US3309996A

US3309996A - Liquid fuel injection pumps

Info

Publication number: US3309996A
Application number: US435416A
Authority: US
Inventors: Rosselli Andrew Carlo
Original assignee: CAV Ltd
Current assignee: CAV Ltd
Priority date: 1964-02-05
Filing date: 1965-02-26
Publication date: 1967-03-21
Anticipated expiration: 1984-03-21

Description

March 21, 1967 A. c. ROSSELLI 3,309,996

LIQUID FUEL INJECTION PUMPS Filed Feb. 26, 1965 2 Sheets-Sheet 1 March 21, 1967 c, oss 9 3,309,996

LIQUID FUEL INJECTION PUMPS Filed Feb. 26, 1965 2 Sheets-Sheet 2 u. J" 4v United States Patent 3,309,996 LIQUID FUEL INJECTION PUMPS Andrew Carlo Rosselli, Teddington, England, assignor to C.A.V. Limited, London, England Filed Feb. 26, 1965, Ser. No. 435,416 2 Claims. (Cl. 103-41) This invention relates to liquid fuel injection pumps for internal combustion engines and has for its object to provide such a pump in a convenient form.

According to the invention a liquid fuel injection pump comprises in combination a pump body, a cylindrical bore in the body, a co-axial cylinder at the inner end of the bore, an axially movable plunger in the bore, a piston formed or secured on the inner end of the plunger and acting within the cylinder, resilient means urging the plunger and piston in a direction out of the bore and cylinder respectively, said plunger and piston being adapted to be moved inwardly in timed relationship with an engine with which the pump is associated, an outlet passage at the outer end of the bore adapted for connection to a cylinder of the engine with which the pump is associated, a delivery valve in the outlet passage for preventing the flow of fuel from the outlet passage into the bore, a fuel inlet passage at the inner end of the cylinder adapted to be uncovered by the piston near the outward limit of its stroke, a transfer passage through which the inner end of said cylinder is in communication with a port in the wall of the bore intermediate the ends thereof, said port being positioned to be uncovered by the plunger as the latter nears the outward limit of its travel, valve means in the transfer pas-sage for preventing the flow of fuel from the bore to the-cylinder and for permitting the escape of excess fuel from the cylinder during inward movement of the piston, and a variable restrictor in the inlet passage, the arrangement being such that, in use, as the plunger and piston are moved outwardly by the resilient means voids will form in the fuel remaining in the bore and the cylinder until the piston uncovers the inlet passage to allow fuel to fiow into the cylinder via the restrictor, whereafter when the plunger and piston are moved inwardly, the inlet passage will be closed by the piston and fuel will be displaced from the cylinder into the bone via the transfer passage, the valve means, and the port, until the latter is covered by the plunger whereafter fuel from the bore will be discharged via the delivery valve and the outlet, and any excess fuel in the cylinder will be allowed to escape via said valve means.

In the accompanying drawings:

FIGURE 1 is a diagrammatic view of one example of a liquid fuel injection pump in accordance with the invention,

FIGURE 2 is a sectional side elevation of another example of a fuel injection pump in accordance with th invention and FIGURE 3 is a view taken on the line 3-3 of FIG- URE 2.

In one example of the invention as shown in FIG" URE 1 there is provided a pump body in which is formed a cylindrical bore 11. At the outer end of the bore is an outlet 12 incorporating a non-return delivery valve 13, and adapted for connection to a fuel injection nozzle (not shown) of an engine. At the inner end of the bore there is formed in the body part a cylinder 14 which is of larger diameter than the bore and is formed co-axially therewith.

In the bore 11 is an axially movable cylindrical plunger 15 on which is formed, or secured, a piston 16 which occupies the cylinder 14. The plunger and piston are urged outwardly by a coiled compression spring 17 accommodated within the cylinder and are moved inwardly Patented Mar. 21, 1967 in timed relationship with the engine with which the pump is associated by means of a rotary cam 18 which acts on the outer end of the piston 16 through a follower 19.

At the inner end of the cylinder is a fuel inlet passage 20 which is adapted to be uncovered by the piston as the latter nears the outward limit of its travel and which communicates with a fuel inlet 20*. Moreover, the inlet passage contains an adjustable restrictor 21 for a purpose to be described.

Communicating with the outer end of the cylinder 14 is a transfer passage 22 by which the cylinder is in communication with a port 23 in the wall of the bore 11, and the port is arranged to be uncovered by the plunger 15 as the latter moves outwardly. Within the transfer passage is a spring loaded non-return valve 24 which is positioned to prevent the flow of fuel from the bore to the cylinder. Moreover, a point in the transfer passage 22, intermediate the valve 24 and the port 23, is in communication with the inlet 20 by way of a further passage which incorporates a non-return valve 25. This valve is arranged to prevent the flow of fuel from the inlet to the transfer passage.

The arrangement is such that as the plunger and piston are moved outwardly by the spring 17 voids will form in the fuel remaining in the bore 11 and cylinder 14 until the inlet passage 20 is uncovered by the piston. When this occurs fuel will flow into the cylinder from the inlet via the restrictor 21. If the rate of fuel flow past the restrictor is sufficient, the cylinder will be filled com- 'pletely. However, no fuel will flow past the non-return valve 24 since the strength of its spring is sufficient to resist this. As the plunger and piston are moved inwardly by the cam 18 a small quantity of fuel will be spilled from the cylinder to the inlet passage 20 until the latter is covered by the piston whereafter fuel will be displaced from the cylinder by the piston and will flow, via the non-return valve 24, along the transfer passage 22 and the port 23 into the bore. Fuel will continue to flow into the bore until the plunger 15 covers the port 23 whereafter with further inward movement of the piston the non-return valve 25 will be opened and excess fuel remaining in the cylinder will be returned to the inlet 20. Moreover the fuel in the bore will be displaced by the plunger to the injection nozzle past the delivery valve 13.

If the restrictor is set so that the cylinder 14 is not filled completely in the time available a reduced quantity of fuel will be spilled directly through the inlet passage 20 and eventually if the restrictor is set to reduce the flow rate sufficiently or the time available for filling is reduced, as when the engine speed increases, there will be insufficient fuel in the cylinder to fill the bore and a reduced quantity of fuel will be delivered to the engine. Thus, by varying the restrictor the pump can be arranged to govern the engine with which it is associated.

In order to control the maximum amount of fuel which can be delivered by the pump a groove 26 is provided on the periphery of the plunger, the angular position of which is adjustable so that fuel may be spilled from the bore via the port and the transfer passage when the groove 26 uncovers the port.

In a modification illustrated in FIGURES 2 and 3 there is provided a pump body 30 in which is formed a stepped drilling. Within the drilling is mounted a barrel 31 and this is held against a step in the drilling by an adaptor 32. Within the barrel is formed an axial bore 33 and this communicates with a fuel outlet 34 by way of a passage 35 defined in the adaptor. Moreover, the passage 35 contains a delivery valve 36.

Slidable Within the bore is a plunger 37 to which is secured a piston 38 mounted in a cylinder constituted by 0 part of the stepped drilling. Furthermore, the plunger 37 is urged in a direction away from the outlet 34 by a coiled compression spring 50 and is arranged to be moved in opposition to the spring by a cam (not shown), the cam being driven in timed relationship to the engine with which the pump is associated.

At the inner end of the cylinder in which the piston 38 is mounted is a fuel inlet pasage 39 and this communicates with one end of a tangentially disposed cylindrical chamber 40 formed in the body part, this end of the chamber communicating with a source of fuel. Furthermore the inlet passage contains a one way valve 41 which is arranged to prevent the flow of fuel in a direction from the cylinder to the chamber 40 and the passage 39 incorporates a restrictor which comprises an angularly adjustable plug 42. The inlet passage is arranged to be uncovered by the piston 38 as the latter nears the limit of its movement under the influence of the spring.

The outer end of the aforesaid cylinder communicates by way of a transfer passage 43 with the other end of the chamber 40 and slidably mounted within this chamber is a cylindrical valve member 44. The valve member is urged by a coiled compression spring 45 towards an adjustable stop 46 mounted in said other end of the chamber. Furthermore breaking into the chamber 40 are a pair of

passages

47 and 48. Passage 47 communicates with the source of fuel and is arranged to be uncovered by the valve member after passage 48 has been uncovered during movement of the valve member against the action of its spring as will be described. Passage 43 constitutes a transfer passage and is in communication with an annular gallery defined between the barrel 31 and the body part and breaking into the gallery is a port 49 in the wall of the bore and which is arranged to be covered by the plunger 37 during its movement by the cam.

In describing the operation of the pump it will be assumed that an injection stroke has just been completed. During the return movement of the plunger voids will form in the fuel remaining in the bore 33 and in the cylinder. However, when the piston 33 uncovers the passage 39 fuel will flow into the cylinder at a rate dependent upon the setting of the restrictor 42. If the cylinder is completely filled then during inward movement of the plunger by the cam, fuel from the cylinder will pass through the transfer passage 43 and will move the valve member 44 to uncover the passage 48. When this occurs fuel will flow into the bore 33, and this will be filled completely. During further inward movement of the plunger fuel from the cylinder will move the valve member to uncover the passage 47 and the excess fuel will flow back to the fuel inlet. Moreover, at the same time when the port 48 has been closed, fuel will be displaced to the outlet 34 and will flow to the associated engine.

If the setting of the restrictor is such that insufficient fuel flows into the cylinder in the time available to fill the bore then the quantity of fuel supplied to the engine will be reduced. Hence as in the previous example the maximum speed of the engine for a given setting of the restrictor will be governed. It will be appreciated that the amount by which the valve member must be moved before the passage 48 is uncovered will determine the maximum amount of fuel which can be supplied to the bore and consequently the adjustable stop 46 provides convenient means of adjusting the maximum amount of fuel which can be delivered to the engine.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A liquid fuel injection pump comprising in combination, a pump body, a cylindrical bore in the body, a cylinder coaxial with the bore and at the inner end thereof, an axially movable plunger slidable within the bore, and a piston mounted on the plunger and sliding within said cylinder, first resilient means urging the plunger and piston out of the bore and cylinder respectively, said plunger and piston being adapted to be moved inwardly in timed relationship with an engine with which the pump is associated, the swept volume of the plunger being less than that of the piston, an outlet at the outer end of the bore, a delivery valve in said outlet for preventing the flow of fuel into the bore, a fuel inlet passage at the inner end of the cylinder, said inlet passage being arranged to be uncovered by the piston near the outward limit of its stroke, a port formed in the wall of the bore, said port being arranged to be uncovered by the plunger near the outward limit of its travel, a transfer passage serving to connect the inner end of said cylinder with said port, a cylindrical chamber in the body part, a valve member mounted in said chamber, a second resilient means loading said valve member in a direction towards one end of the chamber, said one end of the chamber communicating with said cylinder so that the pressure of fuel in the cylinder will move the valve member against the action of said resilient means, said transfer passage opening into said chamber at a position to be uncovered to said one end of the cylinder after an initial movement of the valve member, and a further passage opening into the wall of said chamber at a position to be uncovered to said one end of the chamber when the valve member has moved further, said further passage allowing escape of excess fuel from said cylinder and a variable restrictor in said inlet passage, said restrictor being arranged to restrict the rate at which fuel can flow through said inlet passage.

2. A liquid fuel injection pump as set forth in claim 1 including adjustable stop means at said one end of the cylinder to limit the movement of the valve member under the action of the second resilient means.

References (Iited by the Examiner UNITED STATES PATENTS 1,171,825 2/1916 Wood 103-153 1,760,237 5/1930 Iversen 103-168 1,943,162 1/1934 Coatalen 103-168 2,841,085 7/1958 Evans 103-168 2,958,289 11/1960 Hafele 103-154 3,058,455 10/1962 Hofer et al. 103-411 FOREIGN PATENTS 1,192,604 4/1959 France.

DONLEY J'. STOCKING, Primary Examiner.

MARK NEWMAN, Examiner.

W. J. KRAUSS, Assistant Examiner.

Claims

1. A LIQUID FUEL INJECTION PUMP COMPRISING IN COMBINATION, A PUMP BODY, A CYLINDRICAL BORE IN THE BODY, A CYLINDER COAXIAL WITH THE BORE AND AT THE INNER END THEREOF, AN AXIALLY MOVABLE PLUNGER SLIDABLE WITHIN THE BORE, AND A PISTON MOUNTED ON THE PLUNGER AND SLIDING WITHIN SAID CYLINDER, FIRST RESILIENT MEANS URGING THE PLUNGER AND PISTON OUT OF THE BORE AND CYLINDER RESPECTIVELY, SAID PLUNGER AND PISTON BEING ADAPTED TO BE MOVED INWARDLY IN TIMED RELATIONSHIP WITH AN ENGINER WITH WHICH THE PUMP IS ASSOCIATED, THE SWEPT VOLUME OF THE PLUNGER BEING LESS THAN THAT OF THE PISTON, AN OUTLET AT THE OUTER END OF THE BORE, A DELIVERY VALVE IN SAID OUTLET FOR PREVENTING THE FLOW OF FUEL INTO THE BORE, A FUEL INLET PASSAGE AT THE INNER END OF THE CYLINDER, SAID INLET PASSAGE BEING ARRANGED TO BE UNCOVERED BY THE PISTON NEAR THE OUTWARD LIMIT OF ITS STROKE, A PORT FORMED IN THE WALL OF THE BORE, SAID PORT BEING ARRANGED TO BE UNCOVERED BY THE PLUNGER NEAR THE OUTWARD LIMIT OF ITS TRAVEL, A TRANSFER PASSAGE SERVING TO CONNECT THE INNER END OF SAID CYLINDER WITH SAID PORT,