JP2787706B2 - Gear pump - Google Patents

Description

The present invention relates to a gear pump that can be used in the field of hydraulic equipment and the like.

[Prior Art] In a general gear pump, as shown in FIG. 7, a gear 2 mounted on a drive shaft 2a and a gear 3 mounted on a driven shaft 3a mesh with each other in a casing 1. The movable side plates 4, 5 are provided on both sides of the gears 2, 3.
Are brought into sliding contact to seal the tooth side surfaces. For example, the side plate 5 will be described. As shown in FIG. 8, the inside surface of the side plate 5 is provided with portions other than the inlet opening 6 and the outlet opening 7 as contact surfaces with the gears 2 and 3. The portion corresponding to the middle Y forms a seal land that is closely fitted to the inner periphery of the casing 1 and that clearly separates the high and low pressure regions.
The seal land Y generally exists for approximately two pitches (or more) between the high pressure side seal land point Ya and the inlet opening edge 6a. Further, when the gears 2 and 3 rotate, a high-pressure region H and a low-pressure region L are formed on both sides with the seal land Y as a side, and the outer surface of the side plate 5 corresponds to these pressure distributions. A gasket groove 9 for area division as shown in FIG. 9 is provided. Then, a gasket is attached to the gasket groove 9 and a pressurized liquid is introduced into one of the divided areas (high-pressure introduction area 9 _H ).
It is provided so that the hydraulic pressure acting on the side plate 5 from the high pressure region H can be statically balanced. The above configuration is completely the same for the side plate 4.

[Problem to be Solved by the Invention] By the way, as the gears 2 and 3 rotate, a portion y (particularly shaded in the figure) extending one pitch from the high pressure side seal land point Ya toward the inlet opening edge 6a. In the following, the pressure range will be high when the tooth groove communicates with the high-pressure region H and low when the tooth groove communicates with the low-pressure region L (negative pressure during high-speed driving, etc.) in accordance with the rotational phase of the gears 2 and 3. ), And has the property of becoming an intermediate pressure when not communicating with any of them. In contrast, the outer surface of the side plate 5 is included in the high-pressure introduction zone 9 _H (throughout as the case may be) to the middle portion of the gasket groove 9 corresponds to the switching換域y described above as shown . Thus, although when the result in switching換域y is the high pressure can be balanced fluid pressure acting on the side plate 5 between the high-pressure introduction zone 9 _H, when the switching換域y becomes low pressure, the side plate 5 is high It becomes the pressurized liquid introduction zone 9 _H to being strongly pressed against the side surfaces of the gears 2 and 3, resulting in inconvenience of increasing the torque loss with result in damage to the side plate 5.

In contrast, although liquid at positions corresponding to the switching換域y by narrowing the scope of the high-pressure introduction zone 9 _H can be set so as not to be introduced, in this case, switching換域y is the pressure When this occurs, the side plate 5 separates from the side surface of the gear 2, resulting in an increase in internal leakage.

The present invention has been made in view of such a problem, and by taking measures to effectively cope with the pressure imbalance of the side plate in the switching region which is destined to be caused by the rotation of the gear, the side plate is provided. An object of the present invention is to appropriately reduce problems such as damage, generation of torque loss, and internal leakage.

[Means for Solving the Problems] The present invention employs the following configuration in order to achieve the object.

That is, in the gear pump of the present invention, a pair of gears meshing with each other are disposed in the casing, and a movable side plate is slid on the side surfaces of the two gears to form a seal land set on the inner surface of the side plate. In what is configured to be able to divide high and low pressures, the seal land is provided with a recess over the entire area of the intermediate pressure, and a pressure pocket of substantially the same shape is formed on the outer side surface of the side plate corresponding to the recess, It is characterized in that the recess and the pressure pocket communicate with each other through a hole.

[Operation] With such a configuration, the pressure state in the concave portion provided on the inner surface of the side plate is switched according to the rotation phase of the gear. The concave portion communicates with the pressure pocket provided on the outer surface of the side plate. Therefore, the same pressure is always introduced into the pressure pocket as in the recess. This allows
The hydraulic pressure acting on the side plate can always be kept in a static pressure balance by overcoming the pressure change which is destined to occur in the seal land.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

As shown in FIG. 1, the longitudinal section of the gear pump according to this embodiment is substantially the same as that already shown in FIG. For this reason, parts that are substantially common and need not be described in particular are denoted by the same reference numerals, and description thereof is omitted.

Thus, the side plate 12 (11) that is characteristic of this pump
As shown in FIG. 2, a seal land X for two pitches is set at substantially one place with the seal land Y of the side plate 5 shown in FIG. A region H and a low pressure region L are formed. In the center of the seal land X, there is provided a one-pitch recess 13 extending in a fan shape from the tooth root surface to the outside and opening to the tooth tip surface (that is, the seal land X is thereby provided on both sides with one pitch). / 2
Each pitch is left). Also, with this, the side plate
A substantially U-shaped groove portion 14a having substantially the same shape as shown in FIG. The groove 14a is integrally continuous with the main gasket groove 14. By mounting a gasket in the gasket groove 14, a pressure pocket 15 is formed inside the U-shaped groove 14a.
The hole 13 communicates with the recess 13 through a hole 16 having no aperture effect. In addition, the above configuration is the side plate
The same is true for 11.

Next, the operation of the present embodiment will be described. 4 to 6 show how the internal pressure of the recess 13 changes with the rotational phase of the gears 2 and 3, as in the conventional switching area y. In FIG. 4, the inside of the recess 13 communicates with the high-pressure region H,
It is neutral in the figure and communicates with the low pressure range L in FIG.
In the related art, the pressure balance state of the side plate has been changed accordingly.However, in the illustrated case, the pressure liquid of the same pressure in any state passes through the through hole 16 from the concave portion on the inner surface side and the rear surface has Since it is also introduced into the pressure pocket 15, the side plate 12 is always in a state of static pressure balance from both sides. For this reason,
In the gear pump according to the present embodiment, the sliding resistance between the gears 2 and 3 and the side plate 12 (11) is reduced, and wear and loss torque are reduced. At the same time, internal leakage can be appropriately prevented. As a result, stable operation and durability are ensured for a long time.

Moreover, by providing a recess in the seal land where the inner surface of the side plate is pressed most strongly against the gear side surface, the frictional resistance between the inner surface of the side plate and the gear side surface is reduced, and damage to the side plate and the gear and increase in torque loss are prevented. It becomes possible. In addition, since the entrance of the through hole communicating with the inner and outer surfaces of the side plate is provided in the recess on the inner surface, the timing at which the pressurized liquid communicates with the outer surface can be the time when the recess communicates with the tooth space, The static pressure balance state of the side plate can be realized for a long time by appropriately responding to the pressure change.

As mentioned above, although one Example of this invention was described, the cross-sectional shape of a recessed part and a pressure pocket, the means for communicating these, etc. are not limited to the example of illustration, and various deformation | transformation is possible in the range which does not deviate from the meaning of this invention. It is possible.

[Effects of the Invention] According to the present invention, even when a pressure change occurs in a seal land, the side plate can be balanced by a static pressure balance between a concave portion provided in the seal land and a pressure pocket formed on the back surface thereof. Therefore, it is possible to provide an excellent gear pump in which the wear of the side plates and the torque loss are surely reduced without causing internal leakage. Moreover, by providing a recess in the seal land where the inner surface of the side plate is pressed most strongly against the gear side surface, the frictional resistance between the inner surface of the side plate and the gear side surface is reduced, and damage to the side plate and the gear and increase in torque loss are prevented. be able to. In addition, since the inlet of the through hole communicating with the inner and outer surfaces of the side plate is provided in the recess, the timing at which the pressurized liquid communicates with the outer surface is defined as when the recess communicates with the tooth space, so that it can appropriately respond to pressure changes. Thus, the static pressure balance state of the side plate can be realized for a long time.

[Brief description of the drawings]

1 to 6 show an embodiment of the present invention, FIG. 1 is an overall vertical sectional view, FIG. 2 is a sectional view taken along line II-II in FIG.
FIG. 3 is a sectional view taken along the line III-III in FIG. 1, and FIGS. 4 to 6 are operation explanatory views corresponding to FIG. 7 to 9 show a conventional example, FIG. 7 is a longitudinal sectional view corresponding to FIG. 1, FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 7, and FIG. FIG. 7 is a cross-sectional view along the line IX-IX in FIG. 1 ... Casing, 2, 3 ... Gear 11, 12 ... Side plate, 13 ... Recess 15 ... Pressure pocket, X ... Seal land

Claims (1)

(57) [Claims] A pair of gears meshing with each other are disposed in a casing, and movable side plates are slidably contacted on the side surfaces of both gears, and high and low pressures are partitioned by seal lands set on the inner surfaces of the side plates. The seal land is provided with a concave portion over the entire region of the intermediate pressure, and a pressure pocket having substantially the same shape is formed on the outer side surface of the side plate corresponding to the concave portion, and the concave portion and the pressure pocket are formed. A gear pump characterized by communicating with a through hole.