Test stand with an apparatus for calibrating a force-measuring device
A test stand encompasses a dynamometer, which is supported to oscillate about a main axis, from which a lever arm extends perpendicularly. For calibrating a force-measuring device, which is coupled to the lever arm, provision is made for a pneumatic cylinder as reference force-generating device. The reference force can be measured by a load cell and can be applied to the lever arm via a yoke. The force-measuring device, which is to be calibrated, the pneumatic cylinder, the load cell, and the yoke are disposed on the same side of the dynamometer and act on the same lever arm.
1. A force-measuring calibration test stand, comprising a load device:
comprising a housing and a main axis;
being supported at the housing; and
being operable to oscillate about the main axis;
a lever arm extending away from the housing perpendicular to the main axis;
a force-transmission device coupled to the lever arm and operable to transmit a force oriented perpendicular to the main axis and perpendicular to the lever arm;
a force-measuring device coupled to the lever arm by the force-transmission device; and
a force-measuring calibration device comprising:
a reference force-generating device operable to generate a reference force;
a reference force-measuring device coupled to the reference force-generating device and operable to measure the reference force generated; and
a reference force-transmission device coupled to the lever arm and operable to transmit the reference force to the lever arm
wherein the force-measuring device, the force-transmission device, the reference force-generating device, and the reference force-transmission device are on the same side of the housing relative to the main axis.
2. The test stand according to claim 1 , wherein the reference force-generating device comprises one of a pneumatic cylinder unit and a hydraulic cylinder unit.
3. The test stand according to claim 1 , wherein:
the load device is a dynamometer having a stator housing; and
the lever arm is fastened to the stator housing and extends perpendicular to the main axis.
4. The test stand according to claim 1 , wherein:
the lever arm has an outer end; and
the reference force-transmission device is at the outer end of the lever arm.
5. The test stand according to claim 4 , wherein the reference force-transmission device comprises a yoke.
6. The test stand according to claim 5 , wherein the yoke encloses the outer end of the lever arm.
7. The test stand according to claim 1 , wherein:
the lever arm has an outer end; and
the reference force-transmission device comprises a yoke enclosing the outer end of the lever arm.
8. The test stand according to claim 7 , wherein:
transfer pairs each comprising a knife edge and a knife edge support are respectively disposed above and below the lever arm between the yoke and the lever arm and are operable to transfer the reference force; and
one of:
the knife edge of each transfer pair is provided on the lever arm and the opposing knife edge support is provided on the yoke; and
the knife edge of each transfer pair is provided on the yoke and the opposing knife edge support is provided on the lever arm.
9. The test stand according to claim 7 , wherein:
the yoke comprises a rectangular frame enclosing the outer end of the lever arm;
a flange of a piece of foil is fastened respectively to the frame on at least one of the upper side of the frame and the lower side of the frame; and
an area of the piece of foil located between the upper and lower sides of the frame is fastened to the outer end of the lever arm.
10. The test stand according to claim 9 , wherein:
the lever arm has a frontal end; and
the piece of foil has:
an upper flange clamped to the upper side of the frame;
a lower flange clamped to the lower side of the frame; and
a middle area clamped to the frontal end of the lever arm.
11. The test stand according to claim 9 , wherein:
the frame has upper flange and a lower flange;
the lever arm has a frontal end;
the piece of foil is formed by two separate pieces of foil;
one of the pieces of foil is an upper piece of foil clamped between the upper flange of the frame and the frontal end of the lever arm; and
the other one of the pieces of foil is a lower piece of foil clamped between the lower flange of the frame and the frontal end of the lever arm.
12. The test stand according to claim 1 , further comprising:
a test stand base;
a support comprising a compensating device, being coupled to the test stand base, and supporting the reference force-generating device; and
the compensating device being operable to compensate for at least one of alignment errors and angle errors.
13. The test stand according to claim 1 , further comprising a control device operable:
to control the reference force-generating device; and
to effect one of:
a force higher than a nominal reference force temporarily in response to an adjustment of a desired nominal reference force when the reference force is increased; and
a lower force than the nominal reference force temporarily in response to an adjustment of a desired nominal reference force when the reference force is reduced.
14. A method for calibrating a force-measuring device in a test stand, which comprises:
providing a test stand comprising:
a load device supported to oscillate about a main axis, the load device having a housing;
a lever arm extending perpendicular to the housing of the load device;
the force-measuring device coupled to the lever arm;
a reference force-generating device disposed the same side of the housing as the force-measuring device and coupled to the lever arm; and
a reference force-measuring device disposed in a flux of force between the reference force-generating device and the lever arm and operable to measure a reference force generated;
generating the reference force with the reference force-generating device;
measuring the reference force with the reference force-measuring device;
measuring a force acting on the force-measuring device in the form of an actual force value;
determining a nominal force value that would have to apply to the force-measuring device due to a measured reference force and effective lever ratios; and
calibrating the force-measuring device by comparing the actual force value measured by the force-measuring device with the nominal force value.
15. The method according to claim 14 , which further comprises initially effecting an overshoot of the reference force beyond a desired reference force value when generating the reference force.
16. The method according to claim 14 , which further comprises controlling the reference force-generating device so that the lever arm is not loaded with a force from the reference force-generating device.