WO2019220466A1 - An improved planetary gear train for automatic transmission system - Google Patents

Abstract

Disclosed herein is a planetary gear train assembly for an automatic transmission system for having optimum drive efficiency. The planetary gear train assembly comprises of: an input shaft coupled to a drive source (i/p); a first planetary gear set with two sun wheels(S1 and S1') and two sets of planet wheels on a single carrier; a second planetary gear set with two sun wheels(S2 and S2') and two sets of planet wheels on a single carrier, wherein the first planetary gear set and the second planetary gear set are coupled using shafts. Input power is given to the first stage and output power is taken from the second stage. The present invention advantageously provides low maintenance cost and higher efficiency without losses (ideally). This machine is a load sensing transmission mechanism.

Description

AN IMPROVED PLANETARY GEAR TRAIN FOR AUTOMATIC TRANSMISSION SYSTEM

FIELD OF THE INVENTION:

The present invention relates generally to an automatic transmission system and more particularly, to an automatic transmission system which optimises the drive efficiency for connecting between any rotary power traction power source and load.

BACKGROUND:

Transmission system in automobiles are used to produce the required torque by limiting or increasing rpm for a given engine power. The rpm range of an engine is not having a good range and cannot be connected directly to the axle of wheels(in the case of automobile).

Automatic gear trains are manual/automatic/semi-automatic. Conventionally, in a transmission system with any gear trains, engagement and disengagement of clutch/clutches are involved usually, or some other switching mechanism. The engagement or disengagement of clutches results in deterioration in fuel efficiency, as the engaging elements have a sliding resistance between the friction plates.

An Automatic Gear Box is also called as Automatic Transmission System which can be either a stepped type, which provides different rpm in a few steps or Continuously Variable Transmission(CVT) type which provides rpm by gradually changing the same and not in steps, or infinitely variable transmission system.

While comparing these systems, the CVT system is smoother in operation. Here are a few sample patents with a similar idea. United States Patent No. 6527671 to Seppo Lauri Paalasmaa, et. al. entitled“Planetary gear transmission with variable ratio” relates to a planetary gear variable transmission mechanism in which the planetary gear comprises two sun wheels with two sets of planet wheels on a common carrier without ring gear. A coupling means in the mechanism allows the whole rotary force or part thereof to taken out from the planetary gear and/or fed therein. An operation means is used to control the planetary carrier rotation velocity, remains to be locked stationary or to be freely rotatable.

Chinese Patent Application No. 101825162 to Shao Wanzhen, et. al. entitled“Planetary gear continuously variable transmission” relates to a continuously variable transmission system having gear box which comprises two planetary gears with common planet carrier fixed through common shaft without using ring gear. A step less speed regulating device is fixed on the box body and connected to the speed regulating gear shaft for controlling rotational speed of the sun gear.

The usage of above-mentioned engaging components causes energy waste in the form of heat energy due to friction between clutches. Also, it reduces the drive efficiency of transmission system and increases the maintenance cost. Hence, there is always a scope for mechanisms to improve the drive efficiency of transmission system in the automobiles or other rotary traction systems.

OBJECTS OF THE INVENTION:

The primary objective of the present invention is to optimise the drive efficiency in automatic transmission system without the help of any additional elements other than gears and other essentials such as bearings, casing etc, and without compromising in its simplicity, size.

Another objective of the present invention is to provide a cost-effective system that results in optimising the energy usage in the system, at the same time making easy on its maintenance (compared to a conventional sophisticated automatic transmission system). SUMMARY:

The present invention provides a gear train arrangement which ensures optimum drive efficiency(in ideal conditions). It has: an input shaft coupled to a drive source; a pair of planetary gear train (with two sun wheels and two sets of planet wheels in each; and a carrier common to the two sets of planet wheels). These two planetary gear trains, named as Stage 1 and Stage 2 are coupled suitably with shafts.

According to the present invention, the two-stage-set of planetary gear trains are compactly arranged in a suitable casing coupled together as in figure 1. The assembly has only various gears on shafts, shafts fixed in bearings. No odd shaped elements or sliding pairs are there inside the assembly.

The conventional planetary gear train with a ring wheel is modified as in Fig-2, to serve the same purpose, at same time reducing its overall radius. The ring wheel substituted with another sun wheel and a set of planet wheels around it.

These objectives and advantages of the present invention will become more evident from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS:

The objective of the present invention will now be described in more detail concerning the accompanying drawings, in which:

FIG. 1 illustrates the two-stage planetary gear used in the automatic transmission system; and

FIG. 2 illustrates the planetary gear train assembly used in the transmission system. REFERENCE NUMERALS OF THE DRAWINGS:

Pl: Planetary Gear Train 1 or Stage 1 ;

P2: Planetary Gear Train2 or Stage 2;

Sl, Sl’, S2, S2’: Sun wheels;

Cl, Cl’: Carriers;

i/p: In put;

o/p: Out put;

DETAILED DESCRIPTION OF THE INVENTION:

The present invention discloses an improved gear assembly for automatic transmission system. The improved gear train mechanism describes a two-stage planetary gear train (Each gear train includes a two independent sun wheels with two sets of planets on a single carrier around it).

The mechanical assembly includes: an input shaft coupled to a drive source; a pair of modified planetary gear train coupled suitably as in figure- 1. No additional components are used for functioning of the gear box. This machine is a load sensing transmission mechanism.

A tentative assembly scheme between the gear trains, for the automatic transmission system is elaborately depicted in FIG. 1. As depicted in the FIG. 1, the planetary gear train (Pl, P2) at two stages have four sun wheels such as (Sl, S2, Sl’, S2’) and two common carriers (Cl, Cl’). The couplings of the two-stage planetary gear trains are preferably made as mentioned in the below steps: A planetary gear train has three drives from 1) two sun wheels and 2) carrier wheel.

1. Any of the drives from the first planetary gear train (Stage 1) is provided with input power. 2. The remaining two of the drives from Stage 1 is coupled to any two drives of other planetary gear train (Stage 2).

3. The remaining free drive of the Stage-2 is coupled to the load.

Fig-2 shows the modified conventional planetary gear train. This modification allowed to avoid ring gear and thus reducing its overall diameter. This serves the same purpose of a typical planetary gear train.

While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed

Claims

aim:

1. A Gear assembly having planetary gear trains in two stages, for providing better drive efficiency in automatic transmission system, comprising: a. the input shaft from stage 1 is intended for coupling to a drive source;

b. a first planetary gear set with two sun wheel (Sl and S2), two sets of planet wheels and a common Carrier C 1.

c. a second planetary gear set with two sun wheels(S l’ and S2’),two sets of planet wheels and a common carrier Cl’, wherein the first planetary gear set and the second planetary gear set are coupled using shafts;

d. the output shaft from stage 2 is indeded for coupling to a load.

2. This assembly doesn’t use any other elements other than gears and essentials like bearings, shafts, and fixtures for it, and casing.

3. The assembly will respond to load changes dynamically. In other words, it is a load sensing machine.