JPH05280472A - Internal gear pump - Google Patents

Abstract

PURPOSE:To suppress the cavitation in the high revolution, securing the transport flow rate in the low revolution, by drilling a control hole toward the inside of each tooth from the inner or outer peripheral side of an outer rotor and forming a valve seat inside. CONSTITUTION:An outer rotor 12 which is installed in rotatable manner in a casing 11 and has the inner peripheral teeth X and an inner rotor 13 which has the outer peripheral teeth Y meshed with the inner peripheral teeth X of the outer rotor 12 are provided. In the inner peripheral teeth X of the outer rotor 12, a control hole 14 opened to one between the inner or outer peripheral side of the outer rotor 12 is formed. A valve seat 15 is installed in the intermediate part in the lengthwise direction of the control hole. Further, inside the control hole 14, a valve body 16 is installed in shiftable manner in contact with the valve seat 15, when the outer rotor 12 reaches a prescribed number of revolution. Accordingly, the generation of cavitation in the high revolution can be prevented, securing the transport quantity of the fluid in the low revolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises an outer rotor rotatably mounted in a casing and having inner peripheral teeth, and an inner rotor having outer peripheral teeth meshing with the inner peripheral teeth of the outer rotor. It relates to an internal gear pump.

[0002]

2. Description of the Related Art Conventionally, an internal gear pump having a structure shown in FIG. 3 is known. The internal gear pump shown in this figure includes an outer rotor 2 that is rotatably provided in a casing 1 and has inner peripheral teeth X, and an inner rotor Y that is meshed with the inner peripheral teeth X of the outer rotor 2. A rotor 3 and a drive shaft 3a that supports the inner rotor 3 and that holds the rotation center O2 of the inner rotor 3 by eccentricity in a predetermined direction from the rotation center O1 of the outer rotor 2 are provided.

The gap S formed between the tooth surfaces of the teeth X and Y of the pair of rotors 2 and 3 is defined by the two rotors 2.3.
When is rotated and is located in a portion indicated by the symbol B on a straight line passing through the respective rotation centers O1 and O2, its volume is minimum, and when it is located in a portion indicated by the symbol A, the volume is maximum. The configuration is as follows.

Further, both rotors 2 and 3 of the casing 1
The suction port 4 for supplying a fluid such as hydraulic oil into the gap S and the fluid sucked and sealed in the gap S are discharged to a portion facing the end surface of the casing S, and the fluid is guided to the outside of the casing 1. The discharge port 5 is formed.

The internal gear pump having the above structure is
By changing the volume of the gap S formed between the inner peripheral tooth X and the outer peripheral tooth Y by the relative rotation of the two rotors 2 and 3, the suction port 4 increases when the gap S increases.
The fluid is sucked from the
Is conveyed by the rotation of and the fluid is discharged from the discharge port 5 when the gap S is reduced.

[0006]

In the conventional internal gear pump described above, the discharge amount of the pump increases as the rotation speed increases, and the discharge amount becomes higher than necessary at high speed rotation. As a method for preventing this oversupply, it is generally practiced to provide a relief valve on the downstream side of the discharge port 5 and return the fluid for the oversupply to a tank or the like. Since the relief valve is provided on the discharge port 5 side, power loss occurs in the pump at the time of excessive supply, which adversely affects the pump efficiency.

On the other hand, there is also a method of limiting the flow rate of the fluid on the suction side, but due to the pressure drop in the gap S at the time of high rotation, a gas-liquid two-phase state is established in this gap S, and when it is sent to the discharge port 5. Cause cavitation in the.

As one method for suppressing the occurrence of such cavitation, the gas-liquid two-phase fluid in the gap S is sufficiently compressed in the course of transportation to be completely in the liquid state. It is to send out to the discharge port 5 later. For that purpose, in order to sufficiently reduce the volume of the clearance S, the distance between the end portion of the suction port 4 and the start end portion of the discharge port 5 is set sufficiently, and the communication timing between the clearance S and the discharge port 5 is established. Need to be delayed. (This technique is disclosed, for example, in Japanese Patent Laid-Open No. 3-175182.)

However, also in this measure, when the fluid to be sucked is in a complete liquid phase such as during low-speed rotation, as described above, the communication timing between the gap S and the discharge port 5 is delayed. However, there is still a problem that the fluid is over-compressed and causes a large power loss. Therefore, the above-mentioned JP-A-3-175182 also discloses the following improvement plan at the same time. There is.

That is, a control hole for communicating two adjacent gaps S is formed in each of the inner peripheral teeth X or each of the outer peripheral teeth Y, and in the control hole, at the time of low rotation, the fluid conveying direction (both rotors). The flow of the fluid in the opposite direction is allowed by allowing the fluid to flow in the rotation direction (2, 3) and contacting the inner wall of the control hole to shield the inside in the longitudinal direction at the time of high rotation. A valve body for blocking is provided, and at the time of low rotation in which a fluid in a complete liquid phase is conveyed, each control hole is in a communication state, and is communicated with the discharge port 5 through the gap S immediately after being separated from the suction port 4. By establishing a communication state up to the gap S, the compression of the fluid between the suction port 4 and the discharge port 5 is minimized, and the fluid to be conveyed is a gas-liquid two-phase fluid at the time of high rotation, Shield the control hole with the valve body By isolating the gap S airtight it is obtained by allowing the compression of the fluid therein.

With this structure, the gap S immediately after being separated from the suction port 4 at the time of low speed rotation.
After the fluid is sent to the discharge port 5 at a pressure almost equal to the pressure generated in the above, and the gas-liquid two-phase fluid is sufficiently compressed until it reaches the discharge port 5 at the time of high rotation, it becomes a complete liquid phase state. In addition, it is possible to send it to the discharge port 5.

By the way, in the above-mentioned conventional technique,
A check valve is formed between the valve body and the inner wall of the control hole. In order to install the check valve having such a structure in the rotor, the rotor is divided into two in the thickness direction. According to the above configuration, the half of the valve seat constituting the control hole and the check valve is formed on the joint surface of each half body, and the half body is sandwiched between the two half bodies to join the two half bodies. I am trying.

However, with such a configuration,
In the state where both halves are joined, it is necessary to completely match the surfaces of the inner and outer teeth formed on both halves (This is because in the internal gear pump, the tooth shape of the rotor has a large pump efficiency. However, it requires extremely high precision manufacturing technology, or
High precision post-processing is required after joining, which is disadvantageous in terms of manufacturing cost.Also, even if each half is formed in the same shape, accuracy is required in positioning to eliminate misalignment when joining them. Improvements such as required are left.

[0014]

SUMMARY OF THE INVENTION The present invention provides an internal gear pump capable of effectively solving the above-mentioned problems remaining in the prior art. In particular, it is rotatably mounted in a casing. An outer rotor that is mounted and has inner peripheral teeth, and an inner rotor that has outer peripheral teeth that mesh with the inner peripheral teeth of the outer rotor are provided. A control hole is formed on either the peripheral side or the outer peripheral side, a valve seat is formed in the middle of the control hole in the longitudinal direction, and the outer rotor is provided inside the control hole. A valve body that is brought into contact with the valve seat and closes the control hole when a predetermined number of rotations is reached is movably mounted, and the inner peripheral teeth have outer peripheral sides of the control hole. The end of the inner rotor A communication passage that communicates with an adjacent tooth bottom portion in the rear in the rotation direction and a communication passage that communicates the inner peripheral side end portion of the control hole with the adjacent tooth bottom portion in the rotation direction front of the outer rotor are formed. A closing member for sealing the opening of the control hole is mounted.

[0015]

The internal gear pump according to the present invention is carried out by forming the control hole by piercing from the inner peripheral side or the outer peripheral side of the outer rotor toward the inside of each tooth. The valve seat is formed in the inside by the same processing as the installation. Then, the valve body is inserted into each of the drilled control holes, and then the opening end of the control hole is closed by a closing member to be assembled. Therefore, the check valve can be formed inside the outer rotor without dividing the outer rotor in the thickness direction.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, reference numeral 10 indicates an internal gear pump according to this embodiment, which is rotatably mounted in a casing 11 and has an outer peripheral tooth X, and an inner peripheral tooth of the outer rotor 12. An inner rotor 13 having outer peripheral teeth Y meshed with X, and inside each inner peripheral tooth X of the outer rotor 12,
A control hole 14 that opens to the outer peripheral side of the outer rotor 12 is formed, and the valve seat 1 is formed in the middle of the control hole 14 in the longitudinal direction.
5 is formed inside the control hole 14, and the outer rotor 12 is abutted against the valve seat 15 when the outer rotor 12 reaches a predetermined rotational speed, thereby closing the control hole 14. 16 is movably mounted, and the outer peripheral side end of the control hole 14 is attached to each inner peripheral tooth X.
2 is a communication passage 17 that communicates with the tooth bottom portion that is adjacent to the rear side in the rotation direction of FIG. It has a schematic structure in which a closing member 19 for sealing the opening of the control hole 14 is attached.

Next, these will be described in detail. Among the inner walls of the casing 11, the rotors 12 are
A suction port 20 and a discharge port 21 are formed at positions facing the side surfaces of the 13 teeth X and Y so as to follow the movement loci of the teeth X and Y.

The starting end of the suction port 20 and the discharge port 2
The end of No. 1 is located before and after the portion where the inner peripheral teeth X and the outer peripheral teeth Y are deepest in mesh, and the suction port 2
The end of 0 is located immediately before the position where the inner peripheral tooth X and the outer peripheral tooth Y are most meshed with each other, and the start end of the discharge port 21 is formed between the inner peripheral tooth X and the outer peripheral tooth Y. Gap S
The (fluid-carrying cell) is positioned corresponding to the fully reduced position.

The control hole 14 is, in this embodiment,
The outer rotor 12 is formed so as to straddle the outer rotor 12 and the closing member 19 fitted to the outer periphery thereof. The outer rotor 12 side is formed by sintering the outer rotor 12 and then drilled from the outer peripheral surface side. The outer rotor 12 is formed such that its tips are located near the tips of the inner peripheral teeth X of the outer rotor 12.

In the present embodiment, the closing member 19 is formed in a tubular shape, the inner diameter of which is slightly smaller than the outer diameter of the outer rotor 12, and the closing member 19 is press-fitted to the outer periphery of the outer rotor 12 by means such as press fitting. By fitting and mounting, the openings of the control holes 14 are airtightly closed. The annular contact portion between the closing member 19 and the inner rotor 13 is preferably seal-welded over the entire circumference on both side surfaces of the inner rotor 13.

Further, a part of the control hole 14 formed in the closing member 19 has a large-diameter portion as a perforation formed in the outer rotor 12, and an inner surface cone formed at a position continuous with the large-diameter portion. The valve seat 15 in the present embodiment is constituted by the inclined portion and the small diameter portion following the inclined portion.

In this embodiment, the valve body 16 is a sphere, and has an outer diameter larger than the small diameter portion of the control hole 14 and smaller than the large diameter portion thereof. The valve seat 15 constitutes a check valve.

The communication passages 17 and 18 are formed in the closing member 19 and the outer rotor 12 in the tooth thickness direction, respectively, and are formed in the side surface of the outer rotor 12 and the outer peripheral side end portion and inner peripheral portion of the control hole 14. Communication hole 22 that connects the end on the side
23, and the one communication hole 22 formed from the side surface of the outer rotor 12 to the side surface of the closing member 19.
With the communication groove 24 that communicates with the bottom of the outer rotor 12 in the rotation direction and the communication groove 2 that communicates the other communication hole 23 with the bottom of the outer rotor 12 in the rotation direction with respect to the front.
5 and.

The internal gear pump 1 of this embodiment as described above
0 is manufactured as follows. First, the outer rotor 12 and the inner rotor 13 are formed by pressure-molding metal powder and then sintering. Next, a large-diameter portion of the control hole 14 is bored from the outer peripheral side at a position corresponding to each inner peripheral tooth X of the outer rotor 12, and a position corresponding to each inner peripheral tooth X of the closing member 19. The valve seat 15 and the small diameter portion of the control hole 14 are bored from the inner peripheral side thereof, and the side surface of the closing member 19 and the outer rotor 1 are formed.
The communication holes 22 and 23 are bored from the side surface of No. 2 in the respective thickness directions. Next, the valve body 16 is inserted into the portion of each control hole 14 formed in the outer rotor 12.

Thus, by press-fitting the closing member 19 onto the outer periphery of the outer rotor 12, these formed control holes 14 are made continuous to form the closed control holes 14 and inside thereof. Blame the valve seat 15. Further, if necessary, seal welding is applied to the contact portion between the outer rotor 12 and the closing member 19 on both side surfaces of the outer rotor 12.

Then, on the side surfaces of the outer rotor 12 and the closing member 19, connecting grooves 24 and 25 extending from the connecting holes 22 and 23 to the above-mentioned tooth bottoms are formed by cutting or the like.

By assembling the outer rotor 12 thus assembled together with the inner rotor 13 into the casing 11 and fixing the inner rotor 13 to the drive shaft, the internal gear pump 10 of this embodiment is assembled.

As described above, according to the internal gear pump 10 of this embodiment, when the check valve is incorporated in the outer rotor 12, the outer rotor 12 is drilled and the closing member 19 is provided.
Can be carried out by press-fitting work, and it can be incorporated without affecting the shape and surface condition of the inner peripheral teeth X of the outer rotor 12, which is an important part of the inner gear pump 10.

Further, the manufacturing is easy because the processing is performed on a portion that does not affect the accuracy of the outer rotor 12.

Also in the internal gear pump 10 of this embodiment, fluid can be conveyed at low speed rotation and cavitation is suppressed at high speed rotation.

That is, at the time of low rotation, the valve body 16
The centrifugal force applied to the discharge port 21 is small, and the discharge port 21 is located on the upstream side (rearward in the rotational direction of the rotors 12 and 13) of the internal pressure in the gap S communicated with the discharge port 21. Since the internal pressure of the gap S that is not open is high, the valve element 16 is separated from the valve seat 15, and the control hole 14 located between the discharge port 21 and immediately after the end of the suction port 20 is in a communication state. A communication state is established between the discharge port 21 and the suction port 20 and the gap S immediately after being separated from each other.

Therefore, the fluid sucked in the suction port 20 is compressed in the gap S immediately after being separated from the suction port 20, and is sequentially fed into the gap S located in the front by the pressure at that time, and finally is discharged. To the discharge port 21.

Therefore, overcompression of the fluid at low rotation is eliminated, and the fluid can be conveyed.

On the other hand, when the flow rate of the fluid into the internal gear pump 10 is limited at the time of high rotation, the suction port 2
The gas-liquid two-phase fluid flows from 0 into the gap S. At this time,
The valve element 16 is pressed against the valve seat 15 by the centrifugal force to close the control holes 14, and the gaps S become independent.

When the rotors 12 and 13 continue to rotate in this state, the volume of each gap S is successively reduced between the suction port 20 and the discharge port 21, whereby the gas-liquid two-phase fluid is compressed and the gap By the time S is communicated with the discharge port 21, the vapor phase component is condensed or melted into the liquid phase component, and is brought into a complete liquid phase state immediately before the discharge port 21.

Therefore, the fluid is sent to the discharge port 21 in a completely liquid state, and the occurrence of cavitation is suppressed.

The shapes, dimensions, etc. of the constituent members shown in the above embodiment are merely examples, and can be variously changed based on design requirements and the like.

For example, in the above embodiment, the control hole 1
Although the example in which 4 is formed in parallel with the side surface of the outer rotor 12 is shown, it is also possible to provide it in an inclined manner. In the case where the control holes 14 are inclined as described above, when the outer rotor 12 is assembled, the valve bodies 16 inserted into the respective control holes 14 are used by utilizing the inclination of the control holes 14. Since the detachment from the control hole 14 can be prevented, the work becomes easy.

Further, the communication holes 22 and 23 and the communication grooves 24 and 2
5 may be formed at the same time when the inner rotor 12 and the closing member 19 are formed into a compressed powder. Further, the communication grooves 24 and 25 are omitted, and the communication passages 17 and 18 are constituted only by the communication holes 22 and 23. It is also possible to do so.

Further, the closing member 19 is not limited to the annular shape, but may be a plug-like member press-fitted into the opening of each control hole 14.

[0041]

As described above, the internal gear pump according to the present invention is rotatably mounted in the casing and has the outer rotor having the inner peripheral teeth and the inner peripheral teeth of the outer rotor meshed with each other. And an inner rotor having outer peripheral teeth that are formed, and a control hole that opens to either the inner peripheral side or the outer peripheral side of the outer rotor is formed in each inner peripheral tooth of the outer rotor. A valve seat is formed at an intermediate portion in the depth direction, and the control hole is formed inside the control hole by being brought into contact with the valve seat when the outer rotor reaches a predetermined rotation speed. A valve element to be closed is movably mounted, and each inner peripheral tooth has
A communicating passage that connects the outer peripheral side end of the control hole to a tooth bottom part adjacent to the outer rotor in the rotational direction rear side, and an inner peripheral side end part of the control hole that is adjacent to the inner rotor front side in the rotational direction front side. And a closing member that seals the opening of the control hole is mounted, and has the following excellent effects.

In order to prevent cavitation during high rotation while ensuring the amount of fluid to be conveyed during low rotation, when a check valve is incorporated in the outer rotor, a drilling process for the outer rotor and a press-fitting operation of a closing member, etc. It is possible to maintain the shape and surface condition of the inner peripheral teeth of the outer rotor, which is an important part of the internal gear pump, in good condition.

Further, as the processing for the portion that does not affect the accuracy of the outer rotor, the manufacturing of the internal gear pump can be facilitated while maintaining the accuracy.

[Brief description of drawings]

FIG. 1 is a partial sectional front view showing an embodiment of the present invention.

FIG. 2 is a vertical sectional view showing an embodiment of the present invention.

FIG. 3 is a partially sectional front view showing a conventional example.

[Explanation of symbols]

 10 Inner gear pump 11 Casing 12 Outer rotor 13 Inner rotor 14 Control hole 15 Valve seat 16 Valve body 17 Communication passage 18 Communication passage 19 Closing member X Inner peripheral tooth Y External peripheral tooth

Claims (1)

[Claims] 1. An outer rotor rotatably mounted in a casing and having inner peripheral teeth, and an inner rotor having outer peripheral teeth meshing with inner peripheral teeth of the outer rotor, each of the outer rotors A control hole is formed in the inner peripheral tooth, the control hole opening to either the inner peripheral side or the outer peripheral side of the outer rotor, and a valve seat is formed at an intermediate portion in the longitudinal direction of the control hole. Inside the control hole, a valve element that is brought into contact with the valve seat when the outer rotor reaches a predetermined number of rotations to close the control hole is movably mounted, and The peripheral teeth include a communication passage that connects the outer peripheral end of the control hole to a tooth bottom portion adjacent to the outer rotor in the rotational direction rear side, and an inner peripheral end of the control hole that is forward in the rotational direction of the outer rotor. Adjacent to the root An internal gear pump, wherein a communication passage communicating with the portion is formed, and a closing member that seals the opening of the control hole is attached.