above, the side plate 10 is urged against one side surface of the pair of gears 3 and 4 by the discharge pressure to prevent the liquid from leaking, and the two gears 3 and 4 The liquid can be confined from the liquid confining portion G, and the liquid can be prevented from being compressed.
[Brief description of the drawings]
FIG. 1 is a sectional front view showing a first embodiment of the present invention.
FIG. 2 is a perspective view in which a lid member is removed.
FIG. 3 is a sectional view taken along line XX of FIG. 1;
FIG. 4 is a sectional view taken along line YY of FIG. 1;
FIG. 5 is an exploded perspective view with a lid member removed.
FIG. 6 is a developed front view.
FIG. 7 is a perspective view of a lid member.
FIG. 8 is a front view of the seal member.
FIG. 9 is an explanatory view showing a gear meshing portion.
FIG. 10 is a sectional view showing a second embodiment.
FIG. 11 is a sectional view showing a third embodiment.
[Explanation of symbols]
1a High-pressure side relief part 6 Discharge path 8 Suction path 10 Side plate 10g Long hole 11 Seal member 11a Outer seal part 11b Inner seal part 11c Connection part 11e Depression C Cavity E Mesh end G oil confinement part H High pressure application part K Casing P Gear pump S Meshing start end

Claims (2)

A suction passage and the discharge passage forms a cavity communicating with the casing, the drive gear and從動gear to mesh engagement with each other within the cavity disposed, the side plates between the one side surface and the inner surface of the casing of the gears A high-pressure applying portion that urges the side plate toward the gear side by the discharge pressure is formed between the side plate and the inner surface of the casing, and a seal member that partitions the high-pressure applying portion from the periphery thereof is provided. the liquid confinement portion of the gears and the relief on the high pressure side relief portion formed by discharge passage communicating with the casing by the other side of the closure vital gears with side plates at one side of the gears, the sealing member Has an inner seal portion surrounding the shaft portion and the suction passage of both gears, and an outer seal portion surrounding the high pressure applying portion together with the inner seal portion and having both ends connected to the inner seal portion. C The part has a concave part which is narrowed toward the gear meshing start part in the middle of the part surrounding both gear shaft parts, and the concave part of the inner seal part and the high-pressure side relief part of the casing are over at the gear axial center projection position. A gear pump characterized by being wrapped . Gear pump according to claim 1, characterized that you have to form a low-pressure side relief portion for communicating the liquid confinement portion of the suction passage and the gears in the casing or the side plates.

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