WO2018017031A1

WO2018017031A1 - A gear control system

Info

Publication number: WO2018017031A1
Application number: PCT/TR2017/000081
Authority: WO
Inventors: Can Ulas DOGRUER; Abbass Khoshvaght PISOLTAN
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-07-22
Filing date: 2017-07-12
Publication date: 2018-01-25
Anticipated expiration: 2019-01-22
Also published as: TR201610232A2

Abstract

The present invention relates to a gear control system (1) wherein dynamic transmission error is reduced by controlling the torque having effect on gear (2) pairs, on a time-dependent basis. With the inventive gear control system (I), dynamic and transmission errors of gear boxes are decreased and noises among gear pairs reduced by controlling the torque having effect on gear (2) pairs; pure and error-free motion transmission, error-free transfer ratio, constant and optional error-free output speed are enabled by reducing noise and also effect of inertial forces to occur in gear (2) system is reduced.

Description

A GEAR CONTROL SYSTEM Technical Field

The present invention relates to a gear control system wherein dynamic- transmission error is reduced by controlling the torque having effect on gear pairs, on a time-dependent basis.

Background of the Invention

When gear pairs work under pressure, number of gear teeth being in contact with two gears varies between certain integer numbers. Number of gear teeth being in contact for a gear pair, the contact ratio of which is less than two. varies between one and two. This variation causes the effective elasticity coefficient calculated between the gear pair to vary periodically. Speed ratio and angular positions of gear pairs need to vary in accordance with the gear ratio as a result of kinematic analysis of a gear pair working under constant load. Variable elasticity coefficient leads to angular velocity and position errors called as dynamic transmission error in gear pairs working under constant load. The said error causes noise and leads to metal fatigue on gear teeth although margin of error is very small. Today, profiles of gears are improved in order to overcome the above-mentioned problems. In addition, effective periodical elasticity coefficient is modified and it is aimed to reduce dynamic transmission error by going beyond standard gear profiles in studies performed. Solutions being used in prior art do not eliminate problems but they only reduce negative effect of the problem. Profile modification is sensitive to errors made in mounting of gear wheel. Errors occurring in center distance between two gears and angular mounting errors of gears with respect to one another reduce the effect of gear teeth profile modification method. The United States patent document no. US5574646 discloses a gear noise evaluation system. The said system comprises a host (neuro) computer wherein sound pressure values received from a FFT analyser are transferred. At this time, an evaluator simultaneously presets a sensual evaluating value as a teacher signal from a control unit. The host computer repeatedly performs a learning. This learning continues until desired level of sound pressure values. The said system also comprises a tachometer for measuring speed of a shaft on which a gear is mounted, also a microphone used for receiving noises coming from gears, a FFT evaluator such as a frequency evaluator for receiving values measured by microphone and tachometer.

The International patent document no. WO1998030813 discloses a method and apparatus wherein noise and vibration occurring in gears is prevented by removing and adjusting drive torque or power. In the said invention, information is received by using sensors and noise and vibration occurring in gears are used in order to generate an error message. Information of error message indicator is processed upon being transmitted to a control mechanism and they are used to generate a related drive torque. It is aimed to reduce sound and vibration occurring in gears by transmitting the torque to a related shaft.

Summary of the Invention

An objective of the present invention is to realize a gear control system which decreases dynamic transmission error of gear boxes and reduces noise among gear pairs by controlling the torque having effect on gear pairs.

Another objective of the present invention is to realize a gear control system wherein pure and error-free motion transmission, error-free transfer ratio, constant and optional error-free output speed are enabled by reducing noise and also effect of inertial forces that occur in gear system is reduced. Another objective of the present invention is to realize a gear control system which enables spur gears particularly and also other gear types such as helical, bevel, helical-bevel to operate noise-free and without transmission error.

Another objective of the present invention is to realize a gear control system which is used to stabilize output speed of a gear pair loaded by constant torque and is preferably a tachometer.

Detailed Description of the Invention

"A Gear Control System" realized to fulfil the objectives of the present invention is shown in the figure attached, in which:

Figure 1 is a schematic view of an embodiment of the inventive system.

The components illustrated in the figure are individually numbered, where the numbers refer to the following:

1. System

2. Gear

3. Controller unit

4. Sensor unit

5. Control unit

The inventive gear control system (1 ) essentially comprises:

a plurality of gears (2) which are in contact with one another, wherein torque is applied on at least one of them over shaft and which preferably composes of a gear box;

a plurality of controller units (3) which are attached to the gears (2) and measure speeds of the gears (2) in order to find out full state vector; - at least one sensor unit (4) which is placed to the gear (2) wherein the torque is preferably applied at first and calculates angular positions of the gears (2);

- at least one control unit (5) which calculates the torque to be applied to the gears (2) by calculating the values received from the controller unit

(3) and the sensor unit (4) and the non-linear effects instantly, changes parameters of the gears (2) based on the torque value calculated continuously and carries out a time-dependent torque control. In the inventive gear control system (1 ), a plurality of tachometers is used as the controller unit (3). The tachometers are attached to the gear teeth and thus they share the speed information with the control unit (5) instantly.

In one preferred embodiment of the gear control system (1), absolute encoder sensor is used as the sensor unit (4). The absolute encoder sensor shares the information of what kind of change does the non-linear periodical elasticity coefficient of the gears (2) undergo together with the angular positions of the gears, with the control unit (5). The sensor unit (4) calculates absolute angular positions by following the marks created in the gear (2) pairs at the mounting stage in order to detect angular changes. In one preferred embodiment of the invention, when initiating operation of the gear (2) system, the sensor unit (4) - which is absolute encoder sensor- is mounted to the input gear (2) for the purpose of measuring absolute angular positions in order to know angular positions of the gears (2).

In one preferred embodiment of the invention, the control unit (5) uses two feedback loops. The feedback loops used in the control unit (5) are inner loop and outer loop. The control unit (5) sends the signal -which is calculated by using the effects of the non-linear motions in the gear (2) system by using the inner loop and which is control torque- back to the system via negative feedback and eliminates effect of non-linear forces that arise from periodical elasticity coefficient having effect on gear (2) pairs. The dynamic model used by the control unit (5) transform into a second-degree linear differential equation as a result of this transaction. Whereas the forces having effect on this linear system are adjusted by changing the parameters of the control unit (5) controlling the outer loop. The control unit (5) can adjust response of the gear (2) systems as requested by using two independent second-degree systems. Thus, the control unit (5) determines speed follow-up and speed regulation features of the gears (2) as requested. The control unit (5) uses the full state vector of the gear (2) systems in order to deactivate effects of non-linear forces by inner loop. In one preferred embodiment of the invention, the control unit (5) receives speed information by using the tachometers attached to the gears (2). In addition, the control unit (5) learns how does the non-linear periodical effective elasticity coefficient change by the angular positions of the gears (2) by means of a sensor unit (4) which is an absolute encoder sensor placed to the input gear.

In one preferred embodiment of the gear control system (1 ). the control unit (5) carries out mechanical analysis of the gear system consisting of the gears (2) by means of finite elements method and the effective elasticity coefficient is calculated according to the position of the gear (2). The elasticity coefficient calculated by the control unit (5) is approximately in square wave form. High and low edges of the square wave vary by the contract ratio of the gear (2). Analysis of the gear system arises from the fact that elasticity coefficient changes in square wave form of even under constant torque. A reverse model, wherein the elasticity coefficient calculated by the finite elements method will be used, is used in the control unit (5). The control unit (5) uses the reference acceleration signal of the input gear (2) wherein the torque is applied as the input of the reverse model, and the gear (2) speed information measured by means of the tachometer in the gear box. The control unit (5) calculates the position and the acceleration of the gear (2) by the gear speed information. In this case, the control unit (5) finds out the torque that should affect the input gear (2) by using the reference acceleration signal, the gear position information and the speed measurements. The torque, which is calculated from the reverse model since the torque calculated by the control unit (5) uses the reference gear signal, is enabled to follow-up the reference acceleration signal of the gear (2) under ideal conditions. However, calculations occurring in the gear system and delays arising from the measurement may cause distortion of ideal conditions given the non-linear structure of the system. In this case, the control unit (5) calculates the error dynamics of the gear (2) in the outer loop which is a second loop. The control unit (5) uses PI (proportional. Integral) control loop method for this transaction. The control unit (5) calculates the difference between the torque changing within a measured process and desired and the measured torque as an error value by using PI controller. The control unit (5) preferably calculates regulation characteristic in this loop. In the control unit (5) wherein two loops are used, namely inner loop and outer loop; it is enabled to calculate the torque value necessary for making the gear system linear by the torque value obtained from the reverse model by using the gear status vector in the inner loop. The first loop used in the control unit (5) can also be called as linear loop. As a second loop in the control unit (5), the PI controller enables that errors which arise from delays occurring in the gear system in the inner loop are observed so that the linear error dynamics are stable.

With the inventive gear control system (1), transmission error -which is seen as the main reason of the noise occurring preferably in the spur gears (2)- is controlled by the control unit (5) and fluctuations around a constant value are reduced. The control unit (5) finds out transmission error and changes of gear elasticity coefficient (mesh stiffness) by using finite element analysis. In one preferred embodiment, the control unit (5) uses the elasticity coefficient calculated by the finite elements method and the outputs of the controller and the sensor unit (3, 4) measuring the position and the speed data of the gears (2). The control unit (5) reduces the effect of non-linear forces occurring in the gear (2) system controlled by using the elasticity coefficient. The control unit (5) has material and size information of the gears (2) in a gear (2) system consisting of gear (2) pairs.

Within these basic concepts; it is possible to develop various embodiments of the inventive "Gear Control System (1)", the invention cannot be limited to examples disclosed herein and it is essentially according to claims.

Claims

1. A gear control system ( 1 ) essentially comprising

a plurality of gears (2) which are in contact with one another, wherein 5 torque is applied on at least one of them over shaft and which preferably composes of a gear box;

and characterized by

- a plurality of controller units (3) which are attached to the gears (2) and measure speeds of the gears (2) in order to find out full state ] 0 vector;

at least one sensor unit (4) which is placed to the gear (2) wherein the torque is preferably applied at first and calculates angular positions of the gears (2):

at least one control unit (5) which calculates the torque to be applied to 1 5 the gears (2) by calculating the values received from the controller unit

(3) and the sensor unit (4) and the non-linear effects instantly, changes parameters of the gears (2) based on the torque value calculated continuously and carries out a time-dependent torque control. 0

2. A gear control system (1 ) according to Claim 1 ; characterized by the controller unit (3) wherein a plurality of tachometers is used.

3. A gear control system (1) according to Claim 1 or 2; characterized by the sensor unit (4) which is absolute encoder sensor.

5

4. A gear control system (1) according to Claim 3; characterized by the absolute encoder sensor which shares the information of what kind of change does the non-linear periodical elasticity coefficient of the gears (2) undergo together with the angular positions of the gears, with the control unit (5).

0

5. A gear control system (1 ) according to any of the preceding claims; characterized by the sensor unit (4) which calculates absolute angular positions by following the marks created in the gear (2) pairs at the mounting stage in order to detect angular changes.

6. A gear control system (1) according to any of the preceding claims; characterized by the sensor unit (4) which is mounted to the input gear (2).

7. A gear control system (1 ) according to any of the preceding claims; characterized by the control unit (5) which uses two feedback loops, namely inner loop and outer loop, sends the signal -that is calculated by using the effects of the non-linear motions in the gear (2) system by using the inner loop and that is control torque- back to the system via negative feedback and eliminates effect of non-linear forces that arise from periodical elasticity coefficient having effect on gear (2) pairs.

8. A gear control system (1) according to Claim 7; characterized by the control unit (5) which uses the full state vector of the gear (2) systems in order to deactivate effects of non-linear forces in the inner loop.

9. A gear control system (1 ) according to any of the preceding claims; characterized by the control unit (5) which carries out mechanical analysis of the gear system consisting of the gears (2) by means of finite elements method and calculates the effective elasticity coefficient according to the position of the gear (2).

10. A gear control system (1) according to Claim 9; characterized by the control unit (5) wherein a reverse model, wherein the elasticity coefficient calculated by the finite elements method will be used, is used.

1 1. A gear control system ( 1 ) according to Claim 10; characterized by the control unit (5) which uses the reference acceleration signal of the input gear (2) wherein the torque is applied as the input of the reverse model, and the gear (2) speed information measured by means of the tachometer in the gear box.

12. A gear control system (1) according to Claim 11 ; characterized by the control unit (5) which finds out the torque that should affect the input gear (2) by using the reference acceleration signal, the gear position information and the speed measurements.

13. A gear control system (1) according to any of Claim 7 to 1 1 ; characterized by the control unit (5) which calculates the error dynamics of the gear (2) in the outer loop that is a second loop.

14. A gear control system (1) according to Claim 13; characterized by the control unit (5) which uses PI (proportional. Integral) control loop method.

15. A gear control system ( 1) according to Claim 14; characterized by the control unit (5) which calculates the difference between the torque changing within a measured process and desired and the measured torque as an error value by using PI controller.