JP2010265797A - Gear pump or motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely and simply detect a gear pump or motor erroneous in an assembling direction of a body. <P>SOLUTION: In partial areas near a discharge passage 113 in an inner peripheral surface of a gear receiving chamber 111 of the body 11, grooves or recesses 115 for putting tooth grooves of gears 2, 3 into communication with the discharge passage 113 are provided by enlarging gaps between the partial areas and addendum surfaces of the gears 2, 3, and when the body 11 is assembled with a discharge side and an intake side directed oppositely, addendum leakage of hydraulic fluid is caused through the grooves or recesses 115. With this, the performance of a discharge flow rate or discharge pressure can be obviously deteriorated as compared with a normal product, and the product erroneous in the assembling direction of the body 11 can be surely and simply detected. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a gear pump or a motor.

  As one of hydraulic pumps (or motors), a gear pump that arranges a pair of meshing gears in a casing and rotates the gears to transfer hydraulic fluid caught in a tooth groove is well known.

  The casing of a gear pump is usually composed of a plurality of members. In a typical external gear pump, a cover provided with a gear bearing is assembled to a body in which a spectacle hole-shaped gear housing chamber for housing both gears is formed, and the gear housing chamber is closed (for example, (See the following patent document).

  A hydraulic fluid suction passage and a discharge passage are connected to the gear housing chamber inside the body. The former has a larger cross-sectional area than the latter. This is because the suction performance of the hydraulic fluid is ensured on the suction side (low pressure side), while the peripheral wall is thickened on the discharge side (high pressure side) to ensure the strength against the high pressure fluid.

  The seal gasket interposed between the body and the cover has a shape along the peripheral edges of the gear housing chamber, the suction passage, and the discharge passage, and is asymmetric between the suction side and the discharge side. Therefore, if the cover is assembled with the body discharge side and suction side reversed by mistake, the suction passage will be located outside the gasket, leading to leakage of hydraulic fluid out of the casing. .

Therefore, the following tests are conducted before shipment of the gear pump to check whether the assembly direction of the body is correct.
(1) Measurement of discharge flow rate performance (2) Visual check for leakage of hydraulic fluid out of casing However, in this test, the pump is operated at a lower rotational speed than during actual operation. In addition, since the inner peripheral shape of the spectacle hole that accommodates the gear is symmetrical between the suction side and the discharge side, even if the discharge side and the suction side of the body are reversed, the tooth tip surface of the gear and the spectacle hole An optimum gap is formed between the inner peripheral surface and the tooth tip seal is established.

  For this reason, even if the assembly direction of the body is wrong, the required flow rate performance specification may be satisfied during the test. Even if the hydraulic fluid leaks out, the surface seal between the body and the cover functions to some extent, so the amount of leakage may be small and may be overlooked by visual inspection during the test.

  Moreover, gear pumps are demanded for mass production and supply, and it is difficult to inspect each product over a long time.

JP 2006-266090 A JP 2009-002316 A

  The present invention, which has been made paying attention to the above problems, is intended to reliably and easily detect a gear pump or a motor having an incorrect body assembly direction.

  According to the present invention, in a gear pump or motor in which a pair of meshing gears are housed in a gear housing chamber in the body, a tooth tip surface of the gear is formed in a partial region near the discharge passage on the inner circumferential surface of the gear housing chamber. A groove or recess is provided to enlarge the clearance between the body and the discharge side and the suction side of the body are reversed, and the tip of the hydraulic fluid leaks through the groove or recess when it is assembled. . As a result, the discharge flow rate or discharge pressure of the product with the wrong body assembly direction reliably interrupts the required performance specifications, so that the product can be easily detected.

  According to the present invention, it is possible to reliably and easily detect a gear pump or a motor with the wrong body assembly direction.

The rear view of the gear pump or motor of one Embodiment of this invention. The side view of the gear pump or motor. AA line sectional view of the gear pump or motor. The BB line end elevation of the gear pump or motor. In the same embodiment, the BB line end elevation which shows the state assembled by making the suction side and discharge side of a body reverse.

  An embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 1 to 4, the gear pump (or gear motor) of the present embodiment includes a drive gear 2 in an internal space in which a casing 1 including main body 11, front cover 12 and rear cover 13 is contained. And the driven gear 3 are accommodated in a meshed state, and the pumping action is to transfer the hydraulic fluid caught in the tooth gap as the gears 2 and 3 rotate from the suction side (low pressure side) to the discharge side (high pressure side). (Or motor action).

  More specifically, a spectacle hole 111 having a shape in which two perfect circles are lined up and down in front view is formed in the body 11, and both the gears 2 and 3 are accommodated by using the spectacle hole 111 as a gear accommodation chamber. To do.

  Then, the movable side plates 4 are arranged on both side surfaces of the gears 2 and 3. The movable side plate 4 has a contour shape that traces the locus of the tooth tips of both gears 2, 3, and is a front-view glasses-like plate that has shaft holes through which the gear shafts 21, 31 of the gears 2, 3 are inserted, respectively. The inner surface of the body is brought into contact with the outer surfaces of the gears 2 and 3.

  The movable side plate 4 receives a pressure in a direction away from the side surfaces of the gears 2 and 3 due to the hydraulic pressure of the hydraulic fluid caught in the gear grooves of the gears 2 and 3, but the inward pressure opposite to the outward pressure. Is applied to the outer surface of the movable side plate 4 (the surface on the side opposite to the gears 2 and 3) to maintain the pressure balance. That is, a three-shaped gasket 5 having a three-letter shape in front view is fitted on the outer side surface of the movable side plate 4, and a gap serving as a pressure balance region is provided between the movable side plate 4 and the casing 1 (covers 12 and 13 thereof). Thus, the inward pressure approaching the gears 2 and 3 is applied to the movable side plate 4 by introducing high-pressure hydraulic fluid on the discharge side into this pressure balance region. The figure 3 gasket 5 isolates the pressure balance region while being sandwiched between the movable side plate 4 and the casing 1 and prevents the working fluid on the discharge side from returning to the suction side.

  Suction passages 112 and discharge passages 113 are respectively connected to the left and right sides of the eyeglass hole 111 of the body 11 and on both sides in the tangential direction of the gear 2 and the three pairs of meshing pitch circles. The cross-sectional area of the suction passage 112 is larger than the cross-sectional area of the discharge passage 113. The boundary between the spectacle hole 111 and the suction passage 112 has a chamfer 114. The same applies to the boundary between the spectacle hole 111 and the discharge passage 113.

  The front cover 12 is assembled to the front end surface of the body 11 and the rear cover 13 is assembled to the rear end surface to close the eyeglass hole 111. Slide bearings 14 are provided on the front cover 12 and the rear cover 13, and these bearings 14 support the gear shafts 21 and 31 of the gears 2 and 3. In the present embodiment, the rear cover 13 is provided with a suction port 131 and a discharge port 132 for hydraulic fluid. The suction port 131 communicates with the suction passage 112 of the body 11, and the discharge port 132 communicates with the discharge passage 113 of the body 11.

  A seal gasket 6 is interposed between the body 11 and the covers 12 and 13. The seal gasket 6 has a shape along the peripheral edges of the spectacle hole 111, the suction passage 112, and the discharge passage 113, and is asymmetric between the suction side and the discharge side.

  Therefore, in this embodiment, a part of the inner peripheral surface of the eyeglass hole 111 of the body 11 near the discharge passage 113 is recessed more radially than the other regions, and between the tooth tip surfaces of the gears 2 and 3. Grooves (in other words, concave portions) 115 for expanding the gaps are formed. The groove 115 extends in the circumferential direction so as to allow a plurality of adjacent tooth grooves of the gears 2 and 3 to communicate with the discharge passage 113.

  The expanded width substantially corresponds to the size of the tooth tip seal portion 117 on the suction side. The tooth tip seal portion 117 optimizes the gap between the tooth tip surfaces of the gears 2 and 3 and the inner peripheral surface of the spectacle hole 111 to suppress tooth tip leakage, that is, backflow of hydraulic fluid caught in the tooth gap. Say the area where you can. As is well known, the gear pump in operation is mechanically imbalanced, that is, there is a pressure difference between the suction side and the discharge side, and the gears 2 and 3 and the gear shafts 21 and 31 in the casing 1 are high on the discharge side. Pressed against the suction side under pressure. For this reason, regardless of the presence or absence of the groove 115, the gap between the portion on the discharge side on the inner peripheral surface of the spectacle hole 111 and the tooth tip surfaces of the gears 2 and 3 is enlarged. A sufficient contribution to the sealing of the hydraulic fluid is limited to a predetermined angular range from the boundary between the spectacle hole 111 and the suction passage 112 to the high / low pressure parting position (high / low pressure switching position) 116. This range is the tooth tip seal portion 117. In the present embodiment, the groove 115 is formed in a region that is symmetrical with the central axis 7 of the tooth tip seal portion 117. The central shaft 7 is a straight line that passes through the shaft centers of the gear shafts 21 and 31 of the meshing gears 2 and 3.

  If the covers 12 and 13 are assembled in the assembly process of the gear pump with the suction side and the discharge side of the body 11 reversed in the wrong direction, as shown in FIG. The groove 115 is located at the same time, and the high / low pressure parting position 116 communicates with the suction passage 113. As a result, the tooth tip seal portion 117 does not function effectively as a seal for the hydraulic fluid, and tooth tip leakage occurs and the discharge flow rate or discharge pressure is reliably reduced. On the contrary, in the normal product in which the suction side and the discharge side of the body 11 are correctly positioned, the tooth tip seal portion 117 functions effectively, so that the required flow performance specifications can be achieved as expected.

  According to the present embodiment, the gap between the gears 2 and 3 and the tooth tip surfaces is enlarged in a partial region near the discharge passage 113 on the inner peripheral surface of the gear housing chamber 111 of the body 11 to thereby generate the gears 2 and 3. Since the groove or recess 115 for communicating the tooth groove and the discharge passage 113 is provided, when the body 11 is assembled with the discharge side and the suction side reversed, the tooth tip of the hydraulic fluid is passed through the groove or recess 115. Leakage can be caused, and the discharge flow rate or discharge pressure performance can be clearly reduced as compared with a normal product. By utilizing this fact, it becomes possible to reliably and easily detect a product in which the assembly direction of the body 11 is wrong.

  The present invention is not limited to the embodiment described in detail above. In the above embodiment, the casing is composed of three main members, the body, the front cover, and the rear cover. However, the casing and the front cover are integrated, or the body and the rear cover are integrated. The present invention can also be applied to the present embodiment.

  Other specific configurations of each part can be variously modified without departing from the spirit of the present invention.

  The present invention can be used as, for example, a hydraulic pump or a motor mounted on an industrial machine, an industrial vehicle, or the like.

DESCRIPTION OF SYMBOLS 11 ... Body 111 ... Gear accommodation chamber 112 ... Suction passage 113 ... Discharge passage 115 ... Groove or recessed part 2, 3 ... Gear

Claims (1)

In a gear pump or motor that houses a pair of meshing gears in a gear housing chamber in the body,
A groove or a recess is provided in a partial area near the discharge passage on the inner peripheral surface of the gear housing chamber to enlarge the gap between the gear tip and the discharge side and the suction side of the body are reversed. When assembled, the gear pump or motor is characterized in that the discharge flow rate or discharge pressure is lowered by causing leakage of the tip of the hydraulic fluid due to the groove or recess.

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