Patent GB-806061-A (GB)
Title: Improvements in or relating to fuel injection pumps
Inventor: FRIEDLANDER WILLIAM
IPC: F02M59/36
Filed: 1954-03-17
Abstract: 806,061. Fuel injection pumps. MONOCAM Ltd. March 17, 1955 [March 17, 1954], No. 7821/54. Class 102(1). [Also in Group XXIX] Construction. Pump cylinders 5 are disposed around and parallel with the housing 1 and accommodate pistons 7, each cylinder embodying radial bores 8 leading to a recess 10. A disc-shaped regulating member 13, which is disposed in the spill chamber 3, has a ring 14 secured to its lower face, the member 13 and ring 14 serving to position sleeves 17 that are a close sliding fit on the pistons 7, the sleeves 17 being capable of lateral but not axial movement with respect to the member 13. The pistons 7 incorporate axial bores 7a leading from their operative faces to radial bores 7b which are opened as the pistons move out of their sleeves 17 during delivery strokes. The pistons 7 pass through both oversize apertures 19 in an abutment 20 secured in the chamber 3, and a spring-loaded packing washer 21, which latter seals the chamber 3 from a compartment 2a that communicates with a cam housing 2 via a passage 24. The lower extremity of each piston 7 bears upon a sliding element 25 which supports rollers 26 for contacting a cam 27 rotatable within the housing 2 by means of an engine driven shaft 28. In the pump housing 1, is a further pump cylinder 30 connected by a channel 31 to a valve casing 32 having an inlet 33 from the fuel supply and a non-return valve 34 ; the casing 32 also contains a cylinder 35 supplied from the inlet 33 by ducts 36, 37 and co-operating with a priming piston actuated by a handle 39. Duct 36 and housing 2 are both connected to a non- return valve leading to the recess 10 through a filter, not shown. Within the cylinder 30 is a hollow piston 40 having a spring-loaded rod 41 operable by an extension 42 of a pin 43 which supports one of the rollers 26. A spigot 52, which slides in a liner 51 in a central aperture in the abutment 20, has the inner edge of a diaphragm 55 secured thereto the outer rim of which is fixed to the abutment 20 thereby providing a chamber 57 that is constantly open to the compartment 2a via bores 53, 54 in the spigot. The enlarged inner end 11 of a bore 11a in the housing 1 is fitted with a sleeve 58 through which the stem 12 of the member 13 extends with a sliding fit, the stem having a bore 59 opening into the bore 53 by way of a passage 60 in the member 13, the passage 60 communicating with the spill chamber 3 by way of radial ports 62. To provide for manual adjustment of the member 13 the stem 12 has an extension sleeve 63 that is loaded by a spring 65 to urge the stem 12 away from the position corresponding to engine idling. The outer end of the bore 11a is closed by members 69 and 69b which constitute a reservoir for fuel that has leaked from the spill chamber 3. A throttle pin 66 with a sliding fit in the bore 59 extends into the passage 60 and is loaded by a spring 68 so that relative movement of the pin 66 and stem 12 will vary the loading of the spring 68 and hence alter the protrusion of the pin into the passage 60 to modify the resistance offered to fuel flowing therethrough. The outer end of the pin is surrounded by a spring 70 that tends to withdraw it from the passage 60. In a modification, Fig. 4 (not shown) the diaphragm 55 and bores 54 are dispensed with, the stem 12 embodying a flat part whereby the interior of member 69b is in free communication with the spill chamber 3 whilst the stem 12, member 13, ring 14 and spigot 52 constitute a piston which takes the place of the diaphragm. In a further modification, Fig. 5 (not shown) the spring 68 is in two parts which act separately. Operation-General. The axial position of the member 13 controls the point at which the piston bores 7b clear the sleeves 17 thereby determining the effective length of pump stroke and regulating engine speed. Fuel from the bores 7b spills into the chamber 3 and tends to pass into the compartment 2a via the constriction between the passage 60 and the frustoconical end of the throttle pin 66, the resistance offered being dependent upon the protrusion of the pin into the passage and the effective crosssection of the latter ; such resistance causes a pressure build up in the chamber 3 which is a function of the speed and loading of the engine and the degree of constriction in the passage 60 so that upon setting the pin 66 to a given position by means of a pedal, not shown, for example, the spring 68 will correspondingly move the member 13. Constant engine speed. If, due to loading, for example, the engine speed is reduced below that set the pressure in the chamber 3 will drop and produce a corresponding drop in the pressure difference across the diaphragm 55 which will therefore actuate the member 13 to increase the delivery of pistons 7 to oppose the speed variation, which movement of the member 13 slightly reduces the loading of the spring 68 and therefore increases the resistance to fuel flow in the passage 60 so tending to increase the pressure differential across the diaphragm 55 thereby producing stabilizing effect and preventing hunting. The governing action is independent of variation in the fuel pressure supplied to the compartment 2a. In a further modification, Fig. 3 (not shown) the stabilizing effect is not produced. Varying engine speed. When it is necessary to vary the engine speed the throttle pin 66 is adjusted accordingly thereby setting the member 13 to a new axial position determined by the balance between the loading of the spring 68 and the pressure difference across the diaphragm 55. Facilitating engine starting. Axial movement of the member 13 beyond the position shown is prevented by a stop 72 on the latter abutting an extension 73 of a spindle 74 which may be rotated out of engagement with the stop 72 to increase the effective stroke of pistons 7 when starting a cold engine. Modified form. In the modified construction, Fig. 5 (not shown) the first spring part has no effect on the member 13 when the pump is set for engine idling whilst the second spring part tends to urge the member 13 toward the position for maximum pump delivery. If the pin 66 is moved upwardly to reduce the resistance offered by the passage 60 of the loading on the second spring part is increased. Further upward movement of the pin causes the first spring part to assume effective control. At low engine speeds variations in the setting of the pin 66 produce simultaneous variations in the resistance offered to the fuel flow and the loading of the second spring part, whereas at higher speed variations in the setting of the pin merely control the resistance offered by passage 60. The spill chamber may communicate with the low pressure side of the pump by way of a passage in the member 13 and a flat or recess in the pin 66 to thereby provide a passage in parallel with the main constriction. Specification 727,391 is referred to.