Back-to-back dog-cone clutch pairs assembled symmetrically about a translational detent to provide smooth gear engagement

Clutches

The block represents a double-sided synchronizer that contains two back-to-back dog clutches, two back-to-back cone clutches, and one translational detent. Shift linkage translation along the negative direction causes the clutches to engage the ring with hub A. Shift linkage translation along the positive direction causes the clutches to engage the ring with hub B. When the magnitude of the shift linkage translation is smaller than the cone clutch ring-hub gap, the synchronizer is in neutral mode and does not transmit torque.

The schematic illustrates a double-sided synchronizer in the
disengaged state. In this state, the ring (R) and hub (H_{A} and
H_{B}) shafts can spin independently at different
speeds. As the shift linkage (S) translates in the negative direction,
the faces of cone clutch A (CC_{A}) come into
contact. The friction in the cone clutch decreases the difference
in rotational speed between the shafts. When the force on the shift
linkage exceeds the peak force of detent (D), the dog clutch teeth
(T) can engage. The detent peak force should be such that the cone
clutch has enough time and normal force to bring the shafts to sufficiently
similar speeds to allow engagement of the dog clutch. Similarly, translating
the shift linkage along the positive direction allows the faces of
cone clutch B (CC_{B}) to come into contact, and
can allow the shaft of the ring to engage with the shaft of the hub
B (H_{B}).

The model implements two Dog Clutch blocks, one Translational Detent, and two modified Dog Clutch blocks. Refer to each block reference page for more information on the corresponding block function.

Connections R, H_{A}, and H_{B} are
mechanical rotational conserving ports that represent the ring (R),
hub A (H_{A}), and hub B (H_{B}),
respectively. Connection S is a mechanical translational conserving
port that represents the ring shifter handle.

Connections X1 and X2 are physical signal ports that output the shift linkage positions of the dog clutches and cone clutches, respectively. The following tables provide the values of X1 and X2 in common clutch engagement cases.

Dog Clutch State | X1 |
---|---|

Disengaged | 0 |

Fully engaged with hub A | Negative sum of ring-hub gap and tooth height |

Fully engaged with hub B | Positive sum of ring-hub gap and tooth height |

Cone Clutch State | X2 |
---|---|

Disengaged | 0 |

Fully engaged with hub A | Negative value of ring-hub gap |

Fully engaged with hub B | Positive value of ring-hub gap |

The values of X1 and X2 are zero when the synchronizer is fully disengaged. When the dog clutch is fully engaged with hub A, X1 is equal to the negative sum of its ring-hub gap and tooth height. When the dog clutch is fully engaged with hub B, X1 is equal to the positive sum of its ring-hub gap and tooth height. When the cone clutch is fully engaged with hub A, X2 is equal to the negative of its ring-hub gap. When the cone clutch is fully engaged with hub B, X2 is equal to its ring-hub gap.

The model does not account for inertia effects. You can add a Simscape™ Inertia block at each port to add inertia to the synchronizer model.

**Torque Transmission Model**Model used to represent torque transmission. The default setting is

`Friction clutch approximation - Suitable for HIL and linearization`

.The models provide the following common parameters:

**Clutch teeth mean radius**Mean radius of the clutch teeth. The parameter must be greater than zero. The default value is

`200 mm`

.**Maximum engagement speed**The relative angular speed between the ring and hub shafts above which the dog clutch cannot engage. The value is specific to the specific gearbox or transmission and must be minimized to avoid high dynamic impact during engagement. The default value is

`inf rad/s`

Friction clutch approximation - Suitable for HIL and linearization

**Contact surface maximum diameter**Outer diameter of the friction material linen that lines the cone clutch disks. The parameter must be greater than zero. The default value is

`150 mm`

.**Contact surface minimum diameter**Inner diameter of the friction material linen that lines the cone clutch disks. The parameter must be greater than zero, but smaller than the value of

**Contact surface maximum diameter**.**Cone half angle**Half angle of the clutch cone. The parameter must be greater than zero and less than or equal to 90°. The default value is

`12 deg`

.**Friction model**Specification method for the kinetic friction coefficient between cone clutch disks in slipping conditions. Options include:

`Fixed kinetic friction coefficient`

— Specify a single value for the kinetic friction coefficient. This value is constant across all clutch relative velocities. Selecting this option exposes an additional parameter,**Kinetic friction coefficient**.`Table lookup kinetic friction coefficient`

— Specify a lookup table with the kinetic friction coefficient values as a function of the clutch slip velocity. Selecting this option exposes additional parameters for the lookup table values and interpolation/extrapolation methods.

**Kinetic friction coefficient**Kinetic friction coefficient between the friction surfaces of the cone clutch disks. The parameter must be greater than zero. The default value is

`0.3`

.**Kinetic friction coefficient relative velocity vector**Vector with the clutch slip velocities at which to define the kinetic friction coefficient.

**Kinetic friction coefficient vector**Vector with the kinetic friction coefficient values corresponding to the clutch slip velocities in

**Kinetic friction coefficient relative velocity vector**.**Friction coefficient interpolation method**Method for calculating kinetic friction coefficients between lookup-table data points. Options include

`Linear`

,`Cubic`

, and`Spline`

.**Friction coefficient extrapolation method**Method for calculating kinetic friction coefficient values outside of the lookup-table data range. Options include

`From last 2 points`

and`From last point`

.**Static friction coefficient**Static friction coefficient between the friction surfaces of the cone clutch disks. The parameter must be greater than the kinetic friction coefficient. The default value is

`0.35`

.**Velocity tolerance**Relative velocity between the cone clutch disks below which the disk friction surfaces lock. Surface locking requires that the torque across the R and H rotational ports be smaller than the product of the effective radius, the static friction coefficient, and the applied normal force. The default value is

`0.001 rad/s`

.**Threshold force**Minimum value of the applied normal force for frictional torque transmittal to occur. If the value of the parameter exceeds the value of the applied normal force, no frictional torque is transmitted.

**Peak force**Peak shear force of the detent. The default value is

`500 N`

.**Notch width**Width of the region where the detent exhibits shear force. The default value is

`3 mm`

.**Viscous friction coefficient**Viscous friction coefficient at the contact surface of the detent. The parameter must be greater than or equal to zero. The default value is

`0.1 N/(m/s)`

.**Friction to peak force ratio**Ratio of the kinetic friction to the peak shear force of the detent. The parameter is used to set the value of the kinetic friction. The parameter must be greater than or equal to zero. The default value is

`0.01`

.**Friction velocity threshold**Velocity required for peak kinetic friction at the contact surface of the detent. The parameter ensures the force is continuous when the travel direction changes, increasing the numerical stability of the simulation. The parameter must be greater than zero. The default value is

`0.05 m/s`

.

**Ring-hub clearance when dog clutch disengaged**Distance between ring and dog clutch hub with the ring fully retracted. The parameter specifies the maximum travel distance if engagement requirements are not met. The parameter must be greater than the value of

**Ring-hub clearance when cone clutch disengaged**. The default value is`5 mm`

.**Tooth overlap to engage**Minimum value of the tooth overlap beyond which the dog clutch is considered engaged. The parameter must be greater than zero. The default value is

`3 mm`

.**Tooth height**Height of dog clutch teeth. The parameter must be greater than zero. The default value is

`10 mm`

.**Ring-hub clearance when cone clutch disengaged**Distance between the ring and cone clutch hub when the ring is fully retracted. The cone clutch can begin to engage once the slider has translated this distance. The ring can travel only this distance if the engagement requirements are not satisfied. The parameter must be greater than zero. The default value is

`3 mm`

.

**Dog clutch ring stop stiffness**Stiffness of the hard stops on both sides of the dog clutch ring. The model assumes the ring and stops behave elastically. Contact deformation is proportional to the applied force and the reciprocal of the contact stiffness. The value of the stiffness must be assigned with reference to the parameter

**Tooth overlap to engage**. Too low a stiffness could cause the deformation to exceed the required overlap and initiate a false engagement. The parameter must be greater than zero. The default value is`1e+6 N/m`

.**Cone clutch ring stop stiffness**Stiffness of the hard stops on both sides of the cone clutch ring. The model assumes the ring and stops behave elastically. Contact deformation is proportional to the applied force and the reciprocal of the contact stiffness. The parameter must be greater than zero. The default value is

`1e+6 N/m`

.**Dog clutch ring stop damping**Translational contact damping between the dog clutch ring and the hub. The value of the damping is inversely proportional to the number of oscillations that occur after impact. The parameter must be greater than zero. The default value is

`1e+3 N/(m/s)`

.**Cone clutch ring stop damping**Translational contact damping between the cone clutch ring and the hub. The value of damping is inversely proportional to the number of oscillations that occur after impact. The parameter must be greater than zero. The default value is

`1e+3 N/(m/s)`

.**Viscous friction coefficient**Viscous friction coefficient for the relative translational motion between the hub and the ring. The value of the parameter depends on lubrication state and quality of contacting surfaces. The coefficient must be greater than or equal to zero. The default value is

`100 N/(m/s)`

.

**Initial state**Beginning configuration of cone and dog clutches. Choices include:

`Cone clutch A and dog clutch A locked`

`Cone clutch A locked`

`All clutches unlocked`

`Cone clutch B locked`

`Cone clutch B and dog clutch B locked`

The default setting is

`All clutches unlocked`

.**Dog clutch initial shift linkage position**Initial position of the shift linkage section that attaches to the dog clutch. The value of the parameter has the following restrictions:

Dog Clutch State Parameter Restriction Dog clutch A Initially engaged Negative of the parameter value must be greater than the sum of parameters **Ring-hub clearance when dog clutch disengaged**and**Tooth overlap to engage**Dog clutch A Initially disengaged Negative of the parameter value must be smaller than the sum of parameters **Ring-hub clearance when dog clutch disengaged**and**Tooth overlap to engage**Dog clutch B Initially engaged Parameter value must be greater than the sum of parameters **Ring-hub clearance when dog clutch disengaged**and**Tooth overlap to engage**Dog clutch B Initially disengaged Parameter value must be smaller than the sum of parameters **Ring-hub clearance when dog clutch disengaged**and**Tooth overlap to engage**The default value is

`0 mm`

.**Cone clutch initial shift linkage position**Initial position of the shift linkage section that attaches to the cone clutch. The value of the parameter has the following restrictions:

Dog Clutch State Parameter Restriction Cone clutch A initially engaged Negative of parameter must be greater than the value of **Ring-hub clearance when cone clutch disengaged**Cone clutch A initially disengaged Negative of parameter must be smaller than the value of **Ring-hub clearance when cone clutch disengaged**Cone clutch B initially engaged Parameter must be greater than the value of **Ring-hub clearance when cone clutch disengaged**Cone clutch B initially disengaged Parameter must be smaller than the value of **Ring-hub clearance when cone clutch disengaged**The default value is

`0 mm`

.**Initial dog clutch ring-hub offset angle**Initial angle between the ring and hub portions of the dog clutch. To edit the parameter, you must set

**Dog Clutch**>**Torque transmission model**to`Dynamic with backlash`

. If the clutch is disengaged, the initial angle must lie in the range -π/N ≤ θ ≤ +π/N, where*N*denotes the number of teeth in the dog clutch. If the clutch is engaged, the initial angle must be in the range -δ/2 ≤ θ ≤ +δ/2, where*δ*is the backlash angle. The default value is`0 deg`

.

Port | Description |
---|---|

S | Conserving translational port that represents the shift linkage |

R | Conserving rotational port that represents the ring shaft |

HA | Conserving rotational port that represents hub shaft A |

HB | Conserving rotational port that represents hub shaft B |

X1 | Physical signal output port that measures the magnitude of the dog clutch translation |

X2 | Physical signal output port that measures the magnitude of the cone clutch translation |

Cone Clutch | Dog Clutch | Synchronizer | Translational Detent

Was this topic helpful?