JPS63277878A - Gear pump - Google Patents

Abstract

PURPOSE:To improve the durability of a bearing, by forming a low pressure oil introducing hole in a low pressure area of a cover and suction ports, which communicate with this hole, to be deflectively located in an opposite side to the cover from the center of face width of a gear. CONSTITUTION:A low pressure oil introducing hole 54 is provided in a low pressure area in the side of a cover 7, and the hole 54 maintains its depth reaching 1/3 or more times the effective length of bearing holes 8, 9. The low pressure oil introducing hole 54 communicates with suction ports 55, 56 through chambers 44, 45. The ports 55, 56 are formed deflecting in an opposite direction to the cover 7 from the center of face width of both gears 12, 15. Accordingly, the low pressure oil introducing hole 54 maintains its inside always in a low temperature, and also the inside of roll bushes 10, 11 is forcedly cooled, thus a bearing enables its durability to be enhanced by high increasing the viscosity of working fluid.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a gear pump formed by meshing a pair of external gears.

(Prior Art) The conventional gear pump shown in FIGS. 7 to 11 has a body bore 1 formed in its body B, and a pair of bearing holes 3.4 formed in the bottom 2 of the body bore 1. A winding bushing 5.6 is press-fitted into the hole 3.4.

Further, a cover 7 is provided on the side surface of the body B, and a bearing hole 8.9 is also formed in this cover 7. A wound bushing 10.11 similar to that on the body B side is press-fitted into this bearing hole 8.9.

The gear shafts 13 and 14 of the drive gear 12 are rotatably supported by the winding bushings 5 and 10 as described above, and the gear shafts 1B and 1 of the driven gear 15 are supported by the winding bushings 6 and 11.
7 is rotatably supported.

Both gears 12.15 and bottom part 2 inserted into body bore l
A side plate 19 is interposed between the gear 12.15 and the cover 7.

The inner surface of the bearing hole 3.4 is the gear shaft 13.
．． Lubricating return grooves 20 to 23 are formed along the axis of 16. These return grooves 20 to 23 have one end open to the bottom 2 of the body bore 1, and the pair of return grooves 20 and 22, 21 and 23 are connected to a line connecting the axial centers of the gear shafts 13 and 16. return grooves 20 and 21.
．． 22 and 23 are vertically symmetrical with respect to a horizontal center line that is perpendicular to the line connecting the axis center lines.

Note that numerals 24 to 27 in FIG. 8 are depressions formed in the bottom 2 of the body bore 1, which are continuous with the openings of the return grooves 20 to 23.

A concave groove is formed on the inner surface of the winding bushing 5.6 press-fitted into the bearing hole 3.4, and the gear shaft 13.6 is formed in the winding bushing 5.6.
16, the groove forms a lubrication introduction passage 28.2S. This lubrication introduction passage 28.29 has one end opened into an annular groove 30.31 formed at the boundary between gear 12.15 and gear shaft 13.1G, and the other end opened at the tip of gear shaft 13.16. It opens into relay rooms 32 and 33 facing the sky.

As shown in FIG. 9, the side plate 1B maintains a shape that fits snugly into the body bore l, and
A through hole 34.35 is formed through which the gear shaft 13.16 passes. Further, this side plate 18 is formed with a window hole 36 that opens simultaneously into both the recesses 24 and 25 or 26 and 27, and a notch 37 that is continuous with the through hole 34 and 35 on the side of the window hole 36. .38 is formed.

Furthermore, a seal insertion groove 39 is formed on the cover 7 side, and a seal member 40.41 is installed in this seal insertion groove 39, thereby dividing a low pressure area L and a high pressure area H on the outside of the side plate 19. ing.

Furthermore, this cover 7 is formed with lubrication passages 42, 43 as shown in FIG. 10.11. In other words, this lubrication passage 42.43 is formed along the axis of the gear shaft 14.17, and its open end on the low pressure area L side is a straight line passing through the axial center of the gear shaft 14.17. It is opened in the direction of a straight line that is perpendicular to the straight line a connecting the axial centers of the shafts.

Now, if both gears 12.15 are rotated in the direction of the arrow in FIG. 8, one chamber 44 becomes a suction chamber, and the other chamber 45
becomes the discharge chamber. When rotating both gears in the direction of the arrow in this manner, the window hole 38 of the side plate 18 is positioned on the suction chamber 44 side.

If the window hole 36 is located on the suction chamber 44 side, this window hole 36
The depression 24.25 opens to the suction chamber 44 side through the depression 24.25, and the other depression 26.27 and the lubrication return groove 22.23 continuous to this depression are metal-sealed by the side play H8.

Therefore, the low pressure oil sucked into the suction chamber 44 is contained in the tooth grooves of both gears 12, 13 and is discharged to the discharge chamber 45 side. At this time, a part of the low pressure oil contained in the tooth groove flows from the notch 37.38 to the annular groove 30.31 to the lubrication introduction passage 28.
29→Relay chamber 32.33→Lubrication return groove 20.21→
It returns to the suction chamber 44 via the depressions 24, 25 and the window hole 3B.

When both gears 12,15 of the pump are rotated in the direction opposite to the arrows in FIG. 8, chamber 45 becomes a suction chamber and chamber 44 becomes a discharge chamber. At this time, the side plate 18 is also rotated 180 degrees to position the window hole 36 on the side of the chamber 45 which becomes the suction chamber, and the cover 7 is also rotated 180 degrees to reverse the low pressure area L and the high pressure area H.

In this way, the lubrication return grooves 20.21 and the depressions 24.25 continuous with these passages can be formed on the side plate 1.
Since the metal seal is formed, low pressure oil for lubrication is returned to the suction chamber 45 side via the return grooves 22, 23, depressions 2B, 27, and window hole 36.

Further, the pressure loading on the cover 7 side also functions in response to changes in the rotational direction of the gear pump.

(Problems to be Solved by the Present Invention) In the conventional gear pump as described above, when using hydraulic oil contaminated with contamination, for example, when the hydraulic oil is shared with transmission system hydraulic oil. However, the following problems arise.

That is, when this gear pump is driven, the gear shaft 14.
17, a load in the direction of the force indicated by the arrow Fs in Fig. 10 acts, but the distribution of oil film pressure in the winding bush 1O1If at this time is as shown in Fig. 10, and the maximum pressure portion is greater than the load direction FS. It will be slightly lower. As described above, although the maximum part of the oil film pressure and the load direction FS appear to be different from each other, in reality, these forces are exactly balanced due to the friction of the oil film.

However, if the hydraulic oil is contaminated as described above, the inner surface of the winding bushing 10, 11 will be scratched, and no oil film will be formed inside the winding bushing. Therefore, no oil film pressure is generated and the bearing performance deteriorates.

Moreover, if oil film pressure is not generated, the winding bushing will directly receive the load of the gear shaft, and the direction of the load will be in the direction of the above-mentioned FS.

When the load FS acts directly on the winding bushing in this way, the winding bushing in that part may be deformed because the rigidity of this part is insufficient due to the lubrication passages 42, 43.

If oil film pressure is not generated in this way and the wound bushing is deformed, the bearing performance will be extremely poor.

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

(Means for Solving the Problems) In order to achieve the above object, the present invention forms a low pressure oil introduction hole on the cover side at a position corresponding to the low pressure area of the side plate, and also forms a low pressure oil introduction hole at a position corresponding to the low pressure area of the side plate. The hole has a depth that reaches at least 1/3 or more of the bearing effective length of the bearing hole, and the suction port is biased in a direction opposite to the cover from the gear width center of the gear, This suction port is configured to communicate with the low pressure oil introduction hole.

(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 this low pressure oil introduction hole is communicated with the suction port, so that the low pressure oil sucked from the suction port is It flows into the oil introduction hole. Moreover, since the suction port is biased toward the opposite side of the cover from the center of the gear width, when the low-pressure oil flowing from this suction port is sucked into the tooth groove, the flow toward the low-pressure oil introduction hole is prevented. arise.

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

(Effects of the present invention) According to the gear pump of the present invention, the temperature of the hydraulic oil in the bushing on the cover side can be kept low and its viscosity can be maintained high, so even if there is a scratch in the bushing, the hydraulic oil can be maintained. It becomes difficult to leak out. In other words, even if the wound bushing is scratched, the oil film can be maintained, so the bearing performance will not deteriorate.

(Embodiment of the present invention) In the embodiment shown in FIGS. 1 to 6, the bearing hole 3.4 of the body B is
Return grooves 46 and 47 for lubrication are formed in the lubrication grooves, but the positional relationship of the return grooves 46 and 47 is different from that of the conventional one.

That is, the lubrication return groove 46.47 is formed between the opposing parts of the re-press fit hole 3.4 and on a line connecting the axial centers of the gear shafts 13.14.

In each of the return grooves 46 and 47, there is a pair of expansion grooves 4 whose legs are spread to the left and right with the line connecting the axial centers of the gear shafts as the border.
8.48 and 50.51 are connected.

Then, as shown in FIG. 5, one lubrication return groove 46
The bulge 48 that communicates with the lubrication return groove 47 and the bulge 50 that communicates with the other lubrication return groove 47 communicate with each other through the window hole 36 of the side plate 18 . Also, this side plate 18
When rotated by 0° and set in the body bore 1, the bulge 48 communicating with one of the return grooves 46 for lubrication and the bulge 51 communicating with the return groove 47 of the other side are connected to the window hole 36 of the side plate 18. communicate via.

Fig. 6 shows the oil film pressure distribution when the gear is rotated in the direction of arrow 52 or 53, where α is the arrow 5.
The oil film pressure distribution when rotating in two directions and the oil film pressure distribution when β rotates in the arrow 53 direction are shown.

As is clear from FIG. 6, the lubrication return groove 46
．． At the position where 47 is formed, that is, on the line connecting the axial centers of the gear shafts, the oil film pressure at the winding bushing 5.6 does not become so high even if both gears 12.15 are rotated in either the left or right direction.

Since the oil film pressure at the portion where the return grooves 4B and 47 for lubrication are formed does not become so high regardless of the direction of rotation of the gear, the grooves 46, 47 of the winding bushing
The part corresponding to 7 will no longer deform.

Furthermore, the cover 7 side has a low pressure oil introduction hole 54 formed in its low pressure area L;
The depth is maintained to reach 1/3 or more of the effective length of the bearing hole 8.9.

The low-pressure oil introduction hole 54 communicates with a port 55 or 56 formed in the body B, which also serves as a suction port, via the chamber 44 or 45, which is on the low-pressure side depending on the rotational direction of the pump. And this port 5
5.56 is biased toward the opposite direction of the cover 7 from the center of the gear width of both gears 12.15, as shown in FIG.

In addition, the reference numeral 57 in the figure is a relief groove formed in the cover 7.

Therefore, when both gears 12, 15 are rotated in either direction and low pressure oil is sucked from the port 55, the hydraulic oil is contained in the tooth groove because the suction port 55 is biased as described above. In the process until it is released, a flow occurs in the direction of arrow 58 in FIG. Due to this flow, the low-pressure oil is guided to the low-pressure oil introduction hole 54 and the inside thereof is stirred, so that the inside of this low-pressure oil introduction hole 54 is always maintained at a low temperature.

If the inside of the low-pressure oil introduction hole 54 is maintained at a low temperature, the winding bushing 1 fitted into the bearing holes 8 and 9 adjacent to this low-pressure oil introduction hole
0.11 is cooled. Therefore, volume 10.
The viscosity of the hydraulic oil in 11 can be kept high.

In this way, the viscosity of the hydraulic oil in the bushing can be kept high, so even if the inner surface of the bushing 10, 11 is scratched, the oil film can be maintained due to its viscosity.

In this embodiment, the depth of the low pressure oil introduction hole 54 is set to reach a depth of at least 173 or more with respect to the effective length of the bearing hole 8.9. This is because the area where the contact point is strongest is approximately 1/3 of the area above.

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 low-pressure lubrication is carried out there, while on the cover 7 side that requires a loading area, Instead of low-pressure lubrication, the shaft is cooled to maintain bearing performance.

If either the body B side or the cover 7 side has poor bearing performance, the gear 1
2.15 is tilted. When the gear is tilted in this way, a gap is formed between the side plate 18. do not have.

Note that reference numeral 59 in FIG. 3 is a high pressure oil introduction hole formed on the high pressure area H side.

[Brief explanation of the drawing]

Drawings 1 to 6 show embodiments of this invention.
The figure is a cross-sectional view, Figure 2 is a cross-sectional view with the gear in Figure 1 removed, Figure 3 is a cross-sectional view taken along the line m-m in Figure 1, and Figure 4 is a cross-sectional view taken along the line ■〒■ in Figure 3. Figure 5 is a sectional view taken along the line V-V in Figure 1, Figure 6 is a diagram showing the distribution of oil film pressure within the bushing, and Figures 7 to 11 show a conventional gear pump.
Fig. 7 is a sectional view, Fig. 8 is a sectional view taken along the line ■-■ in Fig. 7, Fig. 9 is a front view of the side plate, and Fig. 10 is a
11 is a cross-sectional view of the blade in FIG. 10. B...Body, l...Body bore, 3.4.8.9
...bearing hole, 12.15...gear, 18.19...
・Side plate, L...Low pressure area, H...High pressure area, 54...Low pressure oil introduction hole, 55.56...Port constituting a suction port or a discharge port.

Claims (1)

[Claims] A pair of gears is housed in a body bore formed in the body, and a suction port and a discharge port are formed in this body, and a cover is provided on one side of the body, and a bearing hole formed in the body and cover is provided with a cover. In the gear pump, a gear shaft is inserted, and a side plate is provided on the side surface of the gear on the cover side, and a low pressure area and a high pressure area are divided on the outer surface of the side plate. A low-pressure oil introduction hole is formed at a position corresponding to the low-pressure area, and the low-pressure oil introduction hole has a depth that reaches at least ⅓ or more of the bearing effective length of the bearing hole, and A gear pump in which a suction port is biased in a direction opposite to the cover relative to the gear width center of the gear, and the suction port is communicated with the low pressure oil introduction hole.