JP4872845B2 - Gear pump - Google Patents

Description

  The present invention relates to a gear pump, and more particularly to a multistage gear pump in which a gear pair is housed in a plurality of gear chambers.

  In a gear pump, the presence of backlash can be cited as one of the causes for increasing the discharge pulsation that occurs when the pressurized fluid is discharged in the gear chamber. It is known that the discharge pulsation is reduced by reducing the backlash to 0 or substantially 0, that is, backlashless, and the generation of noise due to the discharge pulsation can be suppressed. Further, the reduction of the discharge pulsation can be realized by dividing the gear chamber into a plurality of parts, housing the gear pairs therein, making the gear pump a multistage structure, and shifting the timing at which each gear pair discharges the fluid. It is known.

  For example, Patent Document 1 discloses a two-stage gear pump including two gear chambers separated by a partition plate and two sets of gear pairs accommodated therein. According to this, two gears are arranged on the drive shaft and the driven shaft, and the two gears on the driven shaft side are connected to the driven shaft by spline fitting. The splines of these gears are formed so as to shift the mounting position of the gear with respect to the driven shaft by a predetermined amount in the circumferential direction, and by shifting the mounting positions in the circumferential direction of the two gears, It is possible to change the meshing phase. The two gears on the driven shaft side are attached to the driven shaft so that the gear teeth on the outer peripheral portion are shifted from each other by ½ teeth. It is comprised so that it may discharge alternately.

JP-A-9-287578

By the way, in order to further reduce the discharge pulsation in the gear pump described in Patent Document 1, it is necessary to reduce the backlash of the gear pair. On the other hand, since there is a variation that occurs at the time of manufacture in the dimensions of the parts that constitute the gear pump, there is also a variation in the backlash in the two pairs of gears. Therefore, in order to further reduce the discharge pulsation, it is necessary to individually reduce the different backlash for each gear pair.
Further, during the operation of the gear pump, due to the pressure difference of the fluid generated in the gear chamber, a load is applied to the gear pair in a direction approaching each other, that is, a direction in which the backlash is reduced. However, in the gear pump described in Patent Document 1, the distance that the gear pair can move in the direction in which the gear pair approaches each other is only a minute gap formed between the drive shaft and the driven shaft and the bearing that supports them. is there. Therefore, the gear pump described in Patent Document 1 has a problem in that it is difficult to absorb the dimensional variation generated between the two sets of gear pairs and simultaneously reduce the backlash to further reduce the discharge pulsation. It was. In order to reduce the backlash of the two pairs of gears simultaneously, extremely high machining is required on the distance between the center of the drive shaft and the driven shaft, the spline formed on the driven shaft and the gear, and the tooth surface of the gear teeth. There is a problem that accuracy is required and manufacturing cost increases.

  The present invention has been made to solve such problems. In a gear pump having a multi-stage structure, a plurality of gear pairs are engaged at the same time without backlash without requiring improvement in accuracy of parts processing. An object of the present invention is to provide a gear pump that realizes the above operation.

A gear pump according to the present invention is a gear pair comprising a plurality of separated gear chambers, and a drive gear and a driven gear that mesh with each other and rotate, and each of the plurality of gear pairs accommodated in the plurality of separated gear chambers. And a plurality of drive gears individually connected to each other, a drive gear rotating shaft to which a driving force is applied from the outside, a driven gear rotating shaft to which a plurality of driven gears are individually connected, and a drive gear rotating shaft are rotatably supported. In a gear pump that includes a drive-side slide bearing that rotates and a driven-side slide bearing that rotatably supports the driven gear rotating shaft, and that boosts and discharges the fluid sucked from outside in the gear chamber, the driving gear rotating shaft and the driven gear At least one of the rotating shafts is supported by a driving side sliding bearing or a driven side sliding bearing so as to be movable in the radial direction, and at least one of the driving gear and the driven gear is movable in the radial direction. Is connected to the drive gear rotating shaft or the driven gear axis of rotation, the drive gear driving gear rotation shaft, the driven gear is the driven gear rotation axis, are connected by spline fitting, splines between the drive gear and the drive gear rotating shaft fitting, and the spline fitting between the driven gear and the driven gear rotation axis, in which the gap in the circumferential direction are respectively formed, characterized in Rukoto.

At least one of the drive gear rotation shaft and the driven gear rotation shaft can be moved in the radial direction with respect to the drive-side slide bearing or the driven-side slide bearing, and at least one of the drive gear and the driven gear can be moved to the drive gear rotation shaft or Since it is movable in the radial direction with respect to the driven gear rotation shaft, the drive gear and the driven gear move in a direction approaching each other due to a load caused by the pressure difference of the fluid sucked into the gear pump. The range in which the drive gear and the driven gear can move is within the range in which the drive gear rotary shaft and the driven gear rotary shaft can move, the range in which the drive gear can move relative to the drive gear rotary shaft, and the driven gear rotary shaft Since the range in which the driven gear can move is added, a sufficient moving distance can be secured to absorb the variation in backlash existing between the gear pairs. In addition, since the plurality of drive gears are individually connected to the drive gear rotating shaft and the plurality of driven gears are also individually connected to the driven gear rotating shaft, each drive gear and each driven gear has a backlash. It moves individually to the optimal position where it engages with less. Therefore, in a multistage gear pump, it is possible to operate in a state where a plurality of gear pairs are engaged at the same time without backlash without requiring improvement in the accuracy of parts processing. By forming a backlash in the spline fitting portion, the connection of the drive gear to the drive gear rotation shaft and the connection of the driven gear to the driven gear rotation shaft can be engaged in the radial direction and can be moved in the circumferential direction. A structure can be easily realized. Since it is possible to absorb the dimensional variation in the circumferential direction that exists between the gear pairs due to the dimensional variation that occurs during component manufacture, it is possible to operate the gear pairs in contact with each other at the same time.

A gear pump according to the present invention is a gear pair comprising a plurality of separated gear chambers, and a drive gear and a driven gear that mesh with each other and rotate, and each of the plurality of gear pairs accommodated in the plurality of separated gear chambers. And a plurality of drive gears individually connected to each other, a drive gear rotating shaft to which a driving force is applied from the outside, a driven gear rotating shaft to which a plurality of driven gears are individually connected, and a drive gear rotating shaft are rotatably supported. In a gear pump that includes a drive-side slide bearing that rotates and a driven-side slide bearing that rotatably supports the driven gear rotating shaft, and that boosts and discharges the fluid sucked from outside in the gear chamber, the driving gear rotating shaft and the driven gear At least one of the rotating shafts is supported by a driving side sliding bearing or a driven side sliding bearing so as to be movable in the radial direction, and at least one of the driving gear and the driven gear is movable in the radial direction. Is connected to the drive gear rotating shaft or the driven gear axis of rotation, the drive gear includes a cylindrical driving gear inner circumferential surface is formed, the drive gear rotating shaft, opposed to the drive gear peripheral surface of the drive gear position The driven gear rotating shaft has an outer peripheral surface, the driven gear has a cylindrical driven gear inner peripheral surface, and the driven gear rotating shaft has a driven gear at a position facing the driven gear inner peripheral surface. A rotary shaft outer peripheral surface is formed, and the radial movement of the drive gear with respect to the drive gear rotary shaft is caused by a drive gear restraint gap that is a gap formed between the drive gear inner peripheral surface and the drive gear rotary shaft outer peripheral surface. constrained, movement in the radial direction with respect to the driven gear axis of rotation of the driven gear, the Rukoto constrained by the driven gear restraint gap is a gap formed between the inside driven gear peripheral surface and the driven gear rotation shaft outer circumferential surface It is a feature .
When the range in which the drive gear can move relative to the drive gear rotation shaft is constrained by the spline fitting part, due to the accuracy of the spline, the axis center line of the drive gear rotation shaft and the shaft center of the tooth tip of the drive gear The distance to the line is not constant. In this case, since a gap is generated between the inner peripheral surface of the gear chamber and the tooth tip of the drive gear at a specific angle in the circumferential direction, fluid leaks from the gap and the performance of the gear pump is deteriorated. For processing, the drive gear inner peripheral surface that makes it easy to keep the shaft center line of the tooth tip of the drive gear at a fixed distance from the shaft center line of the drive gear rotation shaft, and the drive that faces the drive gear inner peripheral surface Since the outer peripheral surface of the gear rotation shaft is formed and the movement of the drive gear with respect to the drive gear rotation shaft is constrained by the clearance, there is no gap between the inner peripheral surface of the gear chamber and the tooth tip of the drive gear. It becomes possible to prevent the performance deterioration. Further, the movement of the driven gear relative to the driven gear rotation shaft is restricted by the clearance between the driven gear inner peripheral surface and the driven gear rotation shaft outer peripheral surface as in the drive gear and the drive gear rotation shaft side.

The drive gear may be connected to the drive gear rotation shaft, and the driven gear may be connected to the driven gear rotation shaft by spline fitting. By forming a backlash in the spline fitting portion, the connection of the drive gear to the drive gear rotation shaft and the connection of the driven gear to the driven gear rotation shaft can be engaged in the radial direction and can be moved in the circumferential direction. A structure can be easily realized.
In the spline fitting between the drive gear and the drive gear rotating shaft and the spline fitting between the driven gear and the driven gear rotating shaft, gaps in the circumferential direction may be formed respectively. Since it is possible to absorb the dimensional variation in the circumferential direction that exists between the gear pairs due to the dimensional variation that occurs during component manufacture, it is possible to operate the gear pairs in contact with each other at the same time.
The drive gear restraint gap may be formed at both ends of the drive gear, and the driven gear restraint gap may be formed at both ends of the driven gear. The drive gear contacts the drive gear rotation shaft at both ends thereof, and the driven gear also contacts the driven gear rotation shaft at both ends thereof, so that the drive gear is inclined with respect to the drive gear rotation shaft and the driven gear is driven Inclination with respect to the gear rotation shaft is prevented, and the meshing can be performed more reliably without backlash.

  When the number of gear pairs is two and the number of teeth of the driving gear and the driven gear is N, the two gear pairs may be arranged so that the meshing phase is shifted by 360 / (4N) °. . By meshing without backlash, the two pairs of gears that generate discharge pulsation with a cycle of 360 / (2N) ° alternately discharge fluid, so that it is possible to further reduce the discharge pulsation. .

  According to the present invention, a multistage gear pump can be operated in a state in which a plurality of gear pairs are engaged with each other without backlash without requiring improvement in the accuracy of parts processing.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 shows a two-stage gear pump 1 according to Embodiment 1 of the present invention. In the following description, the gear pump 1 is applied as a hydraulic pump for a cargo handling device.
The gear pump 1 includes a body 2. A hollow portion separated into two by a wall portion 2 a is formed inside the body 2, and a pair of housings 3 are provided on both sides of the body 2 so as to close the hollow portion. Side plates 4 are respectively provided between the cavity portion of the body 2 and the housing 3, and the side plate 4 surrounds the cavity portion of the body 2, whereby the first gear chamber 5 a is provided in one of the insides of the gear pump 1. The second gear chamber 5b is formed on the other side. Here, the first gear chamber 5a and the second gear chamber 5b constitute a gear chamber. The first gear chamber 5a accommodates a gear pair 13 composed of a drive gear 11 and a driven gear 12 that are circumscribed and meshed with each other. On the other hand, a gear pair 16 including a drive gear 14 and a driven gear 15 that are circumscribed and meshed with each other is housed in the second gear chamber 5b.

The gear pump 1 has a drive gear rotating shaft 17 and a driven gear rotating shaft 18 extending through the wall portion 2a of the body 2 into the first gear chamber 5a and the second gear chamber 5b. Is provided. A drive gear 11 in the first gear chamber 5a and a drive gear 14 in the second gear chamber 5b are connected to the drive gear rotation shaft 17, and a driven gear rotation shaft 18 is connected to the interior of the first gear chamber 5a. The driven gear 12 and the driven gear 15 in the second gear chamber 5b are connected.
As shown in FIG. 2, a female spline 11 a is formed inside the drive gear 11. The female spline 11a is formed from one end side of the drive gear 11 beyond the intermediate portion in the axial direction, but does not reach the other end side, and the remaining portion excluding the female spline 11a has a cylindrical shape. A concave inner peripheral surface 11b which is a drive gear inner peripheral surface having a cylindrical inner peripheral surface is formed. In addition, a female spline 14a and a concave inner peripheral surface 14b, which is an inner peripheral surface of the drive gear, are also formed inside the drive gear 14. The drive gear 11 and the drive gear 14 are configured in the same manner except for the width dimension in the axial direction, and the concave inner peripheral surface 11b of the drive gear 11 and the concave inner peripheral surface 14b of the drive gear 14 are the same. It has an inner diameter d1. The drive gear 11 and the drive gear 14 are arranged on both sides of the drive gear rotating shaft 17 so that the recess inner peripheral surface 11b of the drive gear 11 and the recess inner peripheral surface 14b of the drive gear 14 sandwich the wall 2a of the body 2. Has been inserted.

  On the other hand, a male spline 17 a that can be engaged with the female spline 11 a is formed at a portion of the outer periphery of the drive gear rotating shaft 17 that faces the female spline 11 a of the drive gear 11. A male spline 17b that can be engaged with the female spline 14a is also formed at a portion of the drive gear rotating shaft 17 that faces the female spline 14a of the drive gear 14. The drive gear 11 and the drive gear 14 are respectively connected to the drive gear rotation shaft 17 by spline fitting, and the drive gear 11, the drive gear 14, and the drive gear rotation shaft 17 can rotate together. Further, a cylindrical shape is provided between the male spline 17a and the male spline 17b of the drive gear rotating shaft 17, that is, at a position facing the concave inner peripheral surface 11b of the drive gear 11 and the concave inner peripheral surface 14b of the drive gear 14. A cylindrical portion 17c which is an outer peripheral surface of the drive gear rotation shaft having an outer peripheral surface is formed. The outer diameter D of the cylindrical portion 17c of the drive gear rotating shaft 17 is smaller than the inner diameter d1 of the recess inner peripheral surface 11b of the drive gear 11 and the recess inner peripheral surface 14b of the drive gear 14, and a drive gear restraint gap is formed therebetween. Yes.

  Also on the driven gear rotating shaft 18 side, a female spline 12 a and a cylindrical concave inner peripheral surface 12 b are formed inside the driven gear 12. A female spline 15 a and a cylindrical concave inner peripheral surface 15 b are also formed in the driven gear 15. Here, the concave inner peripheral surface 12b of the driven gear 12 and the concave inner peripheral surface 15b of the driven gear 15 constitute a driven gear inner peripheral surface. The driven gear 12 is configured similarly to the drive gear 11 that meshes with each other, and the driven gear 15 is configured similarly to the drive gear 14 that meshes with each other. A male spline 18 a that engages with the female spline 12 a of the driven gear 12 and a male spline 18 b that engages with the female spline 15 a of the driven gear 15 are formed on the outer peripheral portion of the driven gear rotating shaft 18. Further, between the male spline 18a and the male spline 18b, a cylindrical portion 18c which is an outer peripheral surface of the driven gear rotation shaft is formed. Both the concave inner peripheral surface 12 b of the driven gear 12 and the concave inner peripheral surface 15 b of the driven gear 15 have the same inner diameter d 1 as the concave inner peripheral surface 11 b of the drive gear 11. Further, the cylindrical portion 18 c of the driven gear rotation shaft 18 also has an outer diameter D that is the same as the cylindrical portion 17 c of the drive gear rotation shaft 17. Accordingly, the driven gear 12 is driven between the concave inner peripheral surface 12b and the cylindrical portion 18c of the driven gear rotating shaft 18, and between the concave inner peripheral surface 15b of the driven gear 15 and the cylindrical portion 18c of the driven gear rotating shaft 18. Gear restraint gaps are respectively formed. The driven gear 12 and the driven gear 15 have a driven gear rotating shaft inserted so that the concave inner peripheral surface 12b of the driven gear 12 and the concave inner peripheral surface 15b of the driven gear 15 sandwich the wall 2a of the body 2. The driven gear 12, the driven gear 15, and the driven gear rotating shaft 18 can rotate together.

  Returning to FIG. 1, bearing holes 3 a are respectively formed at positions facing the drive gear 11 or the drive gear 14 of the pair of housings 3, and the bearing holes 3 a have a cylindrical shape with both ends open. Drive-side plain bearings 19 are respectively inserted. Both ends of the drive gear rotation shaft 17 are inserted into two drive side slide bearings 19, respectively, and the drive gear rotation shaft 17 is rotatably supported by the drive side slide bearing 19. One end of the drive gear rotating shaft 17 on the first gear chamber 5a side is exposed to the outside of the gear pump 1 through the housing 3 and connected to a drive source (not shown). Further, the housing 3 on the first gear chamber 5 a side is provided with an oil seal 20 for the drive gear rotation shaft 17 to prevent oil in the gear pump 1 from leaking outside along the drive gear rotation shaft 17. is doing. On the other hand, bearing holes 3b are formed at positions facing the driven gear 12 or the driven gear 15 of the pair of housings 3, respectively, and a driven side sliding bearing having a cylindrical shape with both ends open in the bearing holes 3b. 21 is inserted. Both ends of the driven gear rotating shaft 18 are inserted into two driven sliding bearings 21, and the driven gear rotating shaft 18 is rotatably supported by the driven sliding bearings 21.

Here, the structure of the spline fitting portion between the driving gear 11 and the driving gear 14 and the driving gear rotation shaft 17 and the spline fitting portion between the driven gear 12 and the driven gear 15 and the driven gear rotation shaft 18 will be described.
The female spline 11a (see FIG. 2) of the drive gear 11 and the male spline 17a of the drive gear rotating shaft 17 are formed so that a backlash exists between them. Further, the female spline 14a of the drive gear 14 and the male spline 17b of the drive gear rotating shaft 17 are formed so that a backlash exists between them. Therefore, the drive gear 11 and the drive gear 14 can be individually moved in the radial direction with respect to the drive gear rotating shaft 17 within the range of the backlash existing in each spline fitting portion. On the other hand, the inner diameter d1 of the recess inner peripheral surface 11b of the drive gear 11 and the recess inner peripheral surface 14b of the drive gear 14 is formed to be larger than the outer diameter D of the cylindrical portion 17c of the drive gear rotating shaft 17. Therefore, also between the recess inner peripheral surface 11b of the drive gear 11 and the cylindrical portion 17c of the drive gear rotation shaft 17, and between the recess inner peripheral surface 14b of the drive gear 14 and the cylinder portion 17c of the drive gear rotation shaft 17. The drive gear 11 and the drive gear 14 are movable in the radial direction.

  The size of the drive gear restraint gap formed between the inner peripheral surface 11 b of the recess of the drive gear 11 and the cylindrical portion 17 c of the drive gear rotation shaft 17 is determined by the female spline 11 a of the drive gear 11 and the male of the drive gear rotation shaft 17. In the spline fitting portion with the spline 17a, the drive gear 11 is formed smaller than the distance that can be moved in the radial direction. The size of the drive gear restraint gap formed between the inner circumferential surface 14 b of the recess of the drive gear 14 and the cylindrical portion 17 c of the drive gear rotation shaft 17 is also the same as that of the female spline 14 a of the drive gear 14 and the drive gear rotation shaft 17. In the spline fitting portion with the male spline 17b, the drive gear 14 is formed smaller than the distance that can be moved in the radial direction. Therefore, the drive gear 11 and the drive gear 14 are driven by the drive gear restraint gap between the concave inner peripheral surface 11b of the drive gear 11 and the concave inner peripheral surface 14b of the drive gear 14 and the cylindrical portion 17c of the drive gear rotating shaft 17. The movement is constrained.

  On the other hand, backlash also exists between the female spline 12a of the driven gear 12 and the male spline 18a of the driven gear rotating shaft 18, and between the female spline 15a of the driven gear 15 and the male spline 18b of the driven gear rotating shaft 18. The driven gear 12 and the driven gear 15 are movable in the radial direction. Further, since the driven gear 12, the driven gear 15 and the driven gear rotating shaft 18 are configured similarly to the driving gear 11, the driving gear 14 and the driven gear rotating shaft 18, respectively, the driven gear 12 and the driven gear 15 are driven. It can move in the radial direction with respect to the gear rotation shaft 18 within the range of d1-D. This movable range d1-D is smaller than the spline fitting portion of the driven gear 12, the driven gear 15, and the driven gear rotating shaft 18, and the driven gear 12 and the driven gear 15 are also the concave inner peripheral surface 12b of the driven gear 12. In the range of the driven gear restraint gap formed between the inner peripheral surface 15b of the recessed portion of the driven gear 15 and the cylindrical portion 18c of the driven gear rotating shaft 18, the radial movement is possible.

Next, the structure in the support part of the drive gear rotating shaft 17 by the drive side sliding bearing 19 and the support part of the driven gear rotating shaft 18 by the driven side slide bearing 21 will be described.
A gap is formed between the drive-side slide bearing 19 that rotatably supports the drive gear rotation shaft 17 and the drive gear rotation shaft 17, so that the drive gear rotation shaft 17 can move in the radial direction. . Further, a clearance is also formed between the driven-side slide bearing 21 that rotatably supports the driven gear rotating shaft 18 and the driven gear rotating shaft 18, so that the driven gear rotating shaft 18 can move in the radial direction. ing. Therefore, the gear pump 1 is movable in the radial direction, that is, the direction in which the driven gear rotation shaft 18 and the driven gear rotation shaft 18 come in contact with each other, and the gear pair 13 and the gear pair 16 also in the direction in which they come in contact with each other. On the other hand, it can be moved individually.

Next, referring to FIG. 3, taking the gear pair 13 in the first gear chamber 5 a as an example, a connection portion between the drive gear 11 and the drive gear rotation shaft 17 and a connection portion between the driven gear 12 and the driven gear rotation shaft 18. The positional relationship of the drive gear rotating shaft 17 and the driven gear rotating shaft 18 in the support portion will be described. In the following description, the inside of the first gear chamber 5a is shown, but the inside of the second gear chamber 5b is configured similarly.
The difference between the outer diameter of the drive gear rotation shaft 17 and the inner diameter of the drive side slide bearing 19 and the difference between the outer diameter of the driven gear rotation shaft 18 and the inner diameter of the passive side slide bearing 21 are defined as CL1. Further, the difference between the inner diameter d1 of the recess inner peripheral surface 11b of the drive gear 11 and the outer diameter D of the cylindrical portion 17c of the drive gear rotating shaft 17, that is, the drive gear restraint gap and the inner diameter of the recess inner peripheral surface 12b of the driven gear 12. The difference between d1 and the outer diameter D of the cylindrical portion 18c of the driven gear rotating shaft 18, that is, the driven gear restraint gap is defined as CL2. Further, the distance between the center axes of the concave inner peripheral surface 11b of the drive gear 11 and the concave inner peripheral surface 12b of the driven gear 12 in a state where the gear pair 13 is engaged without backlash is L, and the drive side sliding bearing 19 and the driven side The distance between the center axes of the slide bearing 21 is A. In the gear pump 1, the distance A between the center axes of the driving side sliding bearing 19 and the driven side sliding bearing 21 is:
A <L + CL1 + CL2 (1)
A> L-CL1-CL2 (2)
That is,
L- (CL1 + CL2) <A <L + (CL1 + CL2)
It is determined to satisfy.
By determining the distance A between the center axes so as to satisfy the above equation (1), the drive gear rotation shaft 17 and the drive side slide bearing 19 come into contact with each other, and the driven gear rotation shaft 18 and the driven side slide bearing 21 Before the contact, the gear pair 13 meshes with no backlash. Further, the above expression (2) is a conditional expression for allowing the gear pair 13 to be accommodated in the first gear chamber 5a even when the drive gear 11 and the driven gear 12 are farthest apart.

Next, the circumferential direction formed in the spline fitting part of the driving gear 11 and the driving gear 14 and the driving gear rotating shaft 17 and the spline fitting part of the driven gear 12 and the driven gear 15 and driven gear rotating shaft 18 respectively. The gaps in FIG.
Backlash is formed between the female spline 11a of the drive gear 11 and the male spline 17a of the drive gear rotation shaft 17, and between the female spline 14a of the drive gear 14 and the male spline 17b of the drive gear rotation shaft 17. As a result, a gap is formed between them in the circumferential direction. Similarly, the driven gear 12, the driven gear 15, and the driven gear rotating shaft 18 side are also connected between the female spline 12 a of the driven gear 12 and the male spline 18 a of the driven gear rotating shaft 18, and the female spline 15 a of the driven gear 15. A clearance in the circumferential direction is formed between the driven sprocket 18 and the male spline 18b. here,
Gap Δθ1 in the circumferential direction between the drive gear 11 and the drive gear rotating shaft 17
A clearance Δθ2 in the circumferential direction between the drive gear 14 and the drive gear rotating shaft 17
A circumferential clearance Δθ3 between the driven gear 12 and the driven gear rotating shaft 18
Gap Δθ4 in the circumferential direction between the driven gear 15 and the driven gear rotating shaft 18
Then, the gaps Δθ1 to Δθ4 are
Δθ1 <Δθ2 + Δθ3 + Δθ4 (4)
Or
Δθ2 <Δθ1 + Δθ3 + Δθ4 (5)
It is formed to satisfy.

  When the gaps Δθ1 to Δθ4 satisfy the above expression (4), the drive gear rotating shaft 17 is rotated by the driving force applied from the outside, and drives the drive gears 11 and 14, respectively. Further, before the drive gear rotation shaft 17 rotates the drive gear 11, the driving force transmitted from the drive gear 14 to the driven gear 15 is transmitted to the drive gear 11 via the driven gear rotation shaft 18 and the driven gear 12. This prevents the drive gear 14 from driving the drive gear 11. On the other hand, when the gaps Δθ1 to Δθ4 satisfy the above expression (5), the drive gear rotating shaft 17 rotates and drives each of the drive gears 11 and 14. Further, before the drive gear rotation shaft 17 rotates the drive gear 14, the driving force transmitted from the drive gear 11 to the driven gear 12 is transmitted to the drive gear 14 via the driven gear rotation shaft 18 and the driven gear 15. This prevents the drive gear 11 from driving the drive gear 14.

As shown in FIG. 4, in the meshing portion of the gear pair 13, oil on the right side of FIG. 4 is sucked into the first gear chamber 5 a from the outside of the gear pump 1, so that a suction port (not shown) is provided. It is provided and communicates the outside of the gear pump 1 and the inside of the first gear chamber 5a. In addition, on the left side of the meshing portion of the gear pair 13 in FIG. 4, a discharge port (not shown) is provided to discharge the oil boosted in the first gear chamber 5 a to the outside of the gear pump 1. The outside communicates with the first gear chamber 5a. In the first gear chamber 5a, a suction side space IN which is a space communicating with the suction port is formed on the right side of the gear pair 13 in FIG. 4, and a discharge port is connected on the right side of the gear pair 13 in FIG. A discharge-side space OUT that is a space to be formed is formed. Further, a substantially closed space S is formed by the teeth of the drive gear 11 or the teeth of the driven gear 12, the inner peripheral surface of the body 2, the wall 2 a of the body 2, and the side plate 4.
The above description using FIG. 4 shows the first gear chamber 5a side in which the gear pair 13 is accommodated, but the second gear chamber 5b side is the same as the first gear chamber 5a side. The suction port and the discharge port are provided, and the suction side space IN and the discharge side space OUT are formed.

  Further, as shown in FIG. 5, the drive gear 11 and the drive gear 14 are 360 / (4N) ° in the circumferential direction, that is, 1/1 of the gear tooth formation pitch, where N is the number of gear teeth on the outer peripheral side. It is connected to the drive gear rotation shaft 17 so that the angle is shifted by four teeth. Therefore, the meshing phase between the gear pair 13 and the gear pair 16 is configured such that the phase is shifted by 360 / (4N) ° in the circumferential direction.

Next, the operation of the gear pump 1 according to Embodiment 1 of the present invention will be described.
As shown in FIG. 4, in the gear pump 1, when a driving force is applied to the driving gear rotating shaft 17 from the outside, the driving gear 11 starts to rotate in the direction indicated by the arrow B in FIG. As the drive gear 11 rotates, the driven gear 12 that meshes with the drive gear 11 also starts synchronous rotation. The drive gear rotating shaft 17 also drives the drive gear 14 not shown in FIG. 4, and the driven gear 15 that meshes with the drive gear 14 starts synchronous rotation as the drive gear 14 rotates. Here, the female splines 11a and 14a of the drive gears 11 and 14 and the male splines 17a and 17b of the drive gear rotating shaft 17 engaged therewith, the female splines 12a and 15a of the driven gears 12 and 15, and the engagement thereof. A gap in the circumferential direction is formed between the male splines 18a and 18b of the driven gear rotating shaft 18 to be combined. Therefore, the variation of the part dimension in the circumferential direction that exists between the gear pair 13 and the gear pair 16 is absorbed, and the gear pair 13 and the gear pair 16 rotate in a state of being engaged with each other. Furthermore, clearances Δθ1 to Δθ4 in the circumferential direction between the female splines of the respective gears and the male splines of the respective rotating shafts engaged therewith are:
Δθ1 <Δθ2 + Δθ3 + Δθ4
Or
Δθ2 <Δθ1 + Δθ3 + Δθ4
Therefore, the drive gear 11 is prevented from driving the drive gear 14 via the driven gear 12, the driven gear rotating shaft 18 and the driven gear 15 in order, and the drive gear 14 is rotated by the driven gear 15 and the driven gear. Driving the drive gear 11 through the shaft 18 and the driven gear 12 in order is prevented.

  When the gear pair 13 rotates while meshing, oil is sucked into the suction side space IN in the first gear chamber 5a from the outside of the gear pump 1 through a suction port (not shown). The oil sucked into the suction side space IN is confined in the space S, is carried to the discharge side space OUT, and is discharged to the outside of the gear pump 1 through a discharge port (not shown) in a pressurized state, thereby performing a so-called pump action. Due to this pump action, a difference between the pressure of the oil before the pressure increase and the pressure of the oil after the pressure increase occurs in the first gear chamber 5a, and the high pressure side space region HP indicated by the thick solid line in FIG. A low-pressure side space region LP is formed. The high-pressure side space region HP is a region that communicates with the discharge-side space OUT through small chamfers (not shown) provided in the side plate 4 and the wall 2a of the body 2, respectively. It is a filled area. The range of the high-pressure side space region HP is formed from the discharge side space OUT to at least the center and a range of α ° entering the suction side space IN. On the other hand, the remaining area around the suction side space IN becomes the low pressure side space area LP. The low-pressure side space region LP is a region filled with oil before being pressurized in the first gear chamber 5a, and there is a gap in the oil pressure between the low-pressure side space region LP and the high-pressure side space region HP. is there.

Thus, during operation of the gear pump 1, a pressure difference is generated in the oil in the first gear chamber 5a. Therefore, the load F resulting from the oil pressure difference is applied to the drive gear 11 and the driven gear 12 in FIG. It acts in the direction from the high-pressure side space region HP toward the low-pressure side space region LP as shown by the arrows shown. Assuming that the direction in which the drive gear 11 and the driven gear 12 are contacted and separated from each other is the vertical direction, the drive gear 11 and the driven gear 12 are moved closer to each other by the vertical component Fv of the load F, that is, in the direction of meshing without backlash. And move. When the drive gear 11 and the driven gear 12 approach each other, the concave inner peripheral surface 11b of the drive gear 11 and the cylindrical portion 17c of the drive gear rotating shaft 17 come into contact with each other, and the concave inner peripheral surface 12b of the driven gear 12 and the driven gear rotate. The cylindrical portion 18c of the shaft 18 comes into contact. Next, the vertical component Fv of the load F acts on the drive gear rotation shaft 17 through the contact portion between the inner peripheral surface 11 b of the recess of the drive gear 11 and the cylindrical portion 17 c of the drive gear rotation shaft 17. A vertical component Fv of the load F acts on the driven gear rotation shaft 18 through a contact portion between the inner peripheral surface 12 b of the recess and the cylindrical portion 18 c of the driven gear rotation shaft 18. When the vertical component Fv of the load F acts on the drive gear rotation shaft 17 and the driven gear rotation shaft 18, the drive gear rotation shaft 17 and the driven gear rotation shaft 18 move in a direction approaching each other. Further, the positional relationship between the connection portion of the drive gear 11 and the drive gear rotation shaft 17, the connection portion of the driven gear 12 and the driven gear rotation shaft 18, and the support portion of the drive gear rotation shaft 17 and the driven gear rotation shaft 18 is as follows.
L- (CL1 + CL2) <A <L + (CL1 + CL2) (see FIG. 3)
Therefore, the drive gear 11 and the driven gear 12 mesh with each other in a backlash-less manner before the drive gear rotating shaft 17 and the driving side sliding bearing 19, the driven gear rotating shaft 18 and the driven side sliding bearing 21 come into contact with each other. Rotate.

  Usually, after the gear pump 1 is assembled, a break-in operation is performed. During the break-in operation, the inner peripheral surface of the body 2 is shaved with the tooth tips of each gear, whereby the inner peripheral surface of the body 2 and the tooth tips of each gear are It has a structure that eliminates the generation of a gap between them. When the drive gear 11 and the drive gear rotating shaft 17 are brought into contact with the female spline 11a and the male spline 17a, it is difficult to form the spline with high precision. The 17 axis center line may be displaced. In this case, since the locus drawn by the rotation of the tooth tip of the drive gear 11 with respect to the axis center line of the drive gear rotation shaft 17 is not constant, the inner circumferential surface of the body 2 is at a specific angle in the circumferential direction. A gap is formed between the teeth of the drive gear 11 and oil leaks from the gap, so that the performance of the gear pump 1 is deteriorated. In the gear pump 1, the drive gear 11 and the drive gear rotation shaft 17 are brought into contact with the inner peripheral surface 11 b of the concave portion and the cylindrical portion 17 c, which can be easily machined with high accuracy. The locus drawn by rotation of the tooth tip of the drive gear 11 with respect to the line becomes constant, and continues to rotate without a gap between the inner peripheral surface of the body 2 and the tooth tip of each gear. The same applies to the connecting portion between the driving gear 14 and the driving gear rotating shaft 17 and the connecting portion between the driven gears 12 and 15 and the driven gear rotating shaft 18.

  Further, as shown in FIG. 6, the discharge pulsation cycle of the gear pair 13 and the gear pair 16 is 360 / (360 / () which is half of the cycle in the case of meshing in the presence of backlash by meshing them in a backlash-less manner. 2N) °. Further, since the meshing phase of the gear pair 13 and the gear pair 16 in the circumferential direction is 360 / (4N) ° (see FIG. 5), the gear pair 13 and the gear pair 16 alternately discharge oil. Thus, the discharge pulsation is further reduced.

  As described above, the drive gear rotation shaft 17 and the driven gear rotation shaft 18 can be moved in the radial direction, and the drive gears 11 and 14 and the driven gears 12 and 15 can be moved in the radial direction. The drive gear 11, the driven gear 12, the drive gear 14, and the driven gear 15 move in directions approaching each other due to a load resulting from the pressure difference of the oil sucked into the oil. In the gear pair 13 on the first gear chamber 5a side, the range in which the drive gear 11 can move is driven with respect to the drive gear rotary shaft 17 within the range in which the drive gear rotary shaft 17 and the driven gear rotary shaft 18 can move. This is a range to which a range in which the gear 11 can move is added. On the other hand, the range in which the driven gear 12 can move is also within the range in which the drive gear rotating shaft 17 and the driven gear rotating shaft 18 can move, and the range in which the driven gear 12 can move with respect to the driven gear rotating shaft 18. It has been added. Also in the gear pair 16 in the second gear chamber 5b, the range in which the drive gear 14 and the driven gear 15 are movable is the same as that of the drive gear 11 and the driven gear 12 in the first gear chamber 5a. In this way, in the drive gears 11 and 14 and the driven gears 12 and 15, a sufficient moving distance is secured to absorb variations in backlash existing between the gear pair 13 and the gear pair 16. Further, since the drive gears 11 and 14 are individually connected to the drive gear rotating shaft 17 and the driven gears 12 and 15 are also individually connected to the driven gear rotating shaft 18, the drive gears 11 and 14 and the driven gear 12 are connected. , 15 individually move to an optimum position where the gear pair 13 and the gear pair 16 mesh with each other without backlash. Therefore, the gear pump 1 can be operated in a state in which the gear pair 13 and the gear pair 16 are engaged at the same time without backlash without requiring improvement in parts processing accuracy.

  Further, since the drive gears 11 and 14 and the drive gear rotating shaft 17, the driven gears 12 and 15 and the driven gear rotating shaft 18 are respectively connected by spline fitting having a backlash therebetween, the drive gear rotating shaft 17 is driven. The gears 11 and 14 can be structured such that the driven gears 12 and 15 can be engaged with the driven gear rotating shaft 18 in the radial direction and can move in the circumferential direction.

  Further, in the spline fitting between the drive gears 11 and 14 and the drive gear rotating shaft 17 and the spline fitting between the driven gears 12 and 15 and the driven gear rotating shaft 18, gaps Δθ1 to Δθ4 in the circumferential direction are formed, respectively. Due to the variation in the dimensions of the parts constituting the gear pump 1, the variation in the dimension in the circumferential direction existing between the gear pair 13 and the gear pair 16 can be absorbed. Therefore, the gear pump 1 can be operated in a state where the gear pair 13 and the gear pair 16 are in contact with each other at the same time.

  In addition, a recess inner peripheral surface 11b and a recess inner peripheral surface 14b having a cylindrical inner peripheral surface are formed in the drive gear 11 and the drive gear 14, respectively, and the drive gear rotating shaft 17 facing these is formed. A cylindrical portion 17c is also formed on the outer peripheral portion of the drive gear 11, and the drive gear restraint gap between the recess inner peripheral surface 11b of the drive gear 11 and the recess inner peripheral surface 14b of the drive gear 14 and the cylinder portion 17c of the drive gear rotating shaft 17 Since the movement of the drive gears 11 and 14 in the radial direction is constrained, the shaft center line of the tooth tips of the drive gears 11 and 14 can be kept at a constant distance with respect to the shaft center line of the drive gear rotation shaft 17. Thus, it is possible to prevent a gap from being generated between the inner peripheral surfaces of the first gear chamber 5a and the second gear chamber 5b and the tooth tips of the drive gears 11 and 14, and the performance of the gear pump 1 from being deteriorated. The same applies to the driven gears 12 and 15 and the driven gear rotating shaft 18.

  Further, since the number of teeth of the drive gears 11 and 14 and the driven gears 12 and 15 is N, the two gear pairs 13 and 16 are arranged so as to mesh with each other with a shift of 360 / (4N) °. And the gear pair 16 alternately discharge the pressurized oil, and the discharge pulsation is further reduced.

Embodiment 2. FIG.
Next, a gear pump according to Embodiment 2 of the present invention will be described. In the following embodiments, the same reference numerals as those in FIGS. 1 to 6 are the same or similar components, and thus detailed description thereof is omitted.
FIG. 7 shows a gear pump 31 according to the second embodiment. In the first gear chamber 5 a of the gear pump 31, a gear pair 34 including a drive gear 32 and a driven gear 33 that are circumscribed and meshed with each other is accommodated. The second gear chamber 5b accommodates a gear pair 37 including a drive gear 35 and a driven gear 36 that are circumscribed and meshed with each other. A drive gear rotating shaft 38 is connected to the drive gear 32 in the first gear chamber 5a and the drive gear 35 in the second gear chamber 5b, and the second gear 33 and the second gear 33 in the first gear chamber 5a are connected. A driven gear rotating shaft 39 is connected to the driven gear 36 in the gear chamber 5b.

  As shown in FIG. 8, a female spline 32a is formed in a part of the inside of the drive gear 32, and a concave inner peripheral surface having a cylindrical inner peripheral surface at both ends of the female spline 32a. 32b and the recessed part internal peripheral surface 32c are formed. The concave inner peripheral surface 32b of the drive gear 32 is configured similarly to the concave inner peripheral surface 11b of the drive gear 11 in the first embodiment. Further, the female spline 32a of the drive gear 32 is formed to have a shorter length in the axial direction than the female spline 11a of the drive gear 11 in the first embodiment. A concave inner peripheral surface 32c is formed in the remaining portion generated by forming the female spline 32a of the drive gear 32 shorter than the female spline 11a of the drive gear 11. The drive gear 35 is configured in the same manner as the drive gear 32 except for the width dimension in the axial direction, and a female spline 35a, a concave inner peripheral surface 35b, and a concave inner peripheral surface 35c are formed therein.

  On the other hand, a male spline 38a and a male spline 38b are respectively formed in a portion of the outer periphery of the drive gear rotating shaft 38 that faces the female spline 32a of the drive gear 32 and a portion of the drive gear 35 that faces the female spline 35a. Each is formed. Further, the space between the male spline 38a and the male spline 38b of the drive gear rotation shaft 38 is configured similarly to the cylindrical portion 17c of the drive gear rotation shaft 17 in the first embodiment. Therefore, a drive gear restraint gap is formed between the recess inner peripheral surface 32 b of the drive gear 32 and the recess inner peripheral surface 35 b of the drive gear 35 and the cylindrical portion 38 c of the drive gear rotation shaft 38. Further, the recess inner peripheral surface 32c of the drive gear 32 and the recess inner peripheral surface 35c of the drive gear 35 are formed between the outer peripheral surface 38d of the drive gear rotating shaft 38 and the same gap as the gap d1-D. It has an inner diameter d2. Therefore, the drive gear 32 and the drive gear 35 are in a state in which drive gear restraint gaps are formed at both ends thereof. Further, the driven gear 33, the driven gear 36, and the driven gear rotating shaft 39 are configured similarly to the driving gear 32, the driving gear 35, and the driving gear rotating shaft 38, respectively. Other structures are the same as those in the first embodiment.

  As described above, the recess inner peripheral surface 32b and the recess inner peripheral surface 32c, and the recess inner peripheral surface 35b and the recess inner peripheral surface 35c are formed at both ends of the drive gear 32 and the drive gear 35, respectively. Drive gear restraint gaps are formed at both ends of 35, and the movement in the radial direction is restrained. Therefore, the drive gear 32 and the drive gear 35 are supported by being in contact with the drive gear rotation shaft 38 at both ends thereof, so that the drive gear 32 and the drive gear 35 are not inclined with respect to the drive gear rotation shaft 38. Further, since the concave inner peripheral surface 33b and the concave inner peripheral surface 33c, the concave inner peripheral surface 36b and the concave inner peripheral surface 36c are formed on both ends of the driven gear 33 and the driven gear 36, respectively, the driven gear 33 and the driven gear 36 are also formed. The driven gear restraint gap is formed at both ends of the shaft, and the movement in the radial direction is restrained. Therefore, the driven gear 33 and the driven gear 36 are supported in contact with the driven gear rotating shaft 39 at both ends thereof. Therefore, the driven gear 33 and the driven gear 36 are prevented from being inclined with respect to the driven gear rotating shaft 39. Since the inclination of the driving gear 32 and the driving gear 35 with respect to the driving gear rotation shaft 38 and the inclination of the driven gear 33 and the driven gear 36 with respect to the driven gear rotation shaft 39 are prevented, the gear pair 34 and the gear pair 37 are meshed without backlash. But it will be more certain.

  In the first and second embodiments, the drive gear rotation shaft and the driven gear rotation shaft are not limited to being movable in the radial direction, and the drive gear rotation shaft is intended to improve the reliability with respect to the oil seal. Can also be constrained in the radial direction.

It is a cross-sectional side view which shows the structure of the gear pump which concerns on Embodiment 1 of this invention. FIG. 3 is a partial cross-sectional side view schematically showing a connection structure of a gear pair, a drive gear rotation shaft, and a driven gear rotation shaft of the gear pump according to the first embodiment. It is a partial cross section side view for demonstrating the structure of the gear pump which concerns on Embodiment 1. FIG. 1 is a cross-sectional front view showing a structure of a gear pump according to a first embodiment. FIG. 3 is a partial cross-sectional front view schematically showing a phase difference of a gear pair of the gear pump according to the first embodiment. FIG. 3 is a chart showing fluid discharge timing of the gear pump according to the first embodiment. It is a cross-sectional side view which shows the structure of the gear pump which concerns on Embodiment 2 of this invention. FIG. 6 is a partial cross-sectional side view schematically showing a connection structure of a gear pair, a drive gear rotation shaft, and a driven gear rotation shaft of the gear pump according to the second embodiment.

Explanation of symbols

  1,31 Gear pump, 5a First gear chamber (gear chamber), 5b Second gear chamber (gear chamber), 11, 14, 32, 35 Drive gear, 11b, 14b, 32b, 32c, 36b, 36c Drive gear recess Inner peripheral surface (drive gear inner peripheral surface), 12, 15, 33, 36 driven gear, 12b, 15b, 33b, 33c, 36b, 36c Recessed inner peripheral surface of the driven gear (driven gear inner peripheral surface), 13, 16 , 34, 37 Gear pair, 17, 38 Drive gear rotary shaft, 17c, 38c Drive gear rotary shaft cylindrical portion (drive gear rotary shaft outer peripheral surface), 18, 39 Drive gear rotary shaft, 18c, 39c Drive gear rotary shaft Cylindrical part (driven gear rotating shaft outer peripheral surface), 19 Drive side slide bearing, 21 Drive side slide bearing, CL2 Clearance between the cylindrical part of the drive gear and the cylindrical part of the drive gear rotary shaft (drive gear restraint gap), Circle The gap between the cylindrical portion of the parts and the driven gear rotation shaft (driven gear restraint gaps), Δθ1, Δθ2, Δθ3, gaps in Δθ4 circumferential direction.

Claims (6)

A plurality of separated gear chambers;
A pair of gears comprising a driving gear and a driven gear that mesh with each other and rotate, and a plurality of gear pairs respectively housed in the plurality of gear chambers;
A plurality of drive gears connected to each other, and a drive gear rotation shaft to which drive force is given from the outside;
A driven gear rotating shaft to which a plurality of the driven gears are connected;
A drive-side plain bearing that rotatably supports the drive gear rotation shaft;
A driven-side slide bearing that rotatably supports the driven gear rotation shaft, and a gear pump that boosts and discharges fluid sucked from outside in the gear chamber;
At least one of the drive gear rotary shaft and the driven gear rotary shaft is supported by the drive side slide bearing or the driven side slide bearing so as to be movable in a radial direction,
At least one of the drive gear and the driven gear is connected to the drive gear rotation shaft or the driven gear rotation shaft so as to be movable in a radial direction ,
The drive gear is connected to the drive gear rotation shaft, the driven gear is connected to the precursor driven gear rotation shaft by spline fitting, respectively.
The spline fitting between the drive gear rotating shaft and the drive gear, and in the spline fitting between the driven gear rotation shaft and the driven gear, gear pump gap in the circumferential direction are respectively formed, characterized in Rukoto. A plurality of separated gear chambers;
A pair of gears comprising a driving gear and a driven gear that mesh with each other and rotate, and a plurality of gear pairs respectively housed in the plurality of gear chambers;
A plurality of drive gears connected to each other, and a drive gear rotation shaft to which drive force is given from the outside
A driven gear rotating shaft to which a plurality of the driven gears are connected;
A drive-side plain bearing that rotatably supports the drive gear rotation shaft;
A driven-side slide bearing that rotatably supports the driven gear rotating shaft;
In a gear pump that boosts and discharges fluid sucked from outside in the gear chamber,
At least one of the drive gear rotary shaft and the driven gear rotary shaft is supported by the drive side slide bearing or the driven side slide bearing so as to be movable in a radial direction,
At least one of the drive gear and the driven gear is connected to the drive gear rotation shaft or the driven gear rotation shaft so as to be movable in a radial direction,
The drive gear has a cylindrical drive gear inner peripheral surface, and the drive gear rotary shaft has a drive gear rotary shaft outer peripheral surface at a position facing the drive gear inner peripheral surface of the drive gear. ,
The driven gear has a cylindrical driven gear inner peripheral surface, and the driven gear rotary shaft has a driven gear rotary shaft outer peripheral surface at a position facing the driven gear inner peripheral surface of the driven gear. ,
Movement of the drive gear in the radial direction with respect to the drive gear rotation shaft is restricted by a drive gear restraint gap that is a gap formed between the drive gear inner peripheral surface and the drive gear rotation shaft outer peripheral surface.
Movement in the radial direction with respect to the driven gear axis of rotation of the driven gear, to be bound by the driven gear restraint gap is a gap formed between the inner driven gear peripheral surface and the driven gear rotary shaft outer circumference Gear pump characterized by The gear pump according to claim 2 , wherein the drive gear is connected to the drive gear rotation shaft, and the driven gear is connected to the precursor driven gear rotation shaft by spline fitting. 4. The gear pump according to claim 3 , wherein a gap in the circumferential direction is formed in the spline fitting between the drive gear and the drive gear rotation shaft and the spline fitting between the driven gear and the driven gear rotation shaft. . The drive gear restraint gap is formed at both ends of the drive gear,
The gear pump according to any one of claims 2 to 4, wherein the driven gear restraint gap is formed at both ends of the driven gear. When the plurality of gear pairs are two sets, and the number of teeth of the drive gear and the driven gear is N,
The gear pump according to any one of claims 1 to 5, wherein the two pairs of gear pairs are arranged with meshing phases shifted by 360 / (4N) °.

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