JP2000009055A - Gear pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an influence of an escape part on a seal member with which a high pressure applied part between a side plate and a casing is partitioned from surrounding area thereof. SOLUTION: A cavity, in which a suction passage 8 communicates with a discharge passage 6, is formed within a casing K. A driving gear 3 and a driven gear 4 engaging with each other are disposed in this cavity, while a side plate 10 is disposed between an inner face of the casing K and one-side faces of both the gears 3, 4. A high pressure applied part H, where the side plate 10 is urged toward the gears 3, 4 by a discharge pressure, is formed between the side plate 10 and the inner face of the casing K, while the high pressure applied part H is partitioned from a surrounding area thereof with a seal member 11. The casing K is formed with a high pressure side escape part 1c toward the other side faces of both the gears 3, 4 such that the discharge passage 6 communicates with a liquid enclosing part formed between the gears 3, 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear pump for discharging a liquid such as oil and water.

[0002]

2. Description of the Related 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. A portion G is formed, and oil compression / expansion occurs in the oil confinement portion G, causing noise / vibration and pulsation of the discharge pressure. In order to avoid the adverse effects due to the oil confinement, the discharge passage and the suction passage and the oil confinement portion G
(See "Hydraulic Technology Handbook" published by Nikkan Kogyo Shimbun).

[0003]

By the way, the oil which has flowed out from the inner peripheral surface of the casing and between the gear teeth of the driving side gear and the driven side gear in the gear axis direction leaks from the split surface of the casing, and the pump In order to prevent this oil leakage, a side plate is provided between the side surfaces of the two gears and the casing, and a back pressure is applied to the side plates to press the side surfaces of the two gears. Technology has been developed.

When providing such a side plate,
If the relief portion communicating with the oil confinement portion is formed on the casing on the same side as the side plate, it becomes difficult to partition the high pressure application portion for applying back pressure to the side plate from the periphery with a seal member. 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.

SUMMARY OF THE INVENTION The present invention has been made to solve these various problems. A pair of gears has a side opposite to a side on which a high pressure side relief portion communicating with a liquid confining portion is formed. It is an object of the present invention to provide a gear pump in which a plate is arranged, and a seal member that partitions 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]

A first concrete means for solving the problems 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. A drive gear 3 and a driven gear 4 meshing with each other are arranged, and a side plate 10 is arranged between one side surface of the two gears 3 and 4 and the inner surface of the casing K. And a high-pressure applying portion H that urges the side plate 10 toward the gears 3 and 4 with the discharge pressure.
And a sealing member 11 for partitioning the high-pressure applying portion H from the periphery thereof, and a discharge passage 6 and a liquid confining portion of the two gears 3, 4 in the casing K on the other side of the two gears 3, 4. That is, a high-pressure side relief portion 1c communicating with G is formed.

As a result, 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, and to close the liquid from the liquid closing portions G of the two gears 3 and 4. To prevent liquid compression. 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 and 4a of both gears 3 and 4 and the suction passage 8. Inner seal part 11
b and an outer seal portion 11a surrounding the high pressure applying portion H together with the inner seal portion 11b and having both ends connected to the inner seal portion 11b. The inner seal portion 11b is composed of two gear shaft portions 3a, 4a. Is provided with a concave portion 11e which is narrowed toward the gear meshing start end portion in the middle of the portion surrounding.

As a result, the sealing member 11 reliably surrounds the high-pressure applying portion H, and the size of the high-pressure applying portion H is ensured by 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.

As a result, even if the high-pressure 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 relief portion 1c. The pressure for pressing the side plate 10 is prevented from becoming excessively large without making the high-pressure application part H excessively large. A fourth specific means for solving the problem in the present invention is the above-mentioned casing K or the side plate 1 in addition to any one of the first to third specific means.
0, a low pressure side relief portion 10g for communicating the suction passage 8 with the liquid confining portion G of both gears 3, 4 is formed.

Thus, the liquid closing portions G of the gears 3 and 4 are opened on the low pressure side to prevent the negative pressure of the liquid.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 8, the gear pump P
The casing K is formed by a casing main body K1 and a lid member K2, and can be divided into two, and forms a cavity C in which the discharge path 6 and the suction path 8 communicate with each other. A driving gear 3 and a driven gear 4 are provided.

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 formed.
Is rotatably supported by the casing body K1 and the lid member K2 via the bush 5, and the shaft portion 3a of the drive side gear 3 projects from the casing K, and is rotatably driven by a power source such as an engine. It has become. The discharge passage 6 is open to the cavity C so as to face the meshing start portion S of the gears 3 and 4, and the suction passage 8 is open to the cavity C so as to face the meshing end portion E of the gears 3 and 4. A pair of horizontally long grooves 1a for collecting oil leaking to the vicinity of the shafts 3a and 4a, and a recess 1b connecting the pair of grooves 1a and the suction passage 8 are formed in the casing body K1 facing the cavity C. It is formed on the back surface.

The cover member K2 can open one side surface (side surface of the cavity C) of the drive side gear 3 and the driven side gear 4, and has a recess 2 facing the discharge passage 6 of the casing body K1.
a is formed, and the suction pipe 9 communicating with the suction passage 8 is brazed (or welded), and the shaft portions 3a, 4a of both gears 3, 4 are formed.
Are rotatably supported via a 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 first groove 2b
A second groove (inner groove) 2c having a closed loop shape surrounding the suction passage 8 and the shaft portions 3a, 4a and communicating with the recess 2a is formed inside the first passage, and the first and second grooves are formed on the suction passage 8 side.
The grooves 2b and 2c are 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 and 4a and the suction passage 8. .

Since the cover member K2 has the grooves 2b, 2c and 2d, the first protrusion 2e and the pair of second protrusions located between the first groove 2b, the recess 2a and the second groove 2c are formed. 2f and a third convex portion 2h located so as to surround the suction passage 8 and the bush 5 inside the second groove portion 2c are formed respectively. 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.

On the side plate 10, both gears 3,
A pair of holes 10a through which the shafts 3a, 4a are inserted, and a first hole for preventing the discharge passage 6 of the casing body K1 from closing.
Notch 10c, second notch 10d for preventing suction passage 8 of casing body K1 from closing, and suction passage 8 in the outer peripheral portion
A pair of flat notches 10e formed at positions closer to the side
And an elongated hole (low-pressure side relief portion) 10g opposed to the meshing end portion E of the gears 3, 4.

On the end face of the cover member K2, there is provided a seal member 11 which is fitted into the first and second grooves 2b, 2c and abuts on the side plate 10. This sealing member 11
Has a closed loop-shaped outer seal portion 11a fitted in the first groove portion 2b, and a closed loop-shaped inner seal portion 11b fitted in the second groove portion 2c, and has inner and outer seal portions 11a, 11b on the suction passage 8 side. Are connected to form a connection portion 11c, and the connection portion 11c has inner and outer seal portions 11a, 11c.
A groove 11d is formed so as to communicate in the circumferential direction between b.

The inner seal portion 11b surrounds the suction passage 8 and the shaft portions 3a, 4a of the gears 3, 4 to form a low-pressure side seal. The outer seal portion 11a surrounds the inner seal portion 11b. A high-pressure side seal is formed in which a high-pressure applying portion H communicating with the discharge path 6 is formed between the inner seal portion 11b and the inner seal portion 11b. That is, the seal member 11 regulates the flow of oil between the casing body K1 and the side plate 10 and the cover 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 application portion H together with the inner seal portion 11b so as to be partitioned from the outside and has both ends connected to the inner seal portion 11b.

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.

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 the inner seal portion 11b surrounding the shaft portions 3a, 4a of the gears 3, 4 is a concave portion (a portion protruding from the high-pressure application portion H side) 11e narrowed toward the gear meshing start portion S. Has become. The concave portion 11e changes the pressure receiving area of the side plate 10 depending on the size of the constricted area, and is a portion where the pressure receiving area can be adjusted.

A discharge passage 6 is provided at the back of the casing body K1.
And a high-pressure side relief portion 1c that communicates with the oil confining portions G of the gears 3 and 4. The high-pressure side relief portion 1c is paired with the long hole 10g of the side plate 10,
As shown in FIG. 8, when the oil confining portion G is generated between the meshing start end portion S and the meshing end portion E at the meshing portion of the pair of gears 3 and 4, the oil closing portion G side of the meshing start end portion S , The high pressure side relief portion 1c communicates, and the oil confinement portion G at the time of compression is opened so that high pressure oil can be released.

The high-pressure side relief portion 1c has a meshing start end portion S
And overlaps with the concave portion 11e of the seal member 11 at the projection position in the gear axis direction. Although it is possible to increase the amount of depression of the concave portion 11e of the seal member 11 and form a long hole that does not interfere with the concave portion in the side plate 10 similarly to the long hole 10g for low-pressure escape,
If the amount of depression of e becomes large, the back pressure applied to the side plate 10 becomes too large, and the sliding friction resistance with the gears 3 and 4 becomes too large, which is not preferable.

As described above, if the high-pressure side relief portion 1c is formed in the deep portion of the casing 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. become. In the gear pump P described above, when the driving gear 3 is driven to rotate clockwise in FIG. 6, the driven gear 4 is driven to rotate counterclockwise, whereby the cover member K2 and the suction passage 8 in 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.

Accordingly, part of the high-pressure oil in the discharge path 6
After entering the high-pressure applying portion H of the seal member 11, the side plate 10 is pressed against the side surfaces of the gears 3 and 4,
To reduce oil leakage from the sides. Part of the oil conveyed by the gear teeth of the gears 3 and 4 also communicates with the high-pressure applying section H via the flat notch 10e. In the meshing portion of the gears 3 and 4,
The oil confining portion G extends from the engagement start end portion S to the engagement end portion E.
Is generated, the volume of the oil confinement portion G is reduced after the volume of the oil confinement portion G is reduced along with the rotation of the gears 3 and 4. Communicates with the high-pressure side relief section 1c to release high-pressure oil and eliminate compression,
At the time of the oil negative pressure accompanying the expansion of the volume, 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 eliminate the negative pressure.

FIG. 10 shows a second embodiment.
The suction passage 8 is formed in the casing main body K1 together with the discharge passage 6, and the pipe 9 is inserted into the casing main body K1 and brazed (or welded). The recessed portion 2e facing the suction passage 8 is formed in the lid member K2. Has formed. FIG. 11 shows a third embodiment, in which the gear pump P is of a double type, in which an intermediate casing body K3 is arranged between a casing body K1 and a cover member K2 of the second embodiment. Driving gear 3 and driven gear 4 arranged in K1
And the drive-side gear 3 and the driven-side gear 4 disposed in the intermediate casing main body K3 are concentrically connected to each other.

In this case, between the casing body K1 and the intermediate casing body K3, and also between the casing body K1 and the intermediate casing body K3.
The side plate 10 and the seal member 11 are also arranged between the cover member 3 and the cover member K2. The casing body K
Although the pipe 9 is connected to both the first casing 1 and the intermediate casing main body K3, the suction passages 8 of both the casing main body K1 and the intermediate casing main body K3 are separated from one pipe 9 using the cover member K2 of the first embodiment. May be supplied to the oil.

The present invention is not limited to the above embodiment, but can be variously modified. For example, oil is exemplified, but other liquids such as water and chemicals may be used, or two or more pumps may be used. Instead of the long hole 10g that opens the engagement end portion E, the back surface of the casing body K1 is used. A low-pressure side relief groove may be formed in the recess (the concave portion 1b has a low-pressure side relief groove function).

Further, a casing body K1, a cover member K2,
The intermediate casing body K3 and the like are usually formed of an aluminum alloy or the like, but may be a casting of another metal. The relief portion, groove, concave portion, etc. are integrally formed by casting during casting, but machining is performed after casting. May be.

[0028]

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 to prevent the liquid from leaking. The confined liquid is released from the liquid confining portions G of the two gears 3 and 4, and the compression of the liquid can be prevented.

[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 with a lid member 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 portion 6 discharge path 8 suction path 10 side plate 10g long hole 11 seal member 11a outer seal portion 11b inner seal portion 11c connection portion 11e concave portion C cavity E engagement end portion G oil trap portion H high-pressure applying portion K casing P Gear pump S Meshing start end

Claims (4)

[Claims] 1. A cavity in which a suction path and a discharge path communicate with each other in a casing, and a driving gear and a driven gear that mesh with each other are disposed in the cavity. A seal member is provided between the side plate and the inner surface of the casing, between the side plate and the inner surface of the casing, for forming a high-pressure applying portion for urging the side plate toward the gear side by the discharge pressure, and separating the high-pressure applying portion from the periphery thereof. And a casing on the other side of the two gears, the casing having a high pressure side relief part for communicating the discharge path and the liquid confinement part of the two gears. 2. The seal member includes an inner seal portion surrounding the shaft portions and the suction passages 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. 2. The gear pump according to claim 1, wherein the inner seal portion has a concave portion that is narrowed toward a gear engagement start end portion in a middle of a portion surrounding both gear shaft portions. 3. 3. The gear pump according to claim 2, wherein the concave portion of the inner seal portion and the high-pressure side relief portion of the casing overlap at a projection position in the gear axis direction. 4. The casing or the side plate according to any one of claims 1 to 3, wherein a low-pressure side relief portion that connects the suction passage and the liquid confining portions of both gears is formed. Gear pump.