JP2003113781A - Gear pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems that a conventional clearance groove cannot prevent occurrence of cavitation and generates vibrations and noises in a step of expanding a closing area. SOLUTION: The closing area 38 is produced between mesh points A and B of a driving gear 7 and a coupled driving gear 8. At an early stage of the step of expanding the closing area 38, as shown in Figure 6 (a), working fluid is pressure-transferred from a discharge chamber 15 via a first clearance groove 21 and an extending groove 36, preventing generation of negative pressure in the closing area 38. At the later stage of the step expanding the closing area 38, as shown in Figure 6 (b), before a second clearance groove 20 communicates with the closing area 38, a communication is shut off between the extending groove 36 and the closing area 38.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear pump that performs a pumping action by rotating a pair of gears meshing with each other.

[0002]

2. Description of the Related Art Conventionally, a gear pump has been used in various industrial fields as a small and lightweight pump having a simple structure. Generally, in this type of gear pump, a pair of side plates are fitted in a cavity inside the housing to define a gear chamber. A pair of gears that mesh with each other are housed inside the gear chamber. Both ends of the support shaft of each gear are fitted into and supported by support holes formed in each side plate. Further, inside the gear chamber, a suction chamber and a discharge chamber for the working fluid are formed with the meshing position of both gears sandwiched therebetween.

[0003]

By the way, in the vicinity of the meshing portion of the gear of the gear pump, the working fluid is confined in a confinement region formed by each side plate and each gear tooth meshing with each other, so-called trapping (trapping). )
Cause a phenomenon. There is a problem in that the working fluid trapped in the confined region is compressed and expanded with the rotation of the gear and abruptly changes in pressure, resulting in vibration and noise.

To solve this problem, a gear pump is provided in which a side plate near a meshing portion of a gear is formed with an escape groove for allowing a working fluid to flow between a closed region and a discharge chamber or a suction chamber. There is. The escape groove is provided as a pair of a high pressure side escape groove extending from near the meshing portion of the gear toward the discharge chamber and a low pressure side escape groove extending from near the meshing portion of the gear toward the suction chamber. The pair of clearance grooves communicate with the closed area in the vicinity of the meshing portion of the gear. The high-pressure side escape groove allows the working fluid to escape from the confined region, which has a high pressure during contraction, to the discharge chamber. On the other hand, the low-pressure side escape groove supplies the working fluid sucked from the suction chamber to the closed region, which has a low pressure when expanded.

However, when the gear rotates at a high speed, the working fluid cannot be completely sucked from the suction chamber into the expanding confinement region through the relief groove on the low pressure side, and cavitation occurs in the confinement region, which causes vibration and noise. Cause of. Therefore, an object of the present invention is to solve the above-mentioned technical problems and to provide a gear pump capable of reliably preventing vibration and noise due to cavitation during high rotation.

[0006]

Means for Solving the Problems and Effects of the Invention In order to achieve the above object, the invention according to claim 1 has a housing having a void therein, and a gear fitted into the void and provided inside the housing. A pair of side plates partitioning the chamber, a pair of gears housed in the gear chamber, a confined region of the working fluid generated near the meshing portion of the pair of gears in relation to the rotation of the pair of gears, In a gear pump including a suction chamber and a discharge chamber for a working fluid, which are arranged in the gear chamber with the meshing portion interposed therebetween, a gear-side side surface of at least one side plate communicates a closed region of a compression process with the discharge chamber. And a second groove for communicating the closed region of the expansion process with the suction chamber, and a second groove for preventing interference with the line of action of gear engagement from the first groove. An extension groove extending toward the second groove is formed, and the extension groove and the closure region are disconnected from each other before the closure region communicates with the second groove as the gear rotates. It is characterized by being present.

In the present invention, in the step of expanding the confined region, the high pressure oil in the discharge chamber is pumped into the confined region through the groove extending from the first groove, so that the pressure in the confined region drops. Therefore, it is possible to suppress the occurrence of cavitation even at high rotation speed and reduce noise and vibration. Before the confinement region communicates with the second groove, the communication between the extended groove and the confinement region is cut off, so that the flow efficiency does not decrease. The invention according to claim 2 is a housing having a void therein, a pair of side plates fitted into the void to define a gear chamber inside the housing, and a pair of gears housed in the gear chamber. And a confinement region of the working fluid generated near the meshing portion of the pair of gears in relation to the rotation of the pair of gears, and a suction chamber and a discharge chamber of the working fluid arranged with the meshing portion sandwiched in the gear chamber. A gear pump including a chamber, a first groove for communicating a closed region in the compression process with the discharge chamber, and a closed region in the expansion process communicated with the suction chamber on a gear side surface of at least one side plate. A second groove for allowing the discharge chamber to pass through at least one side plate from the discharge chamber to form an opening on the side surface on the gear side, and through the opening, the discharge chamber is formed in a closed region in the expansion process. A high-pressure fluid introduction path for introducing a high-pressure working fluid is provided, and the communication between the opening and the closed area of the high-pressure fluid introduction path is disconnected before the confinement area communicates with the second groove as the gear rotates. It is characterized by being soaked.

According to the present invention, in the step of expanding the confined region, the high pressure oil in the discharge chamber is pumped into the confined region through the high pressure fluid introduction passage to reduce the pressure drop in the confined region. As a result, it is possible to suppress the occurrence of cavitation even at high rotation speed and reduce noise and vibration. Before the confinement region communicates with the second groove, the communication between the high-pressure fluid introduction path and the confinement region is cut off, so that the flow rate efficiency does not decrease.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described with reference to the accompanying drawings. 1 is a cross-sectional view of a gear pump according to an embodiment of the present invention, and FIG. 2 is a II-II of FIG.
It is a sectional view taken along the line, and hatching is omitted. 3 is a sectional view taken along line III-III in FIG. 1, and FIG. 4 is a sectional view taken along line IV-IV. With reference to FIG. 1, the present gear pump closes both sides of a main body cylinder 2 having a cavity 1 having an oval cross section that penetrates the central portion thereof with a pair of cover plates 3 screwed to cover the entire surface thereof. The housing 4 is composed of Inside the housing 4, a gear chamber 6 is defined between a pair of side plates 5 and 5 made of aluminum alloy which are fitted and inserted from both sides of the cavity 1. A drive gear 7 and a driven gear 8 forming a pair are arranged. 9
Is a seal that is housed in the annular groove of the cover plate 3 and is interposed between the cover plate 3 and the main body tube 2 to seal the gear chamber 6.
A seal 10 is housed in the housing groove 50 of the side plate 5 and partitions the space between the opposing side plate 5 and the cover plate 3 in the gear chamber 6 into a low pressure side region and a high pressure side region.

Support shafts 7a of the drive gear 7 and the driven gear 8,
8a are respectively located on the axial centers of arcs on both sides of the gear chamber 6 having an oval cross section, and are laid in parallel to each other. That is, the support shafts 7a and 8a are attached to the side plates 5
Bearing holes 11, 1 as a pair of bearings formed in each
Both sides are supported by 2. One of the support shafts 7a supported by the pair of support holes 11 extends through the one cover plate 3 to the outside, and is rotationally driven by the driving force from a motor (not shown) transmitted to this extended end. It constitutes the axis. A drive gear 7 is mounted on the support shaft 7 a so as to be integrally rotatable inside the gear chamber 6. An oil seal 13 is arranged at a portion where the support shaft 7a penetrates the cover plate 3.

The other support shaft 8a supported by the pair of support holes 12 has a support hole 12 for each side plate 5.
A driven shaft having a shaft end therein is configured. A driven gear 8 is mounted inside the gear chamber 6 on the support shaft 8a. When the driven gear 8 is mounted on the support shaft 8a, the rotation around the shaft may be restricted or the rotation around the shaft may be allowed. The driven gear 8 meshes with the drive gear 7 in a plane including the shaft centers of both the support shafts 7a and 8a, and along with the rotation of the drive gear 7 driven by the support shaft 7a (or of the support shaft 8a). It is designed to rotate driven (without rotation).

In FIG. 2, the rotation directions of the drive gear 7 and the driven gear 8 interlocked with the drive gear 7 are indicated by arrows. The rotation directions of the gears 7 and 8 are predetermined and rotate in mutually opposite directions. The state in which the gears 7 and 8 are rotating in a predetermined rotation direction is called normal rotation. Both gears 7,
A suction chamber 14 is formed on the rotation direction side and a discharge chamber 15 is formed on the opposite rotation direction side on both sides of the meshing position of 8. The suction chamber 14 and the discharge chamber 15 are the main body tube 2
Are connected to a suction destination and a discharge destination (not shown) outside the housing 4 via a suction port 16 and a discharge port 17 which are opened at corresponding positions. In FIG.
The white arrows indicate the flow of the working fluid (Fig. 3).
And also in FIG. 4).

In FIG. 3, reference numeral 31 denotes an intersection of a plane 34 including the rotation centers 32 and 33 of both gears 7 and 8 and a line of action 35 of meshing of both gears 7 and 8. The meshing action line 35 is the meshing points A and B of both gears 7 and 8 [FIG.
(See (a)]. On the gear side surface 5a of the side plate 5, a first relief groove 21 as a first groove extending from the vicinity of the intersection 31 toward the discharge chamber 15 and an intersection 31.
As a second groove extending from the vicinity of the to the suction chamber 14 side
And an escape groove 20 are formed. Further, on the gear side side surface 5a of the side plate 5, the side surface 5a is extended from the first clearance groove 21 toward the second clearance groove 20 side so as not to interfere with the line of action 35 of the meshing of the gears 7 and 8. An elongated groove 36 having a narrow width is formed. Further, the gear side surface 5a is formed with a communication groove 22 that communicates the support holes 11 and 12 with the suction chamber 14 side.

Referring to FIG. 3 and FIGS. 5A and 5B, which are sectional views of the side plate, the extending groove 36 has a triangular pyramidal taper shape, and the tip 37 of the extending groove 36 is a flat surface. 34
Extends toward the second relief groove 20 side. On the other hand, in FIG. 4, the seal 10 is accommodated in the substantially gear-shaped accommodating groove 50 on the side 5b of the side plate 5 opposite to the gear, and the side plates facing each other with the seal 10 as a boundary. 5 is a space between the lid plate 3 and the suction chamber 14
It is partitioned into a low pressure side space communicating with the side and a high pressure side space communicating with the discharge chamber 15 side. As described above, the low-pressure working fluid and the high-pressure working fluid act as back pressure on the side opposite to the gear side 5b, which is the back surface of the side plate 5, in a state of being partitioned by the seal 10, and this acts on the side plate 5 as back pressure. Since the load is applied according to the discharge pressure, the clearance between the side plate 5 and both gears 7 and 8 is maintained with high accuracy, and as a result, the pump efficiency at high pressure can be maintained high. Further, on the side 5b opposite to the gear side, the support holes 11,
A pair of communication grooves 23 are formed which respectively communicate 12 and the suction chamber 14 side.

With this structure, the working fluid introduced into the suction chamber 14 through the suction port 16 is received between the teeth of the drive gear 7 and the driven gear 8 facing the suction chamber 14,
Due to the rotation of both gears 7 and 8, the space between each tooth and the main body tube 2
The discharge chamber 1 is conveyed while being sealed between the inner peripheral surface of
Sent to 5. The drive gear 7 and the driven gear 8 that have finished sending to the discharge chamber 15 face the suction chamber 14 side through the meshing position of both gears 7, 8 and re-receive the working fluid in the suction chamber 14 to discharge the working chamber. It acts to send it to the 15 side.

Next, with reference to FIGS. 6 (a), 6 (b) and 6 (c), the functions of the relief grooves 20, 21 and the extended groove 36 will be described. FIG. 6A shows each side plate 5 and each meshing gear tooth 7 between meshing points A and B of both gears 7 and 8.
The confined region 38 of the working fluid formed by b and 8b is
The compression process of contracting with the rotation of the gears 7 and 8 is shown. In this compression step, the working fluid in the closed region 38 that is compressed to a high pressure is released to the discharge chamber 15 through the first relief groove 21, so that the high pressure is prevented from being generated in the closed region 38. It

Next, FIG. 6B shows the moment when the confinement region 38 changes from compression to expansion. At the beginning of this expansion process, the confinement region 38 is not yet in communication with the second clearance groove 20, so if the extension groove 36 were not present, the confinement region 38 would be decompressed with the expansion, and cavitation would occur. May occur. However, in the present embodiment, since the extended groove 36 from the first relief groove 21 communicates with the closed region 38 at the beginning of the expansion process, the first relief groove 21 and the extension groove 36 extend from the discharge chamber 15. The working fluid is supplied through the groove 36, and as a result, a negative pressure is prevented from being generated in the closed area 38. Therefore, the generation of cavitation can be suppressed, and the generation of vibration and noise due to this can be reduced.

When the expansion process further proceeds with the rotation of the gears 7 and 8, the confinement region 38 communicates with the second clearance groove 20 toward the suction chamber 14 side, as shown in FIG. 6 (c). Then
The working fluid is supplied from the suction chamber 14 to the expansion region 38 that expands via the second escape groove 20, but before that, the communication between the closure region 38 and the extension groove 36 is cut off. It is designed to If the extension groove 36 extending from the first relief groove 21 and the second relief groove 20 are communicated with the closing region 38 at the same time, the suction chamber 14 and the discharge chamber 15 are communicated with each other. This is to prevent the flow rate efficiency from lowering.

As described above, according to the present embodiment, especially at the time of high speed rotation, it is possible to prevent the occurrence of cavitation, and it is possible to surely prevent the vibration and noise accompanying it. FIG. 7 shows a side plate according to another embodiment of the present invention. With reference to FIG. 7, the present embodiment is shown in FIG.
3 is different from the embodiment of FIG. 3 in that in the embodiment shown in FIG. 3, an extension groove 36 continuous with the first clearance groove 21 is provided on the gear side side surface 5a of the side plate 5. Instead, the high-pressure fluid introduction path 39 formed of a through hole extending parallel to the first relief groove 21 is provided. One end of the high-pressure fluid introduction path 39 is opened to the peripheral wall surface 5b of the side plate 5 to form an opening 40 facing the discharge chamber 15, and the other end is connected to the gear side surface 5a of the side plate 5 to the closed region 38. The opening 41 is formed. As shown in FIGS. 8A and 8B, the opening 41 is arranged so as not to interfere with the line of action 35 of meshing of the gears 7 and 8, as shown in FIG.
This is similar to the escape groove 36 in the above embodiment.

Also in this embodiment, as shown in FIG. 8 (a) [corresponding to the state of FIG. 6 (b) in the above-mentioned embodiment], from the discharge chamber 15 to the high-pressure fluid introduction path at the beginning of the expansion step. The working fluid is supplied to the confinement region 38 through the opening 41 of 39, and as a result, a negative pressure in the confinement region 38 is prevented. Therefore, the generation of cavitation can be suppressed even when the gear pump rotates at high speed, and the generation of vibration and noise due to this can be reduced.

Further, as shown in FIG. 8B [corresponding to the state of FIG. 6C in the above-described embodiment], the confinement region 38 communicates with the second clearance groove 20 in the latter stage of the expansion process. Since the communication between the opening 41 of the high-pressure fluid introduction path 39 and the confinement region 38 is cut off before, there is no fear of reduction in flow rate efficiency.
It should be noted that the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the claims of the present invention.

[Brief description of drawings]

FIG. 1 is a sectional view of a gear pump according to an embodiment of the present invention.

2 is a schematic cross-sectional view taken along the line II-II in FIG. 1, in which hatching is omitted.

FIG. 3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

5A and 5B are cross-sectional views of a main part of a side plate.

6A and 6B are schematic diagrams of gear meshing, in which FIG. 6A shows a state of a compression process in a confinement region, FIG. 6B shows an initial state of an expansion process in a confinement region, and FIG. The state of the latter stage of an expansion process is shown.

FIG. 7 is a front view of a side plate according to another embodiment of the present invention.

8A and 8B are schematic diagrams of the meshing of gears in the embodiment of FIG. 7, where FIG. 8A shows the initial state of the expansion process in the closed region, and FIG. 8B shows the latter state of the expansion process.

[Explanation of symbols]

1 cavity 2 body tube 3 lid plate 4 housing 5 Side plate 5a Gear side 5b peripheral wall 6 gear chamber 7 drive gear 8 driven gear 14 Suction chamber 15 Discharge chamber 20 Second relief groove (second groove) 21 First relief groove (first groove) 31 intersection 32,33 rotation center 34 plane 35 Action line of meshing 36 Extension groove 38 Confinement area 39 High pressure fluid introduction path 40, 41 openings A, B meshing point

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ryosuke Yamanaka             3-5-8 Minamisenba, Chuo-ku, Osaka Koyo             Within Seiko Co., Ltd. F-term (reference) 3H041 BB02 CC12 DD04 DD12 DD13                       DD17 DD18 DD24                 3H044 BB02 CC11 DD04 DD12 DD13                       DD15 DD16

Claims (2)

[Claims] 1. A housing having a void therein, a pair of side plates fitted in the void to define a gear chamber inside the housing, a pair of gears accommodated in the gear chamber, and a pair of these. A closed region of the working fluid generated in the vicinity of the meshed portion of the pair of gears in relation to the rotation of the pair of gears, and a suction chamber and a discharge chamber of the working fluid arranged in the gear chamber sandwiching the meshed portion. In the gear pump, the first side groove for communicating the closed region in the compression process with the discharge chamber and the first groove for communicating the closed region in the expansion process with the suction chamber are formed on the gear side surface of the at least one side plate. A second groove and an extending groove extending from the first groove toward the second groove side so as not to interfere with the action line of meshing of the gear are formed, and are closed as the gear rotates. Second area Gear pump, wherein you have to communicate with the extension 設溝 and closed off area is broken before communicating with the groove. 2. A housing having a void therein, a pair of side plates fitted into the void to define a gear chamber inside the housing, a pair of gears accommodated in the gear chamber, and these. A closed region of the working fluid generated in the vicinity of the meshed portion of the pair of gears in relation to the rotation of the pair of gears, and a suction chamber and a discharge chamber of the working fluid arranged in the gear chamber sandwiching the meshed portion. In the gear pump, the first side groove for communicating the closed region in the compression process with the discharge chamber and the first groove for communicating the closed region in the expansion process with the suction chamber are formed on the gear side surface of the at least one side plate. A second groove is formed to penetrate the at least one side plate from the discharge chamber to form an opening on the side surface on the gear side, and through the opening, the high pressure of the discharge chamber A high-pressure fluid introduction path for introducing the dynamic fluid is provided, and the communication between the opening and the closed area of the high-pressure fluid introduction path is interrupted before the confinement area communicates with the second groove as the gear rotates. A gear pump characterized by being soaked.