| 摘要 |
1,240,328. Rotary positive-displacement pumps; jet pumps. ROBERT BOSCH G. m.b.H. Aug.14, 1968 [Aug. 23, 1967], No.38773/68. Headings F1E and F1F. A supercharged hydraulic rotary pump has a cylindrical rotor 20 with outwardly-sliding radialvanes 24 engaging with an abutment ring 13 that is held against an end cover 11 by the pressure of a spring 16 and fluid in an outlet, or pressure, chamber 27 acting on a check-plate 14. The chamber 27 is connected to an outlet bore 48 by a throttling bore 46 and a larger bore 47 to which a chamber 45 for a spring-loaded nozzle 39 is also connected by way of a bore 50. The incoming fluid passes to the working chambers between the vanes through bores 37, 36, a jet pipe 33, the nozzle 39 and a bifurcated-diffuser channel 51. At low rotor-speeds the nozzle abuts the jet pipe; and when the speed rises the pressure in the chamber 45 becomes appreciably less than that in the chamber 27 due to the throttling action of the bore 46, thus causing the nozzle to retract and a proportion of the outgoing fluid to recirculate. Extra fluid is drawn through the jet pipe by the recirculating fluid and thereby prevents cavitation in the working chambers. The outer surface of the jet pipe may be tapered or straight, Figs. 6 to 7a (not shown). Excess pressure in the bore 47 is relieved by way of the chamber 45, a spring-loaded valve, Fig. 4 (not shown), in a bore 57, and the bore 36. |
