JPS6248075B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a gear pump in which the length of the gear track is sufficiently long while maintaining an appropriate depth.

(Prior Art) The conventionally known gear pump shown in FIG. 4 has a structure in which the center of a gear hole 0g in which a pair of gears is housed coincides with the center of the bearing hole 12 of the gear at point O. was.

Then, by driving this gear pump, the discharge chamber 1
When a load pressure is applied to the gear 7 side, the center 0s of the gear shaft is eccentric toward the illustrated suction chamber 16 side due to the action of the load pressure, and the tip circle a of the gear is also eccentric.

If the tooth tip circle a is biased in this way, the inner surface of the gear hole 0g will be scraped off by the gear tooth tip to a depth t according to the amount of bias, but this scraped area will be used as a gear track. It's something that works.

(Problems to be Solved by the Invention) In this conventional gear pump, a gear track is formed according to the amount of deviation of the tip circle a, but as described above, the center O between the gear hole 0g and the bearing hole 12 is Therefore, the gear track can only have a length within the range of rotation angle _θ0 .

However, with such a gear track length,
There was a problem in that high-pressure oil leaked from the tips of the gear teeth, thereby reducing the volumetric efficiency of the gear pump.

Therefore, if the length of the gear truck is to be increased while the center O of the gear hole 0g and the bearing hole 12 are aligned, the inner diameter of the gear hole 0g must be made smaller.

If the inner diameter of the gear hole 0g is made smaller in this way,
Since the relative difference in the reduced inner diameter is directly added to the depth of the gear track, the depth t inevitably becomes deep.

However, if the depth of the gear track is increased, in other words, if the gear hole 0g is cut deeply with the tip of the gear, the gear track surface will suffer from peeling or galling, especially if the body is made of iron. A problem arises in that the applied surface is of poor quality and the volumetric efficiency is extremely reduced.

The purpose of this generation is to provide a gear pump in which the length of the gear track can be made sufficiently long without increasing the depth of the gear track.

(Means for Solving the Problems) In order to achieve the above object, the present invention makes the distance between the centers of the gear holes shorter than the distance between the centers of the bearing holes of the gear shaft.

(Action of the present invention) In this invention, since the distance between the gear hole centers is made shorter than the distance between the bearing hole centers of the gear shaft, the gear hole is aligned in the straight direction connecting the bearing hole centers with respect to the tooth tip circle, in other words. This is equivalent to relative displacement in the tangential direction of the gear track forming surface.

If the gear hole is relatively displaced in the direction perpendicular to the straight line connecting the centers of the bearing holes and in the opposite direction to the gear track forming surface, the amount of displacement is
Since it adds directly to the depth of the gear track, the gear track becomes too deep, similar to if the gear hole were made smaller.

The closer the displacement direction of the gear hole is to the linear direction connecting the centers, the less the effect of the displacement of the gear hole on the depth of the gear track, and the longer the gear track forming surface becomes. Become.

Therefore, in the present invention in which the direction of displacement of the gear hole is the straight line connecting the centers, the length of the gear track can be increased, and the depth of the gear track does not become too deep.

(Embodiment of the present invention) Figures 1 to 3 show an embodiment of a gear pump according to the present invention, in which a body 1 has a pair of gear holes 2,
3, but these gear holes 2 and 3 open their contact portions to each other.

By inserting the gears 4 and 5 into the gear holes 2 and 3, the gears 4 and 5 are made to mesh with each other at the open portion.

Further, the shafts 6 to 9 of the gears 4 and 5 are connected to the cover 1.
0 or the bearing holes 12 to 15 of the mounting flange 11. The gear hole and the bearing hole configured as described above maintain the following relationship.

That is, as is clear from FIG. 3, with respect to the center O of the bearing hole, the center 0e of the gear hole is eccentric in the direction of the center O' of the other bearing hole. In other words, the distance between the gear hole centers 0e and 0e' is made shorter than the distance between the bearing hole centers O and O'.

In addition, the reference numeral 16 in the figure is a suction chamber, and the reference numeral 17 is a discharge chamber.

Next, the operation of this embodiment will be explained.

When the pump is driven under no load, the center of the gear shaft remains aligned with the center O of the bearing hole.

From this state, when a load pressure acts on the discharge chamber 17, the center of the gear shaft shifts to the above O.
Since it is eccentric from the point to 0s, the tip circle a of the gear is also eccentric according to the amount of eccentricity.

If the tip circle a is biased as shown above, gear hole 2
A gear track corresponding to the amount of deviation of the gear is formed on the inner periphery of the gear. Since the center 0e of the gear hole 2 is eccentric as described above, a gear track is formed within the range of the rotation angle θe, as shown in FIG.

That is, in this embodiment, the center of the gear hole 2 is 0.
Since the distance between e and 0e' is made shorter than the distance between the bearing hole centers O and O' of the gear shaft, the gear hole 2 is aligned with the tip circle a in a straight line connecting the bearing hole centers, in other words, the gear track. This is the same as if there was a relative displacement in the tangential direction of the forming surface.

If the direction perpendicular to the straight line connecting the bearing hole centers O and O' is opposite to the gear track forming surface,
If the gear hole 2 were to be relatively displaced, the amount of displacement would be directly added to the depth of the gear track, so the gear track would become too deep, similar to when the gear hole was made smaller.

The closer the displacement direction of the gear hole 2 is to the linear direction connecting the centers O and O', the less influence the amount of displacement of the gear hole 2 has on the depth t of the gear track. At the same time, the gear track forming surface becomes longer.

The gear truck formed as above is
However, in the conventional case shown in FIG. 4, the gear track is formed only within the rotation angle θo.

As described above, according to this embodiment, the rotation angle θe
Within this range, a sufficiently long gear track can be formed and its depth can be maintained at an appropriate level. Therefore, unlike the conventional tooth tips, high-pressure oil does not leak from the tips of the teeth, and there is no possibility of chipping or galling.

In addition, as mentioned above, the center 0e of the gear holes 2 and 3,
When the distance 0e' is shortened, the length between the centers of the outer peripheries of the pressure plates 18 and 19 must also be shortened to correspond to the gear hole.

(Effects of the Present Invention) As is clear from the above explanation, the gear pump of the present invention can always provide a gear track having an appropriate length and depth, and can reliably prevent leakage of high pressure oil from the tips of the gear teeth. It can be prevented.

In addition, since the depth of the gear truck does not need to be deeper than necessary, for example, when using an iron body, peeling and galling will not occur as with conventional ones, and the effect will be more noticeable. .

[Brief explanation of the drawing]

1 to 3 of the drawings show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view, and FIG.
A line sectional view, FIG. 3 is an explanatory diagram showing the formation state of the gear track, and FIG. 4 is an explanatory diagram showing the formation state of the gear track in a conventional gear pump. 2, 3... Gear hole, 0e, 0e'... Center of gear hole, 4, 5... Gear, 12-15... Bearing hole,
O, O'... Center of bearing hole, t... Depth of gear track.

Claims (1)

[Claims] 1. A gear pump in which a pair of gears that mesh with each other are installed in gear holes of a pump body, and the distance between the centers of the gear holes is shorter than the distance between the centers of the bearing holes of the gear shaft.