JPS63635B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to improving a positive displacement gear pump that transfers and pressurizes incompressible fluid (inelastic fluid, hereinafter simply referred to as "fluid"). This is related.

(Prior art) Conventionally, the mainstream of this type of positive displacement gear pump has an involute tooth profile or a cycloid tooth profile, and the number of teeth is theoretically at least 6 for a constantly meshing gear.
It had to be a combination of at least the same number of teeth, and in practice it would have been 10 or more. It is well known that reducing the number of teeth increases the amount of displacement per rotation and improves the efficiency of the pump, but the currently used pumps with tooth profiles that are constantly in mesh have six teeth. This is the minimum number. There are pumps with six or fewer teeth, but these types of pumps are equipped with a separate timing gear to rotate, which not only complicates the mechanism and requires time and effort to process, but also consumes extra power. This had the disadvantage of reducing pump efficiency.

It is also known that in positive displacement screw gear pumps, screw gears with symmetrical winding directions are incorporated into the rotating shaft in phase to cancel out the thrust force generated by meshing. Good pump efficiency has been difficult to achieve due to insufficient structure to avoid the entrapment phenomenon that occurs between the teeth.

Furthermore, in order to avoid the confinement phenomenon, the teeth are formed in a trochoidal curve, and each tooth is formed in opposite directions from the center of the axial length to the end faces on both sides.
A pair of double hexagonal rotors, whose axial length has been significantly shortened by twisting approximately 180° at a helix angle of 72° to 60°, are meshed with the casing and are housed in the casing for free rotation.
A double helical two-shaft fluid pump in which a suction port and a discharge port are formed on both side walls of the casing is also known (see Japanese Utility Model Publication No. 127391/1983).

However, in this pump, the teeth have a steep helix angle of 72° to 60°, and there is almost no gap between the tooth tip and the tooth bottom, so the tooth groove space due to meshing is narrow and the fluid flow is limited. The disadvantage is that the pressure (resistance) applied to the fluid is large, and since there is only one discharge port, the pressure applied to the fluid is large.

(Problems to be Solved by the Invention) The prior art has various problems as described above.

SUMMARY OF THE INVENTION An object of the present invention is to provide a screw gear pump which has a relatively simple structure, is easy to manufacture, and does not have the disadvantages of the prior art described above.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above problems, the screw gear pump of the present invention consists of a casing and a screw gear having two parallel rotating shafts therein, each screw gear having a helix angle of 60. They have the same winding angle of 360° or less, one screw gear is male threaded, the other screw gear is female threaded, and the number of teeth of the male thread is 4 or less and the number of teeth of the female thread is 6 or less, and they are meshed with each other. In a gear pump for incompressible fluids with the same outer diameter and the same gear width, the screw gears are always in mesh with one-point continuous contact on a pitch circle. In addition to canceling the axial thrust force caused by the winding angle, the incompressible fluid suction port is integrated into one port at the top of the screw gear pump, and the discharge port is integrated into two ports at the bottom of the screw gear pump. The opening is divided into individual parts, and two escape grooves are provided in contact with both end surfaces of the male thread and the female thread to avoid fluid entrapment due to meshing.

(Function) In the present invention, since the number of teeth of the male screw is 4 or less and the number of teeth of the female screw is 6 or less, the amount of fluid discharged is large. Also, the helix angle of the male and female threads is
Since it is smaller than 60°, the pressure (resistance) applied to the fluid
is small. Furthermore, since the center of the double helical is the suction port and both sides are the discharge ports, there is no throttling phenomenon when the fluid is discharged, and pressure is applied equally to both sides of the discharge side, dispersing the pressure on the fluid and reducing the pressure. becomes.

(Example) Embodiments of the present invention will be described based on the drawings.

Four-tooth male screws 1 and 2 with asymmetric circular arc tooth profiles and a symmetrical twisting direction and a helix angle of 45° are attached to the rotating shaft 5 on the drive side.
Female screws 3 and 4 having six teeth of 45 degrees are attached to the rotating shaft 6 on the driven side, and installed in the gear casing 7 in a state where they are meshed with each other. Rotating shafts 5, 6
is supported by a bearing 8, and covers 9 and 10 are attached to both sides of the gear casing 7 to seal fluid and position the bearing 8. There is a gap 1 between the covers 9, 10 and the ends of the rotating shafts 5, 6.
1 and 12 are formed, respectively.

The bearings 8 have a cylindrical shape with a part 13 of the circumferential surface removed to make a flat surface, so that when accommodated in the gear casing 7, the flat parts of the two bearings 8 are in contact with each other as shown in FIG. . In addition, escape grooves 14 and 14' are formed on the side surfaces of the bearing 8 in contact with both end surfaces of the male threads 1 and 2 and the female threads 3 and 4, respectively, to avoid fluid entrapment due to meshing.

When the rotary shaft 5 is driven, both the rotary shafts 5 and 6 rotate in the directions of the arrows, and on the suction side S, the suction volume (hatched portion 16) of the meshing portion between the male screws 1 and 2 and the female screws 3 and 4 is the first The fluid gradually increases from the state shown in the figure to the state shown in FIG. 2, and the fluid is sucked in from above and reaches its maximum at the suction port 15.

Furthermore, when both rotating shafts 5 and 6 continue to rotate, the fourth
The fluid in the tooth groove portion 17 shown in the figure is guided to the discharge side D while being kept in a sealed state by the inner circumferential wall 18 of the gear casing 7 and the side surface of the bearing 8, respectively. The fluid in the sealed tooth groove portion 17 comes to communicate with the discharge side D as it rotates, and is discharged downward from the two discharge ports 19 due to the volume reduction due to the meshing of the teeth.

During rotation of the gear pump, fluid is trapped in the meshing portions of the teeth, as shown in FIG. In other words, the fluid is trapped in the female tooth bottom part (hatched area 20) and the male tooth bottom part (shaded part 20'), but since the trapped position is a helical screw gear, it is different from both end face parts. Become.
To avoid such entrapment, the male thread 1,
Relief grooves 14 and 14' are provided in the side surfaces of the bearing that are in contact with both end surfaces of the female threads 2 and 3 and 4, respectively, in correspondence with the portions 20 and 20', so that the fluid escapes to the discharge side D. By doing so, pump efficiency can be improved.

Further, the thrust force due to the meshing of the teeth is canceled out as shown in Fig. 3. That is, the thrust forces 21 and 22 generated by the meshing of the male screws 1 and 2 with symmetrical torsional directions are canceled out because they have the same magnitude but opposite directions, and the thrust forces 21 and 22 generated by the meshing of the female screws 3 and 4 with symmetrical torsional directions cancel each other out. Forces 23 and 24 are also canceled out.

The inside of the gear casing 7 has a bearing 8 shown in FIG.
Since a cavity is formed in the shape of two connected bearings, the two bearings 8 are inserted in combination into the gear casing 7, and the rotating shafts 5, 6 are inserted into the This can be easily done by inserting the bearing 8 into the gear casing 7, then inserting the bearing 8 on the other side in combination with the other side of the rotating shafts 5, 6, and fixing the covers 9, 10 to the gear casing 7 by appropriate means such as a screwdriver. Can assemble the pump.

In the above embodiment, the rotating shafts 5 of the male screws 1 and 2 were driven, but by using the rotating shafts 6 of the six-tooth female screws 3 and 4 as the driving shafts, a discharge amount 1.5 times that of the four-tooth drive can be obtained. You can also do that.

Further, in the above embodiment, the bearing 8 was formed separately from the gear casing 7 and the covers 9, 10, but the bearing 8 was formed integrally with the covers 9, 10,
Therefore, there is a relief groove 1 on the side surface of the bearing part of the integral part.
A similar effect of preventing entrapment can be achieved by forming the respective portions 4 and 14'.

Further, in the above embodiment, the tooth ratio is 6:4, but this may be changed to a ratio of 5:3 or 4:2. If these tooth number ratios are used, the gap between the tooth grooves becomes larger, so that the discharge amount can be further increased.

〔Effect of the invention〕

Although the present invention has the above-described structure and is relatively simple in structure, it has better pump efficiency than conventional displacement type gear pumps, and is also less prone to fluid entrapment than conventional displacement type screw gear pumps. Avoidance can be made sufficient and pump efficiency can be improved.

[Brief explanation of the drawing]

The figures show an example of the implementation of the present invention, and Fig. 1 is a sectional view of a screw gear pump according to the present invention;
Fig. 2 shows the positional relationship between the suction port and the screw gear when the screw gear pump is viewed from above in the suction state, and Fig. 3 shows the positional relationship between the discharge port and the screw gear when the screw gear pump is viewed from below in the discharge state. FIG. 4 is a diagram showing a confinement phenomenon caused by meshing of screw gears, and FIG. 5 is a diagram showing a combined state of a bearing having relief grooves formed on the side surface. 1, 2... Male thread, 3, 4... Female thread, 5, 6
... Rotating shaft, 7 ... Gear casing, 8 ... Bearing, 9, 10 ... Cover, 14, 14' ... Relief groove, 15 ... Suction port, 19 ... Discharge port.

Claims (1)

[Claims] 1. Consisting of a casing and a screw gear having two parallel rotating shafts therein, each screw gear has the same winding angle of less than 60 degrees and less than 360 degrees, and one screw gear has a male thread, The other screw gear has a female thread, and the number of teeth on the male thread is 4.
A gear pump for incompressible fluids with the same outer diameter and the same gear width. In this system, a screw gear whose winding direction is symmetrical is assembled in phase with the rotating shaft to cancel out the thrust force in the axial direction caused by the winding angle. The discharge port is divided into two at the bottom of the screw gear pump, and two escape grooves are provided on both end faces of the male and female threads to avoid fluid entrapment due to meshing. A screw gear pump characterized by the fact that they are installed adjacent to each other. 2. Claim 1, characterized in that two relief grooves are formed on the side surface of the bearing in contact with both end surfaces of the male thread and the female thread, or on the side surface of the bearing portion of the cover.
Screw gear pump described in section.