JP2001289180A - Gear pump or gear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gear pump or a gear motor reduced in pulsation, noise and the like by bringing backlash to or near zero even without performing so strict dimensional control. SOLUTION: In this gear pump or gear motor, comprising a pair of gears 2, 3 meshed with each other to rotate in a body bore 1, a pair of shafts 4, 5 fixed respectively to a pair of the gears 2, 3, and bearings 6, 7 supporting capable of rotating both the shafts, a worn layer 10 is provided in one or both meshed surfaces of a pair of the above gears 2, 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gear pump or a gear motor with reduced pulsation.

[0002]

2. Description of the Related Art A gear pump shown in FIG. 2 has a body bore 1 provided with a pair of gears 2 and 3 which mesh with each other. The gears 2 and 3 are fixed to shafts 4 and 5, respectively. The shafts 4 and 5 are rotatably supported via bearings 6 and 7 fixed to shaft holes formed in a body (not shown). .

A drive source (not shown) is connected to one shaft 4. In the gear pump described above, when one shaft 4 is rotated by the drive source, the gear 2 and the gear 3 rotate while meshing. When the gear 2 rotates in the direction of the arrow A together with the one shaft 4, the other gear 3 rotates in the direction of the arrow B. At this time, the pressure oil is carried from the suction chamber 8 by the tooth grooves of the two gears 2 and 3 and is discharged from the discharge chamber 9. The gear motor also has a configuration similar to that of the gear pump described above, supplies pressure oil, rotates the gear, and extracts a rotational force from a shaft on which the rotating gear is fixed.

[0004]

The gap between the pair of gears 2 and 3 which are engaged with each other and rotate as described above,
When there is so-called backlash, rattling occurs and pulsation occurs. This pulsation causes a fluctuation in the discharge flow rate of the gear pump and also causes noise. In the case of a gear motor, it causes noise and uneven rotation. Therefore, the smaller the backlash, the better. However, in order to reduce the backlash to zero, the dimensions of each part, such as the shape and dimensions of the gear tooth surface and the mounting position, must be managed with high precision.

[0005] However, it is very difficult to control the dimensions to reduce the backlash to zero. This is because, when the gear pump or the gear motor is operated, the position of the shaft and the gear is shifted from the time of assembly due to the pressure oil. It is very difficult to control the dimensions in consideration of this deviation. This will be described below using the gear pump shown in FIG.

When the gear pump operates, the pressure oil is supplied to the blowing chamber 8.
When it is sent from the side to the discharge chamber 9 side, a pressure distribution is formed in the body bore 1. And for both gears 2 and 3,
In the portion immediately before the pressure oil discharge stroke, arrows C and
High pressure in the D direction acts. When the gears 2 and 3 are pressed in the directions of the arrows C and D, the gears 2 and 3 slightly move in the directions of the arrows C and D together with the shafts 4 and 5. This is because a slight gap is provided between the bearings 6, 7 and the shafts 4, 5 in order to rotatably support the shafts 4, 5. FIG. 2 shows a state in which the gears 2 and 3 have been moved by hydraulic pressure.

As shown in FIG. 2, the gears 2 and 3 move in the directions of the arrows C and D, and the shafts 4 and 5 settle down in a state where they abut against the bearings 6 and 7. Further, in the case of a gear motor, an oil pressure that moves the gear from the side that supplies the pressure oil to the side that discharges the pressure oil acts, so that the shaft rests on the bearing against the bearing. That is,
It is necessary to control the shape of the tooth flank and the dimensions of other parts so that the backlash becomes zero when the shafts 4, 5 are moved by the hydraulic pressure and hit the bearings 6, 7, but this is very difficult. Have difficulty.

An object of the present invention is to provide a gear pump or a gear motor in which backlash is reduced to zero or less and pulsation and noise are reduced without strict dimensional control.

[0009]

According to a first aspect of the present invention, a pair of gears that rotate while meshing with each other, a pair of shafts fixed to each of the pair of gears, and a bearing that rotatably supports both shafts are provided. The gear pump or the gear motor according to the present invention is characterized in that a wear layer is provided on both or one meshing tooth surface of the pair of gears. A second invention is based on the first invention, wherein the wear layer includes:
It is characterized in that it is a coating layer of a fixed lubricant.

[0010]

FIG. 1 shows an embodiment of a gear pump according to the present invention. In the gear pump of this embodiment, a coating layer 10 of a solid fluidizing material is provided on the meshing tooth surfaces of a pair of gears 2 and 3 that rotate while meshing. The solid fluidizing material is made of molybdenum disulfide, ethylene tetrafluoride, or the like, whereby a soft coating layer 10 is formed on the meshing tooth surfaces of the gears 2 and 3. The configuration is the same as that of the conventional gear pump except that the coating layer 10 is provided. In addition, the said coating layer 10 is
3 is a wear layer according to the present invention.

When this gear pump is assembled and started to operate, as shown in FIG. 1, the gears 2, 3 are kept in a state where a clearance is secured between the shafts 4, 5 and the bearings 6, 7.
The dimensions are set so that there is no gap in the meshing part. On the other hand, the gear pump of this embodiment also has
During operation, hydraulic pressure in the directions of arrows C and D acts on the gears 2 and 3. Therefore, when the operation is started, the gears 2 and 3 receive hydraulic pressure in the directions of arrows C and D, and move until the shafts 4 and 5 abut against the bearings 6 and 7 while the soft coating layer 10 is worn. At the start of the operation of the gear pump, the gaps d1 and d2 between the shafts 4 and 5 and the bearings 6 and 7 disappear.

At this point, the bearings 6 and 7 support the oil pressures indicated by the arrows C and D, so that the wear of the coating layer 10 formed on the tooth surface stops. And each gear 2, 3
The tooth surface shape is determined, and the meshing part calms down in a well-balanced state. If the thickness of the coating layer 10 on the tooth surface is made larger than the initial gap between the shafts 4 and 5 and the bearings 6 and 7, the shafts 4 and 5 can move around the inner circumference of the bearings 6 and 7 during operation. The coating layer 10 is easily abraded until it abuts and calms down, resulting in a quick and stable state.

As described above, in this embodiment, during the initial operation, the coating layer 10 provided on the meshing tooth surfaces of the gears 2 and 3 wears out and absorbs the displacement of the shafts 4 and 5 due to the hydraulic pressure. . Therefore, even when the backlash of the meshing portion is reduced to zero, it is not necessary to perform dimensional control in consideration of a deviation due to hydraulic pressure during operation. Therefore, the backlash of the gear pump or the gear motor can be reduced to zero or close to zero without performing very strict dimensional control as in the related art. Therefore, pulsation can be prevented.

Further, since the meshing tooth surfaces mesh with each other via the solid lubricant, the meshing becomes smooth, and in the case of zero backlash, generation of noise can be suppressed even if the backlash is not zero. . In this embodiment, the coating layer 10 is formed of a solid lubricant. However, an abraded layer made of a material that is easily worn even if it is not a lubricant is formed on the meshing tooth surface of each gear. If this is the case, zero backlash can be realized as in the above embodiment. Further, in the above embodiment, the wear layer is formed on both meshing tooth surfaces of the pair of gears 2 and 3, but the wear layer may be provided on only one of the gears 2 and 3. The same effect can be obtained.

[0015]

According to the first aspect of the invention, the backlash can be made close to zero even if the dimensional control of each member is not so strict. Therefore, pulsation and noise can be reduced. According to the second aspect, the rotation of each meshing gear can be made smooth, and the noise can be further reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a gear pump according to an embodiment of the present invention.

FIG. 2 is a diagram showing a conventional gear pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Body bore 2 Gear 3 Gear 4 Shaft 5 Shaft 6 Bearing 7 Bearing 10 Coating layer

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F04C 15/00 F04C 15/00 DF term (reference) 3H041 AA02 BB02 CC05 CC11 DD05 DD07 DD09 DD33 3H044 AA02 BB02 CC05 CC11 DD05 DD06 DD08 DD23 3H084 AA23 BB01 BB02 CC23 CC56 CC57 CC60

Claims (2)

[Claims] 1. A gear pump or a gear motor comprising: a pair of gears rotating in mesh with each other within a body bore; a pair of shafts fixed to each of the pair of gears; and a bearing rotatably supporting both shafts. A gear pump or a gear motor provided with a wear layer on both or one meshing tooth surface of the pair of gears. 2. The gear pump or the gear motor according to claim 1, wherein the wear layer is a coating layer of a fixed lubricant.