JP2001107879A - Gear pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem such as noise, vibration and failure of a shaft seal member caused by application of approximately the same negative pressure as suction pressure to a shaft sealing part in a self-lubricating reflux route for a driving shaft in a gear pump. SOLUTION: In this gear pump lubricating its shaft by itself by refluxing to a shaft sliding clearance 33 a part of liquid fed from a low pressure chamber L in which pump suction pressure is formed to a high pressure chamber H in which pump discharge pressure is formed, a shaft lubricating reflux passage is formed which has an inflow opening 32 opened in a gear chamber 30 on the high pressure chamber side and an outflow opening 38 opened in a region to which intermediate pressure between pump discharge pressure and pump suction pressure is applied from the shaft sliding clearance 33 through a shaft sealing part cavity 52. In the shaft sliding clearance of a driving shaft 10, a restriction part 34 having a desired shaft length may be formed which has a shorter cross sectional area S1 of the shaft sliding clearance on a shaft sealing part 5 than the cross sectional area S2 thereof on an inflow side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a gear pump in which a pressure difference is formed by meshing rotation of a pair of gears to send a fluid, and in particular, a part of the fluid to be sent is put into a shaft sliding gap. The present invention relates to a gear pump having a shaft lubricating annular flow path of a gear pump which is circulated and self-lubricated.

[0002]

2. Description of the Related Art Conventionally, a gear pump P typified by a hydraulic pump, as shown in FIG. 8, has a pair of gears g, g which are supported in a body b and mesh with and rotate in a gear chamber j. j
A high-pressure chamber H in which a pump discharge pressure (hereinafter, referred to as “discharge pressure”) is formed on a meshing side of a meshing portion k, and a pump suction pressure (hereinafter, “suction pressure”) is formed on a disengaging side of the meshing portion k of the gear chamber j. And a low-pressure chamber L formed. The pair of gears g,
g, one of which is attached to the driven shaft s and the other is the drive shaft o
Mounted on The drive shaft o extends outside the body b via a shaft seal material such as an oil seal or packing, and is connected to an external drive means such as a motor. And
The self-lubricating gear pump P adopts a configuration in which a part of a liquid (mainly, an oil liquid) to be pumped is introduced into a bearing hole h of a drive shaft o and a driven shaft s and used as shaft lubrication. An annular flow path for the shaft lubrication flows into the high pressure chamber H or the inflow port i formed in the gear chamber j on the high pressure chamber H side, and is formed in the low pressure chamber L through the bearing hole h and the inside of the shaft sealing portion. The path taken out from the outlet d is taken.

[0003]

However, in the conventional configuration of the recirculation path, there is a problem that the shaft seal material is liable to be damaged or deteriorated at an early stage. That is, since the liquid (mainly, the oil liquid) flowing from the high pressure chamber side is returned from the inside of the shaft sealing section through the outlet hole communicating with the low pressure chamber, the shaft sealing section has substantially the same pressure as the suction pressure. Pressure was acting. For this reason, the shaft seal material is easily affected by the quality of the suction condition of the hydraulic circuit.For example, when the suction pressure becomes a negative pressure, a pressure equal to or higher than the seal withstand pressure acts on the shaft seal material accordingly, External air is sucked from the seal lip portion of the shaft sealing material, and this is mixed into the hydraulic oil, causing problems such as noise, vibration, and defective discharge pressure. In the worst case, the shaft seal material may be damaged and fall off, so that it is necessary to adopt a complicated or expensive structure such as a double oil seal, a gland packing, or a mechanical seal.

[0004]

Therefore, the present invention has been made in view of such a problem, and the position of the outlet of the shaft lubricating ring flow path of the self-lubricating gear pump is removed from the low pressure chamber where the suction pressure directly acts. By providing an optimal position on the gear chamber side, a gear pump is provided which aims to maintain the inside of the shaft enclosing section at a low pressure state other than negative pressure and to have a structure capable of withstanding pressure even with a normal shaft seal material. Is what you do.

[0005]

To achieve the above object, a gear pump according to the present invention is configured as follows. That is, the gear chambers (30, 4,
0), a pair of gears (1, 2) meshing and rotating within the gear chamber (30, 40), and a pump discharge pressure formed at the meshing side of the meshing portion of the gear chambers (30, 40), and a high pressure communicated with the discharge port (7). Room (H)
And a low-pressure chamber (L) in which a pump suction pressure is formed on the disengagement side of the meshing portion of the gear chambers (30, 40) and communicates with the suction port (6). In the gear pump for recirculating a part of the liquid sent to the high-pressure chamber (H) to the shaft sliding gap (33) to lubricate the self-shaft, the high-pressure chamber (H) or the gear chamber (30) on the high-pressure chamber side Inlet (3
2), and the space inside the shaft enclosing part (5
After 2), a shaft having an outlet (38) in a region where an intermediate pressure between the pump discharge pressure and the pump suction pressure acts or in a region where the intermediate pressure and the pump suction pressure alternately act. The lubrication ring channel is formed.

Further, the shaft sliding gap (3) of the drive shaft (10)
In 3), the shaft sliding gap (33) on the shaft enclosing portion (5) side
Is characterized in that a narrowed portion (34) having a predetermined axial length is formed in which the cross-sectional area (S1) is smaller than the cross-sectional area (S2) of the shaft sliding gap (33) on the inflow side.

[0007] In the claims and the means for solving the problems described above, reference numerals in parentheses are added for reference in order to facilitate understanding of the structure of the invention. It is needless to say that the present invention is not limited to the form on the drawing.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of a gear pump according to the present invention will be described in detail with reference to the drawings. 1 is a partially cutaway perspective view showing an overall view of the gear pump of the present embodiment, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG. FIG. 4 is a sectional view taken along the line BB of FIG. 2 (partially displaced), and FIG. 5 is a sectional view (A) showing the sectional view taken along the line CC in FIG. FIG. 6B is a sectional view showing FIG.
FIG. 7 is a cross-sectional view showing another embodiment, and FIG. 7 is a cross-sectional area ratio S1 / S2 (cross-sectional area of a shaft sliding gap on the shaft enclosing portion side: S1; It is a graph which shows the relationship between the cross-sectional area of a dynamic gap: S2) and a time lag,
FIG. 8 is a sectional view showing an outlet and an inlet in a conventional gear pump.

In the gear pump of this embodiment, the front body side (the left side in FIG. 1) is defined as the front side. In general, a gear pump sends a liquid (mainly an oil liquid) by a pressure difference caused by the engagement and disengagement of a pair of gears that rotate in mesh with each other, and is mainly supported by the drive shaft 10. A driven gear 1, a driven gear 2 supported on a driven shaft 20, and a front body 3 and a rear body 4 for accommodating them by matching. Incidentally, these gear pumps include an external gear pump that meshes external gears engraved on the outer circumference, and an internal gear pump that meshes an internal gear engraved on the inner circumference with an external gear engraved on the outer circumference. And both types exist.

This embodiment will be described first when applied to an external gear pump. More specifically, the drive gear 1 and the driven gear 2 are engaged and housed in a gear chamber 40 on the rear body 4 side in a meshed state, and the drive shaft 10 and the driven shaft 20 And fixed by matching with the rear body 4. Then, the drive shaft 10 extends outward from the front body 3 through the shaft enclosing portion 5 and holds the drive shaft. This drive shaft 1
An external drive means (not shown) such as a motor is connected to 0.

An elliptical concave gear chamber 30 is formed in the front body 3 so that the gears 1 and 2 can be fitted therein.
The gear chamber 30 has bearing holes 31 and 35 for both shafts. In addition, bearing means (not shown) such as a bush and a rolling bearing may be fitted and mounted in the bearing holes 31 and 35 as necessary. In the bearing hole 31 on the drive shaft 10 side (hereinafter referred to as “drive shaft bearing hole”) 31, a shaft enclosing portion 5 is formed at the front end (left side in FIG. 1) projecting like a boss. are doing. In the shaft enclosing portion 5, a shaft seal of the drive shaft 10 is performed by a shaft seal material 51 such as an oil seal or a packing via an annular adapter 50 which is screwed into an outer ring with the protruding portion. This shaft sealing material 5
In the inner space 1, the inner space 5 of the shaft enclosing portion, which is an eye of the present invention, is provided.
2 are formed.

The sliding surface 30a of the gear chamber 30 on the high-pressure chamber H side of the front body 3 has an upper portion (on the drawing) on the drive gear 1 side and a lower portion on the driven gear 2 side. An inflow port 32 serving as an inlet of the shaft lubrication ring channel is formed. The inlet 32 is provided in the gear chamber 30
The sliding surface 30a is formed in a substantially scaly groove shape as viewed from the front and connected to the bearing holes 31 and 35 from the outer peripheral portion.

The drive shaft bearing hole 31 has an introduction groove 33 a and a fixed shaft sliding gap 33 between the drive shaft 10 and the outer peripheral surface of the drive shaft 10.
Is formed, and a part of the liquid (usually an oil liquid) is circulated and lubricated. Further, in the drive shaft bearing hole 31, as shown in FIGS. 4 and 5, a throttle portion 34 having a fixed shaft length is formed on the shaft enclosing portion 5 side. The throttle portion 34 determines the cross-sectional area S1 of the shaft sliding gap 33 by the shaft sliding gap 3 on the inflow port 32 side.
3 is smaller than the cross-sectional area S2 (S1 <S2).

The change in the length of the throttle section 34 causes a change in the relationship between the ratio of the two cross-sectional areas (S1 / S2) and the time lag (delay in the liquid feeding time). The time lag can be adjusted by appropriately setting the cross section ratio (S1 / S2) and the pulsation due to liquid feeding can be suppressed. In the present embodiment, the length l of the narrowed portion 34 is set to 25 mm, and the sectional area ratio S1 / S2 is set to 0.3, and the time lag at that time is 20 seconds (sec).
(FIG. 7). By the way, the length l of the narrowed portion 34 is 20 m
Changes in the time lag with respect to various cross-sectional area ratios when m and 30 mm are set are as shown in FIG.

A shaft communication passage 36 is formed between the drive shaft bearing hole 31 and a bearing hole (“driven shaft bearing hole”) 35 on the side of the driven shaft 20 to allow the shaft sliding gaps 33 to communicate with each other. ing.

Further, from the shaft enclosing portion 5, a return flow passage 37 penetrating through the front body 3 and provided in parallel with the drive shaft bearing hole 31 is formed. The return flow path 37 communicates the inside space 52 of the shaft enclosure with the gear chamber 30, and the formation position of the outlet 38 into the gear chamber 30 is the main subject of the present invention.

As shown in FIGS. 2 and 3, the outlet 38 is opened at a position slightly closer to the sliding surface 30a of the gear chamber 30 from the low-pressure chamber L. In other words, the opening position is appropriately set on the sliding surface 30a facing the region where the intermediate pressure between the pump discharge pressure and the pump suction pressure acts or the region where the intermediate pressure and the pump suction pressure alternate. It is formed with an opening diameter. In addition, the outlet 3
8 is opened and closed, the opening position is appropriately selected to obtain an optimum working pressure. In the present embodiment, the opening position is set near the tooth space, and the opening diameter is φ = 2 to 3 mm.
Is set to

As described above, the shaft lubrication ring flow path is provided with the inflow port 32,
It is composed of a shaft sliding gap 33, a shaft communication passage 36, a throttle portion 34, a shaft enclosing portion inner space 52, a return flow passage 37, and a forward path leading to an outlet 38.

Since the self-lubrication of the bearing holes of the drive shaft 10 and the driven shaft 20 on the rear body 4 side employs the same self-lubricating flow path as in the above-mentioned prior art, a detailed description of the structure will be given. Is omitted. Further, a discharge port 7 for sending out liquid is provided in the body on the high pressure chamber H side of the gear pump, and a low pressure chamber L
A suction port 6 for sucking a liquid is formed in the body on the side.

[0020]

Operation of the present embodiment The gear pump of the present embodiment having the above configuration operates as follows. When both gears 1 and 2 are driven in a synchronous reverse rotation manner (arrow t) via the drive shaft 10, as shown in FIG. 2, a low-pressure chamber is formed in the gear chamber on the side where the meshed teeth of both gears 1 and 2 are sequentially disengaged. L, and the side where the teeth bite one after another becomes the high-pressure chamber H. As a result, the feed liquid (oil liquid) is sucked from the suction port 6 communicating with the low-pressure chamber L (arrow I), and is transferred to the high-pressure chamber H and flows out of the discharge port 7 communicating with the high-pressure chamber H at a predetermined flow pressure. (Arrow O).

At the same time, on the front body 3 side, a part of the feed liquid is sucked in from the inflow port 32 and flows through the shaft sliding gaps 33 to wet the bearing holes 31 and 35, and then sequentially. The air flows from the shaft communication passage 36, the throttle portion 34, the shaft enclosure inner space 52, and the return flow passage 37 to the gear chamber 30 via the outlet 38.

At this time, the suction pressure (usually a negative pressure) generated in the low pressure chamber L does not act on the outlet 38 as it is.
A higher intermediate pressure or a pulsating pressure between the suction pressure and the intermediate pressure acts. For this reason, a pressure greater than the suction pressure acts on the shaft sealing material 51 that forms a part of the inner surface of the shaft enclosure inner space 52 that communicates with the outlet 38 via the return flow path 37, and at least the negative pressure is reduced. It does not work.

In this embodiment, the suction pressure (gauge pressure) is-
To 4.9 × ¹⁰ -3 MPa, when the discharge pressure (the gauge pressure) was set to 9.8 × ¹⁰ -3 MPa respectively and 0.44MPa, respectively the outlet 38 0 MPa and 0.
A pressure (gauge pressure) of 012 MPa was acting. Further, since the flow of the lubricating oil flowing from the inflow port 32 is suppressed by the throttle section 34, the pressure (discharge pressure) of the inflow port 32 is prevented from acting on the inner space 52 of the shaft enclosing section at once. In addition, self-lubricating recirculation is performed on the rear body side in the conventional manner.

[0024]

[Possibility of Other Embodiments] In this embodiment, the case of the circumscribed type in the gear pump has been described. However, the structure of the shaft lubricating ring channel which is a feature of the present invention is also used in the inscribed type gear pump. Can be.

That is, as shown in FIG. 6, an internal gear 80 composed of an internal gear 80 having teeth on the inner periphery and a gear (hereinafter referred to as "external gear") 81 having a small number of teeth meshing with the internal gear 80. The present invention is also applicable to the case of the gear pump 8 described above. A crescent-shaped partition plate 8 that fills the air space formed by the difference in the number of teeth between the internal gear 80 and the external gear 81 having a smaller number of teeth.
In relation to 2, there are two regions where an intermediate pressure occurs. That is, a region of approximately one pitch from the end 82t of the internal gear 80 and the gear 82 of the partition 82 facing the rotation of the gear (FIG. 6A), and the end 82t of the external gear 81 and the partition 82.
Thus, a region corresponding to approximately one pitch of the gears and a region where the intermediate pressure or the intermediate pressure and the suction pressure act alternately are formed in a region corresponding to approximately one pitch of the gear (FIG. 6B). Select one of these two areas and set the outlet 83
, The technical idea of the present invention can be realized. The inlet may be provided at any position on the high-pressure chamber H side near the discharge port (not shown).

[0026]

According to the present invention, the position of the outlet of the shaft lubrication ring flow path is
Since the suction pressure is set at the optimum position on the gear chamber side from the low-pressure chamber on which the suction pressure directly acts, the shaft enclosure can be maintained in a low-pressure state instead of a negative-pressure state. For this reason, even with a normal shaft seal material, pressure resistance is possible, and it is possible to prevent air bubbles from being broken due to airtightness and failure of the gear pump due to breakage and detachment.

Further, since the throttle portion is provided in the shaft sliding gap, the flow speed can be reduced by the throttle portion, and the pressure change acting on the shaft sealing material can be reduced. In particular, when the outlet is opened at a position where the intermediate pressure and the suction pressure repeatedly act, there is an effect that the transmission of the pulsation can be reduced and the load on the shaft sealing material can be reduced. In particular, when a rolling bearing or the like is fitted into the drive shaft bearing hole, the flow rate of the lubricating oil in this portion increases, so that the flow suppression by the throttle portion functions effectively.

As described above, by forming the shaft lubrication ring channel of the present invention in the gear pump, a normal shaft seal material can be used, and the structure is formed by a slight modification of a conventional product. Therefore, the increase in cost can be reduced, and the contribution to the development of the industry is remarkable.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing an overall view of a gear pump according to an embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an explanatory view showing an open / closed state of the outlet when the drive gear rotates.

FIG. 4 is a sectional view taken along line BB of FIG. 2 (partially displaced).

5A is a cross-sectional view showing a cross section taken along the line CC in FIG.
It is sectional drawing (B) which shows D cross section.

FIG. 6 is a cross-sectional view showing another embodiment.

FIG. 7 is a graph showing a relationship between a cross-sectional area ratio S1 / S2 and a time lag when the length of the narrowed portion of the present embodiment is changed.

FIG. 8 is a sectional view showing an outlet and an inlet in a conventional gear pump.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 drive gear 10 drive shaft 2 driven gear 20 driven shaft 3 front body 30 gear chamber 30 a sliding surface 31 drive shaft bearing hole 32 inflow port 33 shaft sliding gap 33 a introduction groove 34 throttle section 35 driven shaft bearing hole 36 shaft communication passage 37 Return flow path 38 Outflow port 4 Rear body 40 Gear chamber 5 Shaft enclosure 50 Adapter 51 Shaft seal material 52 Shaft enclosure interior 6 Suction port 7 Discharge port 8 Internal gear pump 80 Internal gear 81 External gear 82 Partition body 82t end Part 83 Outlet H High pressure chamber L Low pressure chamber

[Procedure amendment]

[Submission date] May 16, 2000 (2000.5.1)
6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

To achieve the above object, a gear pump according to the present invention is configured as follows. That is, the gear chambers (30, 4,
0), a pair of gears (1, 2) meshing and rotating within the gear chamber (30, 40), and a pump discharge pressure formed at the meshing side of the meshing portion of the gear chambers (30, 40), and a high pressure communicated with the discharge port (7). Room (H)
And a low-pressure chamber (L) in which a pump suction pressure is formed on the disengagement side of the meshing portion of the gear chambers (30, 40) and communicates with the suction port (6). In the gear pump for recirculating a part of the liquid sent to the high-pressure chamber (H) to the shaft sliding gap (33) and lubricating the self-shaft, the inside of the high-pressure chamber (H) or the gear chamber (30) on the high-pressure chamber side is used. Inflow opened in
From the port (32)) to the shaft sliding gap (33) and the shaft enclosure
Through (52), the sliding surface (30) of the gear chamber (30)
a) a shaft lubrication ring communicating with the outlet (38) opened in a)
And the outlet (38) is used to move the rotating tooth space.
And the pump discharge pressure and the pump suction pressure
Established in the area where the intermediate pressure and the pump suction pressure act alternately
ing.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

As shown in FIGS. 2 and 3, the outlet 38 is opened at a position slightly closer to the sliding surface 30a of the gear chamber 30 from the low-pressure chamber L. In other words, the opening position is such that the outlet 38 is opened and closed by the movement of the rotating tooth space.
And the intermediate pressure between the pump discharge pressure and the pump suction pressure and the
In the area where the pump suction pressure alternates with the
It is formed with Furthermore, the inside of the shaft enclosure
The opening position is appropriately selected so as to obtain the optimum working pressure for the valve 52 . In this embodiment, the opening diameter is set to φ = 2 to 3 mm.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0022

[Correction method] Change

[Correction contents]

At this time, the suction pressure (usually a negative pressure) generated in the low pressure chamber L does not act on the outlet 38 as it is.
A higher intermediate pressure or a pulsating pressure between the suction pressure and the intermediate pressure acts. For this reason, a pressure greater than the suction pressure acts on the shaft sealing material 51 that forms a part of the inner surface of the shaft enclosure inner space 52 that communicates with the outlet 38 via the return flow path 37, and at least the negative pressure is reduced. It does not work. Another
In other words, the outlet 38 is connected to the intermediate pressure of the sliding surface 30a and the suction pressure.
The shaft seal material is provided in the area where
As for the positive pressure acting on 51, the intermediate pressure due to the increase of the discharge pressure rises.
Even when it rises, it can be kept low by the negative suction pressure.
Further, the outlet 38 is intermittently moved by the movement of the gear tooth space.
By closing and opening, when closing, intermediate pressure
And the suction pressure (normally negative pressure) when open
The repetition time (for example, the gear rotation speed:
1800 rpm) and the delay of pressure transmission
It is possible to maintain the pressure almost in the middle range between the intermediate pressure and the suction pressure.
Even if the intermediate pressure rises,
It can be suppressed below the withstand voltage of the screw part.

[Procedure amendment]

[Submission date] May 19, 2000 (2005.1.
9)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

To achieve the above object, a gear pump according to the present invention is configured as follows. That is, the gear chambers (30, 4,
0), a pair of gears (1, 2) meshing and rotating within the gear chamber (30, 40), and a pump discharge pressure formed at the meshing side of the meshing portion of the gear chambers (30, 40), and a high pressure communicated with the discharge port (7). Room (H)
And a low-pressure chamber (L) in which a pump suction pressure is formed on the disengagement side of the meshing portion of the gear chambers (30, 40) and communicates with the suction port (6). In a gear pump in which a part of the liquid sent to the high-pressure chamber (H) is recirculated to the shaft sliding gap (33) and self-lubricated, the inside of the high-pressure chamber (H) or the gear chamber (30) on the high-pressure chamber side is used. Inflow opened in
From the port (32)) to the shaft sliding gap (33) and the shaft enclosure
Through (52), the sliding surface (30) of the gear chamber (30)
a) a shaft lubrication ring communicating with the outlet (38) opened in a)
And the outlet (38) is used to move the rotating tooth space.
And the pump discharge pressure and the pump suction pressure
Established in the area where the intermediate pressure and the pump suction pressure act alternately
ing.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

As shown in FIGS. 2 and 3, the outlet 38 is opened at a position slightly closer to the sliding surface 30a of the gear chamber 30 from the low-pressure chamber L. In other words, the opening position is such that the outlet 38 is opened and closed by the movement of the rotating tooth space.
And the intermediate pressure between the pump discharge pressure and the pump suction pressure and the
In the area where the pump suction pressure alternates with the
It is formed with Furthermore, the inside of the shaft enclosure
The opening position is appropriately selected so as to obtain the optimum working pressure for the valve 52 . In this embodiment, the opening diameter is set to φ = 2 to 3 mm.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0022

[Correction method] Change

[Correction contents]

At this time, the suction pressure (usually a negative pressure) generated in the low pressure chamber L does not act on the outlet 38 as it is.
A higher intermediate pressure or a pulsating pressure between the suction pressure and the intermediate pressure acts. For this reason, a pressure greater than the suction pressure acts on the shaft sealing material 51 that forms a part of the inner surface of the shaft enclosure inner space 52 that communicates with the outlet 38 via the return flow path 37, and at least the negative pressure is reduced. It does not work. Another
In other words, the outlet 38 is connected to the intermediate pressure of the sliding surface 30a and the suction pressure.
The shaft seal material is provided in the area where
The positive pressure acting on 51 increases the intermediate pressure due to the rise of the discharge pressure.
Even when it rises, it can be kept low by the negative suction pressure.
More specifically, as shown in FIG.
It is opened and closed intermittently by the movement of the tooth space of the dynamic gear 1,
In this case, the position of the teeth of the drive gear 1 is changed.
The opening area of the low pressure chamber L and the outlet 38 of the gear chamber 30
Is connected to the suction pressure (usually negative pressure)
In a state where L and the above-mentioned region of the gear chamber 30 are cut off,
Intermediate pressures are respectively applied to the outlets 38 and these pressures
The force also acts on the shaft sealing material 51. Meanwhile, the flow
When the outlet 38 is closed, the shaft sealing material 51 includes:
Although the discharge pressure acts, the tie
Sudden pressure rise on shaft seal material 51 is suppressed due to mug
The applied low pressure will act. In other words, strict
The above three pressures () are sequentially applied to the shaft sealing material 5.
1, but the pressure acting constantly is
Repetition time (for example, gear rotation speed: 1800 rpm)
Combined with the short time of pressure and the delay of pressure transmission,
The value converges with the suction pressure. As a result, even if
Even if the inter-pressure rises, the low pressure
It can be suppressed to below the withstand voltage. ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 12, 2000 (2007.1.
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0022

[Correction method] Change

[Correction contents]

At this time, the suction pressure (usually a negative pressure) generated in the low pressure chamber L does not act on the outlet 38 as it is.
A higher intermediate pressure or a pulsating pressure between the suction pressure and the intermediate pressure acts. For this reason, a pressure greater than the suction pressure acts on the shaft sealing material 51 that forms a part of the inner surface of the shaft enclosure inner space 52 that communicates with the outlet 38 via the return flow path 37, and at least the negative pressure is reduced. It does not work. More specifically, as shown in FIG. 3, the outlet 38 is intermittently opened and closed by the movement of the tooth groove of the drive gear 1. In a state where the chamber L communicates with the opening area of the outlet 38 of the gear chamber 30, the suction pressure (normally, a negative pressure) is reduced.
In a state in which the pressure and the above-mentioned area of the gear chamber 30 are cut off, intermediate pressures are respectively applied to the outlets 38, and these pressures also act on the shaft seal material 51. On the other hand, when the outlet 38 is closed, the discharge pressure acts on the shaft seal material 51, but a rapid rise in pressure on the shaft seal material 51 is suppressed due to the time lag by the throttle portion 34. Low pressure will act. That is, strictly speaking, the above three pressures () are sequentially applied to the shaft sealing material 51.
The pressure that constantly acts is substantially equal to the intermediate pressure and the suction pressure due to the short repetition time (for example, gear rotation speed: 1800 rpm) and the delay in pressure transmission. The value converges between the two.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H041 AA02 BB03 CC02 CC06 CC11 DD02 DD07 DD09 DD15 DD20 DD25

Claims (2)

[Claims] A gear chamber (30, 4) supported in a body;
0) a pair of gears (1 and 2) meshing and rotating within the gear chamber (30), and a high pressure formed by pump discharge pressure formed on the meshing side of the meshing portion of the gear chambers (30 and 40) and communicating with the discharge port (7). And a low-pressure chamber (L) in which a pump suction pressure is formed on the disengagement side of the meshing portion of the gear chambers (30, 40) and which communicates with the suction port (6). A gear pump for recirculating a part of the liquid sent from (L) to the high-pressure chamber (H) to the shaft sliding gap (33) and lubricating the self-shaft; An inlet (32) is provided in the chamber (30), and a region where an intermediate pressure between the pump discharge pressure and the pump suction pressure acts from the shaft sliding gap (33) through the shaft enclosure inner space (52), Alternatively, a shaft lubrication ring channel having an outlet (38) is formed in a region where the intermediate pressure and the pump suction pressure act alternately. And a gear pump. The cross-sectional area (S) of the shaft sliding gap (33) on the side of the shaft enclosing section (5) in the shaft sliding gap (33) of the drive shaft (10).
1) is changed to the sectional area (S2) of the shaft sliding gap (33) on the inflow side.
2. The gear pump according to claim 1, wherein a throttle portion having a predetermined reduced axial length is formed.