Control method for adjusting the transmission ratio of a CVT

US 6,311,113 B1
Filed: 02/16/2000
Issued: 10/30/2001
Est. Priority Date: 02/25/1999
Status: Expired due to Fees

First Claim

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1. Method for ratio control for a continuously variable belt drive transmission with electrohydraulic control by means of a control loop having a linear PID controller with the theoretical ratio of the variator (iv_theor.) as command variable, the actual ratio iv as control variable and the ratio-change speed as correcting variable wherein the correcting variable delivered by the PID controller is limited to limit values subject to the design for an upshift and a downshift, characterized in that a correction member is used which, taking into consideration internal and external system variables, corrects the generated pattern error with the aid of a physicomathematical pattern wherein to the equation based on the physicomathematical pattern $k$

(iv)·



iv

t=p2·

A2·

kp

ks-p1·

A1



with;

$\begin{matrix} k (iv) & ; & ratio - dependent damping coefficient \\ \partial iv / \partial t & ; & variable gradient (ratio gradient) \\ p_{1} & ; & control pressure primary side \\ p_{2} & ; & control pressure secondary side \\ A_{1} & ; & pulley surface primary side \\ A_{2} & ; & pulley surface secondary side \\ k_{p} k_{s} & ; & adjusting force ratio \end{matrix}$ a correction term $\frac{\partial iv}{\partial t} \rangle theor . corr$ is added and as standard for the ratio gradients the following equation is used;

$\frac{\partial iv}{\partial t} \langle theor . = \frac{1}{k (iv)} (p_{2} \cdot A_{2} \cdot k_{p} k_{s} - p_{1} \cdot A_{1}) + \frac{\partial iv}{\partial t} \rangle theor . corr .$

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Abstract

A method for ratio control for a continuously variable belt drive transmission with electrohydraulic control by means of a control loop with a linear PID controller with the theoretical ratio of the variator iv_theor. as command variable, the actual ratio iv as control variable and the ratio-change speed as correcting variable wherein the correcting variable delivered by the PID controller is limited to limit values subject to the design for an upshift and a downshift, a correction member is used which, taking into consideration internal and external system variables, corrects with the aid of a physicomathematical pattern the pattern error generated wherein to the equation based on the physicomathematical pattern $k (iv) \cdot \frac{\partial iv}{\partial t} = p_{2} \cdot A_{2} \cdot k_{p} k_{s} - p_{1} \cdot A_{1} with:$ $\begin{matrix} k (iv) & : & ratio - dependent damping coefficient \\ \partial iv / \partial t & : & variable gradient (ratio gradient) \\ p_{1} & : & control pressure primary side \\ p_{2} & : & control pressure secondary side \\ A_{1} & : & pulley surface primary side \\ A_{2} & : & pulley surface secondary side \\ k_{p} k_{s} & : & adjusting force ratio \end{matrix}$

a correction term $\frac{\partial iv}{\partial t} \rangle theor . corr .$

is added and as standard for the ratio gradients the following equation is used: $\frac{\partial iv}{\partial t} \langle theor . = \frac{1}{k (iv)} (p_{2} \cdot A_{2} \cdot k_{p} k_{s} - p_{1} \cdot A_{1}) + \frac{\partial iv}{\partial t} \rangle theor . corr .$

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6 Claims

1. Method for ratio control for a continuously variable belt drive transmission with electrohydraulic control by means of a control loop having a linear PID controller with the theoretical ratio of the variator (iv_theor.) as command variable, the actual ratio iv as control variable and the ratio-change speed as correcting variable wherein the correcting variable delivered by the PID controller is limited to limit values subject to the design for an upshift and a downshift, characterized in that a correction member is used which, taking into consideration internal and external system variables, corrects the generated pattern error with the aid of a physicomathematical pattern wherein to the equation based on the physicomathematical pattern $k$
- (iv)·
  
  
  
  iv
  
  t=p2·
  
  A2·
  
  kp
  
  ks-p1·
  
  A1
  
  
  
  with;
  
  $\begin{matrix} k (iv) & ; & ratio - dependent damping coefficient \\ \partial iv / \partial t & ; & variable gradient (ratio gradient) \\ p_{1} & ; & control pressure primary side \\ p_{2} & ; & control pressure secondary side \\ A_{1} & ; & pulley surface primary side \\ A_{2} & ; & pulley surface secondary side \\ k_{p} k_{s} & ; & adjusting force ratio \end{matrix}$ a correction term $\frac{\partial iv}{\partial t} \rangle theor . corr$ is added and as standard for the ratio gradients the following equation is used;
  
  $\frac{\partial iv}{\partial t} \langle theor . = \frac{1}{k (iv)} (p_{2} \cdot A_{2} \cdot k_{p} k_{s} - p_{1} \cdot A_{1}) + \frac{\partial iv}{\partial t} \rangle theor . corr .$
- View Dependent Claims (2, 3, 4, 5, 6)
- - 2. Method according to claim 1, characterized in that said correction member as input variable uses the difference between the theoretical value and the actual value of the ratio-change speed e_ivp and the gradient of said difference e_ivpp, and that the output signal is a correction value which is proportional to the sign subjected variables e_ivp and e_ivpp and is produced by means of a fuzzy, logical control mechanism.
  - 3. Method according to claim 2, characterized in that the following control mechanism has been used wherein each field of the table represents one rule with two premises each and the control conclusion is shown when the premises agree by the plotted numeric value (singleton) and the control premises are evaluated by “
    - fuzzy sets”
      
      ;
4. Method according to claim 3, characterized in that the numeric range of the singleton is kept between +100 and −
- 100.
5. Method according to claim 2, characterized in that for generalization of the control mechanism the input variables are passed over special filter steps so that a high-stop filtering is carried out.
6. The method according to claim 2, wherein the resting position (E_ivp=0 AND E_ivpp=0) of the ratio gradient is linked with the absolute control difference of the main control loop so that when change of the control difference of the main control loop is detectable, the start out of the resting position (E_ivp=0 AND E_ivpp=0) of the ratio gradient is accelerated whereby a better follow-up behavior is achieved wherein the control mechanism is complemented by adding the following rules:

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Current Assignee
Zf Transmission Technologies, LLC
Original Assignee
Batavia Transmission LLC (Ford Motor Company)
Inventors
Schwenger, Andreas, Piepenbrink, Andreas, Danz, Wolfgang
Primary Examiner(s)
Marmor, Charles A
Assistant Examiner(s)
Parekh, Ankur

Application Number

US09/505,096
Time in Patent Office

622 Days
Field of Search

701/57, 701/60, 701/61, 474/28, 474/18, 474/69
US Class Current

701/57
CPC Class Codes

F16H 61/66259 using electrical or electro...

Control method for adjusting the transmission ratio of a CVT

First Claim

3 Assignments

0 Petitions

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Abstract

133 Citations

6 Claims

Specification

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Control method for adjusting the transmission ratio of a CVT

First Claim

3 Assignments

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0 Petitions

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Accused Products

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Abstract

133 Citations

6 Claims

Specification

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Use Cases

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