JP2006097568A - Double gear pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double gear pump easy to machine a shaft hole with combining gear pumps of large displacement difference. <P>SOLUTION: This double gear pump has gear mechanisms 1a, 1c and 1b, 1d meshing a pair of gears stored in two independent pump chambers, has drive shafts pivotally supporting gears in a drive side of each gear mechanism 1a, 1c and 1b, 1d connected and feeds oil introduced to a suction port provided on each gear pump A1, A2 to a delivery port provided on each gear pump A1, A2 by each gear mechanism. Distribution of delivery capacity on each gear pump A1, A2 at a time of synchronized rotation is established by changing delivery quantity per unit tooth width of the gear. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dual gear pump that can be used in various construction machines and vehicle hydraulic equipment.

The gear pump has a pair of drive gear and driven gear meshing with each other in the main body, and transfers the fluid confined in the gear tooth gap from the pair of inlets and outlets facing the meshing part by the integral rotation of both gears to the other inlet and outlet. It is comprised so that it may do. Then, the external power is applied to this configuration to transfer the fluid. In many cases, the gear pump is used in duplicate by connecting the drive gear shaft in the axial direction so as to rotate integrally.
JP-A-9-144670

  As an application when used in such a series, for example, forklifts, the discharge ports of the gear pumps assigned for cargo handling and steering are made independent, and the required amount of hydraulic oil is supplied to each. Used for things. In such a forklift, the amount of hydraulic oil required for steering is much smaller than that for cargo handling, so hydraulic oil drawn from a common suction port is distributed and supplied to the required capacity for each gear pump. By doing so, hydraulic oil can be supplied efficiently for cargo handling, which contributes to downsizing of the apparatus.

  However, when the gear specifications other than the distance between the centers and the tooth width in each gear pump are the same, as shown in FIG. 4, the shaft hole in the body 103 can be machined with a through hole, so that the machining cost can be suppressed. When adjusting the capacity of each gear pump A101, A102 by changing only the tooth width with the same center distance s or gear specifications, the range of tooth widths that can be set is narrow in terms of gear strength and performance. Since it is limited, the capacity | capacitance which has a difference more than predetermined in the two gear pumps A101 and A102 cannot be set.

  That is, when the effective tooth width is set with the center distance s and the gear specifications being the same, the relationship between the tooth width and the pump strength and the relationship between the tooth width and the pump efficiency as shown in FIG. The tooth width in the section a cannot be employed because the pump efficiency does not satisfy the regulation and the necessary performance cannot be ensured. Further, the tooth width of the section c cannot be adopted because the pump strength does not satisfy the regulation and the necessary strength cannot be secured. Therefore, the tooth width of the section b excluding these sections a and c is an effective tooth width that can be adopted with the pump efficiency and strength satisfying the predetermined conditions. There is a need to expand b.

  On the other hand, when setting the capacities of the gear pumps without limiting the center-to-center distance and the gear specifications of the gear pumps, the degree of freedom in combining the gear mechanisms is increased, so that a desired capacity difference can be obtained. As shown in FIG. 6, the center-to-center distances s1 and s2 of the gear pumps A201 and A202 are different, and in particular, the shaft centers of the driven gear shaft 211b and the driven gear shaft 211d are misaligned. When machining a shaft hole in the body, it cannot be machined with a through hole, and an adapter 213 is produced by performing complicated hole machining using aluminum die casting instead of cast iron, and the body of the gear pumps A201 and A202. Need to be combined, which increases the processing cost.

  An object of this invention is to provide the double gear pump which distributes discharge capacity with a required capacity | capacitance difference to each gear pump of a double gear pump, without causing the increase in processing cost.

  In order to solve the above-described problems, a dual gear pump provided by the present invention includes a gear mechanism in which teeth of a pair of gears mesh with each other in two pump chambers that are independent of each other. The pump is configured to connect the drive shafts that support the gears on the drive side of each gear mechanism to each other, and the oil introduced from the suction port is discharged to each pump chamber independently by each gear mechanism. A dual gear pump transported to a port, wherein the distribution of the discharge capacity when synchronously rotating in each gear pump is set by changing the discharge capacity per unit tooth width of the gear pump. .

  Since the dual gear pump provided by the present invention is as described above, even if the difference in capacity of each gear pump needs to be significantly increased, the distance between the centers of each gear mechanism is equal, Since the pump can be combined, the machining of the shaft hole in the body is simple and the increase in machining cost can be suppressed.

  Hereinafter, the dual gear pump provided by the present invention will be described according to the embodiment shown in FIGS. FIG. 1 is a sectional view showing a basic configuration of a dual gear pump according to the present invention, and FIG. 2 is a schematic view of the gear mechanism of FIG.

  As shown in FIG. 1, a dual gear pump main body 1 according to an embodiment of the present invention includes two gear pumps A1 and A2 each having a pair of drive gears 1a and 1c and driven gears 1b and 1d that mesh with each other. Bearings 2a, 2c, 2b, 2d, 2e, 2f, 2g, and 2h that are adjacent to each other in the axial direction and support the drive gear shafts 11a and 11c and the driven gear shafts 11b and 11d of both adjacent gear pumps A1 and A2 are provided. The drive gear shafts 11a and 11c of both the adjacent and adjacent gear pumps A1 and A2 are connected by a spline connecting portion 12 that is connected to rotate integrally.

Since the gear pumps A1 and A2 are configured to have the same center-to-center distance s, the shaft hole in the body 13 can be processed by a through hole. On the other hand, the gear pump A2 is configured to have a smaller volume per unit tooth width than the gear pump A1, and the volume per unit tooth width of such a gear pump is a unit length in the case of a spur gear. The discharge capacity per unit _Vth is calculated from the following equation.
_{V th = (π / 2)} · {d 2 -s 2 - (π · m · cosα 0) 2/3}
d: Gear outer diameter
s: Center-to-center distance
m: Module (= pitch circle diameter / number of teeth)
α ₀ : Pressure angle

In this embodiment, since the center distance A is the same for the two gear mechanisms, it is necessary to design the desired gear by changing the remaining parameters (d, m, α ₀ ). Here, in order to reduce the volume V _th per unit tooth width, it is conceivable to make the module m smaller at first glance, but in practice, the gear outer diameter d is reduced, and the continuity of the meshing at that time is maintained. In order to achieve this, a design is made to reduce the module m.

In this embodiment, as shown in FIG. 2, the gear outer diameter u of the gear pump A2 is made smaller and the module m is made smaller than the gear pump A1, so that the center between the two gear pumps is reduced. Even if the distance s is equal, the required gear pump capacity can be obtained by providing the tooth width within the range of the size required for strength and performance. For example, the volume of a unit tooth width per length of the gear pump A1 is 1.0 cm ³ / mm, the effective face width 10 to 40 mm, effective volume 10 to 40 cm ^3, the volume of the unit tooth width per length of the gear pump A2 0 .5 cm ³ / mm, effective tooth width of 10 to 40 mm, and effective capacity of 5 to 20 cm ³ . Accordingly, in this embodiment, the capacity of the gear pump A1 can be set to 40 cm ³ and the capacity of the gear pump A2 can be set to 5 cm ³ , and the capacity difference between the gear pumps A1 and A2 can be increased as compared with the prior art. it can.

  In such a dual gear pump, by driving external power, the drive gear shafts 11a and 11b of the gear pumps A1 and A2 are rotated, and the drive gears 1b and 1d are rotationally driven.

  Thereby, each gear pump A1, A2 performs the operation | movement similar to a well-known gear pump, and conveys the hydraulic fluid suck | inhaled from the suction port to the discharge port by the gear mechanism. For example, when the dual gear pump of this embodiment is mounted on a forklift, the gear pump A1 supplies hydraulic oil for cargo handling from the discharge port, and the gear pump A2 supplies hydraulic oil for steering from the discharge port. Even if the hydraulic oil capacity required for steering is much smaller than the hydraulic oil required for cargo handling, the dual gear pump of the present embodiment is as described above. Can be distributed.

  Therefore, since the required amount of hydraulic oil can be efficiently distributed and supplied for cargo handling, it contributes to downsizing of the apparatus. In addition, since the distance between the centers of the gear mechanisms is equal and two gear pumps can be combined, the machining of the shaft hole in the body is simple, and an increase in machining cost can be suppressed.

  Furthermore, the double gear pump shown in FIG. 3 is also included in the present invention. That is, when the distance between centers in each gear pump is equal, this apparatus is configured by combining single gear pumps A1 and A2. Also in this case, since the intermediate adapter 21 for connecting the bodies 22 and 23 for the single gear pump can also be machined with the through hole, the machining is simple and the body parts can be shared. Cost can be reduced.

It is sectional drawing which shows the structure of the double gear pump by this invention. It is the figure which showed the gear mechanism used for the double gear pump of FIG. It is sectional drawing which shows the modification of the double gear pump by this invention. It is sectional drawing which shows the structure (1) of the conventional double gear pump. It is a figure which shows the relationship between tooth width and the efficiency and intensity | strength of a pump. It is sectional drawing which shows the structure (2) of the conventional double gear pump.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main body A1, A2 Gear pump 1a, 1c Drive gear 1b, 1d Driven gear 11a, 11c Drive gear shaft 11b, 11d Driven gear shaft 12 Spline connection part 13 Body 21 Intermediate adapter

Claims (1)

A gear shaft formed by meshing the teeth of a pair of gears with each other is housed in two pump chambers that are independent of each other to form a gear pump, and a drive shaft that pivotally supports a gear on the drive side of each gear mechanism In the dual gear pump that couples each other and conveys the oil introduced from the suction port to the discharge port provided independently in each pump chamber by each gear mechanism, the gear pumps rotate synchronously. A double gear pump characterized in that the distribution of the discharge capacity is set by changing the discharge capacity per unit tooth width of the gear pump.

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