WO2013133202A1 - Variable displacement gear pump - Google Patents

Description

Variable displacement gear pump

The present invention relates to an external variable displacement gear pump, and more particularly to a variable displacement gear pump capable of increasing and decreasing the displacement during operation.

As a variable displacement gear pump, a so-called external-type variable displacement gear pump is used, in which the sucked fluid is pressurized and discharged by a pair of gears engaged with each other in a mutually contacting manner. With respect to this variable displacement gear pump of the external connection type, a technique capable of changing the discharge flow rate of the fluid according to the demand has been proposed. For example, Patent Document 1 discloses a structure in which the pump displacement is made variable by making the distance between gears of the gear pump variable. According to this, in the gear pump having the drive gear and the driven gear which mutually engage and contact with each other, the pressure compensation device appropriately moves the movable block holding the driven shaft of the driven gear rotatably by the force of the spring, Automatically adjust the distance between the drive gear and the driven gear.

Japanese Patent Application Laid-Open No. 50-55908

Here, in the variable displacement gear pump described in Patent Document 1, it is necessary to translate the shaft of the driven gear in order to change the distance between the gears. However, there are bearings on both sides of the gear, and in order to translate every two bearings, it is necessary to arrange a pair of movable blocks provided with this bearing on both sides of the gear, and the structure as a whole gear pump is complicated. It has become.

The present invention has been made to solve such problems, and it is an object of the present invention to provide a variable displacement gear pump which can increase and decrease the discharge capacity during operation with a simple structure.

A variable displacement gear pump according to the present invention includes a gear pair of a drive gear and a driven gear which are housed in a gear chamber formed inside a housing, and are engaged with each other in a mutually contacting manner, and suctioned fluid is boosted by the gear chamber. A variable displacement gear pump for discharging, comprising: a rotation support shaft portion rotatably supported by the housing; and a driven gear support portion eccentric to the rotation support shaft portion and rotatably supporting the driven gear And an eccentric shaft rotation means connected to the rotation support shaft portion and rotating the eccentric shaft.
Thus, the distance between the gears can be easily adjusted and the displacement can be increased or decreased by rotating the eccentric shaft by the eccentric shaft rotating means.

In addition, the variable displacement gear pump according to the present invention may be provided with a restraining mechanism that holds the phase of the rotation support shaft.
The restraining mechanism may also have a worm wheel fixed to the eccentric shaft and a worm gear meshing with the worm wheel.
Furthermore, the driven gear support can support the driven gear via the driven gear bearing.

According to the present invention, in the variable displacement gear pump, the displacement can be increased or decreased during operation with a simple structure.

FIG. 2 is a schematic plan view showing the inside of the gear chamber of the variable displacement gear pump according to the embodiment of the present invention. FIG. 6 is a schematic plan view showing the inside of the gear chamber when the displacement of the driven gear is changed by changing the position of the driven gear to increase the distance between the drive gear and the driven gear, with respect to the variable displacement gear pump shown in FIG. It is a schematic diagram showing the relationship between rotation of an eccentric shaft and the distance between gears about the variable displacement gear pump shown to FIG. 1 and FIG. It is a cross-sectional side view in the AA of the variable displacement gear pump shown in FIG. It is a figure which shows the shape of the driven-side seal block of the variable displacement gear pump which concerns on another embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 4, the housing 30 of the variable displacement gear pump 1 comprises a first housing 3a and a second housing 3b. By connecting the first housing 3a and the second housing 3b, the gear chamber 10 is formed between the first housing 3a and the second housing 3b. Further, as shown in FIG. 1, in the gear chamber 10, there is accommodated a gear pair 5 consisting of a drive gear 6 and a driven gear 8 which are in contact with each other and mesh.

Further, inside the variable displacement gear pump 1, a drive gear rotary shaft 7 is integrally provided to the drive gear 6. The drive gear rotation shaft 7 extends inside the housing 30. Further, a hole 18 is formed in the first housing 3a, and one end of the drive gear rotating shaft 7 is exposed to the outside through the hole 18 and connected to a drive source (not shown). The drive gear rotating shaft 7 can be rotated by this drive source. Further, in order to prevent oil leakage inside the variable displacement gear pump 1, an oil seal 13 is provided on the first housing 3a on the side where the drive gear rotary shaft 7 is exposed to the outside. Furthermore, on both sides of the drive gear 6, a pair of drive gear bearings 11 is provided so as to be sandwiched between the first housing 3a and the second housing 3b and the drive gear rotary shaft 7, and the drive gear rotary shaft 7 is a drive gear It is rotatable relative to the housing 3 via the bearing 11. Here, let P be a center line on which the drive gear 6 rotates. Further, a circular curve drawn by the tips of the drive gear 6 constitutes a drive gear tip circle 6a.

Next, an eccentric shaft 9 passes through the center of the driven gear 8. The eccentric shaft 9 includes a driven gear support 21 and a rotation support shaft 22 integrally provided at both ends of the driven gear support 21. The driven gear support 21 and the rotation support shaft 22 have a cylindrical shape, and the diameter of the driven gear support 21 is larger than the diameter of the rotation support shaft 22. Further, a driven gear bearing 26 is supported by the driven gear support portion 21. Further, the driven gear 8 is rotatably supported by the driven gear support 21 via a driven gear bearing 26. Here, the rotation center line of the driven gear 8 is assumed to be Q. Further, the rotation center of the driven gear support 21 coincides with the rotation center line Q of the driven gear 8. Furthermore, the circular curve drawn by the tip of the driven gear 8 constitutes a driven gear tip circle 8a. On the other hand, a hole 19 is formed in the first housing 3a separately from the above-mentioned hole 18, and one end of the rotation support shaft 22 passes through the hole 19 of the first housing 3a and is exposed to the outside. An oil seal 17 is provided on the first housing 3a on the side where the rotation support shaft 22 is exposed to the outside. In addition, the rotation support shaft portion 22 is rotatably supported by the first housing 3a and the second housing 3b. Here, the rotation center line O of the rotation support shaft portion 22 is at a position different from the rotation center line Q of the driven gear 8 and the driven gear support portion 21. That is, the rotation center line Q of the driven gear 8 and the driven gear support 21 is eccentric to the rotation support shaft 22.

Further, the worm wheel 45 is fixed and connected to the tip end of the rotation support shaft portion 22 exposed to the outside of the housing 30 (first housing 3a). The worm wheel 45 meshes with the worm gear 41. A stepping motor 43 is connected to the worm gear 41. When the stepping motor 43 is driven, the worm gear 41 rotates, and at the same time, the worm wheel 45 and the rotation support shaft 22 rotate. That is, the combination of the worm wheel 45 and the worm gear 41 constitutes an eccentric shaft rotation means, and the eccentric shaft 9 can be rotated by the eccentric shaft rotation means. In addition, when the stepping motor 43 does not rotate the worm gear 41, the rotation of the rotation support shaft 22 is prevented by the meshing between the worm wheel 45 and the worm gear 41, and the phase is maintained. That is, the combination of the worm wheel 45 and the worm gear 41 also constitutes a restraining mechanism.

Here, the discharge displacement of the fluid by the variable displacement gear pump 1 increases or decreases in accordance with the degree of meshing between the drive gear 6 and the driven gear 8. That is, if the distance between the drive gear 6 and the driven gear 8 is small and the degree of meshing is large, the discharge displacement becomes large. On the other hand, if the distance between the drive gear 6 and the driven gear 8 is large and the degree of meshing is small, the discharge displacement is small. In the present embodiment, the center-to-center distance PQ between the drive gear 6 and the driven gear 8 in the case shown in FIG. On the other hand, the center-to-center distance PQ 'is I when the driven gear 8 is separated from the drive gear 6 as described later and the position of the center line is moved to Q' as shown in FIG. Since I is longer than H (see FIG. 3), the degree of meshing is larger in the case shown in FIG. 1 than in the case shown in FIG. 2, and the displacement of the variable displacement gear pump 1 is large.

Further, as shown in FIG. 1, the discharge port 31 and the suction port 32 formed in the housing 30 are in communication with the gear chamber 10. A discharge area 10A is formed on the discharge port 31 side with the gear pair 5 interposed therebetween, and a suction area 10B is formed on the suction port 32 side. The discharge area 10A and the suction area 10B are separated from each other by the engagement of the drive gear 6 and the driven gear 8 of the gear pair 5. The pressure in the discharge area 10A is higher than the pressure in the suction area 10B.

On the side of the discharge port 31 in the gear chamber 10 of the housing 30, a concave recess 36 for holding a drive-side seal block 14 and a driven-side seal block 15 described later is formed. In the recessed portion 36, on the drive gear 6 side, a drive side seal block holding surface 30a formed of two wall surfaces perpendicular to each other is formed. Further, similarly to the drive side seal block holding surface 30a, a driven side seal block holding surface 30b formed of two wall surfaces perpendicular to each other is also formed on the driven gear 8 side. In particular, a wall surface extending parallel to the discharge port 31 in the driven side seal block holding surface 30b is taken as a movement restriction surface 30c. The drive side seal block 14 is disposed on the drive side seal block holding surface 30a, and the driven side seal block 15 is disposed on the driven side seal block holding surface 30b. That is, the drive side seal block 14 is accommodated between the housing 30 and the drive gear 6, while the driven side seal block 15 is accommodated between the housing 30 and the driven gear 8. Furthermore, oil seals 14b and 15b are disposed on the drive side seal block 14 and the driven side seal block 15, respectively, and the gaps between the drive side seal block 14 and the driven side seal block 15 and the housing 3 are made by the oil seals 14b and 15b. It is sealed. The drive-side seal block 14 and the driven-side seal block 15 are each a hexahedron in which one surface of a substantially rectangular parallelepiped is a curved surface 6 b or 8 b. The curved surfaces 6b and 8b have arc-shaped curved shapes that follow the tip circles 6a and 8a of the drive gear 6 and the driven gear 8, respectively. That is, the curvatures of the curved surfaces 6b and 8b are equal to the curvatures of the tip circles 6a and 8a of the drive gear 6 and the driven gear 8, respectively. The curved surface 6 b of the drive-side seal block 14 is in sliding contact with at least two tips of the rotating drive gear 6. Similarly, the curved surface 8 b of the driven side seal block 15 is in sliding contact with at least two tips of the driven driven gear 8. A sealed space S for pressure-feeding fluid is formed between the two teeth of each of the drive gear 6 and the driven gear 8 and the drive-side seal block 14 and the driven-side seal block 15. The driven side seal block 15 also has a pressure receiving surface 15 a facing the discharge port 31 and receiving the pressure from the discharge port 31. Furthermore, a band-like convex portion 35 extending in the direction perpendicular to the paper surface is formed on the movement restricting surface 30c. The convex portion 35 has a curved cross section, and the driven seal block 15 and the convex portion 35 are in line contact with each other. Here, a portion where the driven side seal block 15 and the housing 30 make a line contact is referred to as a contact portion. That is, the driven seal block 15 can contact the movement restricting surface 30 c of the housing 30 at at least one contact portion.
The discharge port 31 side constitutes a fluid discharge side. Moreover, the convex part 35 comprises a housing side projection part.

The basic operation of the variable displacement gear pump 1 will be described below with reference to FIGS.
First, when a drive force is applied to the drive gear rotary shaft 7 from the outside, the drive gear 6 integrally with the drive gear rotary shaft 7 starts to rotate in the direction indicated by the arrow (see FIG. 1). At the same time, the driven gear 8 meshing with the drive gear 6 also rotates in the arrow direction. At this time, the eccentric shaft 9 penetrating to the center of the driven gear 8 is not rotated by the restraining mechanism formed of a combination of the worm wheel 45 and the worm gear 41. On the other hand, the driven gear 8 rotates around the driven gear support 21 via the driven gear bearing 26.

Next, when the drive gear 6 and the driven gear 8 rotate, the fluid sucked from the suction port 32 is between the teeth of the drive gear 6 and the drive side seal block 14 and between the teeth of the driven gear 8 and the driven side seal It is confined in the space S formed between it and the block 15. Then, the fluid confined in the space S moves with the drive gear 6 and the driven gear 8. The fluid transferred by the rotation of the drive gear 6 and the driven gear 8 is discharged from the discharge port 31.

Hereinafter, a method for increasing and decreasing the displacement while the variable displacement gear pump 1 is in operation will be described with reference to FIGS.
When the discharge displacement is to be reduced from the state of FIG. 1, the worm gear 41 is first rotated by driving the stepping motor 43. As the worm gear 41 rotates, the worm wheel 45 rotates while meshing with the worm gear 41. At the same time, the rotation support shaft 22 connected to the worm wheel 45 integrally rotates clockwise on the paper surface. At this time, as shown in FIG. 3, the eccentric shaft 9 rotates clockwise by an angle x around the rotation center line O of the rotation support shaft portion 22, and the rotation centers of the driven gear 8 and the eccentric shaft 9 The position of the line moves from Q to Q 'and becomes the state of FIG. At the same time, the center-to-center distance between the drive gear 6 and the driven gear 8 changes from H to I. That is, the displacement of the variable displacement gear pump 1 is reduced. On the other hand, when attempting to increase the discharge capacity from the state of FIG. 2, the rotation support shaft portion 22 is rotated counterclockwise on the drawing sheet in the same manner, and the center-to-center distance between the drive gear 6 and the driven gear 8 Changes from I to H.

Further, when the position of the driven gear 8 changes from the state of FIG. 1 to the state of FIG. 2, the driven side seal block 15 can move in accordance with the position change of the driven gear 8 with the convex portion 35 as a fulcrum. Specifically, the driven side seal block 15 moves so that the curved surface 8b abuts on the two tooth tips of the driven gear 8, so that the driven side seal block 15 follows the tooth top circle 8a of the driven gear 8 It is regulated. However, since the pressure in the discharge area 10A in the gear chamber 10 is higher than the pressure in the suction area 10B, the driven side seal block 15 receives the pressure from the discharge port 31 side at the pressure receiving surface 15a, and Try to move to the next. Then, the driven side seal block 15 abuts on the convex portion 35 of the movement restricting surface 30 c to restrict the movement from the left to the right. That is, the driven side seal block 15 is fixed in position by coming into contact with the two tooth tips of the driven gear 8 and the convex portion 35 in response to the pressure from the discharge port 31 side. Therefore, even when the position of the driven gear 8 with respect to the drive gear 6 is changed during operation of the variable displacement gear pump 1, the curved surface 8b of the driven side seal block 15 is always against at least two tips of the driven gear 8. It is comprised so that a contact state may be maintained. The operation of the variable displacement gear pump 1 refers to a state in which the pressure in the discharge area 10A is maintained higher than the pressure in the suction area 10B.

As described above, the driven gear 8 is rotatable with respect to the eccentric shaft 9 and the eccentric shaft 9 is eccentrically rotated with respect to the driven gear 8 about the rotation center line O, whereby the drive gear 6 and the driven gear 6 are driven. The center-to-center distance with the gear 8 can be varied. Therefore, the discharge displacement of the fluid can be easily increased or decreased during the operation of the variable displacement gear pump 1. Further, since the driven gear support portion 21 supports the driven gear 8 via the driven gear bearing 26, the position of the driven gear 8 can be varied with the driven gear bearing 26 with a simple structure.

Also, under the simple structure that does not change the overall shape of the gear chamber 10, the sealed state of the space S during operation of the variable displacement gear pump 1 is obtained by the movement of the small parts interposed inside, ie, the driven side seal block 15. It will always be maintained. Therefore, the variable displacement gear pump 1 functions normally even after the position change of the driven gear 8.

In the embodiment, the eccentric shaft rotation means is a combination of the worm gear 41 and the worm wheel 45 driven by the stepping motor 43. However, the present invention is not limited to this. The rotation support shaft portion 22 is an ultrasonic motor. The restraint mechanism may be configured by the position holding function of the ultrasonic motor that is driven. In addition to the eccentric shaft rotating means, for example, a restraining mechanism such as a latch mechanism capable of selectively engaging with the rotating support shaft portion 22 and holding the phase of the rotating support shaft portion 22 You may provide in an appropriate place.

Moreover, it is not restricted to the convex part 35 of embodiment, As shown in FIG. 5, convex part 35 'may be formed in the driven side seal block 15. As shown in FIG. In this case, the convex portion 35 'of the driven side seal block 15 is in linear contact with the movement restricting surface 30c'. Here, the projection 35 'constitutes a seal block side projection.

Reference Signs List 1 variable displacement gear pump, 5 gear pairs, 6 drive gears, 8 driven gears, 8a tooth top circle of driven gear, 9 eccentric shaft, 10 gear chamber, 15 driven side seal block, 15a pressure receiving surface, 21 driven gear support portion, 22 Rotation support shaft portion, 26 driven gear bearing, 30 housing, 31 discharge port, 32 suction port, 35 convex portion (housing side projecting portion), 35 ′ convex portion (seal block side projecting portion), 36 recessed portion, 41 worm gear (Eccentric shaft rotation means and restraint mechanism), 45 Worm wheel (Eccentric shaft rotation means and restraint mechanism), S Sealed space.

Claims (8)

A variable displacement gear pump includes a gear pair of a drive gear and a driven gear which are accommodated in a gear chamber formed inside a housing and engaged with each other in a mutually contacting manner, and which discharges sucked fluid by the gear chamber.
A rotation support shaft portion rotatably supported by the housing, and an eccentric shaft having a driven gear support portion which is eccentric with respect to the rotation support shaft portion and which rotatably supports the driven gear;
A variable displacement gear pump comprising: an eccentric shaft rotation means connected to the rotation support shaft portion for rotating the eccentric shaft. The variable displacement gear pump according to claim 1, further comprising a restraint mechanism that holds the phase of the rotation support shaft. The variable displacement gear pump according to claim 2, wherein the restraining mechanism includes a worm wheel fixed to the eccentric shaft and a worm gear meshing with the worm wheel. The variable displacement gear pump according to any one of claims 1 to 3, wherein the driven gear support portion supports the driven gear via a driven gear bearing. A suction port formed in the housing and in communication with the gear chamber;
A discharge port formed in the housing and in communication with the gear chamber, wherein the discharge port discharges the fluid drawn into the gear chamber from the suction port;
A variable displacement gear pump comprising: a driven side seal block housed between the housing and the driven gear and forming a sealed space for pumping a fluid between the housing and the driven gear,
The driven side seal block has a pressure receiving surface that receives pressure from the discharge port side, and a curved surface that follows a tip circle of the driven gear, and the driven side seal block changes in position of the driven gear. It is movable according to
The curved surface of the driven-side seal block maintains contact with at least two tooth tips of the driven gear while receiving pressure from the discharge port during operation of the variable displacement gear pump. Variable displacement gear pump as described in. A recess is formed on the discharge port side in the gear chamber of the housing;
The variable displacement gear pump according to claim 5, wherein the driven seal block is capable of contacting the recess. A housing-side protrusion is provided in the recess of the housing;
The variable displacement gear pump according to claim 6, wherein the driven seal block contacts the housing protrusion. The driven side seal block is provided with a seal block side projection,
The variable displacement gear pump according to claim 6, wherein the seal block side protrusion contacts the recess.

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