JPS5874885A - Screw gear pump - Google Patents

Abstract

PURPOSE:To avoid trapping of fluid in a screw gear pump, by cancelling the axial thrust force by mounting screw gears having symmetrical winding directions on respective turning shafts with their phases matched with each other, and forming each two relief grooves at the opposite end faces of male and female screws. CONSTITUTION:Trapping of fluid to be handled by a screw gear pump is caused at the bottom (shadowed portion 20) of male gears and at the bottom (shadowed portion 20') of female gears, and the position where the trapping of fluid is caused is located at the opposite end faces of the gears since they are helical screw gears. In this connection, relief grooves 14, 14' are formed in the side faces of bearings 8 where they are held in contact with the opposite end faces of male screws 1, 2 and female screws 3, 4 respectively, at the portions thereof corresponding to the shadowed portions 20, 20'. By thus relieving the trapped fluid toward the discharge side D, trapping of fluid can be avoided. Further, since thrust forces 21-24 produced by the engagement of the male screws 1, 2 and the female screws 3, 4 having symmetrical winding directions are equal to each other but opposite in their direction, these thrust forces are cancelled with each other out.

Description

DETAILED DESCRIPTION OF THE INVENTION ill Technical Field of the Invention The present invention relates to incompressible fluids (inelastic fluids, hereinafter simply referred to as "fluids").
This relates to an improvement of a positive displacement gear pump that transfers and pressurizes (abbreviated as).

(2) Prior art and its problems 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 six, which is the same number of teeth for a constantly meshing gear. It had to be a combination, and in practice it would be 10 or more. It is well known that by reducing the number of teeth, the displacement per revolution can be increased and the efficiency of the pump can be improved. is the minimum number.

There are pumps with fewer than six teeth, but these types of pumps are equipped with a separate tying gear for rotation, which not only complicates the mechanism but also requires time and effort for machining. This had the drawback of requiring power and reducing pump efficiency.

Furthermore, in a positive displacement screw gear pump, it is known that screw gears with symmetrical arrival directions are assembled into the rotating shaft in a phase-matched state, thereby canceling out the thrust force generated by meshing. Therefore, the structure for avoiding the entrapment phenomenon that occurs between the teeth is insufficient, and good pump efficiency cannot be obtained.

ldl OBJECTS OF THE INVENTION The present invention aims 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.

(4) ``Structure of the Invention'' In order to achieve the above object, the present invention comprises a casing and a screw gear having two parallel rotating shafts therein,
Each screw gear has the same winding angle of 360 or less,
One □ screw gear is a male screw, the other screw gear is a female screw gear, and both screws are engaged with each other as screws. In gear pumps for compressible fluids, screw gears with symmetrical winding directions are installed in the rotating shaft in phase to offset the axial thrust force caused by the winding angle and avoid fluid entrapment due to meshing. The invention is characterized in that two reliefs are provided in contact with both end surfaces of the male thread and the female thread.

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

A thread (1) with an asymmetric circular arc tooth profile, a symmetrical twisting direction, and 4 teeth (12) is attached to the rotating shaft (5) on the drive side, and an internal thread i31 t4 with a symmetrical twisting direction and 6 teeth.
1 is attached to the driven side rotating shaft +61)cIn, and the gears are installed in the gear casing (7) in a meshed state.

The rotating shaft +5) (6) is supported by a bearing (8),
The cylinders on both sides of the gear casing (7) are equipped with fluid sealing and bearings (
A cover (9) aω that also serves as the positioning of item 8) is attached. A gap 11al) (In) is formed between the cover (9) α and the end of the rotating shaft (61(6)).

The bearings (8) have a cylindrical shape with a part 01 of the circumferential surface removed to make a flat surface, and when housed in the gear casing (7), the flat parts of the two bearings (8) as shown in Figure 5. so that they touch each other. In addition, relief grooves Q4) (14) are provided on the 1111 side of the bearing (8) on the side that is in contact with both end faces of the male thread (output 2) and female thread (1.3314) to avoid fluid entrapment due to meshing. each formed.

When the rotating shaft (5) is driven, both rotating shafts +51 and +61 rotate in the directions of the arrows, and on the suction side @, the male screw +
11(2) and the female screw 131 +41, the suction volume (shaded area ae) is 1'
The fluid gradually increases to the state shown in Fig. F2, and the fluid is sucked in from above and reaches its maximum at the point where the suction port (lower end) is reached.

Furthermore, when the rotation shaft +51 (6) of both cars continues to rotate, the
The fluid in the groove part aη of the WJ flows through the gear casing (71 m
1un and the side surface of the bearing (8), each of which is kept in a phase-open state and guided to the discharge side 0. As the fluid rotates, the fluid in the sealed groove part αη becomes connected to the discharge side 0, and is discharged downward from the two discharge ports 111 due to the volume reduction due to the meshing K of the teeth.

During rotation of the gear pump, fluid is trapped in the meshing portion of the teeth, as shown in Figure 4 and 5. In other words, the bottom part of the female tooth (hatched area ■) and the bottom part of the toothed tooth (shaded part -)
Each of these causes fluid confinement, but since the helical screw gear is a helical screw gear, the confinement locations are at both end faces. In order to avoid this kind of confinement, we use the pheasant screw 11)
17 and female threads 13) 14J are provided on the side surfaces of the bearing that are in contact with both end faces of the bearing, respectively, to discharge the fluid 11.
In this way, the pump efficiency can be improved more than k.

Also, the thrust force caused by the meshing of the teeth is canceled out as shown in the diagram. In other words, the male thread (1) has a symmetrical twist direction.
The thrust force clυn generated by the mesh k of +21 is canceled out because it has the same magnitude and opposite direction, and the thrust force Re24) generated by the mesh of the female thread 14) 141 whose twist direction is symmetrical is also canceled out.

Inside the gear casing (7), there are two bearings (8) shown in Figure 5.
Since a cavity is formed in the shape of two connected bearings, insert the two bearings (8) in combination into the gear casing (7) and connect the male thread (1) f2) and the female thread 131 + 41 to the rotating shaft. (Insert 51(6) into the bearing (8)k,
Next, insert the other side bearing (8) in combination with the rotating shaft +51 (61 and IIK), and fix the cover (9) a to the gear casing (71) using an appropriate means such as a screwdriver. Can assemble the pump.

(6) Other embodiments of the invention In the embodiments described above, the male thread flit! The axis of rotation of l (
5) was driven, but if the rotating shaft (6) of 6-tooth female screw i3) 14J is used as the drive shaft, then 4 teeth from K-drive 1.
It is also possible to obtain a discharge lid 5 times larger.

In addition, in the above embodiment, the bearing (81) was formed separately from the gear cage jig (71 and cover 19) 01, but the bearing (8) was formed integrally with the cover +91 (1 (I), so that it was formed integrally with the gear cage jig (71 and cover 19) Escaped to the side of the import/import department @u
4) A similar effect of preventing entrapment can be achieved by forming Q4 respectively.

Furthermore, in the above embodiment, the ratio of the number of teeth is 4:4,
This is 5:! Alternatively, a ratio of the number of teeth such as 4:2 may be used. With these tooth number ratios, the gap between the teeth and grooves becomes larger, so that the discharge amount can be further increased.

(7) Effects of the Invention Although the present invention has the above-mentioned configuration and has a relatively simple structure, it has better pump efficiency than conventional displacement type gear pumps, and also has better fluid flow than conventional displacement type screw gear pumps. It is possible to sufficiently avoid the entrapment phenomenon and improve pump efficiency.

[Brief explanation of the drawing]

The figure shows an example of implementation of the present invention.1. ? Figure 1 is a sectional view of the screw gear pump according to the present invention; A diagram showing the positional relationship between the discharge port and the screw gear in the discharge shape Nk when the gear pump is viewed from below. FIG. 3 is a diagram showing a combined state of bearings with grooves formed therein. 111 +21・・Male thread, 1311411・Female thread,
+51161・Rotating shaft, (7)・Fist gear casing,
(8)... Bearing, (9) (II... Cover, α4) (1
4) Rumor's escape groove, alpha...intake port, a moan... discharge port. D Figure 5

Claims (1)

[Claims] (11 Consists of a casing and a screw gear having two parallel rotating shafts therein, each screw gear having the same winding angle of !606 or less, one screw gear male thread, the other screw gear having the same winding angle of !606 or less, The two screw gears mesh with each other as female threads, and the screw gears are always in mesh with each other due to continuous contact at one point on the pitch circle. The screw gears are symmetrical in direction and are assembled into the rotating shaft in phase, and depending on the degree of winding, [1] to offset the thrust force in the ring direction that occurs, and 2) to avoid fluid entrapment due to meshing. A screw gear pump characterized in that two relief grooves are provided in contact with both end surfaces of the male and female threads. (2) The two relief grooves are provided on the bearing side surface or the bearing part m surface of the cover where the two relief grooves are in contact with both ends of the male and female threads. 13) The screw gear pump according to claim 1, characterized in that the incompressible fluid inlet is provided at the top i1 of the screw gear pump, and the discharge port is provided at the bottom of the screw gear pump. A screw gear pump according to claim 1, wherein the suction ports for the incompressible fluid are opposed to each other, and the discharge ports are divided into two ports. A screw gear pump according to claim 1 or claim 1.