JP2005133557A - Gear pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear pump capable of improving volume efficiency and durability by a simple constitution and coping with increase in volume without requiring high machining precision. <P>SOLUTION: A first gear 1 and a second gear 2 meshing mutually are arranged in a recessed part 10a of a casing 10. A suction port 21 is provided in either of the recessed part 10a of the casing 10 and the vicinity of a part where the first and second gears 1, 2 mesh mutually, and a discharge port 22 is provided in the other of the recessed part 10a of the casing 10 and the vicinity of the part where the first and second gears 1, 2 mesh mutually. A first seal part 3 having a seal face 3a with which a tooth tip of the first gear 1 comes into slide-contact is provided in the vicinity of the suction port 21 of the casing 10 and on a first gear 1 side. A second seal part 4 having a seal face 4a with which a tooth tip of the second gear 2 comes into slide-contact is provided in the vicinity of the suction port 21 of the casing 10 and on a second gear 2 side. Dimension in the peripheral direction of the seal faces 3a, 4a of the first and second seal parts 3, 4 is equivalent to 1.5 to 2 pitch of the first and second gears 1, 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gear pump, and more particularly to a gear pump used for conveying viscous fluid.

  Conventionally, as a gear pump, a seal block type gear pump shown in FIG. 6 has been proposed (see, for example, JP-A-10-252589 (Patent Document 1)). In this gear pump, as shown in FIG. 6, first and second gears 101 and 102 that mesh with each other are disposed in a recess 110a of a casing 110, and a seal block 120 is disposed on the suction port 121 side of the recess 110a. Yes. The seal surface 103 of the seal block 120 is in sliding contact with the tooth tip of the first gear 101, and the seal surface 104 of the seal block 120 is in sliding contact with the tooth tip of the second gear 102. A projection 120a provided on the back side of the seal block 120 (the side opposite to the seal surfaces 103 and 104) is in linear contact with the inner peripheral surface of the recess 110a of the casing 110, and the seal block 120 is a projection. It is supported so as to swing around 120a. In FIG. 6, reference numeral 111 denotes a first rotating shaft connected to the first gear 101, and 112 denotes a second rotating shaft connected to the second gear 102.

  FIG. 7 is a sectional view taken along line VII-VII in FIG. 6, wherein 105 and 106 are side plates whose side surfaces are in sliding contact with both side surfaces of the first and second gears 101 and 102, and 113 is the first plate. A bearing for the rotating shaft 111, 120 is a cover, and 115 is an oil seal.

  In the seal block type gear pump configured as described above, when the first gear 101 rotates in the direction of the arrow R101 (clockwise) by the rotation of the first rotating shaft 111 connected to the first gear 101, as shown in FIG. The second gear 102 meshing with the first gear 101 rotates in the direction of the arrow R102 (counterclockwise) about the second rotation shaft 112 as the axis. Thus, the fluid sucked from the suction port 121 is sent out to the high-pressure chamber communicating with the discharge port 122 by the teeth of the first and second gears 101 and 102 that are in sliding contact with the seal surfaces 103 and 104 of the seal block 120.

  FIG. 8 shows the pressure change around the first gear 101 of the seal block type gear pump. The area D on the suction port 121 side (low pressure chamber side), the area E on the seal surface 103 of the seal block 120, the discharge port 122. The pressure increases stepwise in the order of the side region F (high pressure chamber side), and the pressure distribution is constant in the high pressure chamber side region F (the same applies to the second gear 102 side). Therefore, the pressure balance in the axial direction is improved, and the sealing performance between the side surfaces of the first and second gears 101 and 102 and the side surfaces of the side plates 105 and 106 is kept good.

  By the way, in the seal block type gear pump, there is a problem that in the region where the rotational speeds of the first and second gears 101 and 102 are low speed, the seal block 120 pulsates and leakage increases, so that the volumetric efficiency decreases. (See the curve indicated by the black circle in the graph of FIG. 4).

  Further, in the seal block type gear pump, since the seal block 120 is supported so as to swing around the protrusion 120a, high processing accuracy is required, and since the support structure is based on line contact, the larger the size, the more durable it becomes. There is a problem that the nature is low.

The above-mentioned seal block gear pump is suitable for the use of a small pump with a relatively small capacity for a low-viscosity fuel. It cannot be used for large pumps with large capacity.
Japanese Patent Laid-Open No. 10-252589

  Accordingly, an object of the present invention is to provide a gear pump that can cope with an increase in capacity that can improve volumetric efficiency and durability with a simple configuration without requiring high processing accuracy.

  In order to achieve the above object, a gear pump according to the present invention includes a casing, a first gear and a second gear which are disposed in a chamber in the casing and mesh with each other, and communicate with the chamber of the casing, and the first gear and the first gear. A suction port provided on one side in the vicinity of the meshing portion of the two gears, a discharge port in communication with the casing chamber and provided in the other vicinity of the meshing portion of the first gear and the second gear, and the first gear And a side plate that is in sliding contact with at least one of both side surfaces of the second gear, and a seal that is fixedly provided on the casing so as to be positioned in the vicinity of the suction port, and in which the tooth tip of the first gear slides. A first seal portion having a surface, and a second seal having a seal surface which is fixedly provided on the casing so as to be positioned in the vicinity of the suction port, and where the tooth tip of the second gear slides. And a le portion, characterized in that the first, circumferential dimension of the sealing surface of the second sealing portion is less than half of the circumference of the first, second gear.

  According to the gear pump configured as described above, the first gear and the second gear that mesh with each other rotate, and the fluid sucked from the suction port is in sliding contact with the seal surfaces of the first and second seal portions. The teeth are fed to the high pressure chamber side communicating with the discharge port. Unlike the gear pump, which has a problem with the support structure of the seal block, the first and second seal portions are fixed to the casing and do not swing, so that the first and second seal portions can be used even in a low rotational speed region. Leakage at the sealing surface is reduced, and high volumetric efficiency is obtained. In addition, the first and second gears can be slidably contacted with each other by reducing the circumferential dimension of the seal surfaces of the first and second seal portions to half or less of the circumference of the first and second gears. The pressure fluctuation in the circumferential direction at the second seal portion can be reduced, the pressure balance between the first and second gears can be accurately adjusted, and the pressure imbalance at the seal surface between the first and second gears and the side plate can be achieved. This can prevent a decrease in efficiency. Therefore, without using a seal block that requires high processing accuracy, the volume efficiency and durability can be improved with a simple configuration, and a gear pump that can cope with a large capacity can be realized at low cost.

  In one embodiment, the circumferential dimension of the seal surface of the first and second seal portions corresponds to 1.5 to 2 pitches of the first and second gears.

  According to the gear pump of the above embodiment, the circumferential dimensions of the seal surfaces of the first and second seal portions where the tooth tips of the first and second gears are in sliding contact are set to 1.5 to 2 of the first and second gears. By setting the length corresponding to the pitch, the amount of pressure fluctuation in the circumferential direction at the first and second seal portions can be reduced, and the pressure balance between the first and second gears can be accurately adjusted. It is possible to prevent a decrease in efficiency due to pressure imbalance on the seal surface between the two gears and the side plate.

  Moreover, the gear pump of one embodiment is characterized in that the first and second seal portions are separate members from the casing and are fixed to the casing.

  According to the gear pump of the above-described embodiment, the first and second seal portions, which are separate members from the casing, are fixed to the casing by welding or the like. , And can be used for the second seal portion, and the volumetric efficiency and durability can be further improved.

  As is clear from the above, according to the gear pump of the present invention, the volumetric efficiency and durability can be improved with a simple configuration without requiring high machining accuracy, and the capacity can be increased.

  Further, the circumferential dimension of the seal surface of the first and second seal portions where the tooth tips of the first and second gears are in sliding contact with each other is set to a length corresponding to 1.5 to 2 pitches of the first and second gears. By doing so, the pressure imbalance on the sealing surfaces of the first and second gears and the side plates can be made uniform, and the decrease in volumetric efficiency can be prevented.

  Further, by using the first and second seal portions as separate members from the casing, a material having a good sealing performance different from the casing material can be used for the first and second seal portions, and volume efficiency and Durability can be further improved.

  The gear pump of the present invention will be described in detail below with reference to the illustrated embodiments.

(First embodiment)
FIG. 1 is a schematic diagram showing a cross section of a gear pump according to a first embodiment of the present invention. The gear pump according to the first embodiment is used to convey coolant (cooling liquid) having a relatively low viscosity used for machine tools and the like.

  As shown in FIG. 1, a casing 10 having a concave portion 10a having a cross-sectional glasses shape composed of two cylindrical spaces whose axes are parallel and partially overlapped with each other, and the same shape that is disposed in the concave portion 10a of the casing 10 and meshes with each other. The first gear 1 and the second gear 2, the recess 10a of the casing 10 and the suction port 21 provided in the vicinity of the engaging portion of the first gear 1 and the second gear 2, the recess 10a of the casing 10 and A discharge port 22 provided on the other side in the vicinity of the portion where the first gear 1 and the second gear 2 mesh with each other, a suction port 21 of the casing 10 provided on the first gear 1 side, and a tooth tip of the first gear 1 A first seal portion 3 having a seal surface 3a that is in sliding contact, and a seal surface 4a that is provided in the vicinity of the suction port 21 of the casing 10 and on the second gear 2 side, and the tooth tip of the second gear 2 is in sliding contact. And a second seal portion 4 having. Although FIG. 1 is a schematic diagram and does not show actual dimensions, the circumferential dimensions of the seal surfaces 3a and 4a of the first and second seal portions 3 and 4 are the same as those of the first and second gears 1 and 2, respectively. 2 to a length corresponding to 1.5 to 2 pitches. The casing 10 is made of cast steel, aluminum alloy, or the like. The first gear 1 and the second gear 2 are made of carburized and hardened steel.

  FIG. 2 is a schematic diagram showing a cross section viewed from the line II-II in FIG. 1. The first gear 1 and the second gear 2 are sandwiched between both side surfaces in the recess 10 a of the casing 10. A first side plate 5 and a second side plate 6 are arranged. The first side plate 5 and the second side plate 6 seal the side surfaces of the first and second gears 1, 2 and the side surfaces of the first and second side plates 5, 6, and the low pressure chamber communicating with the suction port 21 and the discharge A high pressure chamber communicating with the port 22 is formed. One of the casings 10 is covered with a casing cover 20, and the casing 10 and the casing cover 20 form a chamber inside. One end (right side in FIG. 2) of the first rotating shaft 11 that drives the first gear 1 is rotatably supported by the casing 10 via a bearing 13A, and the other end of the first rotating shaft 11 (left side in FIG. 2). ) Is rotatably supported by the casing cover 20 via a bearing 13B. A connecting portion 11a on the other end side of the first rotating shaft 11 protrudes from the casing cover 20, and a drive shaft of a motor (not shown) is connected to the connecting portion 11a. Further, one end (right side in FIG. 2) of the second gear 2 of the second gear 2 is rotatably supported by the casing 10 via a bearing 14A, and the other end (left side in FIG. 2) of the second rotation shaft 12 is supported. ) Is rotatably supported by the casing cover 20 via a bearing 14B.

  In the gear pump having the above configuration, as shown in FIG. 1, when the first gear 1 rotates in the direction of the arrow R1 (clockwise) by the rotation of the first rotating shaft 11 connected to the first gear 1, the second gear 2 Rotates around the second rotation shaft 12 in the direction of the arrow R2 (counterclockwise). Thus, the fluid sucked from the suction port 21 communicates with the discharge port 22 by the teeth of the first and second gears 1 and 2 that are in sliding contact with the seal surfaces 3a and 4a of the first and second seal portions 3 and 4. To the high pressure chamber side.

  FIG. 3 shows changes in pressure around the first gear 1 of the gear pump. Region A on the suction port 21 side (low pressure chamber side), region B on the seal surface 3a of the seal portion 3, and region on the discharge port 22 side. The pressure gradually increases in the order of C (high pressure chamber side), and the pressure distribution is constant in the region C on the high pressure chamber side (the same applies to the second gear 2 side).

FIG. 4 is a diagram showing the experimental results of examining the relationship between the rotational speed and the volumetric efficiency in the gear pump. At this time, the experiment was performed under the conditions of a fluid temperature T of 40 ° C. and a pressure of 5 MPa. In FIG. 4, the horizontal axis represents the rotational speed [min ⁻¹ ], and the vertical axis represents the volumetric efficiency [%].

  As shown in FIG. 4, compared with the conventional seal block type gear pump indicated by black circles, the gear pump of the first embodiment indicated by white circles has a high volumetric efficiency even in a region where the rotational speed is low. In the gear pump according to the first embodiment of the present invention, unlike the gear pump having a problem in the support structure of the seal block, the first and second seal portions 3 and 4 are provided integrally with the casing 10 and do not swing. By making the circumferential dimension of the seal surfaces 3a and 4a of the first and second seal portions 3 and 4 into a length corresponding to 1.5 to 2 pitches of the first and second gears 1 and 2, the first and second The pressure fluctuation in the circumferential direction at the two seal portions is reduced. By these two synergistic effects, it is possible to effectively prevent leakage due to pressure imbalance in the seal surface between the first and second gears 1 and 2 and the side plates 5 and 6, and the first and second gears 1 and 2. This is because stable sealing performance can be obtained regardless of the rotational speed.

  Thus, according to the gear pump of the first embodiment, a gear pump with high volumetric efficiency and durability can be realized at a low cost with a simple configuration without using a seal block that requires high machining accuracy. .

(Second embodiment)
FIG. 5: has shown the schematic schematic diagram which shows the cross section of the gear pump of 2nd Embodiment of this invention. The gear pump of the second embodiment has the same configuration as that of the gear pump shown in FIG. 1 of the first embodiment except for the seal portion, and the same components are denoted by the same reference numerals and description thereof is omitted.

  A first seal portion 23 having a seal surface 23a on which the tooth tip of the first gear 1 is slidably contacted is fixed in the vicinity of the suction port 21 of the casing 10 and on the first gear 1 side. Also, a second seal portion 24 having a seal surface 24a that is provided in the vicinity of the suction port 21 of the casing 10 and on the second gear 2 side and in which the tooth tip of the second gear 2 is in sliding contact is welded and fixed. Although FIG. 5 is a schematic diagram and does not show actual dimensions, the circumferential dimensions of the seal surfaces 23a and 24a of the first and second seal portions 23 and 24 are the same as those of the first and second gears 1 and 2, respectively. 2 to a length corresponding to 1.5 to 2 pitches. The first and second seal portions 23 and 24 are made of brass, bronze weld, aluminum alloy, cast iron, PTFE (polytetrafluoroethylene), or the like.

  As described above, in the gear pump of the second embodiment, the first and second seal portions 23 and 24, which are separate members from the casing 10, are fixed in the recess 10a of the casing 10 by welding or the like. A material having a good sealing performance different from the material can be used for the first and second seal portions 23 and 24, and the durability can be further improved.

  In the first and second embodiments, the gear pump for transporting a relatively low-viscosity coolant (cooling liquid) used in a machine tool or the like has been described, but the present invention may be applied to a gear pump that transports other liquids. Good.

  In the first and second embodiments, the gear pump in which the first side plate 5 and the second side plate 6 are disposed so as to sandwich both side surfaces of the first gear 1 and the second gear 2 in the recess 10 a of the casing 10. As described above, the present invention may be applied to a gear pump having a configuration in which the side plate is in sliding contact with one of both side surfaces of the first gear and the second gear of the casing and the other is in sliding contact with the casing.

  In the gear pump according to the present invention, if the circumferential dimension of the seal surfaces of the first and second seal portions is not more than half the circumference of the first and second gears, the circumference of the first and second seal portions will be reduced. The effect of reducing the pressure fluctuation in the direction is obtained, but the circumferential dimension of the seal surfaces of the first and second seal portions is a length corresponding to 1.5 to 2 pitches of the first and second gears. It is desirable.

FIG. 1 is a schematic diagram showing a cross section of a gear pump according to a first embodiment of the present invention. FIG. 2 is a sectional view taken along line II-II in FIG. FIG. 3 is a diagram showing a pressure distribution during the operation of the gear pump. FIG. 4 is a graph showing the relationship between the rotational speed and volumetric efficiency. FIG. 5 is a schematic diagram showing a cross section of a gear pump according to a second embodiment of the present invention. FIG. 6 is a sectional view of a conventional gear pump. FIG. 7 is a view showing a cross section seen from the line VII-VII in FIG. FIG. 8 is a diagram showing the pressure distribution during the operation of the gear pump.

Explanation of symbols

1 ... 1st gear,
2 ... Second gear,
3 ... 1st seal part,
3a ... sealing surface,
4 ... 2nd seal part,
4a ... sealing surface,
5 ... 1st side plate,
6 ... the second side plate,
10 ... casing,
11 ... 1st rotation axis,
12 ... the second rotation axis,
13A, 13B, 14A, 14B ... bearings,
15 ... oil seal,
20 ... casing cover,
21 ... Inhalation port,
22: Discharge port,
23 ... 1st seal part,
23a ... sealing surface,
24 ... second seal part,
24a: Seal surface.

Claims (3)

A casing (10);
A first gear (1) and a second gear (2) disposed in a chamber in the casing (10) and meshing with each other;
A suction port (21) provided on one side in the vicinity of a portion where the first gear (1) and the second gear (2) mesh with each other and communicated with the chamber of the casing (10);
A discharge port (22) provided on the other side in the vicinity of a portion where the first gear (1) and the second gear (2) mesh with each other, and communicating with the chamber of the casing (10);
Side plates (5, 6) in sliding contact with at least one of both side surfaces of the first gear (1) and the second gear (2);
A first seal portion (3) having a seal surface fixedly provided on the casing (10) so as to be positioned in the vicinity of the suction port (21) and having a tooth surface of the first gear (1) in sliding contact therewith. When,
A second seal portion (4) having a seal surface fixedly provided on the casing (10) so as to be positioned in the vicinity of the suction port (21) and having a toothed surface of the second gear (2) slidingly contacted. And
The gear pump according to claim 1, wherein a circumferential dimension of the seal surface of the first and second seal portions (3,4) is not more than half of a circumference of the first and second gears (1, 2). The gear pump according to claim 1, wherein
A gear pump characterized in that the circumferential dimension of the seal surface of the first and second seal portions (3,4) corresponds to 1.5 to 2 pitches of the first and second gears (1, 2). . The gear pump according to claim 1 or 2,
The gear pump characterized in that the first and second seal portions (23, 24) are separate members from the casing (10) and are fixed to the casing (10).

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