GB1151524A - Improvements in or relating to Fluid Controllers - Google Patents

Abstract

1,151,524. Power steering. TRW Inc. 21 July, 1966, No. 32883/66. Heading B7H. [Also in Divisions F1, F2 and G3] A fluid control device for incorporation in a power steering system comprises a valve housing 34 in which is rotatably mounted a valve sleeve 62 within which is rotatably and slidably mounted a valve spool 90. An input shaft 118 connected to the steering wheel is rotatably mounted in a housing member 115 and is connected to the spool 90 so as to permit relative axial but not rotary movement thereto. Helices 107 and 108 on the spool 90 are engaged by balls 113 and 114 located in the sleeve 62 and a spring device permits limited relative movement between the spool 90 and sleeve 62. The stator 37 of an orbital and rotary control device is mounted at the left hand end of the valve housing 34, its rotor 39 being connected to a sleeve 55 having a pinion 54 which engages a ring gear 59 connected to the sleeve 62. A fluid inlet passage 57 is provided through the orbital and rotary device to the interior of the valve spool 90. A fluid return passage 104 leads to a reservoir 22, Fig. 6, and fluid passages 78 and 79, Fig. 12, respectively lead to the opposite ends of a work cylinder 25, operatively connected to the wheels 52 of a vehicle through a mechanism 53. A pump 24 supplies pressure fluid to the inlet passage 57. The spool 62 has a pair of working annuli 94 and 95 and a pair of return annuli 96 and 97 to co-operate through passages with working annuli 74 and 75 and return annuli 84 and 85 in the sleeve 62. The annuli 74 and 75 respectively register with the passages 78 and 79 connected to the working cylinder 25 and passages 84 and 85 are connected to the return passage 104. Opposite sides of a land 72 on the sleeve are connected to a series of passages, 68 and 70, respectively, whose opposite ends penetrate the internal surface of the sleeve in the same plane and are alternately arranged, Fig. 4. The stator 37 has 7 teeth and the rotor 6. The spaces A-G, Fig. 2, in the stator are connected to passages 43 to 49 which have terminal passages in the same plane as the outer ends of the passages 68, 70, Fig. 4. In the neutral position of the device, Fig. 1, supply passages 92 from the interior 91 of the spool 90 are blocked by the land 72 and the pressure fluid is exhausted through passages 105, annuli 100 and 101 and passages 87, 85 and 104. Upon a steering movement of the vehicle steering wheel, the shaft 118 is rotated whereby the spool 90 is rotated within the sleeve 62, with compression of the connecting spring, the sleeve 62 being prevented from rotation by virtue of its connection to the rotor 39. The balls 107, 108 act within the helices 110, 111 to cause axial movement of the spool so that pressure fluid is admitted to either series of passages 68 or 70. Fig. 1 shows a movement to the left, wherein the passages 68 are pressurized, three of which register with passages 43, 49, 48, Fig. 4. The rotor 39 is caused to rotate in an anti-clockwise direction whereby the fluid from spaces C, D and E is expelled through passages 45, 46, 47, through the passages 70 and thence through the annulus 95 into the working annulus 75 and through passage 79 to one side of the cylinder 25 to cause a steering movement of the wheels 52. Fluid from the other chamber of cylinder 25 is returned through passage 78 into passage 74 and thence through annuli 94, 96 and 84 to return passage 104. The anti-clockwise movement of the rotor 39 acts through the sleeve 55 and pinion 54 to rotate the ring gear 59 in a clockwise direction whereby the sleeve 62 is rotated and acts through the balls 107 and 108 to move the spool 90 axially and restore it to its neutral position, thereby providing a follow-up device. If the pump 24 fails, the device will function as a pump. Initial rotation of the steering-wheel will cause compression of the spring connection between the valve spool 90 and sleeve 62 with axial movement of the former to bring about the relative positions indicated above and thence, after maximum compression of the spring, the sleeve and spool are rotated in unison whereby the rotor 39 is driven through the gears 59 and 54 and sleeve 55, the fluid following the same paths as before, except that, the fluid in return passage 104 being at a higher pressure than in the centre 91 of the valve spool, a ball valve 148 is unseated and the expelled fluid from cylinder 25 is returned to the centre 91 of the valve spool. To prevent fluid leakage between that series of apertures 68 and 70 which is at high pressure and the adjacent groove 74 or 75 which is at low pressure during the operation, grooves 128 and 130 are provided with fluid passages through to the valve spool surface so that that groove, 128 or 130, becomes pressurized when the adjacent groove 74 or 75 is at low pressure and the other groove, 128 or 130, is put at low pressure. Similar grooves 134 and 136 are located between the grooves 74, 75 and the lowpressure grooves 84, 85. The grooves 134, 136 are constantly fed with high pressure liquid through a groove 151 and passage 140 and capillary devices 144 and 145. When the groove 74 or 75 is at high pressure, the adjacent groove 134 or 136 is also at high pressure, to prevent leakage, and when groove 74 or 75 is at low pressure, the adjacent groove 134 or 136 is opened to exhaust through passages 135 or 137. A closed centre valve spool, Fig. 11, is also described.