Patent GB-1481836-A (GB)
Title: Semi-automatic multi-ratio transmission
IPC: F16H61/02
Filed: 1974-10-08
Abstract: 1481836 Change speed control EATON CORP 8 Oct 1974 [9 Oct 1973] 43609/74 Heading F2D Automatic speed-responsive shift in a motor vehicle change-ratio transmission is subject to operator control which can restrict the shift to (a) upshift only, (b) downshift only and (c) in either direction to only a preselected ratio, and can also establish direct return to neutral from any ratio. Thus, having preselected, say, the highest ratio by a manual shift lever 11, Fig. 5, the control will automatically and successively upshift thereto and remain there, with downshift prohibited until the operator moves the lever to a lower ratio setting, whereupon automatic downshifts to, but not beyond, that setting will occur. Upshift and downshift speeds are identical, hysteresis being zero. In the example shown three forward ratios, reverse and neutral are established by energizing relays I, II, III, R and N, Fig. 5, from busbars 14, 32 which close respective contacts IC-7, IIC-9, IIIC-7 and RC-2 for energizing solenoid valves for the supply of ratio-establishing fluid pressure. The relays I, II &c. control additional contacts, e.g. IC-1 &c., bearing their designation, and additional relays U, D control contacts UC-1, DC-1 &c., permitting upshift and downshift respectively. Manual shift lever 11, Fig. 5, carries two contacts 12, 13 establishing the following circuits. Neutral.-With manual contact 12 on stud 17, 13 is unconnected and the relay N is energized to open normally-closed contacts NCl ...4 deenergizing all the shift relays R ... III. Reverse.-On stud 16 the manual contact 12 energizes the reverse relay R, provided that vehicle speed is below 3 m.p.h. to close a reverse inhibitor switch PS-R, the relay then remaining energized independently of speed through hold on contact RC-1 closed by the relay R. First ratio hold.-Manual contacts 12, 13 are on studs 18 and 21 respectively, the former at this time ineffective, the latter, through normally closed contacts IIC-3, IIIC-3 and NC-2, energizing the first ratio solenoid I and also closing a contact IC-3 establishing a first ratio hold circuit through normally closed contacts IIC-5 and IIIC-4. Automatic shifts.-Assuming the operator selects third ratio from rest by moving the manual contact 12 direct to the third ratio stud 20, on the way to which the second manual contact 13 makes a transient contact with the first ratio stud 21 which establishes and holds the first ratio relay I energized as above described. At the same time, the contact stud 20, through a contact IC-2, closed by the first ratio relay I, energizes the upshift relay U, closing contacts UC-1, UC-2. Automatic shifts are controlled by two output speed-pressure-responsive switches PS-A and PS-B, Fig. 4, which are initially closed and open for 1-2 and 2-3 upshift at the respective shift speeds (26 and 39À5 m.p.h.). 1-2 upshift occurs when the speed switch PS-A is opened at 26 m.p.h. to de-energize a speed-relay SL-1 which closes a contact AC, whilst the still closed speed switch PS-B continues to energize a relay B, which closes a contact BC-1 and opens BC-2. A speed relay SL-2 is thus energized which closes a speed contact S2-C, Fig. 5, which, through contact IC-4 (closed by relay I), upshift contact UC-1 (closed by relay U) and NC-3, energizes the second ratio relay II, which opens contacts IIC-5 and IIC-3 deÀenergizing the first ratio relay I, and closes a contact IIC-6 completing a second ratio hold circuit to the relay II. 2-3 upshift occurs when the speed switch PSB opens at the second ratio limit (39À5 m.p.h.) to de-energize the relay B, which closes a contact BC-2 and opens BC-1, de-energizing the relay SL-2 and energizing SL-3, which opens contact S2-C and closes S3-C, Fig. 5. With contact IIC-7 closed in second ratio and the upshift contact UC-2 also closed, this energizes the third ratio relay III which then completes a hold circuit by closing a contact IIIC-6, and breaks the second ratio hold circuit by opening a contact IIIC-5. At the same time the upshift relay U is de-energized by opening of the contact IIC-2. Third ratio now persists and downshifts, in response to successive closures of the speed switches PS-B, PS-A at the respective second and first speed limits, will be permitted only if the operator moves the manual lever 11 to the second or first ratio contact studs 19, 18, which energizes the downshift relay D, closing contacts DC-2, DC-1 preparing the respective 3-2 and 2-1 downshift circuits, the action being similar to that described for upshift. As in the case of upshift, if second ratio was selected, this would be established at the respective shift speed (39À5 m.p.h.) and there would then be no further shift down or up without driver permission. If first ratio was selected, 3-2 and 2-1 downshifts would occur automatically at the respective speeds and no further automatic shift would follow without driver permission.