Patent GB-1210688-A (GB)
Title: A step-by-step advance device for programmers
IPC: F16H29/00
Filed: 1967-12-22
Abstract: 1,210,688. Variable-speed ratchet gear; detent brakes. CROUZET. 22 Dec., 1967 [23 Dec., 1966; 18 April, 1967], No. 58380/67. Headings F2D and F2E. [Also in Division H1] An intermittent drive for a domestic washing machine programmer having a block 6 of rotary cams to actuate electrical contacts comprises a variable-speed ratchet gear having a continuously rotating input member 7 coaxial with the cam block 6 and carrying a pawl 12 which orbits round a ratchet wheel 6a integral with the cam block 6, movement of the pawl 12 into and out of driving engagement with the ratchet wheel 6a being controlled by a fixed cam 13 having a generally circular internal cam surface 13c coaxial with the input member 7. Input member 7 and cam block 6 are freely rotatable on a fixed shaft 5, and serve to axially locate the fixed cam 13. The cam block 6 is held against rotation between drive steps by a detent device comprising a crown wheel 10 keyed to the cam block 6 and urged by a spring 11 into engagement with a fixed crown wheel 9. In Figs. 1, 2, the pawl 12, on a pivot pin 7a, includes a cam follower 12c and a resilient tail 12b bearing on an annular surface 6b of the cam block. When the follower 12c enters a notch 13d or 13e of the fixed cam 13, the pawl nose 12a briefly engages the ratchet wheel 6a to advance it one step. A spring 13g urges a mask 14b on an arm 14 pivoted at 4 into a position masking the notch 13e, a cam 6d on the cam block 6 acting on a follower 14a to move the mask 14b clear of the notch 13e during parts of the programme cycle to double the speed of the cam block. More than one notch 13e may be used, notches 13d, 13e being equally spaced round the surface 13c. A mask 15a on the armature 15 of a solenoid 16 masks the notch 13d when a thermostat energizes the solenoid, to prevent drive to the cam block 6 when a temperature is not at a required value. In Fig. 4 (not shown) the pawl (12) is resiliently cantilevered from a stud (7<SP>1</SP>a) on the input member (7) by means of its tail (12b), the follower (12c) and nose (12a) being formed on the free end of the tail (12b). Parts (15a) of armature (15) and (14b) of arm (14) form retractable projections on the cam surface (13c) which act on the follower (12c) to cause the pawl nose (12a) to engage the ratchet wheel. In Fig. 5 (not shown) the pawl has no resilient part and is positively controlled. A second follower (12<SP>11</SP>c) on the pawl engages a projection (17a) on one end of a centrally pivoted lever (17) to force the first follower (12<SP>1</SP>c) into the notch (13d). A mask (17b) for the notch (13d) is formed on the other end of the lever (17), which is pivoted to the armature (15). Similarly the arm (14<SP>1</SP>) carries a projection (14<SP>1</SP>b) which acts in conjunction with a notch (13<SP>1</SP>f). In a three-speed ratchet gear, Fig. 6, cams 6d, 6<SP>1</SP>d, S<SP>11</SP>d act on a follower 24a to move a forked member 24 transversely of the fixed cam 13. In a first position, notches 13e, 13e<SP>1</SP>, 13e<SP>11</SP> are masked by the member 24. In a second position, as shown, the notch 13e is uncovered, and in a third position pins 27, 28 cam the arms of member 24 apart so that notches 13e<SP>1</SP>, 13e<SP>11</SP> are also uncovered. Pins 25-27 guide the member 24. The tail 12b of the pawl engages an abutment 7b on the input member 7. In Fig. 7 (not shown) ratchet teeth (6a) are formed on the inner surface of cam drum (6), and a separate, centrally pivoted resilient member acts on the pawl to urge it against the fixed cam surface 13c.