JP2016205290A - Internal gear pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems such as increase of cost and difficulty of management due to precision processing of a crescent and a crescent fitting part, in an internal gear pump in which the crescent is fitted into the crescent fitting part formed on a side plate.SOLUTION: The cross sectional shape of a crescent 5 is similar with the cross sectional shape of a crescent fitting part 85 (95); the cross sectional shape of the crescent fitting part 85 (95) is formed smaller than the cross sectional shape of the crescent 5; at least the crescent fitting part 85 (95) of a side plate 8 (9) in which the crescent fitting part 85 (95) is formed is made of a material softer than the crescent 5; and the crescent 5 is press-fitted into the crescent fitting part 85 (95) without any interval.SELECTED DRAWING: Figure 5

Description

  According to the present invention, an internal gear axially attached to a rotary shaft and an external gear arranged around the internal gear are installed in a meshed manner inside a case body in which a fluid suction port and a discharge port are formed, and the internal gear The present invention relates to an internal gear pump in which a crescent for high and low pressure partition is arranged between the external gear and the external gear.

  Conventionally, as shown in FIG. 6, an internal gear 3 axially attached to a rotary shaft 2 and a periphery thereof are disposed in a case body 1 in which a suction port 11 and a discharge port 12 for a working fluid such as oil are formed. An internal gear pump in which a crescent-shaped crescent 5 for high-low pressure partitioning is disposed between the internal gear 3 and the external gear 4 is known.

  In the internal gear pump, movable side plates (not shown) are arranged on the side surfaces of the internal gear 3 and the external gear 4 to prevent fluid leakage in the axial direction of the rotary shaft 2. Most of the pumps designed to reduce the amount of leakage by bringing the movable side plate into close contact with each other. The movable side plate is processed with high accuracy, strict dimensional control, and the pressure balance mechanism is made of an elastic material such as rubber. However, its movable range is narrow. Furthermore, when the basic gear pump is used for fluids with extremely low viscosity, the side plate wears significantly and is not durable. However, there is a problem that the pressure balance structure is not established because of the narrowness.

  In order to solve such problems, for example, as shown in Japanese Utility Model Publication No. Sho 62-114183, a side plate is formed in the axial direction by a hydraulic balance mechanism by forming a fitting portion for fitting the crescent to the side plate. There is also known an internal gear pump that does not lose the function of sealing high and low pressure oil even if it moves.

  However, in the internal gear pump in which the crescent is fitted to the fitting portion formed on the side plate, the shape of the curved portion of the crescent 5 and the shape of the curved portion of the crescent fitting portion 85 (95) are as shown in FIG. If they are different, a gap is generated in the curved portion, and as shown in FIG. 8, if the crescent fitting portion 85 (95) is larger than the crescent 5, a gap is generated in the length direction, and the working fluid leaks from these gaps. As a result, the pump performance deteriorates. In particular, as shown in FIG. 8, when there is an error in the length direction, a gap is generated in the high-pressure discharge portion that particularly requires the sealing performance.

  Therefore, it is necessary to perform precision processing so that there is no gap between the crescent 5 and the crescent fitting portion 85 (95) during manufacturing, and there is a problem that the price increases and quality control is not easy.

Japanese Utility Model Publication No. 62-114183

  According to the present invention, in the internal gear pump in which the conventional crescent is fitted to a crescent fitting portion formed on a side plate, the price is increased and managed by precision machining to prevent a gap between the crescent and the crescent fitting portion. The problem is to solve the difficulty.

  The present invention, which has been made to solve the above-described problems, is configured such that an internal gear axially mounted on a rotating shaft and an external gear disposed around it are meshed inside a case body in which a fluid suction port and a discharge port are formed. A crescent crescent for high and low pressure partitioning is disposed between the internal gear and the external gear, and a fixed side plate is disposed along one side surface of the internal gear and the external gear. In the internal gear pump, in which the movable side plate is installed along the other side surface and the crescents are respectively inserted into the crescent fitting portions formed on the fixed side plate and the movable side plate, a cross section of the crescent The shape is similar to the cross-sectional shape of the crescent fitting portion, and the cross-sectional shape of the crescent fitting portion is smaller than the cross-sectional shape of the crescent. At least the crescent fitting portion of the side plate on which the crescent fitting portion is formed is formed of a material that is more flexible than the material forming the crescent, and the crescent is pressed into the crescent fitting portion without a gap. It is characterized by being.

  The crescent fitting portion of the side plate is preferably formed of an elastic material. For example, when the side plate is formed of a fluororesin, other functions of the side plate such as pressure resistance and leakage resistance can be combined.

  According to the present invention, in the internal gear pump in which the crescent is fitted to the crescent fitting portion formed on the side plate, the gap formed between the crescent and the crescent fitting portion is eliminated to reduce the amount of leakage of the working fluid. In particular, it is possible not only to reduce the price without requiring precision processing of the crescent and the crescent fitting portion, but also to solve the difficulty of managing the precise gap between the crescent and the crescent fitting portion.

Sectional drawing of the principal part in the internal gear pump which is preferable embodiment which concerns on this invention. Explanatory drawing which shows the function part of the gear pump which concerns on embodiment shown in FIG. The disassembled perspective view which shows the principal part which concerns on embodiment shown in FIG. Sectional drawing in the principal part which concerns on embodiment shown in FIG. Explanatory drawing which shows the joining state of the crescent in the embodiment shown in FIG. 1, and a crescent fitting part. The principal part schematic explanatory drawing which shows a prior art example. Explanatory drawing which shows the joining state of the crescent and the crescent fitting part in a prior art example. Explanatory drawing which shows the joining state of the crescent and crescent fitting part in a different prior art example.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  FIGS. 1 to 5 show a preferred embodiment of an internal gear pump according to the present invention. The main part is a case body 1 in which a fluid suction port 11 and a discharge port 12 are formed as in the conventional example. The internal gear 3 mounted on the rotary shaft 2 and the external gear 4 inscribed in the outer bearing 6 disposed around the internal gear 3 are installed in mesh with each other and the internal gear 3 and the external gear 4 This is almost the same as a conventionally known one in which a crescent-shaped crescent 5 for high / low pressure partitioning is arranged therebetween.

  In the present embodiment, for example, the DC brushless type motor 7 is formed integrally, the base end side of the case body 1 is integrally fixed on the cover body 71 of the motor 7, and the rotating shaft 2 is fixed. Although the drive shaft of the motor 7 is also used and the whole is compactly formed and the number of parts can be reduced, it goes without saying that the present invention can be similarly applied to a single internal gear pump. Nor.

  And in this Embodiment, it fixes between the cover body 71 of the said motor 7 in the base end side of the said case body 1, and the motor 7 side surface in the said internal gear 3, the outer bearing 6, the external gear 4, and the crescent 5. FIG. A side plate 8 is disposed, and a movable side plate 9 is disposed between a front end side surface of the internal gear 3, the external gear 4 and the crescent 5 and the case body 1 via a support plate 10.

  Further, a compression coil spring 15 formed in communication with the case body 1 and supported by the groove hole 14 is provided in the through hole 101 formed in the central portion of the support plate 10 so as to be compressed. A predetermined load is applied to the movable side plate 9 with a predetermined urging force via the plate 10 to press the movable side plate 9 toward the internal gear 3 and the external gear 4.

  Therefore, as shown in FIG. 3, in the movable side plate 9, the painted portion 91 is a sliding contact portion with the internal gear 3 and the external gear 4, and the portion indicated by reference numeral 92 is a low-pressure and high-pressure seal portion. Further, the movable side plate 9 is formed with a window hole 93 for suction stroke, a window groove 94 having a through hole 96 for discharge process, and a fitting portion 95 for the crescent 5, and on the top surface side for discharge process. A contact portion 97 of the pressure balance rod 110 is formed on the top wall portion of the window groove 94 having the through-hole 96, and the area of the top surface 111 of the pressure balance rod 110 and the high pressure formed on the case body 1. By designing the discharge area to have the same pressure area, the load received by the pressure balance rod 110 and the movable side plate 9 is made equal, so that only the load from the spring 15 is always applied to the movable side plate 9. Friction increases as the pressure of the fluid that is driven and sucked increases, so that the efficiency is not deteriorated and the pressing load is not lowered, thereby causing no discharge failure.

  More specifically, in this embodiment, as shown in FIGS. 3 and 4, the crescent 5 is fitted to the crescent fitting portions 85 and 95 formed on the fixed side plate 8 and the movable side plate 9. .

  In addition, in the present embodiment, the crescent fitting portions 85 and 95 formed on the fixed side plate 8 and the movable side plate 9 are formed of a softer material than the crescent 5 having elasticity and the cross-sectional shape of the crescent 5 The crescent 5 is pressed into the crescent fitting portions 85 and 95 without a gap.

  In this embodiment, for example, the crescent 5 is formed of a material conventionally used for gears such as metal, polyamide, and polycarbonate, and crescent fitting portions 85 and 95 into which the crescent 5 is inserted are formed. It is preferable that the fixed side plate 8 and the movable side plate 9 are made of, for example, a fluororesin that is softer and more elastic than the crescent 5, but in the present invention, the crescent fitting portion 85 (95) is formed from the crescent 5. As long as it is formed of a soft material and the crescent 5 is press-fitted into the crescent fitting portion 85 (95) without a gap, the functions of the crescent 5 and the fixed side plate 8 (movable side plate 9) can be exhibited. Well, not particularly limited.

  FIG. 5 shows a joining state of the crescent 5 and the crescent fitting portion 85 (95) in the present embodiment, and the curvatures of the curved portions 5a and 5b formed on both sides of the crescent 5 are respectively crescent fitting. The fitting margins c and d of the curved portions 5a and 5b formed on both sides of the crescent 5 are equal to the curvatures of the curved portions 85a (95a) and 85b (95b) formed on both sides of the portion 85 (95). In consideration of the material (elastic modulus) of the fixed side plate 8 (movable side plate 9) and the like, the crescent 5 can be fitted into the crescent fitting portion 85 (95) formed on the fixed side plate 8 (movable side plate 9) without any gap. The width will be selected. The fitting margin between the tip 5f of the crescent 5 serving as the high pressure discharge portion and the tip 85f (95f) of the crescent fitting portion 85 (95) formed on the fixed side plate 8 (movable side plate 9) is zero.

  In the present embodiment having the above-described configuration, the amount of fluid leakage is reduced by eliminating a gap formed between the crescent 5 and the crescent fitting portion 85 (95) without performing time-consuming precision processing. In addition to reducing the manufacturing cost, it is possible to solve the difficulty of managing the precise gap between the crescent 5 and the crescent fitting portion 85 (95).

  In the present embodiment, the crescent fitting portion 85 (95) formed on the fixed side plate 8 (movable side plate 9) is shown as being in a penetrating state. However, in the present invention, the crescent fitting portion has a groove shape having a bottom. It can implement similarly about a thing (not shown).

  1 Case body, 2 Rotating shaft, 3 Internal gear, 4 External gear, 5 Crescent, 6 Outer bearing, 7 Motor, 8 Fixed side plate, 9 Movable side plate, 10 Support plate, 11 Suction port, 12 Discharge port, 14 Groove hole, 15 Spring, 71 Cover body, 85 Crescent fitting portion, 91 Filled portion (sliding contact portion), 92 Symbol (low pressure, high pressure seal portion), 93 Window hole, 94 Window groove, 95 Crescent fitting portion, 96 Through hole, 97 Contact part, 101 Through hole, 110 Pressure balance rod, 111 Top surface, 5a, 5b Curved part, 85f, 95f Tip, c, d, e Fitting allowance

Claims (3)

Inside the case body in which the fluid suction port and the discharge port are formed, an internal gear axially attached to the rotary shaft and an external gear arranged around the internal gear are installed in meshing manner, and the internal gear and the external gear are connected to each other. A crescent crescent for high-low pressure partitioning is arranged between them, a fixed side plate is arranged along one side of the internal gear and the external gear, and a movable side plate is installed along the other side of the both gears And an internal gear pump in which the crescents are respectively inserted into crescent fitting portions formed on the fixed side plate and the movable side plate,
The cross-sectional shape of the crescent is similar to the cross-sectional shape of the crescent fitting portion, and the cross-sectional shape of the crescent fitting portion is smaller than the cross-sectional shape of the crescent, and the crescent fitting portion is formed. An internal gear pump, wherein at least the crescent fitting portion of the side plate is formed of a material softer than the crescent, and the crescent is press-fitted into the crescent fitting portion without a gap.   2. The internal gear pump according to claim 1, wherein the crescent fitting portion of the side plate is formed of an elastic material.   The internal gear pump according to claim 1 or 2, wherein the crescent fitting portion of the side plate is formed of a fluororesin.