IDETC2023-118099

Development of Reduction Gears
With Self-Locking Function

Chihiro Kamio(Gunma University, JAPAN)
Tatsuhito Aihara (Hosei University , JAPAN)
Toshiaki Shimada (Ai-esu Corporation , JAPAN)

Background■ In response to global warming…
KeywordLow fuel consumption

Electrification■ Motor research is being conducted vigorously Motors are used not only in cars,
but also in Construction machinery, machine tools, and aircraft Motors are used not only as a drive source for electric vehicles
but also as actuators(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Background■ In situations where a motor is used as an actuator…
It has to maintain its position while being subjected to external forces
If the motor has a mechanism that mechanically locks,
the motor does not need to generate torque to maintain its position→ Power consumption can be reduced■ And, One of the methods to improve motor efficiency is…
To increase the rotational speed
Reduction gears with higher reduction ratios are required(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Objective
If the motor has a mechanism that mechanically locks,
In this study,

Gear system with a high reduction ratio and self-locking
function were developed

Reduction gears with higher reduction ratios(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Developed gear system(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Overview of the system■ Developed reduction gears with self-locking function
It primarily consists of KHV-type planetary gears and three bevel gears
KHV-type planetary gears

Three bevel gears(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Overview of the system■ What is the self-lock function?
When torque is applied to the input shaft

When torque is applied to the output shaft

directly transmit

does not transmit

torquetorqueoutininoutlock

Amplified torque(due to the gearbox reduction)

When torque is applied to the output shaft,it does not transmit to the input shaft. (the gear system locks)(IDETC2023-118099)

Development of Reduction Gears With Self-Locking FunctionStructure■ Overview
B. Oscillating double‐sidedbevel gear

D. Sun gear
(External teeth gear)

Schematic diagram
EBC

D(Fixed to C)

Eccentricity(Collar )Output shaft

Input shaft

A. Fixed bevel gear
C. Revolving bevel gear
E. Ring gear
(Internal teeth gear)(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

A(Fixed to the case)Structure■ Reduction gears
KHV-type planetary gears is used for the developed gear system
Ring gear
Schematic diagram𝑖𝑧 : number of teeth of the sun gear𝑧𝟐 : number of teeth of the ring gear

Sun gear(IDETC2023-118099)

Development of Reduction Gears With Self-Locking FunctionStructure■ Eccentric mechanism
The eccentric mechanism of gear system consists 3 bevel gears
Collarrevolve gears eccentrically

Fixed bevel gear

Oscillating double-sided bevel gear Eccentrically revolved bevel gear
(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Motion■ Power transmission path

(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Motion■ Power transmission path
①Power input(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Motion■ Power transmission path
①Power input②Eccentrically revolved bevel geareccentrically rotates through the collar(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Motion■ Power transmission path
①Power input③Sun gear is fixed to
eccentrically revolved bevel gear

②Eccentrically revolved bevel gear
eccentrically rotates through the collar(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Motion■ Power transmission path
①Power input③Sun gear is fixed to
eccentrically revolved bevel gear

④Sun gear rotates ring gear
while eccentric→ Output speed is decelerated②Eccentrically revolved bevel geareccentrically rotates through the collar(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Motion■ Effect of eccentric mechanism

Sun gear holds its posture(Eccentric mechanism holds it)

Locks when torqueis applied from output
Eccentric mechanism(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Locking performance■ Torque Capacity
Torque capacity is determined by amount of eccentricity
Ring gear

amount of eccentricity

Sun gearAmount of eccentricity is small→ Moment to rotate from the output shaft become small(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

3D multibody dynamics model(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

3D multibody dynamics
The performance of the proposed locking gear was analyzed
and verified using three-dimensional (3D) multibody dynamics.

■ Multibody dynamics
 Multibody dynamics can analyse of the motion of groups ofinterconnected bodies that have forces acting on them
 RecurDyn, a general-purpose multibody dynamics software,
was used to develop the model.

(IDETC2023-118099)

Development of Reduction Gears With Self-Locking FunctionAnalysis model■ Fixed constraints

B. Oscillating double‐sidedbevel gear

D. Sun gear
(External teeth gear)

A. Fixed bevel gear
C. Revolving bevel gear
E. Ring gear
(Internal teeth gear)(IDETC2023-118099)

Development of Reduction Gears With Self-Locking FunctionAnalysis model■ Revolute, Cylindrical, Distance constraints
To reduce analysis load, bearings were modeled using these constraints

B. Oscillating double‐sided
bevel gear

D. Sun gear
(External teeth gear)

A. Fixed bevel gear
C. Revolving bevel gear
E. Ring gear
(Internal teeth gear)(IDETC2023-118099)

Development of Reduction Gears With Self-Locking FunctionAnalysis model■ Contact
The contact was calculated using the penalty method

B. Oscillating double‐sidedbevel gear

D. Sun gear
(External teeth gear)

A. Fixed bevel gear
C. Revolving bevel gear
E. Ring gear
(Internal teeth gear)(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Overview of the analysis■ To clarify locking performance
The following calculation conditions were used in the analysis
0 ~ 2 sec

2 ~ 4 sec

4 ~ 6 sec

6 ~ 8 sec

input : no rotation

input : rotation speed
up to 300 rad/s

input : rotation speed
is 300 rad/s

input : no rotation

output : torque loaded

output : torque loaded

output : torque loaded

Unlock(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

output : torque loaded

LockAnalysis results

Rotational speed [rad/s]■ Rotation speeds of the input shaft & output shaft
400
300
200
100
0-100-200
20
1510
50-5-10

Input shaft
0 ~ 2 sec
input : no rotation
output : torque loadedOutput shaft

01234Time [s]5678The rotation speed is 0 for both input and output
because rotation is not transmitted from the output shaft (it was locked)(IDETC2023-118099)

Development of Reduction Gears With Self-Locking FunctionAnalysis result

Rotational speed [rad/s]■ Rotation speeds of the input shaft & output shaft
400
300
200
1000-100-200
2015
1050-5-10

Input shaft
2 ~ 4 sec
input : rotation speed
up to 300 rad/soutput : torque loaded

Output shaft

01234Time [s]5678・ The rotation decelerated by the reduction section was transmitted to the output
・ Small vibrations were generated in output due to constraints and contact(IDETC2023-118099)

Development of Reduction Gears With Self-Locking FunctionAnalysis result

Rotational speed [rad/s]■ Rotation speeds of the input shaft & output shaft
400
300
200
1000-100-200
20151050-5-10

Input shaft
4 ~ 6 sec
input : rotation speed
is 300 rad/s

Reduction ratio = 60

Output shaft

01output : torque loaded

234Time [s]5678・ The rotation decelerated by the reduction section was transmitted to the output
・ Small vibrations were generated in output due to constraints and contact(IDETC2023-118099)

Development of Reduction Gears With Self-Locking FunctionAnalysis result

Rotational speed [rad/s]■ Rotation speeds of the input shaft & output shaft
400
300
200
1000-100-20020151050-5-10

Input shaft
6 ~ 8 sec
input : no rotation
output : torque loaded

Output shaft

01234Time [s]567

The torque was applied only from the output shaft→ it was locked again(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

8

Locking performanceof the gear system
has been confirmed

Shaft torque fluctuations■ The gear system has an eccentric mechanism→ Shaft torque fluctuations occur in rotational order
When a balancer is added to the sun gear…

Concentrated mass

Torque [Nmm]NoneAnchor shape balancer
Mounting mass

Anchor shape balancer
Frequency [Hz]By mounting mass, vibrations in primary rotation order can be reduced(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Conclusion(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Conclusion
 This study developed a gear system that has both ahigh reduction ratio and a self-locking function.
 When torque was applied to the input,
power was transmitted to the output shaft through the reduction gear.
 When torque was applied from the output,
it does not transmit to the input shaft. (the gear system locks)
 This study analyzed the operation and performance of thedeveloped gear system using a multibody dynamics model.
* This work was supported by JKA and its promotion funds from KEIRIN RACE(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Gear specifications of reduction section
60

Gear specifications of locking section(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function

Parameters involved in the contact calculations(IDETC2023-118099)

Development of Reduction Gears With Self-Locking Function