JPH07293453A - Gear pump - Google Patents

Abstract

PURPOSE:To decrease pump noise in introducing incompressible fluid such as water as well as to secure self priming performance of a pump. CONSTITUTION:One or both gaps G1 and G2 are provided between a driving gear 1 and a driven gear 2 to be rotated by being meshed with each other in a casing 1 and shafts 6, 8 for supporting the gears or between the shafts 6, 7 and a bearing on the casing 3 side for supporting the shafts 6, 8, and respective gears 1, 2 are so supported as to be slightly moved in the radial direction, and the gap between a tooth crest 20 and a casing inner peripheral wall 21 can be adjusted. When compressive fluid such as air is sucked, the gap between the tooth crest 20 and the casing inner peripheral wall 21 is narrowed by force for extending the center distance, to act between the gears 1, 2, so as to improve self priming performance. When compressive fluid is sucked, the gears 1, 2 are pressed in the direction to shorten the center distance by force of compressive fluid, so as to widen the gap, and to prevent generation of pump noise.

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 delivering a fluid between two gears meshing with each other and a casing surrounding the gears. More specifically, the present invention relates to a gear pump suitable for use in sequentially sucking and discharging a compressive fluid such as air and an incompressible fluid such as water.

[0002]

2. Description of the Related Art A conventional gear pump, as shown in FIG. 5, has a pair of gears 101 and 102 meshing with each other and an oval casing 10 surrounding these gears to form a pump chamber.
3 and one gear, for example, a drive source (not shown) for driving the gear 101, and a pair of gears 1 meshed with each other.
The inside of the casing 103 is divided into a suction side chamber 104 and a discharge side chamber 105 by 01 and 102. This gear pump sucks fluid from the suction port 106 by the rotation of the pair of gears 101, 102, and each gear 101, 1
02 and the casing 103 are confined in the space 112, pressure-fed, and discharged from the discharge port 107 communicating with the other chamber 105. Each gear 101, 102 has a shaft portion 108, 109 integrated by insert molding or the like, and by fitting the shaft portion 108, 109 into a bearing hole (not shown) provided on the casing 103 side. It is rotatably supported. One gear on the drive side, for example, the shaft 108 of the gear 101 is projected to the outside of the casing 103 and connected to a drive source (not shown). Gear 1
01 and 102 form a constant gap between the tooth tip surface 110 and the inner peripheral wall 111 of the casing 103, the gap having a size that does not impair the sealing property according to the fluid to be pumped (hereinafter referred to as the fluid to be pumped). Or so as to be in sliding contact with the inner peripheral wall 111 of the casing.

[0003]

However, when it is attempted to pump a compressive fluid such as air and an incompressible fluid such as water by means of this conventional gear pump, for example, as a pump for supplying water to an ice making device of a refrigerator. When it is used, there is a problem that it increases noise in the pump when sucking incompressible fluid, or reduces the ability to suck incompressible fluid before sucking incompressible fluid (so-called self-priming ability). is doing.

That is, when the gear pump is used as a water supply pump, at the beginning of operation, air is sucked in to lower the pressure in the hose / pipe on the suction side and sucked up from the water supply tank to pump the water. ing. After the water supply is completed, the water in the pump chamber is recirculated to the water supply tank to discharge the water from the pump chamber and the hose / pipe connected to it, after the water supply is completed. Therefore, each time the pump is driven, air is sucked and then water is pumped.

However, the tooth top surface 111 and the casing 110 are
The proper gap between and is different when inhaling a compressible fluid such as air and when inhaling an incompressible fluid such as water.

Therefore, in the conventional gear pump used for supplying water in the refrigerator, etc., it is important to improve the self-priming property of the pump that sucks in air and sucks water up to the suction side chamber 104 in the casing 103. , And the gap size was fixed to a value suitable for inhaling air. Therefore, although it is possible to secure the self-priming property of the pump, there is a problem that pump noise is greatly increased at the same time when water is sucked. On the other hand, if the gap size is fixed to a value suitable for sucking water in order to reduce pump noise, the self-priming property of the pump will be lost.

Further, when the tooth tip surface and the casing inner peripheral wall are in contact with each other and slide, there is a problem that noise is generated due to the contact between the tooth tip and the casing.

It is an object of the present invention to provide a gear pump which can secure the self-priming property of the pump and at the same time reduce pump noise when an incompressible fluid such as water is introduced.

[0009]

In order to achieve the above object, the present invention relates to a pump for feeding a fluid by a driving gear and a driven gear which are meshed with each other in a casing, in which a driving shaft is inserted through a central portion of the driving gear. In addition to forming the shaft insertion hole, a rotation support shaft insertion hole through which the rotation support shaft is inserted is formed in the center of the driven gear, and the rotation support shaft and the rotation support shaft insertion hole are formed between the drive shaft and the drive shaft insertion hole. A gap is provided between each of them to support the drive gear and the driven gear so that they can be finely moved in the radial direction.

Further, in the gear pump of the present invention, a gap is provided between the shaft for supporting each gear on the driving side and the driven side and the bearing of the casing so that the driving gear and the driven gear are supported so as to be finely movable in the radial direction. I have to.

Further, in the gear pump of the present invention, the gear and the shaft for supporting the gear are separately formed, and a gap is also provided between each shaft and the hole of each gear through which the shaft is inserted. And a gap between the shaft and the bearing on the casing side.

Further, in the gear pump of the present invention, the fine movement of the driving gear and the driven gear toward the inner peripheral wall of the casing is caused to be caused by the gear at the shaft at the position where the tooth tops of the respective gears are closest to the inner peripheral wall of the casing and do not abut. Are abutted to regulate.

[0013]

Therefore, when a compressive fluid such as air is sucked, the gap between the tooth crest and the inner peripheral wall of the casing is narrowed by the force that acts between the gears to widen the gear shaft distance. Then, when a compressible fluid such as water is sucked, the pressure of the incompressible fluid trapped between the inner peripheral wall of the casing and the teeth of the gear pushes the gear in the direction of reducing the axial distance to widen the gap. . Thus,
A gap suitable for the fluid to be pumped is automatically aligned.

Further, in the case of the invention of claim 4, even if the drive gear and the driven gear slightly move to the casing inner peripheral wall side when the incompressible fluid such as air is sucked, the teeth of each gear are formed on the casing inner peripheral wall. The movement of each gear is restricted by the shaft at a position where the front surfaces are closest to each other and do not come into contact with each other, so that the gears do not come into contact with the inner peripheral wall of the casing.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to the embodiments shown in the drawings.

1 to 3 show an embodiment of the gear pump of the present invention. This gear pump is composed of a casing 3, a drive gear 1 which is meshed with the casing 3, a driven gear 2 and a motor 4 which is a drive source. A drive shaft insertion for inserting a drive shaft 6 into the center of the drive gear 1 is provided. While forming the hole 5, a rotation support shaft insertion hole 7 for inserting the rotation support shaft 8 is formed at the center of the driven gear 2, and the rotation support shaft 8 is rotated between the drive shaft 6 and the drive shaft insertion hole 5. A gap G1 is provided between the support shaft insertion hole 7 and the support shaft insertion hole 7 to support the drive gear 1 and the driven gear 2 so that they can be finely moved in the radial direction. The casing 3 is divided into a suction-side chamber 22 and a discharge-side chamber 23 by a driving gear 1 and a driven gear 2 that mesh with each other.

Here, the drive gear 1 and the driven gear 2 and the drive shaft 6 and the rotation support shaft 8 that support them are formed separately, and a drive shaft insertion hole 5 is formed at the center of each gear 1, 2.
Further, a gap G1 is provided between the rotation support shaft insertion hole 7 and the rotation support shaft insertion hole 7 so that the gears 1 and 2 can be finely moved in the radial direction. The gap G1 is a gap suitable for pumping an incompressible fluid such as water from a state where the tooth crests 20 of the gears 1 and 2 and the casing inner peripheral wall 21 do not come into direct contact with each other, for example, 30 μ.
It is provided so as to make slight movements between the gaps around m. Generally, in the case of air, it is preferable to form a gap of about 10 μm, and in the case of water, it is preferable to form a gap of about 30 μm. Therefore, in the case of the embodiment of FIG. 1, the difference between the hole diameters of the holes 5 and 7 of the gears 1 and 2 and the diameters of the shafts 6 and 8 is set to about 40 μm. In addition, the gap G between the shafts 6 and 8 of the drive gear 1 and the driven gear 2
When the drive gear 1 and the driven gear 2 come closest to the inner peripheral wall 21 side of the casing 3 forming the pump chamber, the tooth tip surface 20 of each gear 1 and 2 causes the fine movement amount in the radial direction due to 1. The amount is set so that it does not come into contact with each other. That is, the casing inner peripheral wall 21 of each gear 1, 2 by each shaft 6, 8
To the inner peripheral wall 21 of the casing and the tooth crest 2
It is provided so as not to contact 0. Of course, the size of the gap G1 is not limited to this, and may be appropriately set depending on conditions such as the type of fluid to be pressure-fed and the material used. The drive shaft 6 and the drive shaft insertion hole 5 of the drive gear 1 are formed in a D-shaped cross-sectional shape, and are provided so as to transmit rotation. Both ends of the drive shaft 6 are formed in a circular shape, and are rotatably supported by bearings 9 and 9 formed of concave portions of the upper casing member 3a and the lower casing member 3c, respectively.

In the case of the present embodiment, the casing 3 surrounding the pair of gears 1 and 2 is divided into an upper casing member 3a, an intermediate casing member 3b and a lower casing member 3c. A seal member 1 such as an O-ring is provided between the upper casing member 3a and the middle casing member 3b.
0 is interposed and sealed to form a pump chamber. The upper casing member has a cylindrical inlet member 1
1 and the discharge port member 12 are integrally formed. Further, the cross-sectional shape of the upper casing member 3a is formed into a substantially eight shape (gourd shape) as shown in FIG.
A large number of chambers 13 for confining the fluid to be pumped are formed between the teeth of the non-compressible fluid and the suction ability (self-priming ability) of the incompressible fluid.
It is provided to increase the

On the back side of the middle casing member 3b, a lid plate 15 for sandwiching the lip seal 14 fitted on the drive shaft 6 penetrating the casing 3 with the middle casing member 3b is fixed by caulking or the like. It is provided so as to prevent water and the like from leaking along the drive shaft 6. The lip seal 14 is not particularly limited, but has a disk shape that is fitted to the drive shaft 6, and has a flange that forms a reservoir portion for storing the leaked fluid in the peripheral portion.

The middle casing member 3b and the lower casing member 3c are provided with chambers for accommodating gears 16 and 17 for decelerating and rotating the drive shaft 6. One reduction gear 16 is press-fitted onto the drive shaft 6, and the other gear 17 is connected to the output shaft 1 of the motor 4.
It is press-fitted in 8. The motor 4 is a lower casing member 3c
It is fixed to. Furthermore, the motor 4 has a protective cap 1
9 is covered. The upper casing member 3a, the middle casing member 3b, and the lower casing member 3c are connected by a tightening screw 24 or the like.

In this embodiment, the drive gear 1 and the driven gear 2 are spur gears. However, the drive gears 1 and the driven gears 2 are not limited to these and may be helical gears.

With the above-mentioned structure, the compressive fluid and the incompressible fluid such as air and water can be pressure-fed while automatically adjusting them to the optimum gap as follows.

First, when sucking air, the gears 1,
The gap between the tooth crest 20 and the casing inner peripheral wall 21 is narrowed by the force that acts between the two to widen the distance between the gear shafts. Here, even if the drive gear 1 and the driven gear 2 slightly move toward the casing inner peripheral wall 21, the tooth crests 20 of the gears 1 and 2 are closest to the casing inner peripheral wall 21 and are not in contact with each other. The movements of the gears 1 and 2 are restricted by the shafts 6 and 8 and do not contact the casing inner peripheral wall 21. Then, when the water is sucked, the pressure of the water confined in the chamber 13 between the inner peripheral wall 21 of the casing and the teeth of the gears 1 and 2 pushes the gears 1 and 2 in a direction to reduce the axial distance, thereby widening the gap. To do. Thus, the gap suitable for the fluid to be pumped is automatically aligned.

The above embodiment is an example of the preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention. For example, a gap G2 is provided between the shafts 6 and 8 supporting the gears 1 and 2 and the bearing 9 of the casing 3, and the drive gear 1
Alternatively, the driven gear 2 may be slightly moved in the radial direction.
Further, the gaps G1 and G2 may be formed at the same time between the gears 1 and 2 and the shafts 6 and 8 supporting them and both the shafts 6 and 8 and the bearing 9 of the casing 3 supporting this. That is, the gears 1 and 2 and the shafts 6 and 8 supporting the gears are separately formed, and the bearings that support the shafts 6 and 8 between the holes 5 and 7 of the gears 1 and 2 and the shafts 6 and 8 are formed. A gap is provided between each of them. In this case, the gap G2 or the sum of G1 and G2 is calculated by calculating the tooth top surface 20 of each gear 1, 2 and the casing inner peripheral wall 21.
It is provided so as to make a slight movement in a gap suitable for pumping an incompressible fluid such as water from a state of almost no direct contact with, for example, a gap of about 30 μm, and more preferably by each shaft 6, 8. Inner peripheral wall 21 of each gear 1 and 2 casing
To the inner peripheral wall 21 of the casing and the tooth crest 2
It is provided so as not to contact 0.

In the present embodiment, the drive gear 1 is driven by the drive shaft 6, but the drive gear 1 is not limited to this.
Although not shown, an internal gear is provided inside the drive gear 1,
The drive gear 1 may be rotated by this internal gear.

[0026]

As is apparent from the above description, in the gear pump of the present invention, the driving gear and the driven gear are provided so as to make a fine movement in the radial direction to adjust the gap between the tooth crest surface and the inner peripheral wall of the casing. Since it is possible, when sucking a compressible fluid such as air, the force between the gears that tries to widen the gear shaft distance narrows the gap between the tooth tip surface and the casing inner peripheral wall, and self-suction When the capacity is improved and the compressive fluid is sucked, the force of the compressible fluid pushes the gear in the direction of decreasing the axial distance, widening the gap and preventing the occurrence of pump noise.

Further, in the case of the invention of claim 4, even if each gear slightly moves toward the inner peripheral wall of the casing, the movement is restricted by each shaft supporting the gear when the gear is closest to the inner peripheral wall of the casing. Therefore, it is possible to secure an optimum gap and prevent sliding between the tooth crest surface and the casing inner peripheral wall.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a gear pump of the present invention with only a casing being sectioned.

FIG. 2 is an explanatory view showing a state in which the gap is adjusted to a minimum value in the gear pump of FIG.

FIG. 3 is a central longitudinal sectional view showing an embodiment of a gear pump of the present invention.

FIG. 4 is a cross-sectional view showing another embodiment of the gear pump of the present invention.

FIG. 5 is a schematic configuration diagram showing a conventional gear pump in a sectional view of only a casing.

[Explanation of symbols]

 1 Drive Gear 2 Driven Gear 3 Casing 5 Drive Shaft Insertion Hole 6 Drive Shaft 7 Rotation Support Shaft Insertion Hole 8 Rotation Support Shaft 9 Bearing 20 Tooth Tip Surface 21 Casing Inner Wall

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[Procedure amendment]

[Submission date] March 22, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

[0013]

Therefore, when a compressive fluid such as air is sucked, the gap between the tooth crest and the inner peripheral wall of the casing is narrowed by the force that acts between the gears to widen the gear shaft distance. The wide gear is pushed in a direction to narrow the distance between the axes gap by the pressure of the incompressible fluid to be trapped between the teeth of the casing wall and the gear when the incompressible fluid such as water is sucked To do. Thus, the gap suitable for the fluid to be pumped is automatically aligned.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

In the case of the invention of claim 4, air or the like
Also the drive gear and driven gear when the compression fluid is inhaled by the fine motion to casing wall side, movement of each gear at a position where the tooth crest of the gear casing wall is not the closest and contact Is regulated by the shaft so that it does not contact the inner peripheral wall of the casing.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

[0026]

As is apparent from the above description, in the gear pump of the present invention, the driving gear and the driven gear are provided so as to make a fine movement in the radial direction to adjust the gap between the tooth crest surface and the inner peripheral wall of the casing. Since it is possible, when sucking a compressible fluid such as air, the force between the gears that tries to widen the gear shaft distance narrows the gap between the tooth tip surface and the casing inner peripheral wall, and self-suction When the capacity is improved and the non- compressible fluid is sucked, the gear is pushed by the force of the non- compressible fluid in the direction of reducing the axial distance to widen the gap and prevent generation of pump noise.

Claims (4)

[Claims] 1. A pump for sending out a fluid by a drive gear and a driven gear meshing with each other in a casing, wherein a drive shaft insertion hole for inserting a drive shaft is formed in a central portion of the drive gear, and a central portion of the driven gear. A rotary support shaft insertion hole through which the rotary support shaft is inserted is formed, and gaps are provided between the drive shaft and the drive shaft insertion hole and between the rotary support shaft and the rotary support shaft insertion hole, respectively. A gear pump characterized in that a driven gear is supported so as to be capable of fine movement in the radial direction. 2. A pump for sending out fluid by a driving gear and a driven gear meshing with each other in a casing, wherein a gap is provided between a shaft supporting each of the gears and a casing-side bearing supporting the shafts. A gear pump characterized in that a gear and a driven gear can be finely moved in a radial direction. 3. The gears are formed separately from the shafts supporting the gears, and a gap is also provided between the shafts and the holes of the gears inserted therethrough. Item 2
Gear pump described. 4. The fine movement of the drive gear and the driven gear toward the inner peripheral wall of the casing is caused to come into contact with the shaft at the position where the tooth top surface of each gear comes closest to the inner peripheral wall of the casing and does not come into contact with the inner peripheral wall of the casing. 4. The method according to claim 1, wherein
Gear pump according to any one of.