JPS6345513B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a technique for preventing noise from a gear pump or motor. (Since a gear pump and a gear motor have almost the same configuration, the gear pump will be described and the application of this invention to a gear motor will be described later.) Gears are housed in a casing, and when a driving force is applied to one of the gears, the gears mesh and rotate to transport fluid from the suction side to the discharge side. Therefore, the suction side and the discharge side are isolated by two gears and a casing (or a side plate may be used). In other words, the tooth tip surface of the gear and the casing fit together with a small gap, and the side surface of the gear and the casing or side plate (which may also serve as a bearing) are in rotatable contact, and there is no external contact. The teeth of the gear have a backlash and a meshing ratio such that the discharge side and the suction side are not communicated when the teeth rotate in mesh with each other. Therefore, if the gear is rotated with the entire side surface of the meshing part where the gear teeth mesh is sealed, the part closed by the seal part (hereinafter sometimes referred to as the "enclosed part") arise. In the confinement section, abnormal high pressure and low pressure are generated due to meshing rotation of the gears, and the gears vibrate due to the abnormal high pressure and low pressure, generating noise.

Below, Figures 1 and 2 show the meshing state of the gears.
Let's talk about the diagram. Figure 1 shows a drive gear g ₁ driven by a drive source such as an engine or a motor.
teeth 1g ₁ , 2g ₁ , 3g ₁ and tooth 1 of driven gear g ₂
This is a diagram showing one meshing state with g ₂ and 2g ₂ , which shifts to the meshing state shown in FIG. 2 as the drive side gear g ₁ rotates. When the drive side gear g ₁ and the driven side gear g ₂ rotate in a meshed state, fluid is conveyed from the suction side 1 to the discharge side 2. In FIG. 1 showing one meshing state during such driving,
Contact point k 1 between teeth 1g ₁ and 1g ₂ (hereinafter referred to as effective meshing point), contact point _{k 2 between} teeth 2g ₁ and 2g ₂ (hereinafter referred to as effective meshing point), and tooth 2g ₁ ,2g ₂
The figure S formed by the tooth profile curves 3 and 4 is a confinement part. (Hereinafter, the enclosing part will be represented as a figure S.) This figure S is a contact point _k3 (hereinafter referred to as an invalid mesh) when the drive side gear _g1 and the driven side gear _g2 are meshed without backlash. It is formed by a driving-side figure _S1 and a driven-side figure _S2 , which are divided by a point (denoted as a point). Although the figure S is divided at the point of ineffective engagement _k3 , it may be divided at the line of action R. In such meshing rotation,
The rate of decrease and increase in the areas of figures S ₁ and S ₂ with respect to the rotation angle is as follows: First, when the ineffective meshing point k ₃ is on the discharge side from the center line l, the rate of decrease in the area of figure S ₁ is that of figure S ₂
The difference in the rate of increase and decrease in the areas of shapes S ₁ and S ₂ becomes smaller, and _the point of ineffective meshing moves toward the suction side from the center line. Accordingly, the difference between the decreasing rate and increasing rate of the areas of figures S ₁ and S ₂ becomes larger. Therefore, the entire figure S becomes abnormally high pressure when the ineffective meshing point _k3 is approaching the center line l from the discharge side, and when the ineffective meshing point _k3 is moving from the center line l to the suction side. , resulting in low pressure. Therefore, the driven gear _g2 vibrates due to the action of these abnormally high and low pressures, which is one of the major causes of noise generation.

Below, FIGS. 3 and 4 show an embodiment of the present invention.
Let's talk about the diagram.

Figures 3 and 4 show the driving gear _g1 and the driven gear.
g ₂ are in the same meshing state as in Figures 1 and 2, and the figure shown by the two-dot chain line is the part of the side plate or casing that seals the sides of the driving gear g ₁ and the driven gear g ₂ . The shape of the grooves 10 and 11 provided in the figure is shown.

The groove 10 has a discharge groove 12 connected to the discharge side 2;
It is composed of a groove 14 (hereinafter referred to as a second small groove) extending from this discharge groove 12. Groove 11
is a suction groove 15 connected to the suction side 1, and grooves 16 and 17 (hereinafter referred to as grooves 16) extending from this suction groove 15.
is referred to as a first small groove, and groove 17 is referred to as a third small groove. ).

The second small groove 14 of the groove 10 has a tip 24 extending from the edge 19 of the groove 10 on the driven gear g ₂ side. This tip 24 is connected to the line of action R and the tooth bottom h ₂ of the driven gear g ₂
and is connected to the figure S ₂ until just before (or almost at the same time) the figure S ₁ is interrupted by the discharge groove 12 . The edge 18 of the groove 10 on the drive side gear _g1 side has an end 13 connected to the end 1.
3 is provided at a position that blocks the figure S ₁ and the discharge groove 12 when the ineffective engagement point k ₃ reaches the center line l (FIG. 4).

The first small groove 16 of the groove 11 has a tip 25 extending from the edge 22 of the groove 11 on the drive side gear g ₁ side. This tip 25 is connected to the line of action R and the tooth bottom h ₁ of the drive side gear g ₁
It is located between the figure S ₁ and the discharge groove 12 so as to be connected to the figure S 1 when the figure S 1 and the discharge groove ₁₂ are cut off.
The third small groove 17 extends from the edge 21 of the groove 11 on the driven gear g ₂ side and has a tip 23 . This tip 2
3 is located between the line of action R and the tooth bottom _h2 of the driven gear _g2 , and is provided so as to connect to the figure _S2 when the figure _S1 and the discharge groove 12 are interrupted.

Next, the operation of this embodiment will be described.

When drive side gear _g1 is rotated in the direction of arrow A by the driving force of the engine or motor, the drive side gear
The driven gear _g2 meshed with _g1 rotates in the direction of arrow B. The fluid on the suction side 1 is conveyed from the suction side 1 to the discharge side ₂ by the meshing rotation of the driving side gear g ₁ and the driven side gear g 2 .

In such a driving state, the driving side gear g ₁ ,
Teeth 1g ₁ , 2g ₁ , 3g ₁ and teeth 2g ₁ , 2 _of driven gear g 2
Immediately before the meshing state with g ₂ reaches the state shown in FIG. 3, the effective meshing point k ₁ and the ineffective meshing point k ₃ have a small gap, and only the effective meshing point k ₂ is in contact. At this time, driving side gear g ₁ and driven side gear g ₂
Figures S′ ₁ , S′ ₂ formed by meshing with
(Although not shown, they have almost the same shape as S ₁ and S ₂ in FIG. 3.) are connected to the discharge grooves 12, respectively. This state remains the same until immediately before the meshing state shown in FIG. 4 (just before the ineffective meshing point _k3 reaches the center line l).

When the meshing state shown in FIG. 3 reaches the meshing state shown in FIG. 4, the shapes S ₁ and S ₂ are cut off from both the discharge groove 12 and the suction groove 15. At this time, the rate of change in the area of figures S ₁ and S ₂ with respect to the rotation angle is almost the same. As the rotation begins to advance from Figure 4, the rate of change in the area of figures S ₁ and S ₂ with respect to the rotation angle gradually becomes larger, but the rate of change in the area of figure _{S 1 and} S ₂ gradually increases. When the rate of change in the area of is extremely small (when slightly rotated from FIG. 4), the tips 25 and 23 of the first and third small grooves 16 and 17 open into the figures S ₁ and S ₂ . Therefore, no abnormal high pressure or low pressure occurs in the figures S ₁ and S ₂ .

In the above explanation, FIG. 4 shows an example in which the figures S ₁ and S ₂ are cut off from the discharge groove 12 and the suction groove 15. However, in the state shown in FIG. ,1
The tips 25 and 23 of 7 may be slightly opened.

Although the embodiments in which the present invention is applied to an external gear type pump have been described above, it can also be applied to a gear motor whose rotational direction is constant. An embodiment applied to a gear motor is not specifically shown, but for example, as shown in FIG. 3, by supplying high pressure fluid from the suction side 1, it performs the same function as the gear pump described above.

As described above, according to the present invention, in a gear pump or motor, when the difference in the rate of change in volume between the drive gear side and the driven gear side of the confinement part that occurs during meshing rotation of the gears is small, In addition to connecting the other parts to either the suction side or the discharge side, it prevents abnormal high pressure or low pressure from occurring in the trapped part, and reduces the noise caused by this. It has the effect of preventing occurrence.

[Brief explanation of drawings]

1 and 2 are diagrams showing the meshing state of gears, and FIGS. 3 and 4 are diagrams showing the relationship between the shape of the groove and the meshing state of the gears in an embodiment of the present invention. 1... Suction side, 2... Discharge side, 3, 4... Tooth curve, 10... Groove (discharge side), 11... Groove (suction side), 13... End, 13... End, 14... Groove (second small groove), 16... Groove (first small groove), 17
... Groove (third small groove), g ₁ ... Drive side gear, g ₂ ...
...Driver side gear, k ₁ , k ₂ ... Effective meshing point, k ₃ ...
...Ineffective meshing point, h ₁ , h ₂ ... Tooth bottom, S ... Figure (enclosed part).

Claims (1)

[Claims] 1 When the point of ineffective meshing between the driving gear and the driven gear is on the center line, there are two effective meshing points between the driving gear and the driven gear, and the tooth profile curve of the driving gear and the tooth profile curve of the driven gear. When the shape on the drive side gear side is cut off from the discharge side from the ineffective meshing point of the shape to be formed, a first small groove connects this shape to the suction side between the line of action and the tooth bottom of the drive side gear. ; A second small groove whose shape on the driven side gear side from the point of ineffective meshing is placed between the line of action and the tooth bottom of the driven side gear at a position where it is cut off from the discharge side; and a third small groove connected to the suction side. Gear pump or motor with and.