Method of testing vehicle parts

• US 5,880,381 A
• Filed: 12/12/1996
• Issued: 03/09/1999
• Est. Priority Date: 12/12/1996
• Status: Expired due to Fees

• Current Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Sathe, Prakash T.
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): FAYYAZ, NASHMIYA SAQIB
• Application Number:
  US08/764,558
• Time in Patent Office: 817 Days
• Field of Search: 73/865.6, 73/118.1, 73/808, 73/811, 73/117.1, 73/117.2, 73/117.3, 73/865.9
• US Class Current: 73/865.6
• CPC Class Codes: G01M 13/027 Test-benches with force-applying means, e.g. loading of drive shafts along several directions

Abstract

A block cycle of stress-inducing test conditions is repeatedly applied to a vehicle part (302) on a test stand (266). The number of applications of the block cycle is predetermined such that the cumulative test conditions applied to the vehicle part (302) correspond to actual driving conditions previously experienced by one or more prototype vehicle parts (200) throughout a predetermined number of driven miles. When the repetitive block cycles have been completed, the vehicle part (302) is inspected to determine an induced degree of deterioration corresponding to the predetermined number of driven miles. The induced degree of deterioration forecasts actual deterioration expected for a plurality of duplicate vehicle parts under actual driving conditions in vehicles driven the same number of miles.

Claims

1. A method comprising the steps of:

applying cumulative test conditions to a sample vehicle part on a test stand by applying a block cycle of test conditions a plurality of times, said plurality of times being predetermined such that said cumulative test conditions correspond to recorded actual driving conditions previously found to cause a measured degree of deterioration in one or more prototype vehicle parts throughout a predetermined number of driven miles; and

subsequently inspecting said sample vehicle part to determine an induced degree of deterioration caused by said cumulative test conditions upon said plurality of applications of said block cycle, whereby said induced degree of deterioration corresponds to said predetermined number of driven miles and thus forecasts deterioration to be experienced by duplicate vehicle parts upon use of said duplicate vehicle parts in vehicles throughout said predetermined number of driven miles.

2. A method as defined in claim 1 wherein said block cycle of test conditions comprises an abridged schedule of real time recordings of actual driving conditions experienced by said one or more prototype vehicle parts throughout said predetermined number of driven miles, said abridged schedule of real time recordings representing actual driving conditions that are selected and compiled in distinction from other actual driving conditions.

3. A method as defined in claim 1 wherein said block cycle of test conditions includes mechanical loads, thermal loads, and stress-inducing environmental factors that occur in said block cycle simultaneously.

4. A method as defined in claim 1 wherein said induced degree of deterioration comprises wear at an interface of two relatively movable portions of said sample vehicle part.

5. A method as defined in claim 1 wherein said sample vehicle part is a hydraulic power steering gear.

6. A method as defined in claim 1 wherein said predetermined number of driven miles is at least approximately 100,000 miles.

7. A method comprising steps of:

recording actual driving conditions experienced by a prototype vehicle part during actual use in a test vehicle over the course of a predetermined number of driven miles;

inspecting said prototype vehicle part upon completion of said actual use to determine an actual degree of deterioration corresponding to said predetermined number of driven miles;

selecting and compiling a plurality of said recorded actual driving conditions to define a block cycle of corresponding test conditions comprising an abridged schedule of said recorded actual driving conditions;

applying said block cycle repeatedly to a duplicate vehicle part on a test stand, and counting the total number of applications of said block cycle, until said duplicate vehicle part experiences an induced degree of deterioration which is substantially the same as said actual degree of deterioration; and

recording said total number of said applications of said block cycle, whereby said total number of said applications of said block cycle can be used to cause another duplicate vehicle part to experience an induced degree of deterioration which is correlated to the actual use in the vehicle over the course of said predetermined number of driven miles.

8. A method as defined in claim 7 wherein said actual degree of deterioration comprises wear at an interface of two relatively movable portions of said prototype vehicle part.

9. A method as defined in claim 7 wherein said actual driving conditions include mechanical loads, thermal loads, and stress-inducing environmental conditions that are experienced by said prototype vehicle part simultaneously, and said block cycle includes corresponding mechanical loads, thermal loads, and stress-inducing environmental conditions that occur in said block cycle simultaneously.

10. A method as defined in claim 7 wherein said actual driving conditions include loads attributable to vehicle ignition starts and stops, said recording step recording said starts and stops, said block cycle including test loads having corresponding starts and stops.

11. A method as defined in claim 7 wherein said prototype vehicle part and said duplicate vehicle parts are hydraulic power steering gears.

12. A method as defined in claim 7 wherein said predetermined number of driven miles is at least approximately 100,000 miles.

13. A method comprising steps of:

recording actual driving conditions experienced by a prototype vehicle part during actual use in a vehicle over the course of a predetermined number of driven miles;

inspecting said prototype vehicle part upon completion of said actual use to determine an actual degree of deterioration corresponding to said predetermined number of driven miles;

compiling said recorded actual driving conditions to define a block cycle of corresponding test conditions; and

applying said block cycle to a duplicate vehicle part on a test stand a plurality of times so as to cause said duplicate vehicle part to experience an induced degree of deterioration which is substantially the same as said actual degree of deterioration, whereby said plurality of applications of said block cycle can be used to cause another duplicate vehicle part to experience said induced degree of deterioration which is correlated to the actual use in the vehicle over the course of said predetermined number of driven miles;

said actual driving conditions including mechanical loads, thermal loads, and stress-inducing environmental conditions that are experienced by said prototype vehicle part simultaneously, said block cycle applied to said duplicate vehicle part including corresponding mechanical loads, thermal loads, and stress-inducing environmental conditions that occur simultaneously;

said environmental conditions include the impingement of rain water, said recording step recording vehicle wiper switch starts and stops, said block cycle including water impingement test conditions having corresponding starts and stops.

14. A method comprising steps of:

recording actual driving conditions experienced by a prototype vehicle part during actual use in a vehicle over the course of a predetermined number of driven miles;

inspecting said prototype vehicle part upon completion of said actual use to determine an actual degree of deterioration corresponding to said predetermined number of driven miles;

compiling said recorded actual driving conditions to define a block cycle of corresponding test conditions; and

applying said block cycle to a duplicate vehicle part on a test stand a plurality of times so as to cause said duplicate vehicle part to experience an induced degree of deterioration which is substantially the same as said actual degree of deterioration, whereby said plurality of said applications of said block cycle can be used to cause another duplicate vehicle part to experience said induced degree of deterioration which is correlated to the actual use in the vehicle over the course of said predetermined number of driven miles;

said prototype vehicle part and said duplicate vehicle parts being hydraulic power steering gears, said predetermined number of driven miles being at least approximately 100,000 miles.