Motor pump unit

Abstract

The invention provides a motor pump unit which comprises a pump assembly, a transmission box device and a motor assembly. The transmission box device comprises an inner gear part. The inner gear partat least comprises three end faces, the first end face, the second end face and the third end face, in the thickness extending direction. The inner gear part comprises an inner gear ring portion, a connecting portion and a fixed ring portion from outside to inside in the radial direction, wherein the inner gear ring portion, the connecting portion and the fixed ring portion are connected in sequence. The inner gear ring portion comprises an inner gear ring. The fixed ring portion comprises a driven shaft mounting hole. A driven shaft is relatively fixedly mounted in the driven shaft mounting hole in the circumferential direction and is connected with the pump assembly. An outer gear is relatively fixedly mounted on a motor shaft included in the motor assembly in the circumferential direction. The outer gear is mounted on the inner gear ring portion in an eccentric engagement manner. In the motor pump unit, due to the fact that inner engagement is adopted by large and small gear engagement, the overlap ratio of the two gears is higher than that of outer engagement, transmission is more stable, and noise is lower.

Description

technical field [0001] The present invention relates to the field of pumps and transmissions, in particular to a motor pump unit, in particular to a motor pump unit of a high-pressure cleaning machine. Background technique [0002] Patent CN107061213A discloses several transmission schemes for hand-held cleaning machines. The patent provides the following transmission schemes: external meshing single-stage reduction device, external meshing bevel gear reduction device, external meshing multi-stage reduction device , Planetary gear reduction device. The above types of reduction gears can be classified into two categories, one is external meshing transmission; the other is planetary gear transmission. The two transmission methods are applied to high-pressure cleaners, especially hand-held high-pressure cleaners, which have the following disadvantages: [0003] The disadvantages of external meshing transmission are: 1. Due to the external meshing, the number of meshing teeth ...

AI Technical Summary

Problems solved by technology

[0003] The disadvantages of external meshing transmission are: 1. Due to the external meshing, the number of meshing teeth of the large and small gears at the same time is small (the gear overlap is less than 1), the continuity and stability of the gear transmission are poor, and the noise is high; when the user holds the gun to clean , the user experience is poor; 2. The grease will be thrown away from the gear surface due to centrifugal force, resulting in lubrication failure and gear wear, which will eventually cause noise and vibration, and the entire system or motor will fail; 3. The center distance between the large and small gears is large, That is to say, the offset distance between the motor and the pump is relatively large, which is unfavorable to the overall design of the machine.

[0004] The disadvantages of the planetary gear transmission are: 1. Although the planetary gear and the ring gear in the transmission are internally meshed, the meshing between the center pinion and the planetary gear is still externally meshing. Due to the small diameter of the pitch circle of the two gears and the small number of teeth, The meshing of the two gears is also discontinuous, with poor stability and high noise; 2. Due to the large number of meshing pairs (at least 4) of the planetary gear transmission gears, in addition to generating large noise, it will also generate large frictional heat , resulting in low transmission efficiency; for handheld cleaning machines that use batteries as power sources, the battery life will be shortened; 3. The planetary gear transmission structure is more complex, requiring higher precision and higher cost

This positioning is an unreliable positioning, because the upper and lower bearing plates of the thrust bearing can be separated without external force, so this positioning method has the following problems in actual use: Instantaneously, because the pressure between the upper and lower plates of the bearing is relatively small (basically the preload of the plunger spring), the force exerted by the small gear on the large gear during operation causes the two bearing plates to leave their original positions, resulting in damage to the bearing and at the same time Poor meshing of large and small gears will cause gear wear, resulting in poor reliability and short life of the machine

Therefore, this scheme can only be used in some occasions that do not require high transmission accuracy and noise, and the rotational torque and rotational speed are small.

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