Patent GB-191204888-A (GB)
Title: Improvements in Variable Speed Gear.
Inventor: MANLY CHARLES MATHEWS
IPC: F16H39/20
Filed: 1912-02-27
Granted: 1913-01-16
Abstract: 4888. Manly, C. M. Feb. 27. Multiple-acting piston pumps; stroke, varying. -A variable-speed gear of the piston-and-cylinder pump and motor type is constructed with the following features. (1) A variable - throw crank - shaft supported on both sides of the crank-pin, (2) balanced rotating parts, (3) a fluid - pressure - opera t e d adjusting - mechanism for the strokevarying device in which the fluid from the main circuit of the gear is used when available for adjusting, but which is provided with an auxiliary power - operated mechanism for actuating the adjusting - mechanism, (4) a control-valve mechanism for the adjusting - mechanism in which the valves are mounted in a single block detachable as a unit from the pump casing, and (5) a bypass valve between the two sides of the fluid circuit. In Fig. 1 the pump P is connected to the motor M through the manifold 47. The pump comprises, as shown in Fig. 2, a casing 10 having five radial cylinders 11 and five radial valve chambers 12 connected to the respective cylinders by channels 13. The connecting-rods 15 of the pistons are connected to the sleeve 17 rotatably mounted on the adjustable crank. The crank comprises a fixed pin 19 secured to the shaft 18, and a rotatable eccentric bush 20 mounted on the pin 19. The bush 20 and pin 19 are of equal eccentricity. The valves 33 are provided with middle heads 34 spaced to close exactly the channel 13 and control the opening from the manifolds 47, 48. The motor shown in Fig. 3 is of similar construction to the pump, and may have a fixed or variable crank. The edges of the pump and motor valves are made with notches to effect a more gradual opening and closing. The eccentric bushing 20 is formed with a spur-wheel 21 gearing with an internal wheel 22 formed on the end of a slotted sleeve 23 rotatable on the shaft 18. This shaft is formed with a screw-thread and carries a nut 26, which, on being moved to the right or left along the thread by the action of the hydraulic piston 31, causes the rotation of the sleeve 23 and thus of the eccentric bushing 20. When the bushing is adjusted around the crank-pin, the line of the crank arm of the composite crank moves angularly through one-half of the angular adjustment of the bushing, as shown in Fig. 17. In order to preserve the proper timed relation of the valves 33 and piston 14, the valves are operated by a pin 50 of fixed eccentricity relative to the centre of rotation but connected to the bushing 20 so as to be angularly adjusted at one-half the rate of adjustment of the bushing. The extension 51 of the crank-pin 19 is fitted with a fixed eccentric sleeve 52 so positioned that its surface is concentric with the shaft 18. Rotatably adjusted on the sleeve 52 is a thimble 54, from which projects the crank - pin 50. The end of the thimble adjacent to the bushing 20 is formed with a flange to which is attached a plate 55, Fig. 14, having transverse guideways in its opposite faces at right-angles to each other, in which shoes 56, 57 respectively are slidably mounted. The shoe 56 adjacent the bushing 20 is rotatably mounted on the end of the bushing, and the shoe 57 is mounted on an eccentric disk 58 attached to the eccentric bushing 20 so that its greatest diameter is opposite that of the bushing 20. When the bushing is adjusted, the double eccentric connexion acts as a two-to-one reducing-gear, but, when the crank-pin and bushing rotate as a whole, the thimble 54 is rotated in unison with them. When the bushing 20 is adjusted from one side of its zero position to the other, the line of the virtual crank arm is changed in relation to the pin 54 from 90 degrees behind to 90 degrees before, thereby reversing the direction of rotation of the motor. The crank-pin is balanced by weights 59, 61, and the eccentric bushing 20 is balanced by counterweights 63, 64. The valve crank-pin is also provided with balance weights. For adjusting the yoke 29, five horizontal cylinders 30 are arranged between the pump cylinders, and pistons 31 in these cylinders act through rods 32. formed in the casing 149 above the shaft 18 is a chamber 150 partially separated from the lower casing by a web 151, and housed in this chamber is a block 152 containing the control valves of the fluid-pressure adjusting - means. The pressure liquid for operating the adjusting-means is conveyed from the manifolds 47, 48 by pipes 65, 66, Fig. 1, to chambers 67, 68, Fig. 2, of the valve block. Fig. 8 shows the valve system arranged schematically. Fig. 7 is a part sectional plan view through the line 7-7 of Fig. 6. Liquid under pressure is fed to one of the chambers 67, 68, Figs. 2 and 8, and by means of the check valve 69 enters the pressure passage 71 and acts upon the spring-loaded double-headed piston valve 73. Below this valve is another externally-operated piston valve 75 controlling the passage of pressure liquid to the passages 83, 84 leading respectively to the front and back ends of the cylinders 30, Fig. 2. The valve 75 is operated by a rod 87, Figs. 1 and 7, connected at one end to the floating lever 88. This lever is attached at its middle point to the valve 75 and at the other end to the yoke 29, Figs. 2 and 7. When the rod 87 is adjusted, say to the left, the lever 88 actuates the valve 75, Fig. 8, to the left and permits of the passage of pressure fluid from the pipe 71. to the channels 83, at the same time allowing liquid to pass from the channel 84 to the low-pressure passage 72 and through the check valve 70 to the low-pressure side of the circuit. The resulting movement of the pistons 31 and yoke 29 causes the return of the valve 75 to its closed position by means of the floating lever 88. To effect the adjustment of the yoke when there is no pressure in the circuit, a small gear pump 90, Fig. 6, driven from the shaft 18 is used. The main purpose of this pump is to collect leakage. From the pressure side of the pump. a pipe 92, Figs. 6 and 8, leads to a passage 93, Fig. 8, in the valve block, which passage connects with the valve 75 immediately near the low-pressure passage 77, and in the normal position of the valve the pump delivers into the passages 77, 72 and so to the low-pressure side of the circuit, while surplus fluid passes through a low-pressure relief valve 94 into a pipe 95, Figs. 6 and 8, which joins the suction pipe 91, Fig. 6. To permit the fluid from the pump 90 to be used to adjust the yoke 29, the passage 93 is provided with a branch 96 leading to the valves 73, 75, so that, when the latter is moved, liquid may flow to either of the channels 83, 84. Since the pressure determined by the valve 94 is not sufficient to operate the stroke-adjusting mechanism, the valve 75 when moved closes the communication between the passages 93, 77, and the only outlet for the fluid is through the high-pressure relief valve 97, Fig. 8; hence the pressure in the pump will rise sufficiently high to operate the stroke mechanism. As soon as the pump P has some stroke, the pressure rises, operates the valve 73, and establishes communication between the passages 96, 77. To prevent damage to the valves 69, 70 due to pounding, these are formed with cylindrical heads closing the valve bore and with stem extensions working in cavities at the bottom of the fluid passages. The cylindrical head is slightly longer than the sliding portion of the stem so that the latter leaves its cavity, which becomes filled with liquid and serves as a dash-pot on the reseating of the valve. To permit the pump and motor to be disconnected, and to prevent damage due to excessive pressure, a by-pass and safety-valve are provided as shown in Fig. 16 between the passages 47, 48. The valve 102 is tubular and has a head 103 located between the passages 100, 101, and is operated by an extension 104. Within the bore of the valve is a differential valve 105, the size of the middle head 106 of which is between that of the two end heads. Pressure fluid acts on either side of this head through apertures in the valve 102 and tends to move the valve 105 to the left relatively to the surrounding valve against the action of a spring 107.