Road simulator system with provision for engine degradation compensation

• US 3,926,043 A
• Filed: 04/24/1974
• Issued: 12/16/1975
• Est. Priority Date: 04/24/1974
• Status: Expired due to Term

• Current Assignee: Edward F. Miller, Richard A. Marshall
• Original Assignee: Edward F. Miller, Richard A. Marshall
• Inventors: Marshall, Richard A., Miller, Edward F.
• Primary Examiner(s): Myracle, Jerry W.
• Application Number:
  US05/463,470
• Time in Patent Office: 601 Days
• Field of Search: 73/117,116,134
• US Class Current: 73/116.06
• CPC Class Codes: G01M 17/0072 the wheels of the vehicle co-operating with rotatable rolls G01M17/022, G01M17/045, G01M17/065 take precedence

Abstract

Method and apparatus for simulating an extended road test on a vehicle, during which test the vehicle may degrade, wherein the vehicle is driven over a predetermined road course while the speed and throttle position thereof is recorded. The vehicle is subsequently operated on a dynamometer in a first simulated road test while the previously recorded throttle position and speed is maintained and the torque provided by the vehicle is measured and recorded. The simulated road test test is then repeated and the throttle position of the vehicle is readjusted to maintain the torque provided by the vehicle substantially similar to that recorded during the first simulated road test. Means are provided to readjust the speed of the vehicle to a value consistent with the torque provided thereby whenever the throttle position is adjusted to the limits of its travel. A frequency controlled feed-back system is provided to maintain accurate speed control of the dynamometer.

Claims

1. The method for simulating a road test of an accelerator controlled vehicle comprising the steps of:

road testing the vehicle to provide a road test record having signals representative of the speed of the vehicle and the corresponding position of the accelerator recorded thereon;

placing a driving wheel of the vehicle in contact with a traction roller of a dynamometer;

simulating a road test by playing back the road test record and adjusting the position of the accelerator in accordance with the position indicated by the accelerator position representative signal recorded on the road test record while simultaneously adjusting the mechanical load provided by the dynamometer traction roller to maintain the speed of the vehicle substantially similar to the speed indicated by the speed representative signal recorded on the road test record;

monitoring the torque provided by the vehicle during the road test simulation and recording a signal representative of the torque corresponding to each speed and accelerator position occurring during the road test simulation;

repeating the road test simulation while playing back the record torque representative signal and comparing the torque indicated by the recorded torque representative signal with the torque provided by the vehicle during the repeated road test simulation; and

adjusting the accelerator position of the vehicle during the repeated road test simulation as rEquired to maintain the torque provided by the vehicle substantially similar to the torque indicated by the recorded torque representative signal obtained during the road test simulation and to maintain the speed of the vehicle substantially similar to the speed indicated by the road test record.

2. The method recited in claim 1 wherein the step of providing the road test record includes the step of road testing a vehicle over a predetermined route and simultaneously recording signals representative of the speed of the vehicle and the corresponding position of the accelerator during the road test.

3. The method recited in claim 1 wherein said accelerator has a limited range of adjustment further including the step of adjusting the mechanical load of the dynamometer traction roller to the value of the torque provided by the vehicle whenever the position of the accelerator approaches a limit of the range thereof to thereby adjust the speed of the vehicle to a value consistent with the torque provided thereby.

4. The method recited in claim 1 wherein the traction roller has a mechanical load adjusting transducer connected thereto, said mechanical load adjusting transducer being controlled by an electrical control signal, wherein the step of monitoring the torque provided by the vehicle includes the step of monitoring the electrical control signal.

5. The method recited in claim 1 wherein the step of monitoring the torque provided by the vehicle includes the step of mounting a torque sensing transducer on a driving shaft of the vehicle and monitoring the signal provided by the torque sensing transducer.

6. A programmable chassis dynamometer system for conducting simulated road tests on a motor vehicle having accelerator means for adjusting the power output of the vehicle and power transmission means, wherein the vehicle operating speed, position of the vehicle accelerator means, and mechanical load applied to the vehicle by the dynamometer system are adjustable in accordance with a preprogrammed record, said system including in combination;

programming means for simultaneously providing three control signals representative of the vehicle operating speed, the position of the accelerator means, and the mechanical load to be applied to the vehicle;

accelerator control means electrically connected to said programming means and mechanically coupled to said vehicle accelerator means, said accelerator control means being responsive to the accelerator position representative control signal for adjusting the position of the accelerator means. mechanical loading means mechanically coupled to the power transmission means of the vehicle for placing a mechanical load thereon, said mechanical loading means including variable load means for varying the magnitude of the mechanical load provided by said mechanical loading means;

speed control means electrically connected to said programming means and said variable load means, said speed control means being responsive to the speed representative control signal for varying the magnitude of the mechanical load provided by the mechanical loading means to maintain the operating speed of the vehicle at a level determined by said speed representative control signal; and

load monitoring means electrically connected to said programming means and coupled to said accelerator means, said load monitoring means being responsive to the load representative control signal for adjusting the position of the accelerator means to maintain the mechanical load provided by said mechanical loading means at a level determined by said load representative control signal.

7. A system as recited in claim 6 wherein said accelerator means has a limited range of adjustment further including accelerator limit detector means coupled to said accelerator means and to said speed control means for varying the mechanical load provided by said mechanical load means to reduce the operating speed of the vehicle when the accelerator means reaches a limit of the adjustment range.

8. A system as recited in claim 6 wherein said speed control means includes tachometer means for providing a speed sensing signal having a frequency proportional to the vehicle operating speed mechanically coupled to said mechanical loading means, and frequency comparison means for comparing the frequency of signals applied thereto connected to said programming means and said tachometer means.

9. A system as recited in claim 8 wherein said speed control means includes second tachometer means mechanically coupled to said mechanical loading means.

10. A system as recited in claim 8 wherein said comparison means includes an up-down counter.

11. A system as recited in claim 10 wherein said comparison means includes a digital to analog converter.

12. A system as recited in claim 6 wherein said variable loading means is adapted to be energized by energizing current, and said load monitoring means includes means responsive to said energizing current connected to said variable load means.

13. A system as recited in claim 12 wherein energizing current responsive means includes a resistor connected in a series circuit with said variable load means.

14. A system as recited in claim 6 wherein said load monitoring means includes torque responsive means having an electrical parameter that varies in accordance with the amount of torque applied thereto mechanically coupled to said power transmission means.

15. A system as recited in claim 6 further including abnormal condition sensing means connected to said load monitoring means and said programming means, said abnormal condition sensing means being responsive to said load monitoring means and said mechanical load representative control signal for providing a signal indicative of an abnormal condition when the mechanical load provided by the mechanical loading means deviates from the mechanical load represented by the load representative control signal by a predetermined amount for a predetermined time duration.

16. A system as recited in claim 15 wherein said abnormal condition sensing means includes electro-mechanical switch means and a capacitor.

17. A programmable chassis dynamometer system for conducting simulated road tests on a motor vehicle having accelerator means for adjusting the power output of the vehicle and power transmission means, wherein the vehicle operating speed, position of the vehicle accelerator means, and mechanical load applied to the vehicle by the dynamometer system are adjustable in accordance with a preprogrammed record, said system including in combination:

programming means for providing a control signal representative of the position of the vehicle accelerator means and a digital control signal having a frequency representative of the operating speed of the vehicle;

accelerator control means electrically connected to said programming means and mechanically coupled to said vehicle accelerator means, said accelerator control means being responsive to the accelerator position representative control signal for adjusting the position of the accelerator means;

mechanical loading means mechanically coupled to the power transmission means of the vehicle for placing a mechanical load thereon, said mechanical loading means including variable load means for varying the magnitude of the mechanical load provided by said mechanical loading means; and

digital speed control means electrically coupled to said variable loading means for varying the magnitude of the mechanical load provided by said mechanical loading means to maintain the operating speed of the vehicle at a level determined by said speed representative digital control signal, said digital speed control means including digital tachometer means for providing a signal having a frequency proportional to the operating speed of the vehicle and frequency comparison means coupled to said tachometer means and said programming means for comparing the frequencies of the signals provided By said digital tachometer means and the digital control signal provided by said programming means.

18. A system as recited in claim 17 wherein said programming means includes means for generating a digital control signal comprising a wheel having second digital tachometer means mechanically coupled thereto, means responsive to said vehicle accelerator means for generating said accelerator position control signal and means for recording and playing back said digital control signal and said accelerator position representative control signal.

19. A system as recited in claim 17 wherein said frequency comparison means further include digital to analog conversion means for providing an analog signal having an amplitude proportional to the difference in the frequencies of the signals compared thereby.

20. A system as recited in claim 19 wherein said digital speed control means includes analog tachometer means for providing an analog signal having an amplitude that varies in accordance with the operating speed of the vehicle, and load control means connected to said variable load means, said load control means being responsive to the analog signals provided by said analog tachometer means and said digital to analog conversion means to vary the mechanical load provided by said mechanical loading means.

21. A system as recited in claim 20 wherein said digital speed control means includes an up-down counter.

22. A system as recited in claim 20 wherein said analog tachometer includes an alternating current producing tachometer and rectifier means for rectifying the alternating current produced thereby.

23. A system as recited in claim 20 wherein said load control means includes high pass filter means responsive to said analog tachometer for damping said variable load means.

24. A system as recited in claim 17 wherein said programming means further includes means for providing a third control signal representative of the mechanical load to be applied to the vehicle.

25. A system as recited in claim 24 further including load monitoring means coupled to said accelerator control means and said programming means, said load monitoring means being responsive to said third control signal for adjusting said accelerator means to maintain the mechanical load provided by said loading means at a level determined by said third control signal.

26. A system as recited in claim 25 further including means coupled to said load monitoring means and responsive thereto for rendering said system and said vehicle inoperative when the mechanical load provided by said loading means deviates from the level determined by said third control signal by a predetermined amount for a predetermined time duration.

27. A system as recited in claim 25 further including means responsive to the position of said accelerator means for readjusting the mechanical load provided by said loading means when said accelerator means reaches a predetermined position.