JP7446210B2 - external gear pump - Google Patents

Description

The present invention relates to an external gear pump.

An external gear pump has a driving gear and a driven gear engaged with each other, and when the driving gear and driven gear rotate, fluid is sucked from one side and fluid is discharged from the other. A device in which a seal member is provided on the side surface of the driven gear and the driven gear is shown in Patent Document 1 described below.

In other words, in Patent Document 1, a drive side gear and a driven side gear are housed inside a case, a partition plate and a seal member are arranged on the side surfaces of these gears, and a lid section is arranged outside of these. A configuration in which the end of the case is closed is described.

In this Patent Document 1, a part of the fluid on the discharge side when the drive side gear and the driven side gear drive and rotate is caused to flow into the loop of the sealing member, and the pressure of this fluid is applied to the partition plate. is configured to be pressed against the side surface of the drive side gear and the side surface of the driven side gear.

Japanese Patent Application Publication No. 10-281081

However, with the device that uses fluid pressure to improve sealing performance as described in Patent Document 1, when the gear rotates at low speed and the amount of fluid is small, sufficient sealing performance cannot be obtained with fluid pressure alone. I could have considered not having one.

In particular, large work vehicles require large-capacity pumps to drive large actuators, but for example, if a pump has poor sealing performance, it is unavoidable to increase the size of the pump when considering the amount of fluid leakage. It was something.

For these reasons, an external gear pump that can effectively suppress fluid leakage is desired.

The external gear pump according to the present invention is characterized by a driving gear that rotates by the driving force of a driving shaft, and a driven gear that is supported by a driven shaft and rotates by the driving force of the driving gear by meshing with the driving gear. A pump case that accommodates a side gear, the drive side gear and the driven gear, and a seal unit that prevents fluid from leaking from the sides of the drive side gear and the driven side gear, and the seal The unit has a drive shaft hole through which the drive shaft is inserted and a driven shaft hole through which the driven shaft is inserted, and a seal disposed with an inner surface in contact with a side surface of the drive side gear and the driven side gear. an outer surface of the seal body opposite to the inner surface; The pump case includes a pressure introduction path for introducing the discharge pressure of the drive side gear and the driven side gear into the inside of the pump case and transmitting the introduced discharge pressure to the outer surface .

According to this characteristic configuration, the seal body that contacts the side surfaces of the driving gear and the driven gear is biased by the biasing member in the contact direction, regardless of the discharge pressure between the driving gear and the driven gear. It is possible to maintain the contact state and suppress leakage of fluid from the side surfaces of the driving gear and the driven gear.
It becomes possible to simultaneously apply the pressure of the fluid from the discharge side and the pressure of the biasing member to the outer surface of the seal body, thereby creating an even better sealing state.
Therefore, an external gear pump that satisfactorily suppresses fluid leakage has been constructed.

In addition to the above configuration, the biasing member is disposed on an outer surface opposite to the inner surface of the seal body, and when viewed in a direction along the axes of the driving gear and the driven gear, A biasing force may be applied to an intermediate position between the drive shaft and the driven shaft.

According to this, although a single biasing member is used, it is possible to press the seal body against the side surface of the driving side gear and the side surface of the driven side gear with uniform pressure, simplifying the structure. Realize.

FIG. 2 is a sectional view of the external gear pump showing a first drive shaft and a second drive shaft. FIG. 3 is a sectional view of the external gear pump showing the first drive shaft. FIG. 3 is a perspective view showing a driving gear, a driven gear, and a seal body.

Embodiments of the present invention will be described below based on the drawings.
[Basic configuration]
As shown in FIGS. 1 to 3, the drive side gear 2 rotates with the driving force of the drive shaft 1, and the driven shaft 3 is supported by the driven shaft 3 parallel to the drive shaft 1 and engages with the drive side gear 2. An external gear pump P includes a driven gear 4 that rotates as the side gear 2 rotates, and a pump case 5 that accommodates these gears.

This external gear pump P supplies hydraulic oil (an example of fluid) to a hydraulic actuator in a work vehicle such as a tractor or a backhoe.

In particular, this external gear pump P includes a first gear unit G1, which is composed of a first driving gear 2a and a first driven gear 4a shown in FIGS. 1 and 2, a second driving gear 2b, and a second gear unit G1. The second gear unit G2 includes a driven gear 4b, and the capacity of the first gear unit is larger than the capacity of the second gear unit.

As shown in FIG. 2, the pump case 5 is formed with a single suction port 5IN, a first discharge port 5P1 corresponding to the first gear unit G1, and a second discharge port 5P1 corresponding to the second gear unit G2. A port 5P2 is formed.

[First gear unit and second gear unit]
As shown in FIG. 1, this external gear pump P includes a drive shaft 1, a first drive shaft 1a having an input section 1D to which driving force from an external drive source is transmitted, and a coaxial shaft with the first drive shaft 1a. It is composed of a first drive shaft 1a and a second drive shaft 1b which are arranged centrally and rotate integrally. Further, the driven shaft 3 is composed of a first driven shaft 3a adjacent to the first driving shaft 1a, and a second driven shaft 3b arranged coaxially with the first driven shaft 3a and adjacent to the second driving shaft 1b. has been done. Note that the input portion 1D at the end of the first drive shaft 1a is made to protrude to the outside of the pump case 5.

The drive gear 2 includes a first drive gear 2a that rotates integrally with the first drive shaft 1a, and a second drive gear 2b that rotates integrally with the second drive shaft 1b. The driven gear 4 includes a first driven gear 4a that rotates integrally with the first driven shaft 3a while meshing with the first driving gear 2a, and a second driven shaft 3b that meshes with the second driving gear 2b. and a second driven gear 4b that rotates integrally.

As shown in FIGS. 1 and 2, the pump case 5 includes a first end case 5a integrally formed with a flange portion 5f, and a second end case disposed on the opposite side of the first end case 5a. 5b, and an intermediate case 5c sandwiched between them.

[Seal unit]
As shown in FIGS. 1 to 3, the seal unit S includes a seal body 10 and a spring 11 (an example of a biasing member).

In other words, the external gear pump P has a drive side gear 2 (first drive side gear 2a, second drive side gear 2b) and a driven side gear 4 (first driven side gear 4a, second driven side gear 4b). Seal bodies 10 are provided at four locations in order to prevent hydraulic oil (fluid) from leaking from the side surfaces of the drive side gear 2 and driven side gear 4 by being placed in contact with the side surfaces of the drive side gear 2 and the driven side gear 4. It is equipped with a compression coil type spring 11 that applies a biasing force to bring it into contact with the side surface.

The seal body 10 is made of sintered metal, and its outer circumferential portion is shaped to be in close contact with the inner circumference of the pump case 5 . Further, as shown in FIG. 1, the pump case 5 is formed with a restriction portion 5r that determines the limit of movement of the seal body 10 in the direction away from the side surface of the gear.

As shown in FIG. 3, the seal body 10 has a drive shaft hole 10a through which the drive shaft 1 (either the first drive shaft 1a or the second drive shaft 1b) is inserted, and the driven shaft 3 (the first driven shaft 3a). A driven shaft hole 10b is formed into which one of the second driven shaft 3b and the second driven shaft 3b is inserted.

The seal body 10 has a flat inner surface corresponding to the side surface of the gear, and a pressure introduction groove 10c through which hydraulic oil is supplied from the discharge side is formed on the outer surface opposite to the inner surface. That is, the pressure introduction groove 10c is formed in a region where the hydraulic oil from the introduction end 10d adjacent to the discharge side is diverted and supplied to the region surrounding the drive shaft hole 10a and the region surrounding the driven shaft hole 10b. .

Note that the pressure introduction groove 10c formed on the outer surface side of the seal body 10 is formed as a flow path for flowing the hydraulic oil on the discharge side to the suction side, but it is not necessarily necessary to form it so that it flows to the suction side. It may be formed into a concave shape that can receive the pressure of the hydraulic oil supplied from the end 10d. Further, the inner surface of the seal body 10 is not limited to being flat, and may be configured to have, for example, a groove through which a portion of the hydraulic oil flows for lubrication.

The spring 11 exerts a biasing force on the outer surface of the seal body 10 at an intermediate position between the drive shaft 1 and the driven shaft 3 when viewed in a direction along the axes of the drive shaft 1 and the driven shaft 3. More specifically, in this embodiment, the center axis of the spring 11 is arranged on a straight line connecting the axis of the drive shaft 1 and the axis of the driven shaft 3. Among the four seal bodies 10, as shown in FIG. A spring 11 is arranged between the four seal bodies 10 , and one spring 11 is disposed between the outer surfaces of the two seal bodies 10 arranged on the inside.

With this configuration, the seal body 10 that contacts the side surfaces of the driving gear 2 and the driven gear 4 is pressed against the side surfaces of the driving gear 2 and the driven gear 4 by the biasing force of the spring 11 (biasing member). Since it is pressed, the seal body 10 can be maintained in an appropriate contact state and leakage of hydraulic oil can be suppressed regardless of the discharge pressure between the drive side gear 2 and the driven side gear 4. As a result, the required hydraulic oil can be supplied without increasing the size of the external gear pump P.

[Another embodiment]
In addition to the embodiments described above, the present invention may be configured as follows (those having the same functions as the embodiments are given the same numbers and symbols as the embodiments).

(a) A plate-shaped spring is used as the biasing member in place of the compression coil type spring 11. Furthermore, the number of biasing members is not limited to one for each seal body 10, and for example, two or more biasing members may be provided.

(b) In the embodiment described above, the pressure introduction groove 10c was formed in the seal body 10, but the seal body 10 does not necessarily require the pressure introduction groove 10c. Furthermore, the seal body 10 is not limited to being made of sintered metal, but may be made of resin or metal.

(c) In the embodiment described above, the external gear pump P has a configuration in which a single drive shaft 1 is provided with two drive side gears 2 and a single driven shaft 1 is provided with two driven side gears 4. However, it is not limited to this. For example, the number of drive-side gears 2 provided on the drive shaft 1 may be one, or three or more. Similarly, the number of driven gears 4 provided on the driven shaft 2 may be one, or three or more. Further, two or more driving shafts 2 and two or more driven shafts 4 may be provided.

(d) In the embodiment described above, both the seal body 10 that abuts one side surface of the drive side gear 2 and the driven side gear 4 and the seal body 10 that abuts the other side surface are biased by the spring 11. However, the present invention is not limited to this, and a configuration may be adopted in which only the seal body 10 that contacts one side surface is biased by the spring 11. For example, among the four seal bodies 10, those disposed at both ends (left and right ends in FIG. 1) are biased by the springs 11, and two of the four seal bodies 10 disposed inside are biased by the springs 11. It is also possible to have a configuration in which no . Alternatively, two of the four seal bodies 10 placed at both ends (left and right ends in FIG. 1) are not biased by the spring 11, and two of the four seal bodies 10 placed on the inside are pressed. It may be biased by a spring 11.

INDUSTRIAL APPLICATION This invention can be utilized for an external gear pump.

1 Drive shaft 2 Drive side gear 3 Drive shaft 4 Drive side gear 5 Pump case 10 Seal body 10a Drive shaft hole 10b Drive shaft hole 10c Pressure introduction groove 11 Spring (biasing member)
S seal unit

Claims (2)

a drive-side gear that rotates by the driving force of the drive shaft;
a driven gear that is supported by a driven shaft and rotates by the driving force of the driving gear by meshing with the driving gear;
a pump case that accommodates the drive side gear and the driven side gear;
a seal unit that prevents fluid from leaking from the side surfaces of the drive side gear and the driven side gear;
The seal unit has a drive shaft hole through which the drive shaft is inserted and a driven shaft hole through which the driven shaft is inserted, and is arranged with an inner surface in contact with a side surface of the drive side gear and the driven side gear. and a biasing member that applies a biasing force to bring the inner surface of the seal body into contact with the side surfaces of the driving gear and the driven gear ,
A pressure formed on the outer surface of the seal body opposite to the inner surface, which introduces the discharge pressure of the drive side gear and the driven side gear into the inside of the pump case, and transmits the introduced discharge pressure to the outer surface. External gear pump equipped with an introduction path . The biasing member is disposed on an outer surface of the seal body opposite to the inner surface, and the biasing member is arranged on an outer surface of the seal body opposite to the inner surface, and when viewed in a direction along the axes of the driving gear and the driven gear, the biasing member The external gear pump according to claim 1, wherein a biasing force is applied to an intermediate position.

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