Device and method for converting vehicle speed signals

• US 20030078702A1
• Filed: 10/18/2002
• Published: 04/24/2003
• Est. Priority Date: 10/19/2001
• Status: Active Grant

• Current Assignee: Kia Motors Corporation (Kia Corp.)
• Original Assignee: Kia Motors Corporation (Kia Corp.)
• Inventors: Park, Sang Bock
• Granted Patent: US 6,801,838 B2
• Time in Patent Office: Days
• US Class Current: 701/1
• CPC Class Codes: G01P 21/02 of speedometers
• CPC Class Codes: G01P 3/489 Digital circuits therefor

Abstract

The present invention relates to a device for converting vehicle speed signals characterized in that it includes a controller for converting vehicle speed signals which has a switch for controlling vehicle speed signals connected thereto and is mounted between a vehicle speed sensor and an electronic speedometer or tachometer. According to the present invention, it is possible to enhance the accuracy of measurement of vehicle speed, and to save separate costs for development of speed gear sets and simplify necessary specifications of a transmission.

Claims

1. A device for converting vehicle speed signals, comprising:

a speed gear set configured and dimensioned to be mounted between a drive shaft and a transmission of a vehicle;

a vehicle speed sensor connected to the speed gear set to generate pulse signals corresponding to a vehicle speed and transmitting said signals to an electronic speedometer or tachometer; and

a controller programmed to convert vehicle speed signals communicating with a switch for controlling vehicle speed signals, said controller being electrically mounted between the vehicle speed sensor and the electronic speedometer or tachometer.

2. The device of claim 1, wherein said switch controls calculation by the controller of the pulse frequency per unit speed based on a designated speed.

3. The device of claim 1, wherein the controller is programmed to execute steps comprising:

storing in a memory factors specifying the vehicle and device characteristics;

setting at least one of an input and an output reference pulse number based on said factors and on measured pulses; and

calculating a number of pulses to be output to the electronic speedometer or tachometer.

4. A method for converting vehicle speed signals in a vehicle having a drive shaft, a speed gear set and a speed sensor, the method comprising:

storing in a memory factors specifying the vehicle and device characteristics;

setting at least one of an input and an output reference pulse number based on said factors and on measured pulses; and

calculating a number of pulses to be output to the electronic speedometer or tachometer.

5. The method of claim 4, wherein:

said storing comprises storing a loaded tire radius, a final reduction ratio of the drive shaft, a gear ratio of the speed gear set, and a number of pulses per revolution of the vehicle speed sensor; and

said setting and calculating comprises;

setting a reference input pulse number in a unit time per unit speed;

setting a reference output pulse number per unit speed based on a specified output pulse number value;

measuring pulse signals input from the vehicle speed sensor;

calculating a vehicle speed by comparing the reference input pulse number with the number of pulses measured per unit time;

calculating the number of pulses to be output per unit time at the calculated vehicle speed; and

returning to measuring the number of pulses from the vehicle speed sensor after an output of pulse signals to an electronic speedometer or tachometer.

6. The method of claim 5, wherein the reference input pulse number is calculated according to the formula

K=□

2 R_w×

(1/R_a)×

(3600/100)×

R_s×

(1/N_p)

where K=reference input pulse number

R_w=loaded tire radius

R_a=final reduction ratio

R_s=speed gear ration

N_p=pulses per revolution.

7. The method of claim 6, wherein the vehicle speed is calculated according to the formula

8. The method of claim 7, wherein the number of pulses to be out put per unit time is calculated according to the formula:

N_out=V×

K_p

where N_out=number of pulses to be output per unit time

K_p=(1/60 kph)×

(a specified number of pulses corresponding to one revolution)×

(the specified reference pulse number value)×

(1/60).

9. The method of claim 8, wherein the specified output pulse number value is 637 rpm at 60 km/hour.

10. The method of claim 8, wherein the specified number of pulses corresponding to one revolution is 4.

11. The method of claim 4, wherein:

said storing comprises storing a designated speed for controlling vehicle speeds; and

said setting and calculating comprises;

setting a reference output pulse number per unit speed on the basis of a specified output pulse number value;

detecting whether a switch for controlling vehicle speed signals is “

ON”

;

if the switch for controlling vehicle speed signals is “

ON”

, measuring pulse signals which are input from the vehicle speed sensor, and setting a reference input pulse number per unit speed, and then detecting whether the reference input pulse number is set corresponding to the state of the switch for controlling vehicle speed signals is “

OFF”

;

if the reference input pulse number is not set, returning to the step of detecting a state of the switch for controlling vehicle speed signal; and

if the reference input pulse number is set, if the switch is not set to be the reference input pulse number, returning to the step of detecting a state of the switch for controlling vehicle speed signals; and

if the switch for controlling vehicle speed signals is set to be the reference input pulse number, measuring pulse signals or the number of pulses which are input from the vehicle speed sensor, calculating a vehicle speed by comparing the number of pulses measured and the reference input pulse number, calculating the number of pulses (frequency) to be output per unit time at the calculated vehicle speed, and returning to the step of detecting a state of the switch for controlling vehicle speed signals after an output of pulse signals to an electronic speedometer or tachometer.

12. The method of claim 11, wherein the reference input pulse number is calculated according to the formula:

K=V_ref/Nm

where K=reference input pulse number

V_ref=a stored designated speed

N_m=number of pulses measured per unit second.

13. The method of claim 12, wherein the pulse number to be output is calculated according to the formula:

N_outV×

K_p

where N_out=number of pulses to be output per unit time

Kp=(1/60 kph)×

(a specified number of pulses corresponding to one revolution)×

(the specified reference pulse number value)×

(1/60).

14. The method of claim 13, wherein the specified output pulse number value is 637 rpm at 60 km/hour.

15. The method of claim 13, wherein the specified number of pulses corresponding to one revolution is 4.