JP2008014292A - Gear pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear pump materializing operation without backlash without requiring improvement of work accuracy of components, and without requiring selective fitting with ranking components according to actual measured dimensions. <P>SOLUTION: A driven gear rotary shaft 8 is supported movably in a contact/separation direction, in a bearing hole 3b having an elongated hole shape via a plain bearing 9. A first pressure chamber 11 is formed between the driven gear rotary shaft 8 and the plain bearing 9. A second pressure chamber 12 and a third pressure chamber 13 are formed between the bearing hole 3b and the plain bearing 9. Communication between the first pressure chamber 11 and the second pressure chamber 12 is established by a communication hole A, and communication between the first pressure chamber 11 and the third pressure chamber 13 is established by a communication hole B. The first pressure chamber 11 communicates with a high pressure side space zone HP in a gear chamber 10 via a communication path 21, the second pressure chamber 12 communicates with a low pressure side space zone LP in a gear chamber 10 via a communication path 22, and the third pressure chamber 13 communicates with the low pressure side space zone LP via a communication path 23. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a gear pump.

In the gear pump, the presence of backlash is one of the causes for increasing the discharge pulsation. As shown in FIG. 13, the backlash is a gap (backlash BR) formed between the tooth surface 72 a of the gear tooth 72 of the drive gear 71 and the tooth surface 74 a of the gear tooth 74 of the driven gear 73. It is. When the backlash BR exists, the closed region 75 on the drive gear 71 side and the closed region 76 on the driven gear 73 side communicate with each other via the backlash BR to form one closed region. It is known that by reducing the backlash BR and separating the closed region 75 and the closed region 76, both an increase in the discharge pulsation of the gear pump and an increase in noise caused thereby are suppressed.
For example, in Patent Document 1, in order to perform the operation with a backlash of 0 or substantially 0, that is, with no backlash, the distance between the bearings of the drive gear side bearing and the driven gear side bearing according to the gear tooth width. By selecting and assembling a combination based on the setting from a plurality of cases and gear pairs that are manufactured in advance and ranked according to the measured values of the dimensions, the backlash-less gear meshing is achieved. A gear pump is described which achieves the optimum possible bearing distance.

JP 2001-32780 A

  However, as in the gear pump described in Patent Document 1, it is not efficient to rank each part according to the actual measurement size and perform selective fitting, which increases the cost. It was. Also, in order to achieve operation without backlash without selective fitting, the inner diameter of the bearing that supports the rotating shaft of the gear, the pitch between the bearings, the outer diameter of the rotating shaft that fits the bearing, An extremely high machining accuracy is required for the gear tooth thickness and the like, and the cost is similarly increased.

  The present invention has been made to solve such problems, and it is possible to operate in a backlash-free state without the need for improving the accuracy of processing parts, ranking parts according to measured dimensions, and selectively fitting. An object of the present invention is to provide a gear pump that realizes the above.

A gear pump according to the present invention is housed in a gear chamber and rotatably supports a gear pair of a driving gear and a driven gear that are circumscribed and meshed with each other, a driven gear rotating shaft that is connected to the driven gear, and a driven gear rotating shaft. In a gear pump that includes a plain bearing and a housing that has a bearing hole for inserting the plain bearing, and that boosts and discharges fluid drawn from the outside in the gear chamber, the bearing hole is movable in the direction in which the gear pair contacts and separates In addition, the first pressure chamber that holds the slide bearing and communicates with the high-pressure side space region in the gear chamber, and in the bearing hole and between the slide bearing and the housing, is opposed to each other with the driven gear rotating shaft interposed therebetween. And a second pressure chamber and a third pressure chamber communicating with the low pressure side space region in the gear chamber. In addition, a first intermediate communication passage that communicates the first pressure chamber and the second pressure chamber, and a second intermediate communication passage that communicates the first pressure chamber and the third pressure chamber, Opening adjusting means for adjusting the opening of the first intermediate communication passage and the second intermediate communication passage according to the position is provided.
By adjusting the opening degree of the first intermediate communication path and the second intermediate communication path, the slide bearing held in the bearing hole of the housing can be operated in a backlash-less state in the direction in which the gear pair contacts and separates. Move autonomously. The gear pump is operated in a backlashless state, and discharge pulsation and noise can be reduced.

  The first pressure chamber is formed between the slide bearing and the driven gear rotation shaft, the second pressure chamber is formed on the drive gear side with respect to the driven gear rotation shaft, and the third pressure chamber is formed on the driven gear. The first intermediate communication passage and the second intermediate communication passage may be formed in a slide bearing, which is formed on the opposite side to the second pressure chamber with respect to the rotation shaft.

The bearing hole includes a parallel portion that allows the slide bearing to move in the direction in which the gear pair contacts and separates, and the parallel portion is substantially parallel to the connecting line between the central axes that connects the central axes of the drive gear and the driven gear. Thus, the contact point at which the driven gear rotation shaft contacts the slide bearing can be set to a position that coincides with the direction perpendicular to the parallel portion when viewed from the center of the driven gear rotation shaft.
Further, the cross-sectional area of the first intermediate communication path can be made equal to the cross-sectional area of the second intermediate communication path.
By configuring as described above, it is possible to realize the operation of the gear pump in a backlashless state by pressing the gear pair by the load due to the pressure of the fluid boosted by the gear pump without generating a force in the direction of separating the gear pair. .

The bearing hole has a parallel portion that allows the sliding bearing to move in the direction in which the gear pair contacts and separates, and the parallel portion is substantially parallel to the connecting line between the central axes connecting the central axes of the drive gear and the driven gear. The contact point where the driven gear rotating shaft contacts the slide bearing coincides with the direction of the load applied to the driven gear rotating shaft due to the fluid pressure generated in the gear chamber when viewed from the center of the driven gear rotating shaft. You may comprise so that it may exist between the contact point and the contact point which corresponds to the direction perpendicular | vertical with respect to the parallel part of a bearing hole.
When the load that the gear pair presses against the load due to the pressure of the fluid boosted by the gear pump is too large, a predetermined force can be generated in the direction of releasing the gear pair, and the gear pair can be pressed with the optimum force. Thereby, the surface pressure applied to the gear pair is optimized, and power loss, tooth surface wear, and pitching are reduced. In addition, wear and pitching of the slide bearing are reduced.

Moreover, the passage cross-sectional area of the first intermediate communication passage can be made larger than the passage cross-sectional area of the second intermediate communication passage, so that the gear pair can be pressed with an optimum force as described above.
And a first low pressure communication passage that communicates the second pressure chamber and the low pressure side space region in the gear chamber, and a second low pressure communication passage that communicates the third pressure chamber and the low pressure side space region in the gear chamber, Even if the passage cross-sectional area of the first low-pressure communication passage is smaller than the passage cross-sectional area of the second low-pressure communication passage, the load with which the gear pair presses can be optimized.

  According to the present invention, by adjusting the opening degree of the first intermediate communication path and the second intermediate communication path according to the position of the driven gear rotation shaft, the force by the fluid applied to the slide bearing changes, and the slide bearing is It is placed autonomously in a suitable position with respect to the driven gear rotation axis, and the gear pump can be operated in a backlash-free state without the need to improve the machining accuracy of the parts, rank the parts according to the measured dimensions, and perform selective fitting. it can.

Embodiments 1 to 3 of the present invention will be described below with reference to the accompanying drawings 1 to 12.
Embodiment 1 FIG.
The structure of the gear pump according to the first embodiment will be described with reference to FIGS. 1 to 4 by taking as an example a case where it is applied as a hydraulic pump for a cargo handling device.
As shown in FIG. 1, the gear pump 1 includes a body 2 having a cavity for housing a gear pair therein, and a pair of housings 3 provided on both sides of the body 2 so as to close the cavity. ing. A pair of side plates 4 is provided between the cavity of the body 2 and the end surface of the housing 3. A gear chamber 10 is formed inside the gear pump 1 by the side plate 4 surrounding the cavity of the body 2.

  The drive gear rotating shaft 6 is fixed to the drive gear 5a so as to rotate as a unit. On the other hand, bearing holes 3a are formed in portions of the pair of housings 3 located at both ends of the drive gear 5a. Cylindrical plain bearings 7 having both ends opened are inserted into the bearing holes 3a. A drive gear rotating shaft 6 is inserted into the plain bearing 7, and the driving gear rotating shaft 6 is rotatably supported by the plain bearing 7. One end of the drive gear rotating shaft 6 extends through the one housing 3 to the outside of the gear pump 1 and is connected to an external power source (not shown). The driving power is applied to the drive gear rotating shaft 6 by the external power source. Is given. An oil seal 14 is provided on the outer peripheral surface in the middle of the drive gear rotation shaft 6 extending to the outside, and oil in the gear pump 1 is prevented from leaking outside along the drive gear rotation shaft 6.

  Further, the driven gear rotating shaft 8 is integrally formed with the driven gear 5b. The bottomed bearing holes 3b are also formed in the portions of the pair of housings 3 located at both ends of the driven gear 5b. A plain bearing 9, which is a bottomed cylindrical slide bearing with one end opened, is inserted into each bearing hole 3 b. A driven gear rotating shaft 8 is inserted into the plain bearing 9, and the driven gear rotating shaft 8 is rotatably supported by the plain bearing 9. The cylindrical surface of the plain bearing 9 is formed with communication holes A and B penetrating in the radial direction. Here, the communication hole A constitutes a first intermediate communication path, and the communication hole B constitutes a second intermediate communication path. The bottom surface 9a of the plain bearing 9 is in contact with the bottom surface 3c of the bearing hole 3b.

  As shown in FIG. 2, a gear pair 5 including a drive gear 5 a and a driven gear 5 b that are externally engaged with each other is accommodated in the gear chamber 10 in an engaged state. In order to suck oil, which is a fluid to be pressurized, from the outside of the gear pump 1 into the gear chamber 10, a suction port (not shown) is provided on the right side of the meshing portion of the gear pair 5 in FIG. And the gear chamber 10 communicate with each other. Further, in order to discharge the pressurized oil to the outside of the gear pump 1, a discharge port (not shown) is also provided on the left side in FIG. 2 of the meshing portion of the gear pair 5, and communicates the outside of the gear pump 1 and the gear chamber 10. .

Here, in the gear chamber 10, the space communicating with the suction port in the right portion of the gear pair 5 in FIG. 2 is defined as the suction side space IN, and the left portion of the gear pair 5 in FIG. This space is referred to as a discharge side space OUT.
When the drive gear 5a rotates in the direction of the arrow, the driven gear 5b that meshes with the drive gear 5a rotates in reverse while meshing. The oil sucked from the suction port is confined in the space S substantially closed by the body 2 and the side plate 4 between the teeth of the drive gear 5a or the teeth of the driven gear 5b from the suction space IN and moves to the discharge space OUT. In addition, a so-called pumping action is performed in which the pressure is increased and discharged from the discharge port.

  Due to this pump action, an oil pressure difference is generated in the gear chamber 10. Specifically, a high-pressure side space region HP indicated by a thick solid line and a low-pressure side space region LP indicated by a thick broken line are formed. The high-pressure side space region HP is a region that communicates with the discharge-side space OUT via a small chamfered portion (not shown) formed in the side plate 4 and is a region that is filled with pressurized oil. The high-pressure side space region HP is formed from the discharge side space OUT to a range at least θ beyond the center and entering θ ° on the suction space IN side. The remaining part around the suction space IN becomes the low pressure side space region LP. The oil pressure in the low pressure side space region LP is a pressure before being increased, and is different from the oil pressure in the high pressure side space region HP.

Next, the support structure of the driven gear rotating shaft 8 will be described with reference to FIG.
FIG. 3 is a view of a cross section including the communication holes A and B of the support structure for the driven gear rotating shaft 8 as seen from the axial center line direction of the driven gear rotating shaft 8. In order to clarify the positional relationship between the driven gear rotation shaft 8 and the drive gear rotation shaft 6, the bearing hole 3a for the drive gear rotation shaft 6 is indicated by a broken line.
Here, the bearing hole 3 b into which the driven gear rotation shaft 8 is inserted through the plain bearing 9 has a shape that is a long hole toward the bearing hole 3 a of the drive gear rotation shaft 6.
That is, the cross-section of the bearing hole 3b is an elongated hole shape in which two semicircular portions 3b1 having the same diameter are arranged opposite to each other and end points of the opposing semicircular portions are connected by parallel portions 3b2 formed of parallel straight lines. It has become. The parallel portion 3b2 is parallel to a straight line connecting the center 3a1 of the bearing hole 3a and the center 3b3 of the bearing hole 3b. Since the plain bearing 9 is inserted into the long hole-shaped bearing hole 3b, the plain bearing 9 has a structure movable in the longitudinal direction of the bearing hole 3b. Therefore, the bearing hole 3b holds the plain bearing 9 so as to be movable in the direction in which the gear pair 5 contacts and separates.
Thus, the mechanism by which the plain bearing 9 can move in the bearing hole 3 b constitutes an opening adjustment means for adjusting the opening of the communication holes A and B according to the position of the driven gear rotation shaft 8.

  The communication hole A provided in the plain bearing 9 is disposed on a line connecting the center 3a1 of the bearing hole 3a of the drive gear rotating shaft 6 and the center 3b3 of the bearing hole 3b of the driven gear rotating shaft 8. Similarly, the communication hole B provided in the plain bearing 9 has the same passage cross-sectional area as the communication hole A, and is provided at a position symmetrical to the communication hole A with respect to the central axis of the plain bearing 9. Although the outer periphery of the plain bearing 9 forms a cylindrical surface, two rectangular flat surfaces 9b are formed by chamfering the cylindrical surface at portions that are 90 degrees out of phase with the communication holes A and B. Has been. Each flat surface 9b is disposed at a position facing the parallel portion 3b2 of the bearing hole 3b, and serves to prevent the plain bearing 9 from rotating. Furthermore, the driven gear rotating shaft 8 is inserted in a state where there is a gap on the inner peripheral surface side of the plain bearing 9.

  The long hole-shaped bearing hole 3b, the plain bearing 9 and the driven gear rotating shaft 8 of the housing 3 are arranged with the above positional relationship. Further, a gap is formed between the outer peripheral surface of the driven gear rotating shaft 8 and the inner peripheral surface of the plain bearing 9, and this gap constitutes the first pressure chamber 11. Further, two gaps are formed between the outer peripheral surface of the plain bearing 9 and the inner peripheral surface of the bearing hole 3b so as to face each other with the plain bearing 9 interposed therebetween. The two gaps are defined by clearance fitting between the plain bearing 9 and the parallel portion 3b2 of the bearing hole 3b, and contact between the bottom surface 9a of the plain bearing 9 and the bottom surface 3c of the bearing hole 3b (see FIG. 1). Of the two gaps, the gap formed on the drive gear side with respect to the plain bearing 9 constitutes the second pressure chamber 12, and the gap formed on the counter drive gear side constitutes the third pressure chamber 13. Since the plain bearing 9 is supported so as to be movable in the vertical direction in FIG. 3 in the bearing hole 3b, the volumes of the second pressure chamber 12 and the third pressure chamber 13 change as the plain bearing 9 moves. To do.

  Further, as schematically shown in FIG. 2, the first pressure chamber 11 communicates with the high pressure side space region HP in the gear chamber 10 through a communication path 21 provided in the side plate 4 (see FIG. 1). Yes. On the other hand, the second pressure chamber 12 communicates with the low pressure side space region LP in the gear chamber 10 through a communication path 22 provided in the side plate 4. The third pressure chamber 13 is also provided in the side plate 4 and communicates with the low pressure side space region LP in the gear chamber 10 through a communication passage 23 having substantially the same passage cross-sectional area and passage length as the communication passage 22. Yes. Here, the communication path 22 constitutes a first low pressure communication path that connects the second pressure chamber 12 and the low pressure side space region LP in the gear chamber 10, and the communication path 23 includes the third pressure chamber 13 and the gear chamber. A second low-pressure communication path that communicates with the low-pressure side space region LP in the interior 10 is configured.

  Next, FIG. 4 is an explanatory diagram for clarifying a range in which the plain bearing 9 can move in the vertical direction within the bearing hole 3b. The elongated hole-shaped bearing hole 3b has a manufacturing variation in the distance H between the shaft centers of the drive gear rotating shaft 6 and the driven gear rotating shaft 8 when the tooth surface of the drive gear 5a and the tooth surface of the driven gear 5b are brought into close contact with each other. Therefore, even if the assembled state of the gear pump 1 changes within the range of H ± α, the second pressure chamber 12 and the third pressure chamber 13 are formed above and below the plain bearing 9, and the first pressure is formed inside the plain bearing 9. The dimensions are such that the chamber 11 is formed.

Next, operation | movement of the gear pump 1 which concerns on this Embodiment 1 is demonstrated based on FIG. 2, FIG.
First, as shown in FIG. 2, when a driving force is applied to the driving gear rotating shaft 6 from the outside, the driving gear 5a rotates accordingly. The driven gear 5b meshing with the drive gear 5a starts synchronous rotation in the opposite direction to the drive gear 5a together with the driven gear rotating shaft 8. When the gear pair 5 starts rotating while meshing, the oil sucked from the suction port is confined to the space S from the suction space IN, moves to the discharge space OUT, and is discharged from the discharge port in a pressurized state. At the same time, due to the pressure difference generated in the gear chamber 10, a force resulting from the pressure difference between the oil pressure is applied to the drive gear 5 a and the driven gear 5 b, and the oil pressure is applied to the drive gear rotating shaft 6 and the driven gear rotating shaft 8. Is acting in a direction from the high-pressure side space region HP toward the low-pressure side space region LP, as indicated by the arrows in the figure.

  Further, the oil whose pressure is increased in the gear chamber 10 is also supplied from the high pressure side space region HP in the gear chamber 10 to the first pressure chamber 11 through the communication path 21. The oil supplied to the first pressure chamber 11 is supplied to the second pressure chamber 12 through the communication hole A of the plain bearing 9 and to the third pressure chamber 13 through the communication hole B. The oil supplied to the second pressure chamber 12 is guided to the low pressure side space region LP in the gear chamber 10 through the communication path 22. Similarly, the oil supplied to the third pressure chamber 13 is guided through the communication path 23 to the low pressure side space region LP in the gear chamber 10.

  By the way, the dimension of each part which comprises the gear pump 1 has the dispersion | variation within a predetermined tolerance range at the time of manufacture. Due to this variation, for example, as shown in FIG. 5, when the plain bearing 9 and the driven gear rotation shaft 8 are in contact at a contact point P that is biased toward the communication hole A, the first of the communication holes A The inlet A1 on the one pressure chamber 11 side is closed by the driven gear rotating shaft 8 and is in a state close to a closed state. On the other hand, the inlet B1 on the first pressure chamber 11 side of the communication hole B is open. For this reason, there is a difference between the amount of oil supplied from the first pressure chamber 11 to the second pressure chamber 12 and the amount of oil supplied from the first pressure chamber 11 to the third pressure chamber 13. Due to the difference in supply amount, the pressure PR2 in the second pressure chamber 12 is lower than the pressure PR3 in the third pressure chamber 13. Since the force due to the pressure difference generated between the pressure PR2 of the second pressure chamber 12 and the pressure PR3 of the third pressure chamber 13 acts on the plain bearing 9, as shown by the arrow in FIG. In the direction of approaching the drive gear rotation shaft 6).

  As the plain bearing 9 moves in the direction approaching the bearing hole 3a for the drive gear 5a, the position of the contact point P between the plain bearing 9 and the driven gear rotating shaft 8 also changes. When the plain bearing 9 moves upward in FIG. 5, the amount of oil supplied from the first pressure chamber 11 to the second pressure chamber 12 through the communication hole A increases, and the pressure PR2 and the third pressure in the second pressure chamber 12 increase. When the pressure PR3 in the chamber 13 becomes equal, the plain bearing 9 stops and stabilizes at the position shown in FIG. At this time, a load Fp is applied to the driven gear rotating shaft 8. On the other hand, the plain bearing 9 is in contact at a contact point P0 that coincides with the direction perpendicular to the parallel part 3b2 of the bearing hole 3b, and the bearing reaction force Fb received from the inner peripheral surface of the plain bearing 9 is perpendicular to the parallel part 3b2. Acting on the driven gear rotating shaft 8 in a substantially horizontal direction in the figure.

  For this reason, the bearing reaction force Fb cancels with the horizontal component Fpx of the load Fp. On the other hand, since the bearing reaction force Fb does not act in the vertical direction, no force is generated to pull the driven gear 5b away from the drive gear 5a. Therefore, since Fpy, which is a vertical component of the load Fp, acts on the driven gear 5b and the driven gear rotating shaft 8 as it is, the driven gear 5b rotates while being pressed against the drive gear 5a, and in a backlashless state. The pump can be operated.

  FIG. 7 shows a case where the plain bearing 9 and the driven gear rotating shaft 8 are in contact with each other at a contact point P which is a position biased toward the communication hole B, contrary to the case of FIG. In this case, the inlet A1 on the first pressure chamber 11 side of the communication hole A is in an open state, and the inlet B1 on the first pressure chamber 11 side of the communication hole B is blocked by the driven gear rotating shaft 8 to be in a closed state. Therefore, the pressure PR2 in the second pressure chamber 12 is higher than the pressure PR3 in the third pressure chamber 13. Therefore, since the force due to the pressure difference generated between the pressure PR2 in the second pressure chamber and the pressure PR3 in the third pressure chamber 13 acts on the plain bearing 9, as shown by the arrow in FIG. Move down. As the plain bearing 9 moves downward, the position of the contact point P between the plain bearing 9 and the driven gear rotating shaft 8 also moves. The plain bearing 9 stops and stabilizes at a position where the pressure PR2 in the second pressure chamber 12 and the pressure PR3 in the third pressure chamber 13 become equal, that is, the position of FIG.

  Thus, in the gear pump 1, the plain bearing 9 can be autonomously arranged at a suitable position by adjusting the opening degree of the communication hole A and the communication hole B according to the position of the driven gear rotation shaft 8. It becomes. Therefore, it is possible to operate the gear pump 1 in a backlash-less state without the necessity of improving the machining accuracy of the parts, or ranking the parts according to the actually measured dimensions, and performing selective fitting, and the discharge pulsation and noise can be reduced. Reduction can be realized.

  Further, since the bearing reaction force Fb applied to the driven gear rotating shaft 8 works perpendicularly to the parallel portion 3b2 of the bearing hole 3b, only the horizontal component Fpx of the load Fp due to the pressure of the pressurized oil is canceled, and the gear pair is No force is generated in the direction of separation. For this reason, the operation of the gear pump in the backlashless state can be realized by the load Fp due to the fluid pressure boosted by the gear pump 1 without weakening the force with which the gear pair presses.

Embodiment 2. FIG.
Next, a gear pump according to Embodiment 2 of the present invention will be described with reference to FIGS. In the following embodiments, the same reference numerals as those in FIGS. 1 to 7 are the same or similar components, and thus detailed description thereof is omitted.

In the gear pump according to the second embodiment, as shown in FIG. 8, instead of the plain bearing 9 of the first embodiment, a plain bearing 19 in which the passage cross-sectional areas of the communication hole A and the communication hole B have different sizes is provided. It is what is used.
The communication hole A ′ provided in the plain bearing 19 is arranged on a line connecting 3a1 which is the center of the bearing hole 3a of the drive gear rotating shaft 6 and 3b3 which is the center of the bearing hole 3b of the driven gear rotating shaft 8. ing. Similarly, the communication hole B ′ provided in the plain bearing 19 is provided at a position symmetrical to the communication hole A ′ with respect to the central axis of the plain bearing 19. Here, the passage sectional area Sa of the communication hole A ′ and the passage sectional area Sb of the communication hole B ′ satisfy Sa> Sb. Other configurations are the same as those in the first embodiment.

The operation of the gear pump according to the second embodiment is similar to that of the first embodiment until the pressure PR2 in the second pressure chamber 12 and the pressure PR3 in the third pressure chamber 12 reach a position where PR2 = PR3. The bearing 19 moves and becomes stable. Here, since the passage cross-sectional areas of the communication holes A ′ and B ′ have a relationship of Sa> Sb, the plain bearing 19 is in the direction of closing the communication hole A ′, that is, the stability in the first embodiment shown in FIG. 6 is moved downward from the position in FIG. 6 and stabilized at a position where the amount of oil supplied from the first pressure chamber 11 to the second pressure chamber 12 and the third pressure chamber 13 becomes equal. Further, as the plain bearing 19 moves downward in FIG. 6, the position of the contact point P moves upward in FIG. 6 from the position shown in FIG. As described above, the stable position of the plain bearing 19 is determined by the difference between the passage sectional area Sa of the communication hole A ′ and the passage sectional area Sb of the communication hole B ′. It becomes possible to set. Therefore, for example, as shown in FIG. 9, the driven gear rotating shaft 8 and the plain bearing 19 come into contact with each other at P <b> 1 that is a contact point that coincides with the acting direction of the load Fp when viewed from the center 8 a <b> 1 of the driven gear rotating shaft 8. Thus, when the magnitudes of Sa and Sb are set, the reaction force Fb received by the driven gear rotating shaft 8 from the plain bearing 19 at the contact point P1 works in the same direction as the load Fp. The relationship between the horizontal and vertical components of the load Fp and the bearing reaction force Fb, Fpx, Fpy, Fbx, and Fby, is
Fpx + Fbx = 0
Fpy + Fby = 0
Thus, the forces acting in the horizontal direction and the vertical direction all cancel each other.

Next, as shown in FIG. 10, when Sa and Sb are set so that the position of the contact point P when the plain bearing 19 is stable is higher than the contact point P1 in the case of FIG. The relationship between the vertical component and the horizontal component of the load Fp and the bearing reaction force Fb is
Fpx + Fbx = 0
Fpy + Fby <0
It becomes. In this case, since the vertical component Fby of the bearing reaction force Fb exceeds the vertical component Fpy of the load Fp, the gear pair 5 is separated and backlash occurs. Therefore, it cannot be said that it is a suitable contact position, and it can be said that the position of the preferred contact point P is desirably set below P1 in FIG.

On the other hand, as shown in FIG. 6, at P0 which is a contact point in the case of the first embodiment,
Fbx = Fb, Fby = 0
Fpx + Fbx = 0
Fby + Fpy = Fpy> 0
It becomes. Only the vertical component Fpy of the load Fp acts on the driven gear rotation shaft 8 in the direction in which the gear pair 5 approaches. In the first embodiment, a backlashless state is realized by this Fpy.

Further, if the difference in passage cross-sectional area between the communication holes A ′ and B ′ is Sa <Sb, as shown in FIG. 11, the position of the contact point P when the plain bearing 19 is stable is shown in FIG. 11 is lower than P0 which is the stable position in this case. in this case,
Fpx + Fbx = 0
Fpy + Fby> 0
It becomes. Although the resultant force of the vertical component Fpy of the load Fp and the vertical component Fby of the bearing reaction force acts on the driven gear rotating shaft 8 in the direction in which the gear pair 5 approaches, a more reliable backlashless state is achieved. The surface pressure acting on the tooth surfaces of the gear pair 5 increases. If this surface pressure becomes too large, power loss, wear and pitching of the tooth surfaces of the gear pair 5, and wear and pitching of the plain bearing 19 will be caused. Therefore, the position of the contact point P is greater than that of P0. It can be said that it is desirable not to be too biased below 11.

As described above, the passage sectional area Sa of the communication hole A ′ is made larger than the passage sectional area Sb of the communication hole B ′, and the difference between Sa and Sb is determined as the contact point between the driven gear rotary shaft 8 and the plain bearing 9. By setting the position of P to be between the contact point P0, which is the same position as in the first embodiment, and the contact point P1 described above, the load Fp due to the oil pressure is reduced while realizing backlashlessness. The load for pressing the gear pairs 5 together can be reduced.
For this reason, when the load which the gear pair 5 presses against by the load Fp due to the pressure of the fluid boosted by the gear pump is too large, a predetermined force is generated in the direction in which the gear pair 5 is released, and the gear pair 5 is generated with an optimum force. Can be pressed against each other. As a result, the surface pressure applied to the gear pair 5 is optimized, and power loss, tooth surface wear, and pitching are reduced. In addition, wear and pitching of the slide bearing are reduced. Therefore, it is possible to improve the durability of components such as the gear pair 5 and the plain bearing 19.

Embodiment 3 FIG.
Next, a gear pump according to Embodiment 3 of the present invention will be described with reference to FIG. In the gear pump 40 according to the third embodiment, the cross-sectional areas of the communication passage 22 and the communication passage 23 in the first embodiment are different sizes.

  As schematically shown in FIG. 12, the side plate of the gear pump 40 communicates with the second pressure chamber 12 and the low pressure side space region LP in the gear chamber 10 and has a communication passage 32 having a passage cross-sectional area S1. Is provided. The side plate communicates with the third pressure chamber 13 and the low pressure side space region LP in the gear chamber 10, has a passage cross-sectional area of S2, and has a passage length substantially the same as that of the communication passage 32. A passage 33 is provided. The passage sectional area S1 of the communication passage 32 and the passage sectional area S2 of the communication passage 33 are in a state of S1 <S2.

  With this configuration, the passage cross-sectional areas of the communication passages 32 and 33 have a relationship of S1 <S2. Therefore, the oil in the second pressure chamber 12 is unlikely to escape to the low-pressure side space region LP through the communication passage 32. The pressure PR2 in the second pressure chamber 12 becomes higher than the pressure PR3 in the third pressure chamber 13. Accordingly, the plain bearing 9 moves downward in FIG. 12 due to this pressure difference, and moves in the direction of narrowing the opening of the communication hole A. Then, the pressure PR2 in the second pressure chamber 12 decreases and the pressure PR3 in the third pressure chamber 13 increases, and the amount of oil supplied from the first pressure chamber 11 to the second pressure chamber 12 and the third pressure chamber 13 is even. Stable at the position. Therefore, the position of the slide bearing 9 can be adjusted so that the position of the contact point P is the same as that of the second embodiment, depending on the set amounts of the passage sectional area S1 of the communication passage 32 and the passage sectional area S2 of the communication passage 33. it can.

Thus, by making the passage cross-sectional area S1 of the communication passage 32 smaller than the passage cross-sectional area S2 of the communication passage 33, the stable position of the plain bearing 9 is changed and the driven gear rotating shaft 8 is changed as in the second embodiment. It can be realized that the contact point between the plain bearing 9 and the plain bearing 9 is set at a suitable position.
For this reason, the load Fp caused by the oil pressure presses against the gear pairs 5 can be reduced while realizing backlash-free, thereby reducing the surface pressure acting on the tooth surfaces of the gear pairs, power loss and It is possible to prevent wear and pitching of the tooth surface and the bearing, and improve the durability of parts such as a gear pair and a plain bearing.

In the first to third embodiments, the gear pump according to the present invention has been described using a hydraulic pump for a cargo handling device as an example, but the present invention is not limited to this. The present invention can also be applied to gear pumps used for other purposes such as a hydraulic pump used for engine oil lubrication and a gear pump used for fuel supply. Further, the fluid to be pressurized is not limited to the oil used in the hydraulic pump for the cargo handling device, and can be applied to light oil and dimethyl ether (DME).
In the first to third embodiments, the communication paths 21 to 23 and 32 and 33 are provided on the side plate, but the present invention is not limited to this. For example, it can be provided in the housing 3.
In the first to third embodiments, the first pressure chamber 11 is formed by the gap generated between the driven gear rotation shaft 8 and the plain bearings 9 and 19, but is not limited thereto. For example, a tank provided outside the gear chamber 10 constitutes the first pressure chamber, and the position of the driven gear rotating shaft 8 and the position of the driven plain bearing 9 with respect to the driving gear rotating shaft 6 can be detected by a sensor. From the first pressure chamber, which is an external tank, to the second pressure chamber 12 and the third pressure chamber so that the plain bearing 9 is stabilized at a suitable position with respect to the detected position of the driven gear rotating shaft 8. It is also possible to control the supply pressure to 13. In the third embodiment, the passage cross-sectional areas of the communication passages 32 and 33 are changed. However, the present invention is not limited to this. A difference may be provided.

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 cross-sectional front view schematically showing the structure of the gear pump according to the first embodiment. It is the figure which looked at the cross section containing the communicating hole A and B from the axial centerline direction of the driven gear rotating shaft about the support structure of the driven gear rotating shaft of the gear pump which concerns on Embodiment 1. FIG. It is a schematic diagram for demonstrating the relationship of a bearing hole, a plain bearing, and a driven gear rotating shaft used for the gear pump which concerns on Embodiment 1. FIG. FIG. 6 is a schematic diagram for explaining the operation of the gear pump according to the first embodiment. FIG. 6 is a schematic diagram for explaining the operation of the gear pump according to the first embodiment. FIG. 4 is a schematic diagram for explaining the operation of the gear pump according to the first embodiment. It is the figure which looked at the cross section containing communication hole A 'and B' from the axial centerline direction of the driven gear rotating shaft about the support structure of the driven gear rotating shaft of the gear pump which concerns on Embodiment 2 of this invention. 6 is a schematic diagram for explaining a force acting on a driven gear rotation shaft of a gear pump according to Embodiment 2. FIG. 6 is a schematic diagram for explaining a force acting on a driven gear rotation shaft of a gear pump according to Embodiment 2. FIG. 6 is a schematic diagram for explaining a force acting on a driven gear rotation shaft of a gear pump according to Embodiment 2. FIG. FIG. 3 is a cross-sectional front view of the gear pump according to the first embodiment. It is a section front view showing typically the structure of the gear pump concerning Embodiment 3 of this invention. It is a sectional front view for explaining meshing of a drive gear and a driven gear of the conventional gear pump.

Explanation of symbols

  1, 30, 40 Gear pump, 3 housing, 3b bearing hole, 5a drive gear, 5b driven gear, 8 driven gear rotating shaft, 9, 19 plain bearing, 10 gear chamber, 11 first pressure chamber, 12 second pressure chamber, 13 third pressure chamber, 22, 32 communication path (first low pressure communication path), 23, 33 communication path (second low pressure communication path) A, A ′ communication hole (first intermediate communication path), B, B ′ communication Hole (second intermediate communication path), HP high pressure side space region, LP low pressure side space region.

Claims (7)

A gear pair of a drive gear and a driven gear housed in the gear chamber and externally meshing with each other;
A driven gear rotating shaft connected to the driven gear;
A plain bearing that rotatably supports the driven gear rotation shaft;
A gear pump including a housing having a bearing hole into which the slide bearing is inserted, and pressurizing and discharging fluid sucked from outside in the gear chamber;
The bearing hole holds the sliding bearing so as to be movable in a direction in which the gear pair contacts and separates,
A first pressure chamber communicating with the high pressure side space region in the gear chamber;
A second hole that is disposed in the bearing hole and between the plain bearing and the housing, facing each other with the driven gear rotation shaft interposed therebetween, and communicated with a low-pressure side space region in the gear chamber; A pressure chamber and a third pressure chamber;
A first intermediate communication path communicating the first pressure chamber and the second pressure chamber;
A second intermediate communication passage communicating the first pressure chamber and the third pressure chamber;
A gear pump comprising opening degree adjusting means for adjusting the opening degree of the first intermediate communication path and the second intermediate communication path according to the position of the driven gear rotation shaft. The first pressure chamber is formed between the sliding bearing and the driven gear rotating shaft,
The second pressure chamber is formed on the drive gear side with respect to the driven gear rotation shaft,
The third pressure chamber is formed on the opposite side to the second pressure chamber with respect to the driven gear rotation shaft.
The gear pump according to claim 1, wherein the first intermediate communication path and the second intermediate communication path are formed in the sliding bearing. The bearing hole includes a parallel portion that allows the sliding bearing to move in a direction in which the gear pair contacts and separates;
The parallel portion is substantially parallel to a connecting line between central axes connecting the driving gear and the central axis of the driven gear,
The contact point at which the driven gear rotating shaft comes into contact with the plain bearing is:
Seen from the center of the driven gear rotating shaft,
The gear pump according to claim 1, wherein the gear pump is in a position that coincides with a direction perpendicular to the parallel portion.   The gear pump according to any one of claims 1 to 3, wherein a passage sectional area of the first intermediate communication passage is equal to a passage sectional area of the second intermediate communication passage. The bearing hole includes a parallel portion that allows the sliding bearing to move in a direction in which the gear pair contacts and separates;
The parallel portion is substantially parallel to a connecting line between central axes connecting the driving gear and the central axis of the driven gear,
The contact point at which the driven gear rotating shaft comes into contact with the plain bearing is:
Seen from the center of the driven gear rotating shaft,
A contact point coinciding with the direction of the load applied to the driven gear rotation shaft by the fluid pressure generated in the gear chamber;
The gear pump according to claim 1, wherein the gear pump is located between a contact point that coincides with a direction perpendicular to the parallel portion of the bearing hole.   6. The gear pump according to claim 1, wherein a passage sectional area of the first intermediate communication passage is larger than a passage sectional area of the second intermediate communication passage. A first low-pressure communication passage that communicates the second pressure chamber and the low-pressure space in the gear chamber;
A second low-pressure communication passage communicating the third pressure chamber and the low-pressure side space region in the gear chamber;
7. The gear pump according to claim 1, wherein a passage sectional area of the first low-pressure communication passage is smaller than a passage sectional area of the second low-pressure communication passage.

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