JP2613052B2 - Gear pump - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a gear pump formed by engaging a pair of external gears.

(Prior Art) In the conventional gear pump shown in FIGS. 7 to 11, a body bore 1 is formed in a body B, and a pair of bearing holes 3 and 4 are formed in a bottom portion 2 of the body bore 1. The winding bushes 5 and 6 are press-fitted into the holes 3 and 4.

A cover 7 is provided on the side surface of the body B, and bearing holes 8 and 9 are formed in the cover 7.
The same winding bushes 10 and 11 as those on the body B side are press-fitted into the bearing holes 8 and 9.

The gear shafts 13 and 14 of the drive gear 12 are rotatably supported by the winding bushes 5 and 10 as described above, and the gear shafts 16 and 17 of the driven gear 15 are rotatably supported by the winding bushes 6 and 11. ing.

A side plate 18 is interposed between the two gears 12 and 15 inserted into the body bore 1 and the bottom 2, and a side plate 19 is interposed between the two gears 12 and 15 and the cover 7.

The inner surfaces of the bearing holes 3 and 4 and the gear shaft 1
The lubrication return grooves 20 to 23 are formed along the axes 3 and 16. One end of each of the return grooves 20 to 23 is opened to the bottom 2 of the body bore 1.
2, 21 and 23 are symmetrical with respect to the line connecting the shaft centers of the gear shafts 13 and 16, and the return grooves 20 and 21, 22 and 23 are horizontal center lines orthogonal to the line connecting the shaft center lines. Is vertically symmetrical.

In FIG. 8, reference numerals 24 to 27 indicate the bottom 2 of the body bore 1.
And is continuous with the openings of the return grooves 20 to 23.

A concave groove is formed on the inner surface of the winding bushes 5, 6 press-fitted into the bearing holes 3, 4, and the gear shafts 13,
By inserting 16, the concave groove will be
28 and 29 are configured. This lubrication introduction passage
The relays 28 and 29 have one ends opened in annular grooves 30 and 31 formed at the boundaries between the gears 12 and 15 and the gear shafts 13 and 16, and the other ends facing the tips of the gear shafts 13 and 16. The chambers 32 and 33 are open.

As shown in FIG. 9, the side plate 18 retains a shape that fits into the body bore 1 and
Through holes 34 and 35 for passing the gear shafts 13 and 16 are formed. Further, the side plate 18 has the recess 24 described above.
A window hole 36 is formed at the same time at 25 or both 26 and 27, and cutouts 37, 38 are formed on the window hole 36 side.

On the cover 7 side, a seal insertion groove 39 is formed, and by attaching seal members 40 and 41 to the seal insertion groove 39, a low-pressure area L and a high-pressure area H are defined outside the side plate 19. ing.

Further, lubrication passages 42 and 43 are formed in the cover 7 as shown in FIGS. In other words, this lubrication passage
42 and 43 are formed along the axis of the gear shafts 14 and 17 and connect the open ends of the low-pressure area L side to the shaft centers of both gear shafts with straight lines passing through the shaft centers of the gear shafts 14 and 17. It is opened in the direction of a straight line b perpendicular to the straight line a.

If both gears 12 and 15 are rotated in the direction of the arrow in FIG. 8, one chamber 44 becomes a suction chamber and the other chamber 45 becomes a discharge chamber. When both gears are rotated in the direction of the arrow, the window 36 of the side plate 18 is positioned on the suction chamber 44 side.

If the window 36 is located on the suction chamber 44 side, the depressions 24 and 25 are opened toward the suction chamber 44 through the window 36, and the other depression 26,
27 and the lubricating return grooves 22 and 23 continuing from the depression are metal-sealed by the side plate 18.

Therefore, the low-pressure oil sucked into the suction chamber 44 is discharged to the discharge chamber 45 side while being included in the tooth grooves of both gears 12 and 13. At this time, a part of the low-pressure oil contained in the tooth space
→ Annular grooves 30, 31 → Lubrication introduction passages 28, 29 → Relay chambers 32, 33
→ Return grooves 20 and 21 for lubrication → Dents 24 and 25 → Return to suction chamber 44 via window hole 36.

When both gears 12 and 15 of the pump are rotated in the direction opposite to the arrow in FIG. 8, the chamber 45 becomes a suction chamber and the chamber 44 becomes a discharge chamber. At this time, the side plate 18 is also rotated by 180 ° to position the window hole 36 on the side of the chamber 45 serving as the suction chamber, and the cover 7 is also rotated by 180 ° so that the low-pressure area L and the high-pressure area H are reversed.

By doing so, the lubricating return grooves 20, 21 and the depressions 24, 25 connected to these passages are metal-sealed by the side plate 18, so that the lubricating low-pressure oil is returned to the return grooves 22, 23, It is returned to the suction chamber 45 side via the depressions 26 and 27 and the window hole 36.

Further, the fresher loading on the cover 7 also functions while responding to the change in the rotation direction of the gear pump.

(Problems to be solved by the present invention) In the conventional gear pump as described above, for example, when the hydraulic oil is shared with the hydraulic oil of the transmission system,
The following problems arise when using contaminated hydraulic oil.

That is, when this gear pump is driven, the gear shaft 14,
The 17, although the load of the arrow F _S direction of FIG. 10 is applied, the distribution of the oil film pressure in the winding bush 10 and 11 at this time, the
As shown in Fig. 10, the maximum pressure part is
Slightly below F _S. As described above, the load direction F _S of the maximum portion of the oil film pressure is apparently different, but in reality, these forces are just balanced by the action of the friction of the oil film.

However, if the working oil is contaminated as described above, the inner surfaces of the winding bushes 10 and 11 will be damaged, so that an oil film will not be formed in the winding bushes. Therefore, no oil film pressure is generated, and the bearing performance deteriorates.

Moreover, when the oil film pressure is not generated, will receive the load of the gear shaft directly winding bush, the direction of the load is in the direction of F _S described above.

When the load F _S acts directly on the winding bush as described above, the rigidity of this portion is insufficient due to the lubricating passages 42 and 43, and the winding bush of this portion is deformed.

If no oil film pressure is generated and the wound bush is deformed, the bearing performance is extremely deteriorated.

An object of the present invention is to provide a gear pump whose bearing performance does not deteriorate even if the working oil is contaminated.

(Means for Solving the Problems) The present invention relates to a cover having a low-pressure oil introduction hole which is opened at a position corresponding to the low-pressure area of the side plate and at a position facing the chamber of the body bore where the suction port opens. In addition, the low-pressure oil introduction hole has a depth that reaches at least 1/3 or more of the effective bearing length of the bearing hole, while the suction port is set at a position larger than the center of the gear width of the gear. The feature is that it is deviated in the opposite direction to the cover.

(Operation of the Present Invention) As described above, the low-pressure oil introduction hole is formed in the low-pressure area of the cover, and the low-pressure oil introduction hole is communicated with the suction port. It flows into the oil introduction hole. In addition, the suction port is deviated to the opposite side of the cover from the center of the gear width, so that when the low-pressure oil flowing from the suction port is sucked into the tooth space, the flow in the direction of the low-pressure oil introduction hole is reduced. Occurs.

Therefore, the inside of the low-pressure oil introduction hole is in a state of being stirred by the low-pressure oil, and is always kept at a low temperature. If the low-pressure oil introduction hole is maintained at a low temperature in this way, the inside of the winding bush is also forcibly cooled, so that the viscosity of the hydraulic oil therein increases.

(Effect of the Present Invention) According to the gear pump of the present invention, the temperature of the hydraulic oil in the winding bush on the cover side can be kept low and its viscosity can be kept high. It becomes difficult to flow. In other words, even if a wound is formed in the winding bush, the oil film can be maintained, so that the receiving performance does not decrease.

(Embodiment of the Present Invention) The embodiment shown in FIGS.
4, lubrication return grooves 46 and 47 are formed, but the positional relationship between the return grooves 46 and 47 is different from that of the related art.

That is, the lubricating return grooves 46 and 47 are formed between the opposing portions of the press-fit holes 3 and 4 and on the line connecting the shaft centers of the gear shafts 13 and 14.

In each of the return grooves 46 and 47, a pair of leg grooves 48 opened to the left and right with respect to a line connecting the shaft centers of the gear shafts,
49, 50 and 51 are connected.

Then, as shown in FIG.
And a leg groove 48 communicating with the other lubricating return groove 47 communicates through the window hole 36 of the side plate 18. When the side plate 18 is rotated by 180 ° and set in the body bore 1, a leg groove 51 communicating with one lubricating return groove 46 and a leg groove 49 communicating with the other lubricating return groove 47 are formed. Communicate with each other through the window hole 36 of the side plate 18.

FIG. 6 shows the oil film pressure distribution when the gear is rotated in the direction of the arrow 52 or 53, where α is the oil film pressure distribution when the gear is rotated in the direction of the arrow 52, and β is that in the direction of the arrow 53. 3 shows the oil film pressure distribution of FIG.

As is apparent from FIG. 6, the lubricating return groove 4
At the positions where the gears 6 and 47 are formed, that is, on the line connecting the shaft centers of the gear shafts, the oil film pressure in the winding bushes 5 and 6 does not increase so much even when the gears 12 and 15 are rotated in either the left or right direction.

Since the oil film pressure in the portion where the lubricating return grooves 46 and 47 are formed does not increase so much regardless of the rotation direction of the gear, the portion of the winding bush corresponding to the grooves 46 and 47 is deformed. No longer.

Further, a low-pressure oil introduction hole 54 is formed in the low-pressure area L on the cover 7 side, and the low-pressure oil introduction hole 54 has a depth reaching at least 1 / of the effective length of the bearing holes 8 and 9. Is maintained.

The low-pressure oil introduction hole 54 thus formed is connected to a port formed in the body B, which is also a suction port, through the chamber 44 or 45 on the low pressure side according to the rotation direction of the pump.
Connect to 55 or 56. And this port 55, 56
2, as shown in FIG. 2, the gears 12 and 15 are deviated in the direction opposite to the cover 7 from the center of the gear width.

Note that reference numeral 57 in the figure denotes a relief groove formed in the cover 7.

Then, rotate both gears 12 and 15 in either direction,
When the low-pressure oil is sucked from the port 55, the suction port 55 is deviated as described above, so that a flow in the direction of the arrow 58 in FIG. 2 occurs in the process until the hydraulic oil is included in the tooth space. By such a flow, the low-pressure oil is supplied to the low-pressure oil introduction hole 54.
The low pressure oil introduction hole
Inside 54 is always kept at low temperature.

If the inside of the low-pressure oil introduction hole 54 is maintained at a low temperature, the winding bush 10 fitted in the bearing holes 8 and 9 adjacent to the low-pressure introduction hole,
11 is cooled. Therefore, the viscosity of the hydraulic oil in the winding bushes 10 and 11 can be kept high.

Since the viscosity of the hydraulic oil in the winding bush can be kept high as described above, for example, even if the inner surfaces of the winding bushes 10 and 11 are damaged, an oil film can be maintained due to the viscosity.

In this embodiment, the depth of the low-pressure oil introduction hole 54 reaches at least one third or more of the effective length of the bearing holes 8 and 9. , 17 has the strongest contact area approximately 1/3 above
Because it is about.

As described above, in this embodiment, a low-pressure lubrication passage is actively provided on the body B side that does not require a loading area, and the low-pressure lubrication is performed. Instead of low pressure lubrication, it cools around its axis to maintain bearing performance.

If the bearing performance of either the body B side or the cover 7 side is inferior, the gear
12, 15 tilt. When the gear tilts in this way,
Although a gap is formed between the side plates 18 and 19 and the gear side surfaces to increase oil leakage, this embodiment has no such problem.

Reference numeral 59 in FIG. 3 denotes a high-pressure oil introduction hole formed on the high-pressure area H side.

[Brief description of the drawings]

1 to 6 show an embodiment of the present invention.
FIG. 2 is a cross-sectional view, FIG. 2 is a cross-sectional view of FIG. 1 with the gear removed, FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 1, and FIG. FIG. 5, FIG. 5 is a cross-sectional view taken along the line VV of FIG. 1, FIG. 6 is a view showing the distribution of oil film pressure in the winding bush, and FIGS.
7 is a sectional view, FIG. 8 is a sectional view taken along line VIII-VIII of FIG. 7, FIG. 9 is a front view of the side plate, FIG. 10 is a sectional view taken along line XX of FIG. FIG. 11 is a sectional view taken along line XI-XI in FIG. B ... body, 1 ... body gear, 3, 4, 8, 9 ...
Bearing holes, 12, 15 ... gears, 18, 19 ... side plates,
L: low-pressure area, H: high-pressure area, 54: low-pressure oil introduction hole, 55, 56: ports constituting a suction port or discharge port.

Claims (1)

(57) [Claims] 1. A body bore formed in a body is provided with a pair of gears, a suction port and a discharge port are formed in the body, and a cover is provided on one side of the body. A gear shaft is inserted into the bearing hole, and a side plate is further provided on a gear side surface on the cover side, and the low pressure area and the high pressure area are partitioned on an outer surface of the side plate. A low-pressure oil introduction hole is formed at a position corresponding to the low-pressure area of the side plate and at a position facing the chamber of the body bore where the suction port opens, and the low-pressure oil introduction hole is formed in the bearing of the bearing hole. While maintaining a depth that reaches at least 1/3 or more of the effective length, the suction port is closer to the cover than the gear shaft center of the gear. Gear pump which is biasing the pair direction.