JPH051398B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to an internal gear pump with variable discharge volume.

(b) Prior art and its problems Conventional variable displacement pumps are only of the vane type, and their structure, as shown in Figure 3, is to rotate a rotor 2 with a fixed drive shaft 1.
By moving the vane 3, which is retractably assembled into the rotor, along the inner surface of the cam ring 4,
The oil sucked in between adjacent vanes at a portion where the confined space volume is widened is discharged at a portion where the space volume is narrowed. In addition, the discharge amount can be adjusted by moving the cam ring using the lever 5, etc.
This is done by changing the eccentricity of the rotor and cam ring.

However, this vane type pump
Since each component must be processed with high precision, it has the disadvantage of being expensive. Furthermore, since the vane slides at a high speed, the vane and cam ring are likely to wear out, and problems remain in terms of durability. That being said,
If expensive materials with excellent wear resistance are used to prevent wear, the cost will increase even more.

(c) Means for solving the problems An object of the present invention is to provide a pump that is inexpensive, highly reliable, and whose discharge amount can be easily adjusted.
To achieve this objective, the pump of the present invention has a plurality of sets of internal pump rotors consisting of externally toothed gears and internally toothed gears. By assembling the pump rotor in a horizontal line in a split housing with plates in between, and changing the drive speed of the pump rotor by axially moving a drive shaft engaged with an external gear or a rod built into the drive shaft. , the discharge amount is changed.

(d) Embodiment An example of the internal gear pump of the present invention is shown in the attached FIGS. 1 and 2.

In the figure, numeral 10 denotes a pump rotor in which a driving external gear 11 and a driven internal gear 12 are combined, and a plurality of sets are assembled in a horizontal line in the divided housing 20.

The housing 20 has a rotor storage chamber 21 on one end surface.
A pair of side plates 21, 2 having a, 21a'
1', a middle plate 22 interposed between each pump rotor, and a ring case 23 disposed between the plates, and the respective housing parts are fluid-tightly connected using bolts or the like. In addition, one side plate 21 has a suction port 2.
1b and a discharge port 21c are provided, and the middle plate 22 also has an inlet port 22b of the same size and shape extending through the same positional relationship as the port.
and a discharge port 22c.

In addition, the pump provided with the illustrated side plate does not require the ring case 23 when the number of rotor combinations is two. However, the rotor storage chamber of the side plate may be formed by joining the ring case 23 to a plate with a flat end surface, and in this case, the ring case is used even if there are two rotors.

Next, a drive shaft 30 supported by side plates 21 and 21' is loosely inserted through the center of the external gear 11 of each pump rotor via a bearing 24 and an oil seal 25. This drive shaft has a built-in rod 31 that slides in the axial direction, and axial protrusions 31a such as serrations and keys provided at appropriate intervals on the outer periphery of the rod protrude outward from the long hole 32 of the shaft. A recess 11a provided corresponding to the inner surface of the center hole is engaged in a removable manner. Therefore, the drive shaft 30
When the external gear 11 is rotated, the external gear 11 rotates, and the internal gear also rotates accordingly. Further, when the rod 31 is moved in the axial direction, an arbitrary number of external gears 11 counted from the left end are disengaged from or engaged with each other again, and the number of drives of the pump rotor 10 changes. Therefore, the discharge amount of the pump changes in stages.

Here, in order to move the rod 31 in the axial direction,
Needless to say, it is necessary to make the elongated hole 32 of the drive shaft a predetermined length longer than the length of the protrusion 31a. Further, it is preferable that chamfers be provided on the corner edges of the protruding ridges 31a of the rod to ensure smooth engagement with the gear 11 even under the rotating state of the drive shaft.

Further, in the pump of the present invention, by loosely inserting the drive shaft into the bearing 24 and providing the shaft with an axial protrusion, the drive shaft itself can be moved in the axial direction to change the discharge amount.

Note that the rod or drive shaft that has been moved in the axial direction is held at a fixed position by a position holding means (not shown). This position holding means may be provided integrally with the pump, but if, for example, the pump discharge amount is to be automatically controlled, a means for moving the rod or drive shaft is required, so it may be provided with a position holding function.

Also, if the number of pump rotors installed increases,
In order to downsize the pump, it is desirable to use a trochoid or cycloid tooth-shaped pump roller with a single tooth difference. This is because the pump rotor with the above-mentioned tooth profile has no crescent (a crescent space where both gears are in a non-contact state) between the gears 11 and 12, so the pump diameter is small, and this also reduces the diameter and wall thickness of the middle plate. This is because it becomes possible to make the size smaller.

(e) Effects As explained above, according to the present invention, multiple sets of internal gear pump rotors, which are easier to manufacture than vane pumps, are arranged horizontally in a row via a middle plate, and the driving speed is changed. Since the discharge amount is changed by this, a variable displacement pump that is inexpensive, has excellent durability, and is highly reliable can be obtained.

Further, the discharge amount can be adjusted by simply sliding a rod having a protrusion or a drive shaft in the axial direction, which is extremely simple and allows automatic adjustment.

Furthermore, pump rotors with a trochoid or cycloid tooth profile with a difference in number of teeth of one tooth can provide a pump with a small diameter and short length even if the number of pump rotor combinations increases, and the sliding speed of the gear is small.
Since pulsation is also small, durability is further improved and vibrations are also reduced.

In addition to general use, the pump of the present invention can also be used as a hydraulic motor or as a variable displacement pump for automatic transmissions, and exhibits stable performance in either case.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a pump of the present invention, FIG. 2 is a sectional view taken along the line -, and FIG. 3 is a sectional view showing a known vane type variable displacement pump. 10...Pump rotor, 11...External gear, 12...
Internal gear, 20...Housing, 21, 21'...Side plate, 21b...Suction port, 21c...Discharge port, 22...Middle plate, 22b...Suction port, 22c...Discharge port, 23...Ring case, 24...Bearing, 25...Oil seal, 30...Drive shaft, 31...Rod, 31a...Protrusion,
32...Long hole.

Claims (1)

[Scope of Claims] 1. A plurality of sets of internal pump rotors each consisting of a driving side externally toothed gear and a driven side internally toothed gear are arranged in a middle structure having suction and discharge ports located in the same position as the suction and discharge ports of the side plate. The plates are assembled horizontally in a line in the divided housing including the side plates with the plates interposed therebetween, and a drive shaft having an axial protrusion on the outer periphery or a rod that slides in the axial direction is built in the center of the external gear. The axial protrusion on the outer periphery of this rod passes through the drive shaft which projects outward from the axial elongated hole, and the protrusion on the drive shaft or rod is a recess provided corresponding to the inner surface of the center hole of the external gear. A variable capacity internal gear that is removably engaged with a pump, and by moving a drive shaft or rod having a protrusion in the axial direction, the number of driven pump rotors is changed and the discharge amount is changed. pump. 2. The variable displacement internal gear pump according to claim 1, wherein the pump rotor is a trochoid or cycloid tooth type pump rotor with a difference in the number of teeth of one tooth.