JPH03202686A - Gear pump - Google Patents

Abstract

PURPOSE:To improve efficiency of a gear pump by forming a groove at least on one side surface of at least one gear so as to reduce power loss of the gear pump. CONSTITUTION:On both the side surfaces of a drive gear 3, a circular groove 3a with a rectangular cross section is formed with the rotation center of this gear as its center. And on both the side surfaces of a driven gear 4, a circular groove 4a with a rectangular cross section is formed with the rotation center of this gear 4 as its center. Even when a clearance alpha between the side surfaces of both the gears 3 and 4 and a housing 5 is set small, the clearance between the side surfaces of the gears 3 and 4 on which these grooves 3a and 4a are formed and the housing 5 becomes relatively large. Thus, by setting the clearance alpha small so as to reduce leakage amount of working fluid, leakage loss can be reduced.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a pump for generating hydraulic pressure for use in hydraulically operated devices, etc., and particularly relates to a gear pump equipped with a pair of gears that mesh with each other. be.

[Prior Art] For example, in a hydraulically operated device such as an automatic transmission whose operation is controlled by hydraulic pressure, in order to generate the necessary hydraulic pressure,
Traditionally, they are often equipped with a gear pump.

An example of such a gear pump is a gear pump 1 used in a hydraulic control device such as an automatic transmission, as shown in FIG. 3, for example. This gear pump 1 includes a drive gear 3 made of external teeth fixed to a rotating shaft 2 to which rotational driving force from a driving means is transmitted, and a driven gear 4 made of internal teeth meshed with this drive gear 3. These pair of gears 3.4 are housed within the housing 5.

As shown in FIG. 4, these pair of gears 3 and 4 are arranged eccentrically with respect to each other, and the gear 3
．． 4 is engaged. Therefore, the li pump chamber 6 is formed in a space surrounded by the upper portion of the outer teeth of the drive gear 3, the upper portion of the inner teeth of the driven gear 4, and both side walls 5a and 5b of the housing 5. This pump chamber 6 is provided with a suction lower and a discharge port 8 with the meshing portion of the gears 3 and 4 as a boundary. In that case, the suction lower is arranged on the upstream side with respect to the rotational direction of the rotating shaft 2, that is, the rotational direction of the gear 3.4, and the discharge port 8 is arranged on the downstream side.

When the single rotation shaft 2 rotates counterclockwise in FIG. 4, the drive gear 3 rotates in the same direction, and the driven gear 4 also rotates in the same direction. As a result, the hydraulic fluid is sucked from the suction lower, and the sucked hydraulic fluid is discharged through the pump chamber 6 as the gears 3 and 4 rotate.
It is discharged from 8.

[Problems to be Solved by the Invention] Incidentally, in such a gear pump 1, as shown in FIG.
A predetermined gap α is formed between the two. In this case, since both gears 3 and 4 are formed of flat plates, this gap α is substantially constant over the entire side surface of both gears 3 and 4.

This gap α causes a power loss in the gear pump 1. As shown in Figure 6, such power loss is expressed as the sum of the leakage loss due to the leakage of the hydraulic fluid through this gap α and the friction loss due to the shear force of the hydraulic fluid in this gap α. Ru. The leakage loss increases as the gap α becomes larger, whereas the friction loss increases as the gap α becomes smaller, which is a contradictory property. For this reason,
In conventional gear pumps, if the gap α is made smaller in order to reduce leakage of hydraulic fluid, friction loss increases, resulting in an increase in drive loss of the gear pump.

Therefore, the optimum gap α is the gap α that minimizes the sum of leakage loss and friction loss. bawl. Therefore, the two-gap α cannot be made smaller or larger than this optimum gap α, so in the conventional gear pump where the gap α is almost constant over the entire side surface of both gears 3.4, there is no further power loss. The problem was that it was not possible to make it smaller.

The present invention has been made in view of such problems, and its purpose is to suppress friction loss to a small level even when the gap between the gear and the side wall of the housing is small. It is an object of the present invention to provide a gear pump capable of reducing power loss of the gear pump.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a gear pump in which a pair of gears that mesh with each other are housed in a housing, and a side surface of at least one of the gears. A groove is formed in at least one of the two.

[Operations and Effects of the Invention] According to the gear pump according to the present invention having such a configuration, the groove is formed on at least one side surface of at least one of the gears, so that the side surface of the gear and the housing are easily connected. Even if the gap between them is set small, the gap between the side surface of the gear where this groove is formed and the 7) housing will be relatively large. By setting the gap small and reducing the amount of hydraulic fluid leakage, the force ζ can reduce leakage loss, and the side surface of the gear where the groove is formed and the housing can be By increasing the gap force between - , , - due to the shear force of the hydraulic fluid
, -1,, AL# + l-at -m 41 to AL
r fp - As a result, the power loss of the gear pump due to the gap can be reduced, so the efficiency of the gear pump is improved and the drive loss of the gear pump is reduced.

Furthermore, by improving the efficiency of the gear pump, the capacity of the gear pump can be reduced, so the gear pump can be made lightweight and compact.

[Example] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a front view similar to FIG. 1 showing an embodiment of the present invention, and FIG. 2 is a partial sectional view of this embodiment. Note that the same components as those of the conventional gear described above are given the same reference numerals, and the explanation thereof will be omitted.

As shown in FIGS. 1 and 2, grooves 3a having a circular shape and a rectangular cross section centered on the rotation center of the gear 3 are formed on both sides of the drive gear 3. A circular groove 4a having a rectangular cross section and having a center around the rotation center of the gear 4 is also formed on both side surfaces.

These grooves 3a.

The width and depth of 4a are appropriately set depending on the pump discharge capacity, rotation speed, and the like.

In this embodiment configured as described above, circular grooves 3a and 4a are formed on both sides of the drive gear 3 and both sides of the driven gear 4, so that the sides of both gears 3.4 and the housing 5 are connected. Even if the gap α between the
The gap α between the housing 5 and the side surfaces of the gears 3 and 4 where these grooves 3a and 4a are formed is relatively large. Therefore, by setting the gap α small to reduce the amount of hydraulic fluid leakage, leakage loss can be reduced. Furthermore, by increasing the gap between the housing 5 and the side surfaces of the gears 3 and 4 where the grooves 3a and 4a are formed, friction loss due to the shear force of the hydraulic fluid is reduced. As a result, the gap α
Since the power loss of the gear pump 1 due to this can be reduced, the efficiency of the gear pump 1 is improved and drive loss of the gear pump is reduced.

Note that the present invention is not limited to the above-described embodiments, and various design changes are possible.

For example, in the embodiment described above, a pair of grooves 3a and 4a are provided on both gears 3.4, but the grooves may be provided on only one gear, or on one side of the gear. It is also possible to provide one. Furthermore, an appropriate number of grooves may be provided.

Further, although the grooves are circular, the grooves may have other shapes, and the cross-sectional shape of the grooves may also have other shapes.

Further, although a trochoid type internal gear is used as the driven gear 4, other gears such as a crescent type internal gear or an external gear may also be used.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of the gear pump according to the present invention, and FIG.
3 is a sectional view taken along the line, FIG. 3 is a diagram showing a conventional gear pump in use, FIG. 4 is a partially cutaway front view of the conventional gear pump, and FIG. 5 is a v- FIG. 6, a cross-sectional view along line v, is a diagram illustrating power loss due to gaps. 1... Gear pump, 2... Rotating shaft, 3... Drive gear, 3a... Otori 4... Driven gear, 4
a...45...Housing, 6...Pump chamber, 7
...Suction port, 8...Discharge port, α...Gap

Claims (2)

[Claims] (1) A gear pump comprising a pair of gears that mesh with each other and housed in a housing, characterized in that a groove is formed on at least one side surface of at least one of the gears. (2) The gear pump according to claim 1, wherein the groove is a circular groove centered on the rotation center of the gear.