JPH0666264A - Gear pump - Google Patents

Abstract

PURPOSE:To enhance the efficiency of a pump by keeping the depth of a gear track constant irrespective of the operating condition of the pump, such as whether the pump is rotated at low or high speeds. CONSTITUTION:A recessed portion 29 is formed in a shaft hole and when a gaer shaft is biased by the effect of pressure on a gear spiral bushes 9-12 to bite into the recessed portion 30 so that an indentation 30 is formed inside the portion 29. The gear shaft is held by the indentation 30 and is always biased in a certain direction even if the direction in which the pressure acts on the gear varies.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear pump whose pump efficiency is stable during both high speed rotation and low speed rotation.

[0002]

2. Description of the Related Art The conventional gear pump shown in FIGS. 5 to 9 has a housing H composed of a body 1 and mounting flanges 2 and covers 3 provided on both sides of the body. A body bore 4 is formed in the body 1, and the body bore 4 is closed by the mounting flange 2 and the cover 3. Then, the mounting flange 2 and the cover 3 are respectively provided with shaft holes 5 to 8
And one axial hole 5 of the mounting flange 2 penetrates the mounting flange 2. Winding bushes 9 to 12, which are plain bearings, are press-fitted into the shaft holes 5 to 8, respectively.

The body bore 4 has a pair of gears 13,
14 and the gear shafts 15 to 18 provided on both sides of the gears 13 and 14 are attached to the winding bushes 9 to 1.
Inserted in 2. However, only the gear shaft 15 supported on the mounting flange 2 side by the gear shaft of the one gear 13 penetrates the mounting flange 2 as a drive shaft, and the tip thereof is projected to the outside. In the figure, reference numerals s ₁ and s ₂ are side plates which are provided along both sides of the gears 13 and 14 to prevent fluid from leaking from the tooth space.

In such a gear pump, the gear shaft 1
When 5 is driven to rotate the gears 13, 14 in the direction of arrow 19 shown in FIGS. 6 and 7, the fluid sucked from the suction port 20 is carried to the tooth space and discharged from the discharge port 21. At this time, the high pressure on the discharge port 21 side acts on the gears 13 and 14, so that the gears 13 and 14 receive a force in the direction of arrow 22 in FIG. 6 or arrow 23 in FIG. When such a force is applied to the gears 13 and 14, as shown in FIG.
8, the gears 13 and 14 are pressed in the directions of the arrows 22 and 23 while being eccentric with respect to the winding bushes 9 to 12, as shown in FIGS. 6 and 7, on the low pressure side of the body bore 4. , Gear tracks 24, 25 are formed. The gear tracks 24 and 25 ensure that the gears 13 and 14 and the body bore 4 are in close contact with each other and prevent fluid leakage there.

The gear track when the gear pump is operated as described above maintains the pump efficiency of the pump while preventing fluid leakage. The gear track is used when the pump rotates at low speed and at high speed. And are formed differently. For example, at low speed rotation, the high pressure region in the tooth space is in the range of arrow 26 as shown in FIG. 6, but at high speed rotation the high pressure region is in the range of arrow 27 as shown in FIG. If the high pressure region in the tooth space is different, the gear 1
Direction of acting force on 3, 14, ie, arrow 2 in FIG.
2 and the direction of arrow 23 in FIG. 7 are different. This difference in direction is, of course, due to the gear tracks 24, 2
Also affects the formation of 5. In other words, at low speed rotation,
The gear track 24 is as shown by the broken line in FIG. 9, and the gear track 25 is as shown by the solid line in FIG. 9 during high speed rotation.

[0006]

In the conventional gear pump as described above, the formation state of the gear track is different between the low speed rotation and the high speed rotation. Under the above circumstances, when the pump is operated at high speed, there is a problem that the amount of fluid leaks in the truck portion and the pump efficiency is significantly deteriorated. An object of the present invention is to provide a gear pump in which a constant gear track is formed regardless of the rotation speed of the pump and stable pump efficiency can be achieved.

[0007]

According to the present invention, a pair of gears are incorporated in a body bore formed in a housing, and a rolling bush, which is a slide bearing, is press-fitted into a shaft hole formed in the housing. It is premised on a gear pump configured to support the. While assuming the above gear pump, the present invention forms a speed slot for guiding high pressure to the tooth space of the gear, and
It is characterized in that a concave portion is formed in the shaft hole surface corresponding to the portion where the gear shaft comes into pressure contact when the gear rotates.

[0008]

Since the present invention is configured as described above, when the gear shaft is eccentric during the operation of the pump, the pressing force at that time causes the winding bush to bite into the recess side. When the winding bush bites into the recess in this way, the inside of the winding bush also dents, but this depression holds the peripheral surface of the gear shaft. Therefore, even if the acting direction of the pressure on the gear is different between the low speed rotation and the high speed rotation, the gear shaft is held in the recess of the winding bush, so that the shift direction of the gear shaft becomes constant and the gear track also It is constant regardless of the rotation speed of the pump.

[0009]

According to the gear pump of the present invention, a constant gear track can be formed regardless of the rotational speed of the pump, so that the pump efficiency can be stabilized regardless of the operating condition of the pump.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment shown in FIGS. 1 to 4, the conventionally known speed slot 28 is formed in the side plates s ₁ and s ₂ , and the shaft holes 5 for press-fitting the winding bushes 9 to 12 are formed. 8 to 8 is different from the conventional one in that a concave portion 29 parallel to the axis is formed. Therefore, the same components as those of the related art will be described with the same reference numerals, and the detailed description of the configuration will be omitted. The recess 29 is formed at a position where the gear shafts 15 to 18 are most strongly pressed against the winding bushes 9 to 12 when the pump rotates at high speed. In other words, the recess 29 is formed at a portion where the extension line of the arrow 23 in FIG. 7 and the shaft holes 5 to 8 intersect. The reason why the speed slot 28 is formed as described above is to stabilize the high pressure region of the tooth space within this speed slot range regardless of the operating condition of the pump.

Next, the operation of this embodiment will be described. First, when the pump is rotated at a high speed, the fluid sucked from the suction port 20 is discharged from the discharge port 21 in the same manner as in the conventional case. At this time, the high-pressure fluid on the discharge port 21 side is guided to the tooth spaces of the gears 13 and 14 via the speed slot 28. By the action of the high pressure guided to the tooth space, the gears 13 and 14 are pressed against the low pressure side of the body bore 4,
Although the gear track 25 is formed, the speed slot 28 stabilizes the high pressure region thereof and stabilizes the formation position of the gear track 25 to some extent. In this way, the gear 13,
When 14 is pressed to the low pressure side, the force is applied to the gear shaft 15
It also acts on the winding bushes 9 to 12 through ~ 18,
The winding bush portion corresponding to the recesses 29 formed in the shaft holes 5 to 8 as described above bites slightly into the recesses 29 as shown in FIG.

[0012] When the wound bush bites in this way, a dent 30 is formed on the inside thereof. The dent 30 holds the gear shafts 15 to 18 and prevents the shift. Therefore, in this embodiment, the gear pump is leveled at a high speed to form the gear track 25 and the recess 30 is formed in the portion corresponding to the recess 29.
Even if the pump is rotated at a low speed, the gear shafts 15 to 18 do not shift so much, so that a gear track 24 different from the gear track 25 formed at a high speed is formed. It will not be formed. Since the gear track is always constant in this way, the pump efficiency will be stable even if the operating condition of the pump changes.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a meshed state of gears and a position of a speed slot.

FIG. 2 is an enlarged partial sectional view of a speed slot forming portion of a side plate.

FIG. 3 is an enlarged partial sectional view showing a relative relationship between a gear shaft, a winding bush, and a recess.

FIG. 4 is an enlarged partial cross-sectional view showing a situation in which a winding bush bites into a recess.

FIG. 5 is a sectional view of a conventional gear pump.

FIG. 6 is an explanatory diagram showing a state of formation of gear tracks when a conventional gear pump rotates at a low speed.

FIG. 7 is an explanatory diagram showing a state of formation of gear tracks when a conventional gear pump rotates at high speed.

FIG. 8 is an enlarged partial sectional view showing a relative relationship between a gear shaft and a winding bush of a conventional gear pump.

FIG. 9 is an explanatory diagram showing a difference in a formation state of a gear track between a low speed and a high speed of a conventional gear pump.

[Code]

 H housing 4 body bore 5-8 shaft hole 9-12 winding bush 13, 14 gear 15-18 gear shaft 28 speed slot 29 recess

Claims (1)

[Claims] 1. A gear pump having a structure in which a pair of gears are incorporated in a body bore formed in a housing, and a rolling bush, which is a slide bearing, is press-fitted into a shaft hole formed in the housing, and the gear bush is supported by the rolling bush. A gear pump having a speed slot for introducing a high pressure to a tooth groove of the gear and a recess formed in the shaft hole surface corresponding to a portion to which the gear shaft is pressed when the gear rotates.