JPS60150492A - Gear pump - Google Patents

Abstract

PURPOSE:To reduce a counter flow running from the discharge side to the suction side and check a partial fluid pressure rise as well as to aim at stabilization in pump performance, by forming one side surface among uncontacted surfaces in a way of being more partially concaved than a gear curve in time of engagement between both driving and driven gears. CONSTITUTION:A tooth top part and a dedendum part between a rotation rear surface 11b of a gear 6a of a driving gear 6 and a rotation front surface 12a of a gear 8a of a driven gear 8 both of whom are uncontacted each other in time of rotation in both gears 6 and 8 due to backlash laying between these gears 6a and 8a are more concaved than a gear curve shown in a chain line in illustration. And, each form of these gears 6a and 8a comes to asymmetry before and behind in a sense of rotation whereby discharge of a liquid inside a clearance 13 between both these gears 6a and 8a is carried out so smoothly. With this constitution, backlash lying between these gears 6a and 8a is reduced as little as possible, and a counter flow of the liquid from the discharge side to the suction side through the clearance 13 is almost entirely preventable and, what is more, a partial pressure rise in the liquid is checked, thus full display for stable performance ranging from high rotation to low one is made possible to be done all the time.

Description

Detailed Description of the Invention (Technical Field) The tooth width pump according to the present invention can be used for transferring various liquids, and in particular, it can be used as a pump for transferring cooling water or lubricating oil for an automatic engine. It can be used when the operating speed is not constant and the operating conditions vary greatly from low flow area to high flow area.

(Background of the Invention) A gear pump shown in FIG. 1 is known as a type of pump for transferring water, oil, and other liquids. This tooth width pump includes a drive gear 6 rotatably driven by a drive shaft 5, which is housed in a casing 4 which is provided with an inlet 2 and a discharge outlet 3, which are opened in opposition to each other in the middle of an oval space 1. This driving tooth width 6 and a driven gear 8 which rotates around the gear 7 are housed. When transferring liquid, the drive tooth width 6 is rotated in the 11ν direction as shown by the arrow in FIG. 1, and the driven gear 8 meshed therewith is rotated in the anti-II! When it is rotated in the 1' direction, the liquid that has entered between the teeth of each tooth width 6.8 and the inner peripheral surface of the space 1 is sent from the suction port 2 toward the discharge port 3.

By the way, in the gear pump constructed and operated as described above, there is a closure in the meshing part between the drive gear 6 and the driven gear 8 that seals the liquid present in the space l near the discharge 1-13. A crowding phenomenon occurs. That is, each tooth 11! , 6.8 rotate simultaneously, both gears 6. and 6.8 rotate as shown by diagonal lines in FIG.
A liquid is sealed between 8 and 8, and this liquid is shown in (B) and (C) in the same figure.
As shown in , it is directly sent toward the suction side. Such a confinement phenomenon causes rapid fluctuations in the pressure of the trapped liquid, which causes noise, vibration, etc., and reduces pump function. four parts 9 communicating with the discharge side and the suction side of the space l, respectively, at positions facing the meshing parts of both gears 6 and 8 on the inner surface of the space l;
However, in conventional gear pumps, prevention of this entrapment phenomenon causes the following disadvantages. gave birth to

That is, the teeth 6 of the gears 6 and 8 constituting the conventional tooth 1j pump
In a and 8a, both the teeth 6a of the drive gear 6 and the teeth 8a of the driven tooth 118 have tooth profiles consisting of gear curves such as cycloid curves or involute curves, and each tooth is formed symmetrically in the front and rear, so that liquid is sealed. Dimensions of the minimum width part of the gap 13 between 1III teeth l1j6.8 (dimensions of puff crush)
is always approximately constant, and this minimum width portion moves as the gear rotates. For example, when looking at the gap 13 between each tooth 6a and 8a of both gears 6.8 in Fig. 2, at the initial stage of meshing of both teeth 6a and 8a, the minimum width portion d is the same. As shown in Figure (A), it exists near the tip of the tooth 6a on the driving gear side, but in the middle of meshing, it is located in the middle of the tooth 6a as shown in Figure CB), and furthermore in the final stage of meshing. In this case, it moves near the base of the tooth 6a as shown in FIG. 6(C). Due to the confinement phenomenon, both I&
Since the pressure of the liquid trapped in the gap 13 between I6a and I6a increases as the volume of this gap 13 changes, the meshing of both gears 6.8 on the inner surface of the casing 4 as described above increases. a discharge side of the space l at a position facing the part, respectively;
Forming a fourth part 9.10 leading to the suction side, and a second gap 13
The internal pressure is released into space 1, but gap 1
9. The pressure of the liquid confined within the concave t'B.
10, both recesses 9.1 are required.
The gap 13 must be made narrower by IeL so that the gap 13 is in contact with one of the recesses 9 (or 10). When the distance between the two recesses 9 and 10 is narrowed in this way, both ends of the gap 13 open into the fourth part 9 and the fourth part 10, and the two recesses 9 and 10 open through the gap 13, as shown in FIG. 2(B). When both recesses 9 and 10 communicate with each other through the gap 13, as at the instant when they communicate with each other, relatively high-pressure liquid on the discharge side flows between the recess 9, the gap 13, and the gap 13. If the rotational speed of the gears 6 and 80 is high and there is a large amount of liquid BL sent from the suction port 1 to the discharge port 3, the liquid may flow backward through the recess 10 to the relatively low-pressure suction side. There is no problem even if a backflow occurs, but if the rotational speed of gear 6, B is h<,
When the amount of liquid pumped is small, the efficiency of the pump becomes inefficient.For this reason, a conventional gear pump with teeth consisting of a meridian curve as shown in Figure 2 is used to generate cooling water for automobile engines. When used as a pump for transferring lubricating oil, there is no problem when the pump rotates at high speeds, but at low speeds such as when idling, the performance of the pump deteriorates.

In order to suppress the above-mentioned backflow, it is possible to reduce the pack crush of both the driving and driven gears 6.8 and reduce the dimension of the minimum width portion d. If it is made smaller, only one end of the gap 13 opens into the fourth part 9 (or 10) as shown in FIG. 2(A).
Or, in the case of the state shown in (C) of the same figure, it becomes impossible to release the pressure of the liquid sealed in the end of the gap 13 located on the opposite side of the recess 9 (or 10) with respect to the minimum width portion d. .

(Objective of the Invention) The present invention solves the above-mentioned inconveniences and improves the flow of 'JI!' from the discharge side to the suction side. IM that can always exhibit stable performance from high rotation to low rotation by reducing the flow and suppressing the pressure of the 1fk body from increasing partially.
Il (intended to provide pumps).

(Structure 1 of the invention) The gear pump of the present invention is characterized in that the surfaces of the drive teeth +l (that mesh with the shingles) and the teeth of the driven gear that come into contact with each other during meshing have a gear curve over the entire surface. Shape it like an eggplant or
At least one of the non-contacting surfaces is partially recessed from the tooth 1 (curve), so that the shape of the tooth is asymmetrical in the rotational direction.

That is, as shown in No. 314, the drives 1 that engage each other
&+ 11t 6 and the driven gear 8, the surfaces of the rotating front surface 11a of the teeth 6a, 6a forming the driving gear 6 and the rotating rear surface 12b of the teeth 8a, 8a forming the driven gear 8 are l&
It forms an I+IC curve, and as each gear 6.8 rotates, the flesh surfaces 11a and 12b are in I contact without sliding against each other. On the other hand, due to the pan crush that exists between i6a and 8a, the rotation rear surface 11b of the tooth 6a of the driving gear 6 which does not come into contact with Ij when the circular tooth L6.8 rotates, and the rotation rear surface 11b of the tooth 6a of the driven gear 8 Rotation = *nr l 2 The tooth tip and root portions of a are recessed from the curved line shown in Fig. 3 (Note 1).

Therefore, the shape of each tooth 6a, 8a is J1 symmetrical in the rotation direction. The position where the rear or front surface in the rotational direction of the teeth 6a, 8a of each tooth 6.8 is recessed relative to the gear curve is such that both ends of the gap 13 formed at the meshing portion of both teeth 6a, 8a Open 1 to any of .10
In the case of a gap, the part opposite to the minimum gap part is the part that is removed. That is, if the recesses 9 and 10 are formed symmetrically as shown in FIG. In the shape fl'j, the minimum clearance part d is opposed to the middle part of the front or rear face of each tooth, so as shown in FIG. Φ, 8
The front middle part of the tooth 8a is left as a gear curve, and each tooth 6
The tip and root portions of the rear or front surfaces of a and 8a are recessed below the small gear curve as shown by chain lines in the figure.

A driving gear 6 and a driven gear 8 constituting the gear pump of the present invention
The shapes of the teeth 6a and 8a are formed as described above, so when 1-4 teeth 6.8 are combined together,
The gap 13 formed between the teeth of the meshing part is
Except when both ends of the 4th part 9.1o are opened at the same time, if the gap 13 is opened to any of the 4th parts 9 (or IO) only at one end, this The Jtk body placed in the gap can flow smoothly from one end of the gap to the other, and the force will not be high, especially if only a part of the gap is inside the gap. As shown in Fig. 2 (B), the L
1 state! In the spoon, the gear curved part at the middle of the rear surface of the drive tooth 11 (6 teeth 6a) and the gear curved part at the middle of the front surface of the driven gear 8 141I8a are opposed to each other, and the four parts 9 on the discharge side
This prevents the liquid from flowing within the gap 13 toward the four parts 10 on the suction side.

For example, as shown in FIG. 3, when the tooth tip portions and the IJiJ redundant portions on both sides of the rotation rear surface 11a of the tooth 6a of the drive tooth C) 16 and the rotation front surface of the tooth 8a of the driven gear 8 are recessed, both At the initial stage of meshing between the teeth 6a and 8a, the 1↓1 medium curved portions of the teeth 6a and 8a do not face each other, as shown by diagonal lines in FIG. The minimum width part of the gap 13 becomes wide enough to allow liquid to sufficiently flow within the gap 13, and in the middle stage of 1llll1, the gap 13 opens at both ends or four parts 9 and 10, as shown in the same figure (B ), the gear curve parts face each other, and the minimum width part of the gap 13 becomes narrow enough to obstruct the flow of liquid. As shown, the minimum width portion of the gap 13 becomes wider again. In the state jE shown in FIG. 4(B), since both ends of the gap 13 are open to the four parts 9 and 10, the liquid in the gap 13 does not flow through the minimum width part. The discharge is carried out smoothly. Therefore, the pack crush of both teeth 6a and 8a is 11f.
The backflow of liquid from the discharge side to the suction side through the gap 13 is almost completely prevented.
can. In addition, in the illustrated example, the four parts are formed on both the rear rotational surface flb of the tooth 6a and the rotational front surface 12a of the tooth 8a, but it is sufficient that at least one surface is recessed more than the cycloid curve. Further, the four portions 9 and 10 formed on the inner surface of the casing 4 do not have to be symmetrical to the left as shown in the figure, and the two concave portions 9 and 10 may be slightly shifted toward the suction side. In this case, the gear curve portion on the rear surface in the rotational direction of the tooth 6a of the drive gear 6 is shifted toward the root of the tooth compared to the example shown by 1Δ,
The gear curved portion on the front surface in the rotational direction of the teeth 8a of the driven gear 8 is as follows:
Shift it 1↓1 ゛, )° from the illustrated example.

(Effects of the invention) (Tooth of the invention 11 Since the pump is configured as described in -1-, the amount of fluid flowing back from the UL outlet side to the suction side can be reduced to 1.
- can be reduced to 11 minutes from high rotation to low rotation
Liquid can be stably transferred up to 1r.

[Brief explanation of drawings]

Figure 1 is a vertical side view of a gear pump, Figure 2 is a conventional gear pump.
These are enlarged views of the X section in Figure 1 to explain the confinement phenomenon in the T-pump, where (A) is the initial stage, (B) is the middle stage, and (C) is the final stage. - are respectively ノ1<shi. Fig. 3 shows an example of the tooth profile of the gear in the gear pump of the present invention.
Figures 2 (A) to (C) show the confinement phenomenon caused by this tooth profile.
) is a similar figure. 1: Space, 2: Suction, 3: Discharge port, 4: Casing, 5 Drive shaft, 6. Drive gear, 6a: Teeth, 7. Shaft, 8:
Driven gear, 8a+teeth, 9, lO: recess, lla, 12a
: Front surface of rotation, 11b, 12b: Rear surface of rotation, 13. Gap.

Claims (1)

[Claims] A casing provided with an inlet and an outlet opening facing each other in the middle of an oval space. In a gear pump equipped with a drive gear that is rotationally driven by a drive shaft and a driven gear that rotates in mesh with the drive gear, and is a gear curve, and a gap formed at the joint of at least one magnetic tooth with the rotating rear surface of the tooth in the I drive mountain is provided on the inner surface of the casing and communicates with the discharge side and the suction side, respectively. A gear pump characterized in that a pair of four parts, excluding the parts facing each other when opened at the same time, are recessed below the gear curve.