Patent GB-1262022-A (GB)
Title: Fluid pressure governor valve
IPC: G05D13/00
Filed: 1970-06-12
Abstract: 1,262,022. Change-speed control; valves. NISSAN MOTOR CO. Ltd. 12 June, 1970 [26 June, 1969 (2)], No. 28547/70. Headings F2D and F2V.  A two-stage fluid pressure unitary-constructed governor 10 for providing a pressure signal, dependent on the speed of rotation of an output shaft, in a fluid pressure control system of an automatic change-speed power transmission (not shown) for a motor-vehicle, comprises primary and secondary spring-loaded centrifugal valve elements 13, 14, the latter secondary element 14 of which is slidably mounted within the primary element 13 which has stepped lands 20, 21 and is slidably mounted in a governor body 11 having a correspondingly stepped bore, whereby line pressure supplied at a port 17 is regulated by the primary and secondary elements 13, 14 to provide a governor pressure at an outlet 16, the secondary element 14 delaying the opening of the governor pressure outlet port 16 by the primary element 13, whereby the two-stage effect illustrated in Fig. 7 is obtained, i.e. no governor pressure is available until a predetermined output shaft speed (e.g. 500 r.p.m.) is reached, at which point a set governor pressure is instantly provided after which the governor pressure rises according to output shaft speed in the usual parabolic manner. As shown, with the output shaft stationary, the primary and secondary elements 13, 14 adapt the positions shown in Fig. 1 under the actions of the springs 26, 28. When the output shaft is rotated at low speeds, line pressure at port 17 is introduced into an outer chamber 13b via vents 23, 27 in the primary and secondary elements 13, 14 causing these elements to jointly move inward toward a retaining circlip 19, against the combined effect of centrifugal loading and spring 26, whereby the primary element 13 seats on the circlip 19 as shown in Fig. 2. As the speed of the output shaft increases (i.e. to about 500 r.p.m.) the secondary element moves centrifugally outwardly, against its spring 28, exhausting the chamber 13b via vents 24, 27 in the elements 13, 14 to an exhaust port 18, whereby the primary element 13 is moved outwardly by the combined spring (26) and centrifugal force acting thereon such that line pressure at 17 is immediately regulated to provide a governor pressure at outlet port 16 by the stepped lands 20, 21 on the primary element 13 co-operating with the inlet line pressure port 17 and a further exhaust port 15 as illustrated in Fig. 3, the governor outlet pressure at 16 being controlled in accordance with the line pressure at 17 acting on the differential area of the lands 20, 21 biasing the element 13 inwards to open exhaust port 15 and reduce governor pressure and opposed by the centrifugal effect biasing the element 13 outwards to close the exhaust port 15 and increase governor pressure. Figs. 4 to 6 (not shown) illustrate a modified governor valve in which the primary element 13 has three lands (20, 21, 30), the secondary element has two lands (32, 33) and only one exhaust port (15) is provided in the governor body 11. With the output shaft stationary, the primary and secondary elements 13, 14 adopt the positions shown in Fig. 4 under the actions of the springs 26, 28. When the output shaft is rotated at low speeds, line pressure at port 17 acts on the differential area lands 20, 21 to inwardly move the primary element 13, together with the secondary element 14, whereby the primary element 13 is balanced in the position shown in Fig. 5 by the exhaust port 15. Again, as before, when the speed of the output shaft increases (i.e. to about 500 r.p.m.), the secondary element 14 moves centrifugally outwardly to the position shown in Fig. 6, establishing communication between the vents 23, 24 of the primary element 13 through a passage (31) formed between the lands (32, 33) of the secondary element 14, whereby a regulated governor pressure is delivered through the passage (31) to the governor pressure outlet port 16, the stepped lands 20, 21 of the primary element, as before, co-operating with the inlet line pressure port 17 and the exhaust port 15, as in the Figs. 1 to 3 embodiment.