GB2252826A

GB2252826A - Operating load measuring mechanism

Info

Publication number: GB2252826A
Application number: GB9102870A
Authority: GB
Inventors: Elizabeth Josephine L Ferguson
Original assignee: Jaguar Cars Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 1991-02-12
Filing date: 1991-02-12
Publication date: 1992-08-19
Also published as: GB9102870D0

Abstract

The load required to operate a control element eg a car-door handle 23 is measured by hooking the sensing arm 39 of a load cell 35 to the element and displacing the cell 35 in a direction away from the element. A displacement transducer 40 senses cell displacement and an XY plot of load v. displacement is produced. The cell 35 is mounted on a screw-threaded arm 25 drivingly connected to an electric motor 29. <IMAGE>

Description

OPERATING LOAD MEASURING MECHANISM The invention relates to an operating load measuring mechanism and in particular, although not exclusively, to a mechanism for measuring the load required to operate the exterior door handle of a motor vehicle.

During development of new latch systems for motor vehicle doors, it is desirable to monitor the load required to operate the exterior door handle in order to release the door latch. Also for quality control purposes, it is desirable to test vehicles on the assembly line to ensure that the load required to release the door latch falls within preset limits.

EIitherto, the only means of measuring the load required to operate the door llalldle was to use a force gauge which was attached to the handle and pulled manually, the gauge giving only an indication of the force required.

The present invention provides a mechanism which will produce a full force profile throughout movement of the handle, so that in addition to the load that is required, smoothness of operation and other parameters may be monitored.

According to one aspect of the present invention a mechanism for measuring the operating load of a control element comprises; mounting means by which the mechanism may be located with respect to the control element; displacement means which may be secured to the mounting means, said displacempnt means including a component which may be moved relative to the control element; means for moving said component of the displacement means in controlled manner; means for connecting the movable component of the displacement means to the control element; a load cell being associated with the movable component of the displacement means to measure the force applied to the control element; and a displacement sensor being provided to monitor movement of the movable component of the displacement means.

With the mechanism described above, the displacement element may be driven to move the control element from a first position to a second position, the movement being monitored by the displacement sensor and the force applied to the control element being monitored by the load cell.

According to a preferred embodiment, the displacement means comprises a linear screw thread actuator having a screw threaded shaft and a nut formation, the nut formation being rotatable by means of an electric motor, through suitable reduction gearing to cause the shaft to move along its axis. A load cell is connected to the end of the screw threaded shaft, a bracket being secured to the load cell for engagement of the control element. The displacement sensor ;= preferably a displacement transducer giving a continuous signal indicative of the amount of movement of the screw threaded shaft.The outputs from the load cell and displacement transducer may be fed to an XY plotter or similar display and/or recording device to provide a profile of the force required to move the control element throughout its movement from its first position to its second position.

According to an alternative embodiment of the invention, the load cell is connected to a digital display to provide a read out of the force applied to the control element, the displacemont sensor being a switch which will indicate when tllo control element has reached its second position. Alarm means may also be operated by the signal from the load ell to give an indication that the force and/or rate of itlcrease of the force applied to the control element has exceeded a preselected maximum limit.

The mounting means by which the mechanism is located with respect to the control element, is preferably adjustable so that the line of action of the displacement means can be set as required, with respect to the control element.

The mounting means may be secured with respect to the control element by means of magnetic elements and/or tie wires.

An embodiment of the invention is now described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 illustrates a perspective view of a mechanism in accordance with the present invention, located with respect to the door handle of a motor vehicle, to measure the operating load required to release the door latch; Figure 2 is a plan vi of the mechanism illustrated in Figure 1, without the mounting means; Figure 3 is a side elation of tlie mechanism illustrated in Figure 2; and Figure 4 is a plot of force against displacement for a typical motor vehicle door handle.

As illustrated in Figures 1 to 3, the operating load measuring mechanism cc'0flprlses a base plate 10 which is mounted on four legs :11, 12, 13 and 14. The ends of legs 11 and 12 remote from the base plate 10 are interconnected by a magnetic pad 15. Legs 13 and 14 are provided with individual magnetic pads 16 and 17 at the ends remote from base plate 10. When the measuring mechanism is fitted as illustrated in Figure 1, the pads 15, 16 and 17 engage and are magnetically attracted to the door panel 18. A pair of tie wires 19 adjustable by means of turnbuckles 20 extend between the ends of legs 11 and 12 adjacent the base plate 10 and hook formations 21 which engage over the top of the door panel 18, to support the weight of the measuring mechanism.A soft padding material may be provided on the pads 15, 16 and 17 to prevent damage to the door panel.

The base plate 10 is connected to the legs 11, 12, 13 and 14 by means of pivotal clamping blocks 22, so that the orientation of base plate 10 and hence the line of action of the measuring inecInnism may be adjusted with respect to the door handle 23.

A linear screw thread actuator 25 is secured to the base plate 10. The actuator 25 comprises a screw threaded shaft 26 which engages a correspondingly screw threaded nut formation 27 rotatably mounted in bearings in a housing 28. The nut formation 27 is drivingly connected to an electric motor 9 through a suitable reduction gear box 30, so that tie motor will cause the nut formation 27 to rotate and interengagement of the threads of the shaft 26 and nut formation 27 will cause the shaft 26 to move linearly along its axis.

A load cell 35 of conventional design is pivotally connected to the end of shaft 26. A bracket formation 36 is secured coaxially of rod 26 to the opposite side of load cell 35 via a rod 37 and spherical bush 38. The bracket 36 has a lip formation 39 for engagement under the lower edge of door handle 23.

A displacement transducer 40 of conventional construction is mounted on the base plate 10, the operating rod 41 of the displacement traducer being connected to a plate 42 secured to the load cell 35.

As illustrated in Figure 1, the measuring mechanism is secured to the vehicle door 18 and the lip 39 of bracket 36 is located under tie lower edge of door handle 23.

The motor 30 is then driven to move shaft 26 so that the door handle 23 is opelled to release the door latch.

Signals from the lod cell 35 and displacement transducer 40 are fed to an XY plotter to provide a plot of force against displacement, as illustrated in Figure 4.

Various modification may be made without departing from the invention. For example, while it is advantageous to provide variable mounting means, if the measuring mechanism is to be used for one application only so that adjustment of the line of action will not be required, the mounting means may be of fixed construction. Also, means other than magnetic pads may be used to secure the mounting means in position. It will be appreciated, that while the measuring mechanism disclosed above is suitable for measuring the operating load of outer door handles of motor vehicles, it is also suitable for measuring the operating loads of the control levers, etc. of other mechanisms. The bracket 36 may be adapted for engagement of other forms of control element.

Claims

1. A mechanism for measuring tie operating load of a control element comprising mounting means by which the mechanism may be located with respect to the control element; displacement means which may be secured to the mounting means, said displacement means including a component which may be moved relative to the control element; means for moving said component of the displacement means in controlled manner; means for connecting the movable component of the displacement means to the control element; a load cell being associated with the movable component of the displacement means to measure the force applied to the control element; and a displacement sensor being provided to monitor movement of the movable component of the displacement means.

2. A mechanism according to Claim 1 in which the mounting means comprises a base plate mounted on legs by which the base plate may be supported on a surface which is fixed with respect to the control element.

3. A mechanism according to Claim 2 in which the base plate is adjustably mounted with respect to the legs so that the orientation of the base plate may be adjusted with respect to the control element.

4. A mechanism according to Claim 2 or 3 in which the legs are provided it magnetic pads by which the mounting means may be secured to a ferromagnetic support surface.

5. A mechanism according to any one of Claims 2 to 4 in which tie wires are provided to support the mechanism.

6. A mechanism according to any one of Claims 2 to 5 in which the displacement means is secured to the base plate.

7. A mechanism according to any one of the preceding claims in which the displacement means comprises a linear screw thread actllator.

8. A mechanism according to Claim 7 in which the screw thread actuator comprises a screw threaded shaft, the screw threaded shaft engaging a correspondingly threaded nut formation, the nut formation being rotatably mounted in a housing and means being provided to rotate the nut formation, so that interengagement of the screw threads will cause the screw threaded shaft to move axially.

9. A mechanism according to Claim 8 in which an electric motor is provided to rotate the nut formation.

10. A mechanism according to Claim 8 or 9 in which a load cell is pivotally connected to one end of the screw threaded shaft, a bracket being secured coaxially of the screw threaded shaft to the other side of the load cell for engagement of the control element.

11. A mechanism according to Claim 10 in which the displacement sensor is mounted between the base plate and the load cell.

12. A mechanism according to any one of the preceding claims in which the displacement sensor is in the form of a displacement transducer giving a continuous indication of movement or a switch giving an indication of a limit of movement.

13. A mechanism according to any one of Claims 1 to 11 in which signalsfrom the load cell and displacement sensor are fed to an XY plotter to provide a profile of the force required-to move the control element throughout its movement.

14. A mechanism according to any one of Claims 1 to 12 in which the signal from the load cell is fed to a digital display to provide a read out of the force applied to the control element.

15. A mechanism according to Claim 14 in which the signal from the load cell operates alarm means to give an indication that the force and/or rate of increase in force applied to the control element has exceeded a preselected maximum limit.

16. A mechanism for measuring the operating load of a control element substantially as described herein with reference to, and as shown in, Figures 1 to 3 of the accompanying drawings.