Patent GB-1467029-A (GB)
Title: Apparatus for controlling a brake power setting device of brake equipment
IPC: A61B5/22
Filed: 1974-04-17
Abstract: 1467029 Adjusting brake power; speed responsive braking M ENGERSTAM 17 April 1974 [19 April 1973] 16771/74 Headings F2E and F2F [Also in Divisions G3 and A6] Apparatus for controlling a brake power setting device 64 of brake equipment utilized for load tests (e.g. of motors) or for appliances for physical training (e.g. bicycle exercizers and/or ergonometers), and acting to maintain the brake power constant or to give it a programmed variation, includes a gear 5 which acts to mechanically compare two r.p.m.'s, one of which corresponds to the power actually existing in the brake equipment and the other of which corresponds to the desired power of the equipment to produce a third r.p.m. representative of the difference between the first and second r.p.m.'s which third r.p.m. is utilized for adjusting the brake power of said brake equipment whereby the desired and existing powers are brought into accordance. Fig. 1 illustrates in block diagram form an embodiment of the invention wherein a device 1 delivers the r.p.m. representing desired power and comprises a rotating device 1a e.g. a centrifugal governor, and a setting device 1b which may be an infinitely variable gear transforming the fixed output r.p.m. from the rotating device. Alternatively the setting device may consist of an r.p.m. adjusting member, e.g. a tensioning device for adjusting a spring counteracting the centrifugal force when the rotating device 1a is a centrifugal governor. The control of the output r.p.m. from device 1 may be accomplished by an adjusting member 2 or through automatic regulation from a programme-storing device 3. The r.p.m. representing the existing power is obtained from a mechanical, analogue integrator 4. The two r.p.m.'s are compared by differential gear 5 which delivers to its output shaft an r.p.m. which is proportional to, or is in another suitable, functional connection with, the difference between the existing and desired powers and this r.p.m. is fed to a mechanism 6 which controls the brake power on the braked element 7 of the brake equipment. In the embodiment of Figs. 2, 3 a constant r.p.m. is provided by means of a centrifugal governor whose pendulum arms 9 are attached to the hub of a friction disc 15 via joints 14, which disc 15 is rotatable with but axially displaceable on shaft 12. A draw spring 11 tends to displace the disc 15 axially towards a pulley 18 rotating freely about the shaft 12, whilst with the shaft 12 rotating the disc 15 is tested to be displaced from the pulley 18. The pulley 18 is driven by a belt 20 from a pulley 19 connected for example to the flywheel of a bicycle exercizer and by interaction between the disc 15 and pulley 18 the r.p.m. of the governor is maintained constant. The centrifugal governor via gear wheels 21, 22 is in driving engagement with an infinitely variable gear 23-28 whose output shaft 25 has a r.p.m. corresponding to the desired power is supplied to the sun wheel 57 of a planetary gear. The setting of the desired r.p.m. of shaft 25 is made by a pull rod 30 whose action can be varied by altering the position of a control lever 33. When the control lever is moved to a slot 37 in a plate 40, a cam 46 driven via gear wheels 48-51 by shaft 12 acts to vary the r.p.m. of the shaft 25 according to a programme determined by the shape of the cam 46. When the control lever 33 is moved to a slot 38, the r.p.m. of shaft 25 is maintained constant. To the outer wheel 58 of the planetary gear is supplied by means of a belt 59 the r.p.m. from a mechanical integrator which r.p.m. represents the existing power and incurs to the outer wheel 58 rotation in the opposite direction to that of sun wheel 57. The difference between the r.p.m.'s acts via an output shaft 61, a friction clutch 62 and a gear 63 on a brake power setting device 64 to bring the two r.p.m.'s into accordance whereupon planet carrier 60 and shaft 61 will come to a standstill. To disengage the automatic power control the lever 33 is moved into a slot 39 to cause disengagement of the friction clutch 62 and of disc 15 from pulley 18. The brake power may then be adjusted manually by rotating a handle 56 of lever 33. In the embodiment of Fig. 4, the output r.p.m. of a centrifugal governor 72 is made adjustable by rendering a pulley 74, co-operable with a friction disc 73, axially displaceable by a lever 76. The lever 76 may be moved to the position 76<SP>1</SP> where it is controlled by a cam 85 to vary the r.p.m. of the governor 72. A differential gear 86 compares the r.p.m. from the governor 72 representing desired power with the r.p.m. from the mechanical integrator representing actual power. The automatic power control may be disengaged by a lever 93, and when such a disengagement has been made the brake power can be adjusted by means of a knob 96. Fig. 5 (not shown), illustrates a differential gear device connected to the rotating element of the brake equipment which acts to measure how large the driving power is that is utilized by the control device at every moment to correct the integrand in the power measuring integrator. The power control device can be provided with devices to indicate, for instance optically, a certain power or change of power.