JP6396377B2 - External gear pump - Google Patents

Description

  According to the present invention, a drive gear fixed to a first shaft and a driven gear supported so as to be relatively rotatable and axially movable on a second shaft are engaged with each other inside the housing to drive the first shaft in one direction. Thus, the present invention relates to an external gear pump that discharges the working fluid sucked from the suction port from the discharge port by rotating the drive gear and the driven gear.

  In a circumscribed gear pump in which a first gear 10 made of an inclined gear supported on the first rotating shafts 11 and 12 and a second gear 15 made of an inclined gear supported on the second rotating shafts 16 and 17 are meshed. The first drag application mechanism 40 applies axial hydraulic pressure to the first rotating shafts 11 and 12, and the second drag application mechanism 60 applies axial hydraulic pressure to the second rotary shafts 16 and 17. Patent Document 1 listed below discloses that the axial thrust force acting on the first gear 10 and the second gear 15 is canceled out.

  The first trochoid pump composed of the first outer rotor 5 and the first inner rotor 7 and the second trochoid pump composed of the second outer rotor 6 and the second inner rotor 8 are connected to a common rotating shaft 9. Patent Document 2 below discloses that the pulsation of the discharge amount is canceled by shifting the meshing phases of the first and second trochoid pumps to each other so as to be in contact with each other.

Japanese Patent No. 5654717 Japanese Patent Laid-Open No. 5-79463

  By the way, if the gear pump uses an inclined gear, the pressure change when oil is sent from the suction port to the discharge port becomes small, so it is possible to reduce the noise caused by the hydraulic shock at the moment when the oil is discharged to the discharge port. However, the pulsation of the discharge amount is not reduced compared to a gear pump using a flat gear. Therefore, two external gear pumps whose meshing phases are shifted from each other are juxtaposed to reduce the pulsation of the discharge amount, and the inclination directions of the tooth traces of the two inclined gears adjacent in the axial direction are opposite to each other. Thus, the thrust force acting on the two inclined gears adjacent to each other in the axial direction can be canceled without requiring the drag applying mechanism described in the cited document 1.

  However, in the circumscribed gear pump, when the pair of drive inclined gears are fixed to the first shaft to which the driving force is input, if the pair of driven inclined gears are fixed to the second shaft to which the driving force is not input, The degree of freedom in the axial direction and rotational direction of the driven bevel gear decreases, and the frictional force of the drive bevel gear and driven bevel gear increases due to subtle errors in the tooth traces. There is a risk of loss.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to achieve both the cancellation of thrust force and the reduction of loss of driving force in an external gear pump that uses an inclined gear.

In order to achieve the above object, according to the first aspect of the present invention, the drive gear supported by the first shaft and the driven gear supported by the second shaft are engaged with each other inside the housing, and the first gear is engaged. An external gear pump that discharges the working fluid sucked from the suction port from the discharge port by driving the shaft in one direction and rotating the drive gear and the driven gear, wherein the drive gear is juxtaposed in the axial direction The first drive toothed gear and the second drive toothed gear, wherein the inclination directions of the tooth traces are opposite to each other, and the first drive toothed gear and the second drive toothed gear are arranged on the first shaft. A first driven inclined gear and a second driven gear, which are fixedly shifted from each other in phase with each other and the driven gears are juxtaposed in the axial direction and mesh with the first driven inclined gear and the second driven inclined gear, respectively; 2 driven bevel gears, the first driven bevel gear The gear and the second driven inclined gear are supported by the second shaft so as to be relatively rotatable and axially movable, and the meshing phase of the first driving inclined gear and the first driven inclined gear is the second driving. The inclined direction of the tooth trace of the first driven inclined gear and the second driven inclined gear is shifted with respect to the meshing phase of the inclined gear and the second driven inclined gear. A circumscribed gear pump is proposed in which the first driven inclined gear and the second driven inclined gear are in contact with each other by a thrust force received from the gear and the second drive inclined gear.

According to the configuration of the first aspect , the first drive inclined gear and the second drive inclined gear are fixed to the first shaft with the tooth surface phases shifted from each other, so that the first drive inclined gear and the first driven gear are fixed. Since the meshing phase of the inclined gear is deviated from the meshing phase of the second drive inclined gear and the second driven inclined gear, the pulsation of the discharge amount of the gear pump can be reduced. Further, since the inclination direction of the tooth traces of the first drive oblique gear and the first driven oblique gear is opposite to the inclination direction of the tooth traces of the second drive oblique gear and the second driven oblique gear, It is possible to cancel the thrust force acting on the first drive oblique gear and the second drive oblique gear and cancel the thrust force acting on the second driven gear and the second driven oblique gear. In addition, the first drive inclined gear and the second drive inclined gear are fixed to the first shaft, and the first driven inclined gear and the second driven inclined gear are rotatable relative to the second shaft and axially movable. The first driven inclined gear and the second driven inclined gear are subjected to a thrust force in the direction of contact with each other, so that the first driven inclined gear and the second driven inclined gear are pressed against the inner wall of the housing. Is prevented, and loss of driving force due to an increase in frictional force is reduced.

The longitudinal cross-sectional view of a circumscribed gear pump. The figure which shows the relationship between the inclined-tooth angle of a circumscribed gear pump which has a pair of inclined-tooth gear, and pipe | tube omission. The figure which shows the relationship between the oblique tooth angle of a circumscribed gear pump (there is no phase shift) which has two pairs of inclined gears, and a cylinder missing. The figure which shows the relationship between the inclined tooth angle of a circumscribed gear pump (with phase shift) which has two pairs of inclined gears, and a cylinder missing. The figure which shows the relationship between tooth tip thickness and a cylinder missing. The figure which shows the relationship between a meshing phase and discharge amount.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a housing 11 of a circumscribed gear pump driven by an automobile engine is fastened with a plurality of bolts 15 in a state where a front housing 13 and a rear housing 14 are superimposed on front and rear surfaces of a center housing 12. Configured. A pump chamber 16 is defined between the inner peripheral wall 12a of the hollow portion of the center housing 12 and the front housing 13 and the inner side walls 13a and 14a of the rear housing 14 that close both axial sides of the hollow portion. 13 and the shaft holes 13b and 14b of the rear housing 14 are rotatably supported by the first shaft 17 through the flat bearings 19 and 20, and the shafts 13c and 14c of the front housing 13 and the rear housing 14 have a second shaft. 18 is supported non-rotatably by press-fitting.

The first drive inclined gear 21A and the second drive inclined gear 21B are fixed to the outer periphery of the first shaft 17 with their tooth surface phases shifted from each other so as not to be relatively rotatable and axially movable. On the outer periphery of the shaft 18, a first driven inclined gear 22A meshing with the first driving inclined gear 21A and a second driven inclined gear 22B meshing with the second driving inclined gear 21B are respectively flat bearings 23. , 24 are supported so as to be relatively rotatable and axially movable. The first drive inclined gear 21 </ b> A and the second drive inclined gear 21 </ b> B constitute the drive gear 21, and the first driven inclined gear 22 </ b> A and the second driven inclined gear 22 </ b> B constitute the driven gear 22.

The first drive inclined gear 21 </ b> A and the second drive inclined gear 21 </ b> B rotate integrally, and may be constituted by one member or may be constituted by two members. On the other hand, the first driven inclined gear 22A and the second driven inclined gear 22B are composed of two members that are in contact with each other so that they can rotate independently of each other. The first drive inclined gear 21A and the second drive inclined gear 21B are fixed to the first shaft 17 with their tooth surface phases shifted from each other, so that the first drive inclined gear 21A and the first driven gear are provided. The meshing phase of the inclined gear 22A is deviated from the meshing phase of the second drive inclined gear 21B and the second driven inclined gear 22B.

  The first shaft 17 receives a driving force from the engine via a sprocket 25 provided at the shaft end. The inclination direction of the tooth traces of the second drive oblique gear 21B and the second driven oblique gear 22B is opposite to the inclination direction of the tooth traces of the first drive oblique gear 21A and the first driven oblique gear 22A. Is set. The rotation direction of the first shaft 17 driven by the engine is constant, and the first drive inclined gear 21A and the second drive inclined gear 21B adjacent in the axial direction of the first shaft 17 are separated from each other. Thrust forces F1 and F1 act, and thrust forces F2 and F2 in directions approaching each other act on the first driven inclined gear 22A and the second driven inclined gear 22B adjacent in the axial direction of the second shaft 18. .

  The first drive inclined gear 21A, the second drive inclined gear 21B, the first driven inclined gear 22A, and the second driven inclined gear 22B are in sliding contact with the inner peripheral wall 12a of the center housing 12, and their shafts. The outer surface in the direction comes into sliding contact with the inner side walls 13a, 14a of the front housing 13 and the rear housing 14. A suction port 26 is provided in the center housing 12 so as to face the meshing portion of the first drive inclined gear 21A and the second drive inclined gear 21B and the first driven inclined gear 22A and second driven inclined gear 22B. And a discharge port 27 is formed. For example, the suction port 26 is formed on the front side of the paper surface in FIG. 1, and the discharge port 27 is formed on the other side of the paper surface in FIG.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  When the first shaft 17 rotates in one direction due to the driving force of the engine, the first drive inclined gear 21A and the second drive inclined gear 21B fixed to the first shaft 17 rotate in one direction together with the first shaft 17. The first driven inclined gear 22A and the second driven inclined gear 22B meshing with the first driving inclined gear 21A and the second driving inclined gear 21B rotate around the second shaft 18 in the other direction. As a result, the oil sucked from the suction port 26 moves confined between the tooth grooves of the first drive inclined gear 21A and the second drive inclined gear 21B and the inner peripheral wall 12a of the center housing 12, and discharged. It is discharged from the port 27. At this time, the meshing portion between the first drive inclined gear 21A and the second drive inclined gear 21B and the first driven inclined gear 22A and the second driven inclined gear 22B is a confined portion (the mesh shown in FIG. 1). Therefore, there is no case where the cylinder is short-circuited from the suction port 26 to the discharge port 27 through the engagement portion.

  FIG. 2 shows a closed portion of a circumscribed gear pump of a first comparative example in which one drive inclined gear and one driven inclined gear mesh, and the closed portion is a drive inclined tooth. A parallelogram-shaped cross section is formed between the gear and the driven inclined gear and the inclined gear.

  FIG. 2 (A) shows a state before the cylinder is pulled out with a small oblique angle β, and even if the point A of the closing part communicates with the suction port, the point D of the closing part does not communicate with the discharge port, There is no short circuit between the suction port and the discharge port due to the oil coming off the cylinder.

  As shown in FIG. 2 (B), when the inclined tooth angle β increases and reaches the limit state of cylinder slipping, the point D communicates with the discharge port at the moment when the point A of the confined portion communicates with the suction port. It will be in the state just before the cylinder comes off.

  As shown in FIG. 2 (C), when the inclined tooth angle β further increases and reaches the state of cylinder omission, the point A of the closed portion communicates with the suction port and the point D communicates with the discharge port. Oil is removed from the suction port to the discharge port.

  FIG. 3 shows a closed portion of a circumscribed gear pump of a second comparative example in which two drive oblique gears and two driven oblique gears mesh in the same meshing continuation region as in FIG. The meshing phases of the two gear pairs are the same, and the phases of the two confinement portions communicating with each other are also the same.

  In this case, since the length in the gear circumferential direction of the confining portion is shorter than that in the case of FIG. 2, even if the inclined tooth angle β increases and reaches the limit state of the cylinder slipping in FIG. Does not reach the limit state (see FIG. 3B), and even if the inclined tooth angle β further increases and reaches the state of cylinder omission in FIG. 2C, no cylinder omission actually occurs ( (See FIG. 3C).

  FIG. 4 shows a closed portion of the external gear pump according to the present embodiment in which two drive bevel gears and two driven bevel gears mesh with each other and the meshing phases of the two pairs of gear pairs are shifted. As shown, the phases of the two confinement portions communicating with each other are also shifted by the shift angle θ.

  In this case, since the length in the gear circumferential direction of the closing portion is longer than that in the case of FIG. 3, from the state before the cylinder removal shown in FIG. 4 (A) and the limit state of the cylinder removal shown in FIG. 4 (B). When the inclined tooth angle β further increases and reaches the cylinder slipping state shown in FIG. 4C, the point A of one closing part communicates with the discharge port through the point E of the other closing part. , Oil is removed from the suction port to the discharge port.

  Therefore, in order to prevent the oil from slipping out in the present embodiment, it is necessary to consider both the oblique tooth angle β and the phase shift angle θ.

  Even if the inclined tooth angle β is set to be small, if the phase shift angle θ becomes excessive, the contiguous portions adjacent to each other in the circumferential direction of the inclined gear communicate with each other, particularly in the vicinity of the tooth tip of the inclined gear. There is a possibility that the cylinder will fall out. In order to prevent this, it is effective to set the tooth tip thickness of the inclined gear shown in FIG. As shown in FIG. 5B, the state in which the tooth tips of two inclined gears adjacent in the axial direction are in contact with each other without being separated in the circumferential direction is the limit phase shift angle that can avoid the occurrence of the above-described cylinder dropout. Therefore, a large phase shift angle θ can be secured by setting the tooth tip thickness of the inclined gear to be large.

  FIG. 6A shows the discharge amount and discharge time of the external gear pump (see FIG. 3) of the second comparative example in which the meshing phases of the two pairs of gears coincide with each other. In the second comparative example, the pulsation of the discharge amount increases because the oil confined in the tooth gap is discharged to the discharge port at a stroke in a short time. On the other hand, FIG. 6B shows the meshing phase of the first drive inclined gear 21A and the first driven inclined gear 22A and the second drive inclined gear 21B and the second driven inclined in the external gear pump of the present embodiment. This corresponds to the case where the deviation angle θ with respect to the meshing phase of the tooth gear 22B is maximized, and the discharge time of the oil sent confined in the tooth gap to the discharge port is increased. It can be seen that the pulsation of is reduced.

  When a pair of inclined gears mesh with each other to transmit driving force, thrust forces in opposite directions act on the inclined gears. Thrust forces F1 and F1 in a direction away from each other act on the first drive inclined gear 21A and the second drive inclined gear 21B supported by the first shaft 17, but the first drive inclined gear 21A and the second Since the two-drive inclined gear 21B is fixed to the first shaft 17, the thrust forces F1 and F1 are generated inside the first drive inclined gear 21A and the second drive inclined gear 21B or the first shaft 17. Is offset inside.

By the way, if the first driven inclined gear 22A and the second driven inclined gear 22B are fixed to the second shaft 18, the first driving inclined gear 21A fixed to the first shaft 17 and the second shaft 18 are fixed. The fixed first driven inclined gear 22A meshes with the second driven inclined gear 21B fixed on the first shaft 17 and the second driven inclined gear 22B fixed on the second shaft 18. Therefore, a slight error in the mounting phase of the first drive inclined gear 21A and the second drive inclined gear 21B with respect to the first shaft 17, the first driven inclined gear 22A and the second driven gear 22A with respect to the second shaft 18, and so on. 2 A slight error in the mounting phase of the driven bevel gear 22B can cause instability in the surface pressure of the meshing portions of these four gears, resulting in a decrease in driving force transmission efficiency and abnormal wear. There is sex.

  However, in the present embodiment, the first driven inclined gear 22A and the second driven inclined gear 22B are independently supported on the second shaft 18 so as to be relatively rotatable and axially movable. The relative rotation and axial movement of the first driven inclined gear 22A and the second driven inclined gear 22B with respect to the second shaft 18 are determined as errors in the mounting phase of the first driven inclined gear 21A and the second driven inclined gear 21B with respect to the second shaft 18. And the surface pressure of the meshing portions of these four gears can be stabilized to prevent a reduction in driving force transmission efficiency and the occurrence of abnormal wear.

  The first driven inclined gear 22A and the second driven inclined gear 22B are subjected to thrust forces F2 and F2 in directions approaching each other, but the first driven is supported by the second shaft 18 so as to be axially movable. The thrust force F2 and F2 are canceled by the contact between the inclined gear 22A and the second driven inclined gear 22B.

  At this time, if a thrust force acting in a direction in which the inclination directions of the tooth traces of the first driven inclined gear 22A and the second driven inclined gear 22B are opposite to those of the embodiment is applied, When the first driven inclined gear 22A is pressed against the inner surface 13a of the front housing 13 and the second driven inclined gear 22B is pressed against the inner surface 14a of the rear housing 14, a driving force loss due to frictional resistance occurs. There is a fear.

  However, in this embodiment, since the thrust forces F2 and F2 in the directions approaching each other act on the first driven inclined gear 22A and the second driven inclined gear 22B, the first driven inclined gear 22A is in front. There is no pressing against the inner side surface 13a of the housing 13 and the second driven inclined gear 22B is not pressed against the inner side wall 14a of the rear housing 14, so that loss of driving force due to frictional resistance is avoided.

As described above, according to the present embodiment, the first drive inclined gear 21A and the second drive inclined gear 21B are fixed to the first shaft 17 with their tooth surface phases shifted from each other, so that the first drive Since the meshing phase of the oblique gear 21A and the second drive oblique gear 21B is shifted from the meshing phase of the second drive oblique gear 21B and the second driven oblique gear 22B, the pulsation of the discharge amount can be reduced. In addition, the inclination direction of the tooth traces of the first drive inclined gear 21A and the first driven inclined gear 22A and the inclination direction of the tooth traces of the second drive inclined gear 21B and the second driven inclined gear 22B are as follows. Since the directions are reversed, the thrust forces F1 and F1 acting in the opposite directions acting on the first drive inclined gear 21A and the second drive inclined gear 21B are canceled out, and the first driven inclined gear 22A and the second driven inclined gear are offset. Mutually opposite directions acting on the tooth gear 22B It is possible to cancel the last force F2, F2.

  Further, the first driven inclined gear 22A and the second driven inclined gear 22B are supported on the second shaft 18 fixed to the housing 11 so as to be relatively rotatable and axially movable, and the first driven inclined gear 22A and the second driven gear 22A. Since the directions of the thrust forces F2 and F2 acting on the two driven inclined gears 22B are set to approach each other, the first driven inclined gear 22A and the second driven inclined gear 22B are driven by the thrust forces F2 and F2. It is no longer pressed against the inner wall 13a of the front housing 13 and the inner wall 14a of the rear housing 14, and therefore the frictional force of the first driven inclined gear 22A and the second driven inclined gear 22B is reduced to reduce the driving force loss. Can be minimized.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, the second shaft 18 is fixed to the housing 11, but the second shaft 18 may be supported by the housing 11 so as to be relatively rotatable. In short, the first driven inclined gear 22A and the second The driven inclined gear 22B may be supported by the second shaft 18 so as to be relatively rotatable and axially movable.

11 Housing 17 First shaft 18 Second shaft 21 Drive gear 21A First drive inclined gear 21B Second drive inclined gear 22 Driven gear 22A First driven inclined gear 22B Second driven inclined gear 26 Suction port 27 Discharge port

Claims (1)

The drive gear (21) supported on the first shaft (17) and the driven gear (22) supported on the second shaft (18) are engaged with each other inside the housing (11), and the first shaft (17) is engaged. An external gear pump that discharges working fluid sucked from a suction port (26) from a discharge port (27) by driving in one direction and rotating the drive gear (21) and the driven gear (22). ,
The drive gear (21) is composed of a first drive oblique gear (21A) and a second drive oblique gear (21B) which are juxtaposed in the axial direction and in which the inclination directions of tooth traces are opposite to each other. The drive oblique gear (21A) and the second drive oblique gear (21B) are fixed to the first shaft (17) with the tooth surface phases shifted from each other, and the driven gear (22) is juxtaposed in the axial direction. The first driven inclined gear (22A) and the second driven inclined gear (22B) meshed with the first driven inclined gear (21A) and the second driven inclined gear (21B), respectively. The first driven inclined gear (22A) and the second driven inclined gear (22B) are supported by the second shaft (18) so as to be relatively rotatable and axially movable, and the first driven inclined gear ( 21A) and the meshing phase of the first driven bevel gear (22A) The second driven inclined gear (21B) and the second driven inclined gear (22B) are shifted from the meshing phase, and the first driven inclined gear (22A) and the second driven inclined gear ( The inclination direction of the tooth traces of 22B) is the first driven inclined gear (22A) and the second driven gear by the thrust force received from the first driving inclined gear (21A) and the second driving inclined gear (21B). A circumscribed gear pump characterized in that the driven inclined gears (22B) are in a direction in which they abut against each other.

Images