JP2010261341A - Gear pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear pump capable of securing volumetric efficiency by absorbing its variation, even if there is the variation in flatness and an angle of a gear side surface and a body side opposed surface in processing. <P>SOLUTION: This gear pump is constituted for sealing a tooth groove of a gear by this side plate, by interposing the side plate between the gear side surface and an inner wall surface of a body, by incorporating a pair of gears into the body. A relative shape of the gear side surface and a side plate side surface is constituted so that an addendum of at least the gear contacts with the side plate, and a clearance between the gear side surface 1a and the side plate 3 becomes gradually large toward the center of a shaft 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a gear pump that can easily ensure volumetric efficiency.

2. Description of the Related Art Conventionally, there is known a gear pump in which a pair of gears meshed with each other is housed in a body, and these gears are rotated to discharge fluid sucked from one side of the body to the other side.
Such a gear pump has a mechanism in which fluid is sucked in from the suction port on the side rotating in the direction in which the gear approaches in the meshing portion of both rotating gears, and fluid is discharged from the discharge port on the opposite side.

In the above gear pump, especially in the high pressure part around the discharge port, if there is a gap between the side of the gear and the body side, fluid will leak from it and the pump function cannot be performed even if the gear rotates. become.
Therefore, it is necessary to seal both side surfaces of both gears in the high pressure section so that fluid does not leak from the side surfaces of the gears. For this purpose, a side plate is interposed between the side surface of the gear and the inner wall of the body, a high pressure is introduced from the discharge port to the body side of the side plate, and the pressure is used so that the side plate is in close contact with the side surface of the gear. (See Patent Documents 1 and 2).

Further, a gap is provided around the shaft provided in the gear so that the low pressure on the suction port side is guided. The clearance around the shaft communicates between the side plate and the gear side surface. However, a seal member is provided between the side plate and the body so that the low pressure is not guided to the discharge port side, thereby dividing the high pressure portion and the low pressure portion.
Therefore, the gear pump operates and the load pressure increases and the body side of the side plate becomes high. However, since the side plate and the gear side face communicate with the low pressure side, there is a pressure difference on both sides of the side plate. Arise. Due to this pressure difference, the side plate is pressed against the side surface of the gear, and volume efficiency can be secured.

In order to secure the volumetric efficiency by bringing the side plate and the gear side surface into close contact in this way, for example, as shown in FIG. 6, one side surface 1a of the gear 1 housed in the gear pump is placed on the axis L of the shaft 2. In addition to finishing the plane A orthogonal, the opposing surface 3a of the gear 1 in the side plate 3 is also formed to be a plane orthogonal to the axis L when it is assembled. Thereby, the side surface 1a of the gear 1 and the opposing surface 3a of the side plate 3 can be brought into surface contact.
The other side surface 1b of the gear 1 and the facing surface of the side plate (not shown) facing the side surface 1b need to be the same as described above.

JP-A-62-206885 JP-A-3-294777

On the other hand, in order to finish the side surface 1a of the gear 1, as shown in FIG. 7, the side surface 1a of the gear 1 on which the shaft 2 is previously provided is ground with a rotating grindstone g, and the side surface 1a has the axis L The plane A is orthogonal to the plane A.
However, when the periphery of the shaft 2 is ground with the grindstone g, it is difficult to accurately finish the side surface 1a to the plane A. In particular, since both side surfaces 1a and 1b of the gear 1 are ground separately, neither side surface can be finished to a plane A orthogonal to the axis L due to variation between left and right or variation between lots due to wheel replacement. There is. Specifically, the center side 1d, which is the shaft 2 side, may be located on the outer side or the inner side than the tooth tip 1c on the gear side surface 1a.

As shown in FIG. 8, if the side surface 1a of the gear 1 is inclined with respect to the plane A and the center side 1d protrudes outward from the tooth tip 1c, the opposing surface of the side plate 3 Even if 3a is finished so as to be perpendicular to the axis L, a large gap is formed between the tooth tip 1c and the side plate 3, and fluid leaks from this gap, resulting in a decrease in volumetric efficiency. End up.
Further, since the side plate 3 and the center side 1d of the gear 1 are in contact with each other in the no-load state, the communication between the shaft 2 and the shaft hole 4 is blocked, and the side plate 3 and the gear side surface 1a are disconnected. The low pressure is not guided. Therefore, even if the discharge pressure increases, the pressure difference between both sides of the side plate 3 does not increase, the pressing force of the side plate 3 is weak, and the volumetric efficiency decreases.
Furthermore, due to variations on the side plate 3 side, a large gap may be formed on the gear tip 1c side of the gear 1 and introduction of low pressure may be hindered. End up.

Thus, the side face 1a of the gear 1 is not sealed with the side plate 3, and the gear pump with low volumetric efficiency is a defective product. In particular, when the gear pump is mass-produced, there is a problem that as the time cycle is reduced, the number of defective products increases due to processing variations.
An object of the present invention is to provide a gear pump that can secure the volumetric efficiency by absorbing the variation even if there is a variation in the gear side surface or the opposing surface of the side plate during processing.

The first invention incorporates a pair of gears in the body, interposes a side plate between the side surface of the gear and the inner wall surface of the body, guides high pressure to the body side of the side plate, In the gear pump, in which a low pressure can be introduced through the periphery of the shaft of the gear and the gear tooth gap is sealed by the side plate, the relative shape between the side surface of the gear and the side plate is at least the gear. And the gap between the side surface of the gear and the side plate gradually increases toward the center of the gear shaft.
The second aspect of the present invention is characterized in that the surface facing the gear in the side plate is a concave surface inclined toward the center of the shaft hole.

According to the first and second aspects of the invention, even if there is a variation in the angle, flatness, etc. of the side surface of the gear and the side plate facing the side surface, Since at least only the tooth tips are in contact with each other, the side plate can be pressed against the side surface of the gear by increasing the load pressure, and the sealing performance can be ensured. Therefore, volumetric efficiency can be ensured, and the productivity can be increased by suppressing the occurrence of defective products.
In the second invention, the concave surface formed on the side plate side increases the gap between the gear side surface and the side plate toward the center of the shaft hole. The side plate can be formed by press working or the like, and can maintain the dimensional accuracy more easily than the side surface of the gear. Therefore, the concave surface can be formed with good reproducibility. Therefore, productivity can be further increased.

It is sectional drawing of the side plate of 1st Embodiment. It is a schematic diagram which shows 1st Embodiment. It is a schematic diagram which shows 1st Embodiment. It is a schematic diagram which shows 1st Embodiment. It is a schematic diagram which shows 2nd Embodiment. It is a figure for demonstrating the relationship between the gear of the conventional gear pump, and a side plate. It is the figure which showed the formation method of a gear side surface. It is the schematic diagram which showed the example of the gear pump used as inferior goods.

The first embodiment shown in FIGS. 1 to 4 is a type of gear pump in which a side plate 3 is provided on the side surface of the gear 1.
As shown in the sectional view of FIG. 1, the side plate 3 includes a shaft hole 4 into which the shaft 2 of the gear 1 is inserted, and a shaft hole 5 into which a shaft of the other gear (not shown) is inserted.
Further, the side plate 3, which faces the gear 1 and the other gear, faces the concave surface 6 inclined toward the center of one shaft hole 4 and the center of the other shaft hole 5. And a concave surface 7 inclined.
In the figure, the symbol L ′ is an axis passing through the center of the shaft hole 5.

The outer peripheries of these concave surfaces 6 and 7 protrude toward the gears facing each other and have a positional relationship corresponding to the tooth tip portion of each gear. Such a side plate 3 can be formed by press working.
Since the concave surfaces 6 and 7 are formed in the same manner and have the same relationship with the opposing gear, only the gear 1 and the concave surface 6 facing the side surface 1a of the gear 1 will be described below.
2 to 4, the gear 1 omits the tooth gap and represents only the outer shape.

In the first embodiment, a concave surface 6 is provided on the surface 3a facing the gear 1 of the side plate 3, but the side surface 1a of the gear 1 facing the concave surface 6 is orthogonal to the axis L as shown in FIG. Plane A to be used. Strictly speaking, grinding is performed for the purpose of setting the side surface 1a to the plane A.
When the side surface 1a coincides with the plane A as shown in FIG. 2 when the gear pump is assembled, the outer peripheral side of the concave surface 6 contacts the tooth tip 1c of the gear 1 when the gear pump is assembled. The gap between the side surface 1 a and the facing surface 3 a of the side plate 3 gradually increases toward the shaft 2.
However, although the concave surfaces 6 and 7 are extremely shown in FIGS. 1 to 4 for the sake of explanation, the concave surfaces 6 and 7 are actually several (μm) dents.

As described above, the side surface 1a of the gear 1 and the facing surface 3a of the side plate 3 are not in close contact with each other, but the facing surface 3a of the side plate 3 contacts the tooth tip 1c portion of the gear 1. The seal function is demonstrated and the volumetric efficiency can be secured.
As described above, the reason why the volumetric efficiency can be ensured by at least the tooth tip 1c portion contacting the side plate 3 is as follows.

When this gear pump is operated and the load pressure is increased, the pressure on both sides of the side plate 3 is increased in the high pressure portion around the discharge port. On the other hand, since the inside of the concave surface 6 on the side of the gear 1 of the side plate 3 communicates with the suction port side via the shaft 2 and the shaft hole 4, the pressure becomes low from the tooth tip 1c toward the center side 1d. As a whole, the pressure is lower than the high pressure on the body side. Therefore, the side plate 3 is pressed against the gear 1. Thereby, the sealing performance of the side surface of the gear 1 is increased, and volume efficiency can be secured.
In particular, the side plate 3 may bend because the pressing force increases on the shaft side where the pressure difference is large. Thus, if the side plate 3 bends and the gap on the center side 1d becomes smaller, the fluid leakage can be further reduced.
Therefore, even if the side plate 3 is not in surface contact with the gear side surface 1a, there is no reduction in volume efficiency that would result in a defective gear pump if at least the tooth tip 1c portion is in contact.

In this way, in the combination of the side plate 3 of the first embodiment shown in FIG. 2 and the gear 1 having the side surface 1a as the plane A orthogonal to the axis L, the tooth tip 1c portion is in contact with the side plate 3. As a result, volumetric efficiency can be secured.
However, when the side surface 1a of the gear 1 is formed, there are variations in the grinding process as described above, and there are cases where the side surfaces 1a of all the gears 1 cannot coincide with the plane A. However, even if the side surface 1a of the gear 1 varies somewhat, the gear pump of the first embodiment can ensure volumetric efficiency.

For example, FIG. 3 shows an example in which the side surface 1a of the gear 1 is recessed on the center side 1d with respect to the tooth tip 1c. If the shaft 2 side is excessively shaved during grinding, a side surface 1a having such a dent tendency is formed. Also in this case, since the tooth tip 1c contacts the opposing surface 3a of the side plate 3, volume efficiency can be ensured.
In FIG. 3 as well, the indentation on the side surface 1a side of the gear 1 is extremely represented, but in actuality, it is a number (μm), and the gap between the concave surface 6 of the side plate 3 is the maximum center side. Even 1d can be made 10 (μm) or less.

On the other hand, FIG. 4 shows a case where the center side 1d of the side surface 1a of the gear 1 protrudes toward the side plate 3 as opposed to FIG. Also in such a case, since the protrusion of the gear side surface 1a is accommodated in the concave surface 6 of the side plate 3, the side plate 3 can be brought into contact with the tooth tip 1c. Therefore, the sealing performance of the tooth gap by the side plate 3 can be ensured, and the volumetric efficiency can be ensured.
As described above, if the side plate 3 of the first embodiment shown in FIG. 1 is used, even if the side surface 1a of the gear 1 is formed to be slightly dispersed with respect to the target plane, the variation is absorbed and the volume is reduced. Efficiency can be ensured. Therefore, the occurrence rate of defective products can be reduced.
In the above description, only the side surface 1 a side of the gear 1 has been described. However, the relationship between the other gear meshing with the gear 1 and the concave surface 7 is the same as that of the side surface 1 a and the concave surface 6. The same applies to the side surface 1b opposite to the side surface 1a.

  In the first embodiment, the concave surface 6 is formed on the opposing surface 3a of the side plate 3, and on the gear 1 side, an example in which processing is performed with the plane A orthogonal to the axis L as the target side surface has been described. The side surface 1a of the gear 1 and the opposing surface 3a of the side plate 3 are not limited to the shape of the first embodiment as long as they are in contact with each other at the tooth tip 1c and the gap gradually increases toward the shaft. Examples of other shapes will be described below as a second embodiment.

In the second embodiment shown in FIG. 5, the side plate 3 is configured such that a surface 3 a facing the gear 1 is a convex surface 8 that is inclined toward the center of the shaft hole 4. Also in FIG. 5, the gear 1 omits the tooth gap and represents only the outer shape.
In the case of the second embodiment, it is necessary to process the side surface 1a of the gear 1 so as to be a concave surface that can accommodate the convex surface 8. For this reason, when the gear 1 is processed, the target side surface 1a is a surface in which the center side 1d is recessed inward with respect to the tooth tip 1c.

Even in the second embodiment, the side surface 1a of the gear 1 varies with respect to the target side surface. Therefore, it is necessary to design the gear 1 and the side plate 3 in consideration of this variation. Even when the center side 1d of the side surface 1a swings toward the side plate 3, the distance between the outer periphery of the convex surface 8 and the tooth tip 1c is less than the distance d1 between the shaft hole 4 side and the center side 1d of the gear 1. If the distance d2 is designed to be larger, the tooth tip 1c comes into contact with the opposing surface 3a to ensure sealing performance, and the incidence of defective products can be reduced.
In the second embodiment, the same configuration as described above is required for the other gear meshing with the gear 1 and the other side surface.

  In any case, on the side surface of the gear, the opposing surface of the side plate and the tooth tip are brought into contact with each other, and a gap between the gear side surface and the opposing surface is positively provided on the shaft side. The variation on the opposite surface side is absorbed. What can be absorbed by the gap includes not only the inclination of the plane but also the unevenness of the plane.

  In the gear pump of the present invention, a concave surface may be formed on either the gear side or the side plate side in order to form a gap between the gear side surface and the side plate. However, since the side plate can be formed by pressing, the dimensional accuracy is easier to obtain than the side surface of the gear finished by grinding. Therefore, the concave surfaces 6 and 7 capable of absorbing the variation on the gear side can be formed on the facing surface 3a of the side plate 3 with good reproducibility. Therefore, it is often advantageous in terms of cost to manage the gap for absorbing the variation by accurately managing the dimensions of the side plate 3 rather than the gear side surface 1a.

DESCRIPTION OF SYMBOLS 1 Gear 1a Side 1b Side 1c Tooth tip 2 Shaft 3 Side plate 3a Opposing surface 4 Shaft hole 5 Shaft hole 6 Concave surface 7 Concave surface

Claims (2)

  A pair of gears are incorporated into the body, and a side plate is interposed between the side surface of the gear and the inner wall surface of the body. High pressure is guided to the body side of the side plate, and the gear shaft of the side play is surrounded by the gear shaft. In the gear pump, in which a low pressure can be introduced through the side plate and the gear tooth gap is sealed by the side plate, the relative shape between the side surface of the gear and the side plate is determined so that at least the tooth tip of the gear is on the side. A gear pump configured to come into contact with the plate and the gap between the side surface of the gear and the side plate gradually increases toward the center of the gear shaft.   The gear pump according to claim 1, wherein a surface of the side plate facing the gear is a concave surface inclined toward the center of the shaft hole.

Images