CN110657093A

CN110657093A - Fluid pump

Info

Publication number: CN110657093A
Application number: CN201910652218.8A
Authority: CN
Inventors: 杨鲁川
Original assignee: CHANGZHOU RICH POWER TECHNOLOGY Co Ltd
Current assignee: CHANGZHOU RICH POWER TECHNOLOGY Co Ltd
Priority date: 2019-07-18
Filing date: 2019-07-18
Publication date: 2020-01-07

Abstract

The invention provides a fluid pump, which is provided with a driving rotor (22), a driven rotor (21) engaged with the driving rotor (22), and a rotor driving shaft (33) driving the driving rotor (22); the driving rotor (22) is provided with a shaft hole (220) for inserting a rotor driving shaft, the inner wall of the shaft hole (220) is provided with inner teeth, the rotor driving shaft (33) is provided with outer teeth meshed with the inner teeth of the inner wall of the shaft hole (220), and the rotating center of the rotor driving shaft (33) is eccentrically arranged relative to the rotating center of the driving rotor (22). The fluid pump of the invention can use a high-speed motor, thereby achieving the purposes of reducing the whole volume of the fluid pump and miniaturizing the product, and simultaneously, the miniaturization of the fluid pump reduces the material consumption, thereby reducing the manufacturing cost and improving the product competitiveness.

Description

Fluid pump

Technical Field

The invention belongs to the technical field of fluid pumps, and relates to a fluid pump.

Background

The spare part that places in the automobile cabin is more, and the space in automobile cabin is limited, consequently all need the miniaturization to each spare part, and along with car intelligent degree is higher and higher in addition, the spare part that will place in the cabin increases gradually, and the miniaturization requirement to each part is higher and higher. The fluid pump used in the transmission is compact, and the whole volume of the fluid pump needs to be reduced again on the existing structure, which brings great challenges to the technical personnel in the field.

Taking an electric oil pump for an automobile transmission as an example, one application scenario is that the oil pump is required to provide higher oil pressure. In such cases, it is generally necessary to use a low speed, high torque motor to accomplish this function. However, the low-speed large-torque motor means a huge motor volume, which not only increases the overall volume of the motor oil pump, occupies a larger installation space, but also greatly increases the cost.

In another application scenario, the installation space occupied by the motor oil pump is reduced on the premise of no change in output power. In order to solve this problem, a high-speed motor may be used instead of a normal rotation speed motor to achieve miniaturization of a motor portion. However, since the torque of the high-speed motor is smaller than that of a conventional motor, it is necessary to add a speed reduction mechanism between the high-speed motor and the conventional oil pump, and the addition of the speed reduction mechanism offsets the effect of downsizing by using the high-speed motor, and it is difficult to achieve the purpose of downsizing the entire motor oil pump. Furthermore, the addition of a set of reduction mechanism means an increase in the number of parts, resulting in an increase in product cost.

Both of the above cases lead to an increase in volume and cost of the product.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a fluid pump that is driven by a high-speed motor, and that increases torque by using a speed reduction mechanism, and that reduces the number of components, the overall volume of the fluid pump, and the cost.

To achieve the above and other related objects, the present invention provides a fluid pump in which a driving rotor, a driven rotor engaged with the driving rotor, and a rotor driving shaft driving the driving rotor are installed;

the driving rotor is provided with a shaft hole for inserting the rotor driving shaft, the inner wall of the shaft hole is provided with inner teeth,

the rotor driving shaft is provided with external teeth meshed with the internal teeth of the inner wall of the shaft hole, and the rotating center of the rotor driving shaft is eccentrically arranged relative to the rotating center of the driving rotor.

In an embodiment of the present invention, the outer peripheral surface of the driving rotor is formed with external teeth, the driven rotor has a hole for accommodating the driving rotor, and the hole wall of the hole is formed with internal teeth engaged with the external teeth of the driving rotor.

In an embodiment of the present invention, the rotation center of the rotor driving shaft is disposed on the same side of the rotation center of the driven rotor with respect to the rotation center of the driving rotor.

In an embodiment of the present invention, the rotation center of the rotor driving shaft is located on a connection line between the rotation center of the driving rotor and the rotation center of the driven rotor.

In an embodiment of the present invention, the outer peripheral surface of the driving rotor and the outer peripheral surface of the driven rotor are both formed with external teeth, and the driving rotor and the driven rotor are externally engaged.

In an embodiment of the present invention, the external teeth of the rotor driving shaft are fixed to the outer circumferential surface of the rotor driving shaft by a ring gear.

In an embodiment of the present invention, the external teeth of the rotor driving shaft are integrally formed with the rotor driving shaft.

As described above, the fluid pump of the present invention uses the speed reduction mechanism to increase the torque reduced by using the high-speed motor, but since the rotor drive shaft is provided with the external teeth that mesh with the internal teeth on the inner wall of the shaft hole of the shaft to reduce the speed, it is not necessary to increase the special parts and the installation space occupied by the parts required for the usual speed reduction mechanism. Meanwhile, the miniaturization of the fluid pump reduces the material consumption, thereby reducing the manufacturing cost and improving the competitiveness of the product.

Drawings

Fig. 1 shows an exploded view of a fluid pump.

FIG. 2 is a schematic cross-sectional view of one embodiment of a fluid pump of the present invention in engagement between a driven rotor and a driving rotor.

Figure 3 shows a front view of the pump body in a gerotor pump.

Fig. 4 shows a schematic view of the pump of fig. 2 with the rotor drive shaft in a first position.

Fig. 5 is a cross-sectional view taken along line D-D in fig. 3.

Fig. 6 shows a schematic view of the pump of fig. 2 with the rotor drive shaft in a second position.

Fig. 7 is a cross-sectional view taken along line D-D of fig. 6.

Fig. 8 shows a front view of the pump body in an external gear pump.

Fig. 9 shows a schematic view of the pump of fig. 8 with the rotor drive shaft in a first position.

Fig. 10 is a sectional view H-H of fig. 8.

Fig. 11 is a schematic view of the pump of fig. 8 with the rotor drive shaft in a second position.

Fig. 12 is a sectional view taken along line H-H in fig. 11.

Fig. 13 shows a schematic view of the ring gear in connection with the rotor drive shaft.

Fig. 14 shows a schematic view of the outer teeth integrally formed on the rotor driving shaft.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions under which the present invention can be implemented, so that the present invention has no technical significance, and any structural modification, ratio relationship change, or size adjustment should still fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.

Fig. 1 shows an exploded view of an electric oil pump 100 for a transmission of an automobile as a fluid pump of an embodiment of the present invention. Fig. 2 schematically shows a cross-sectional view of the electric oil pump of fig. 1, however, this does not mean that the present invention is limited to the electric oil pump, nor that the application of the electric oil pump 100 of the present invention is limited to a transmission of an automobile, and the electric oil pump 100 of the present invention may be various fluid pumps driven by a high-speed motor, such as an electric pump, a mechanical pump, and a working fluid including water, gas, oil, and the like, and its service objects are not limited.

As shown in fig. 1 and 2, the electric oil pump 100 is sequentially provided with a base 1, a pump body 2, a motor 3, and a rear cover 4, the base 1 and an application object (not shown) such as a transmission or a transmitter, and the base 1 is provided with an oil inlet 11 and an oil outlet 12, and when the electric oil pump 100 operates, the motor 3 is started, and the electric oil pump 100 sucks oil in a transmission, pressurizes the oil, and pumps the oil out. The pump body 2 has a plurality of threaded holes (as shown in fig. 1), correspondingly, corresponding threaded holes are also arranged on the base 1, the motor 3 and the rear cover 4, and the base 1, the pump body 2, the motor 3 and the rear cover 4 are sequentially and fixedly connected by bolts penetrating through the threaded holes.

The electric oil pump 100 further includes a driving rotor 22 mounted on the pump body 2, a driven rotor 21 engaged with the driving rotor 22, and a rotor driving shaft 33 for driving the driving rotor 22, and as shown in fig. 1, a chamber 23 for accommodating the driving rotor 22 and the driven rotor 21 is formed on one axial end surface of the pump body 2. In the present embodiment, the rotor drive shaft 33 is also an output shaft of the motor 3. In fig. 1, a motor rotor 32 is fixed to the right side of a rotor drive shaft 33, and a motor stator 34 is disposed around the motor rotor 32. The motor 3 can be connected with an external power supply, and the coil of the motor stator 34 generates magnetism after being powered by the power supply and generates interaction with the motor rotor 32, so that the motor rotor 32 drives the rotor driving shaft 33 to rotate at a high speed.

Referring to fig. 2, in fig. 2, a rotor driving shaft 33 extends from the motor 3 and penetrates through the pump body 2, and the rotor driving shaft 33 penetrates through the pump body 2 to engage with the driving rotor 22 of the electric oil pump 100 to drive the driving rotor 22 to operate.

Referring to fig. 2 to 4, fig. 2 is a schematic view showing the inner mesh of the driving rotor 22 and the driven rotor 21 in the electric oil pump 100, and fig. 3 is an enlarged view of the driving rotor 22 and the driven rotor 21 in fig. 2.

As shown in fig. 2, the drive rotor 22 attached to the pump body 2 has a shaft hole 220 into which the rotor drive shaft 33 is inserted, the inner wall of the shaft hole 220 is provided with internal teeth 222, the rotor drive shaft 33 is provided with external teeth 331 which mesh with the internal teeth 222 of the inner wall of the shaft hole 220 of the drive rotor 22, and the two are internally meshed with each other, and the rotation center of the rotor drive shaft 33 is eccentric with respect to the rotation center of the drive rotor 22. The required reduction ratio is obtained by adjusting the number of teeth of both the external teeth 331 of the rotor drive shaft 33 and the internal teeth 222 of the driving rotor 22.

Currently, for example, because there is a limited space in which the electric oil pump 100 can be mounted in an automobile, there is an increasing demand for downsizing the electric oil pump 100. In this embodiment, since the overall volume of the electric oil pump 100 is mainly based on the size of the adopted motor 3, in order to reduce the overall volume of the electric oil pump 100, the motor 3 in the electric oil pump 100 can be a high-speed motor, and a person skilled in the art can easily understand that the motor with higher speed has smaller volume; meanwhile, since the rotation speed of the driving rotor 22 is constant, the output rotation speed of the high rotation speed motor is suitable for the driving rotor 22, so that the number of teeth of the inner teeth of the driving rotor 22 and the outer teeth of the rotor driving shaft 33 can be respectively adjusted to obtain a proper reduction ratio.

The electric oil pump 100 of the present embodiment is driven by a high-speed motor, and the volume of the motor can be reduced, and the rotor driving shaft 33 is provided with the external teeth 331 engaged with the internal teeth 222 of the inner wall of the shaft hole 220 of the driving rotor 22, and the two are engaged to reduce the speed, so that the installation space occupied by the usual speed reducing mechanism does not need to be increased, the volume of the electric oil pump 100 is reduced, and the requirements of the miniaturization and the weight reduction of the electric oil pump 100 are satisfied.

Because the electric oil pump 100 can use a high-speed motor, the high-speed motor has small volume, and particularly has obviously smaller size in the radial direction, so that the overall size of the electric oil pump 100 in the radial direction can be reduced, the material consumption of the electric oil pump 100 is reduced, the manufacturing cost is reduced, and the product competitiveness is improved.

As shown in fig. 2 and 3, when the driving rotor 22 and the driven rotor 21 are engaged with each other, for example, the electric oil pump 100 is a gerotor pump, and as shown in fig. 4,

external teeth

221, 222, 223, 224, 225, and 226 are formed on the outer peripheral surface of the driving rotor 22, and the driven rotor 21 has a center hole 211 for accommodating the driving rotor 22, and internal teeth 212 engaged with the driving rotor 22 are formed on the hole wall of the center hole 211.

It should be noted that the electric oil pump 100 in fig. 1 is a trochoid pump, the operation principle of the trochoid pump is as shown in fig. 4, the inner rotor 22 and the outer rotor 21 are in inner meshing, the inner rotor 22 has 6 outer teeth, correspondingly, the outer rotor 21 has 7 inner teeth, the inner rotor 22 rotates clockwise according to the direction shown in the figure, each outer tooth of the inner rotor 22 is meshed with a different part of the inner tooth of the outer rotor 21, 7 inter-tooth spaces formed between the inner rotor 22 and the outer rotor 21, in fig. 4, the volume of each inter-tooth space formed by the teeth 224 and 225, the teeth 225 and 226, and the teeth 226 and 221 and the outer rotor 21 respectively decreases from large to small, a pressure oil chamber 281, a pressure oil chamber 282 and a pressure oil chamber 283 are formed on the left side of the inner rotor 22, and the pressure oil chamber 281, the pressure oil chamber 282 and the pressure oil chamber 283 are; three inter-tooth spaces are respectively formed between the teeth 221 and 222, between the teeth 222 and 223, and between the teeth 223 and 224 and the outer rotor 21, the volume of each inter-tooth space is changed from small to large, the right side of the inner rotor 22 forms an oil suction cavity 271, an oil suction cavity 272 and an oil suction cavity 273, and the oil suction cavity 272 and the oil suction cavity 273 are respectively communicated with the negative pressure region 27 on the pump body 2. The negative pressure region 27 is communicated with the oil suction cavity 271, the oil suction cavity 272 and the oil suction cavity 273, and the positive pressure region 28 is communicated with the oil pressing cavity 281, the oil pressing cavity 282 and the oil pressing cavity 283. As the inner rotor 22 rotates in the direction shown in the drawing, the oil in the oil suction chamber 273, the oil suction chamber 272 and the oil suction chamber 271 is sent from the negative pressure region 27 to the positive pressure region 28 in this order.

In the case of the inner mesh, the rotation center of the driving rotor 22 is offset from the rotation center of the driven rotor 21, and in fig. 4, the rotation center of the driving rotor 22 is offset upward from the rotation center of the driven rotor 21. The motor 3 drives the driving rotor 22 to rotate through the rotor driving shaft 33, and it should be noted that the position of the meshing point of the rotor driving shaft 33 and the shaft hole 220 of the driving rotor 22 affects the overall volume of the electric oil pump 100. Fig. 5 shows two position distribution diagrams of the meshing point of the rotor driving shaft 33 and the driving rotor 22, wherein the positions are two extreme positions of the rotor driving shaft 33 in the shaft hole 220 of the driving rotor 22, and the actual installation position of the rotor driving shaft 33 is set in the two extreme positions. As shown in fig. 4 and 5, the meshing point of the rotor drive shaft 33 and the driving rotor 22 is a point a, a point Q is the rotation center of the driven rotor 21, a point P is the rotation center of the driving rotor 22, and the rotation center Q of the driven rotor 21 is offset to the lower side in fig. 3 and 4 with respect to the rotation center P of the driving rotor 22.

In the first position (as shown in fig. 3, 4 and 5), the rotation center B of the rotor driving shaft 33 is disposed on the same side of the rotation center Q of the driven rotor 21 with respect to the rotation center P of the driving rotor 22. They are located below the rotation center P of the driven rotor 21 in fig. 3 and 4, and the meshing point a is located on an extended line connecting the rotation center Q of the driven rotor 21 and the rotation center P of the driving rotor 22, on which the rotation center B of the rotor driving shaft 33 is located, when the entire width of the electric oil pump 100 is a, as shown in fig. 5, and fig. 5 shows a pump schematic when the rotor driving shaft 33 is located at the first position.

In the second position (see fig. 6 and 7), the meshing point a 'is located opposite to the meshing point a, i.e., the meshing point a' and the meshing point a are located approximately in central symmetry with respect to the rotation center P of the driving rotor 22, and the entire width of the electric oil pump 100 is b, as is apparent from fig. 5 and 7, where a is smaller than b.

Although the effect of reducing the speed can be achieved by providing the meshing point between the rotor drive shaft 33 and the driving rotor 22 at any position in the shaft hole 220 of the driving rotor 22, it is preferable to provide the meshing point between the rotor drive shaft 33 and the driving rotor 22 on the same side as the offset direction of the rotation center Q of the driven rotor 21 with respect to the rotation center P of the driving rotor 22, and it is further preferable to provide the first position given above, in order to achieve a reduction in the overall size of the electric oil pump 100.

Fig. 8 shows another embodiment of the invention, adapted to cooperate with the same. Wherein the driving rotor 22 and the driven rotor 21 are externally engaged. For example, the electric oil pump 100 is an external gear pump in which external teeth 227 are formed on the outer peripheral surface of the driving rotor 22 and external teeth 213 are formed on the outer peripheral surface of the driven rotor 21, and the driving rotor 22 and the driven rotor 21 are externally engaged with each other. The driving rotor 22 rotates clockwise according to the direction shown in the figure to drive the driven rotor 21 to rotate, the gear teeth on the upper side of the meshing position between the driving rotor 22 and the driven rotor 21 gradually quit from meshing, the volume of an oil suction cavity (not shown) is increased to form partial vacuum, and oil enters the oil suction cavity under the action of atmospheric pressure. The teeth on the lower side of the meshing part gradually enter into meshing, the volume of the oil pressing cavity is reduced, and oil is discharged out of the pump body 2.

The position of the rotor drive shaft 33 in the case where the driving rotor 22 and the driven rotor 21 are externally engaged will be described with reference to fig. 8 to 11. Fig. 9 and 11 show schematic views of two positions of the meshing point of the rotor driving shaft 33 and the driving rotor 22, which are two extreme positions of the rotor driving shaft 33 in the shaft hole 220 of the driving rotor 22, and the actual installation position of the rotor driving shaft 33 should be set in the two extreme positions.

As shown in fig. 9 and 10, the meshing point between the rotor driving shaft 33 and the driving rotor 22 is a point F, a point M is the rotation center of the driven rotor 21, and a point N is the rotation center of the driving rotor 22.

The first position is that the meshing point F is provided on the same side as the rotation center M of the driven rotor 21 with respect to the rotation center N of the driving rotor 22, i.e., on the left side of the rotation center N of the driving rotor 22 in fig. 9 and 10, while the meshing point B is located on a line connecting the rotation center M of the driven rotor 21 and the rotation center N of the driving rotor 22, on which the rotation center of the rotor drive shaft 33 is located, when the entire width of the electric oil pump 100 is e.

The second position is that the meshing point B 'of the rotor drive shaft 33 and the driving rotor 22 with respect to the rotation center N of the driving rotor 22 is located on the opposite side of the rotation center M of the driven rotor 21, that is, the meshing point B' and the meshing point B are arranged approximately in central symmetry with respect to the rotation center N of the driving rotor 22, where the overall width of the electric oil pump 100 is f, and it is apparent from fig. 10 and 12 that e is smaller than f.

Although the effect of reducing the speed can be achieved by providing the meshing point between the rotor drive shaft 33 and the driving rotor 22 at any position in the shaft hole 220 of the driving rotor 22, it is preferable to provide the meshing point between the rotor drive shaft 33 and the driving rotor 22 on the same side as the offset direction of the rotation center M of the driven rotor 21 with respect to the rotation center N of the driving rotor 22, and it is more preferable to provide the first position given above, in order to reduce the overall size of the electric oil pump 100.

It should be noted that, the external teeth of the rotor driving shaft 33 may be formed by fixing the gear ring 332 on the outer circumferential surface of the rotor driving shaft 33 by a fastener such as a screw, as shown in fig. 13, specifically, the center of the gear ring 332 has a first central hole, a first mounting hole may be radially formed on the side wall of the gear ring 332, correspondingly, a second mounting hole is radially formed at a corresponding position of the rotor driving shaft 33, during installation, the rotor driving shaft 33 is inserted into the first central hole, and the first mounting hole and the second mounting hole are sequentially inserted by a fastener such as a screw, a bolt, or a pin, so as to complete the fixing of the rotor driving shaft 33 and the gear ring 332. This facilitates the disassembly between the ring gear 332 and the rotor drive shaft 33, replacement when the ring gear 332 is damaged, and replacement of the ring gear according to the desired speed ratio.

However, the external teeth of the rotor drive shaft 33 may be formed integrally with the rotor drive shaft 33: as shown in fig. 14, when the rotor drive shaft 33 is formed, external teeth are formed on the outer peripheral surface of one axial end of the rotor drive shaft 33. The integral forming is adopted, so that the manufacturing process can be simplified, the manufacturing cost is reduced, and the competitiveness of the product is improved. Similarly, the internal teeth of the driving rotor 22 may be assembled and combined after being formed separately from the driving rotor, or may be formed integrally with the driving rotor, and will not be described herein again.

The operation of the electric oil pump 100 will be described with reference to the electric oil pump 100 shown in fig. 1. A power supply, not shown in the figure, supplies the motor 3. After the motor 3 is powered on, the motor rotor 32 drives the rotor driving shaft 33 to rotate at a high speed, the shaft end of the rotor driving shaft 33 drives the driving rotor 22 to rotate, the driving rotor 22 obtains the self rotating speed according to the reduction ratio of the rotor driving shaft 33 and the driving rotor 22, and the driving rotor 22 drives the driven rotor 21 to rotate, so that oil is sucked from the oil inlet hole 11 of the base 1 and pumped out from the oil outlet hole 12 of the base 1.

The electric oil pump 100 of the present invention uses the speed reduction mechanism to increase the torque reduced by using the high-speed motor, but since the rotor driving shaft is provided with the external teeth engaged with the internal teeth on the inner wall of the shaft hole 220 of the shaft to form speed reduction, it is not necessary to increase the special parts and the installation space occupied by the parts required for the usual speed reduction mechanism, in other words, the speed reduction mechanism is built in the electric oil pump 100, and the rotating shaft of the driving rotor and the driving rotor are used as the speed reduction mechanism, so that it is possible to reduce the volume of the electric oil pump 100 by using the high-speed motor, and the number of the parts is not increased, thereby satisfying the requirements of the miniaturization and the weight reduction of the electric oil. Meanwhile, the miniaturization of the electric oil pump 100 reduces the amount of material used, thereby reducing the manufacturing cost and improving the competitiveness of the product.

In conclusion, the present invention effectively overcomes various disadvantages of the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A fluid pump, characterized in that,

a driving rotor (22), a driven rotor (21) engaged with the driving rotor (22), and a rotor driving shaft (33) for driving the driving rotor (22) are installed in the fluid pump;

the driving rotor (22) is provided with a shaft hole (220) for inserting the rotor driving shaft, the inner wall of the shaft hole (220) is provided with inner teeth,

the rotor driving shaft (33) is provided with external teeth meshed with the internal teeth of the inner wall of the shaft hole (220), and the rotating center of the rotor driving shaft (33) is eccentrically arranged relative to the rotating center of the driving rotor (22).

2. The fluid pump of claim 1, wherein: the outer peripheral surface of the driving rotor (22) is formed with external teeth, the driven rotor (21) has a hole for accommodating the driving rotor (22), and internal teeth meshed with the external teeth of the driving rotor (22) are formed on the hole wall of the hole.

3. The fluid pump of claim 2, wherein: the rotation center of the rotor drive shaft (33) is disposed on the same side as the rotation center of the driven rotor (21) with the rotation center of the driving rotor (22) as a reference.

4. The fluid pump of claim 3, wherein: the rotation center of the rotor driving shaft (33) is located on a line connecting the rotation center of the driving rotor (22) and the rotation center of the driven rotor (21).

5. The fluid pump of claim 1, wherein: the outer peripheral surface of the driving rotor (22) and the outer peripheral surface of the driven rotor (21) are both provided with external teeth, and the driving rotor (22) is externally meshed with the driven rotor (21).

6. The fluid pump of claim 5, wherein: the rotation center of the rotor drive shaft (33) is disposed on the same side as the rotation center of the driven rotor (21) with the rotation center of the driving rotor (22) as a reference.

7. The fluid pump of claim 6, wherein: the rotation center of the rotor driving shaft (33) is located on a line connecting the rotation center of the driving rotor (22) and the rotation center of the driven rotor (21).

8. The fluid pump of claims 1-7, wherein: the external teeth of the rotor drive shaft (33) are fixed to the outer peripheral surface of the rotor drive shaft (33) by a ring gear (332).

9. The fluid pump of claims 1-7, wherein: the external teeth of the rotor drive shaft (33) are integrally formed with the rotor drive shaft (33).