US3391641A - Output regulated pump - Google Patents

Description

July 9, 196s K. Ecm-:RT ET AL 3,391,641

OUTPUT REGULATED PUMP Filed M ay 1l. 1966 United States Patent O 3,391,641 OUTPUT REGULATED PUMP Konrad Eckert, Stuttgart-Bad Cannstatt, Gerald Hofer, Stuttgart, and Claus Koster, Unterweissach, Germany, assignors to Robert Bosch G.m.b.H., Stuttgart, Germany Filed May 11, 1966, Ser. No. 549,227 Claims priority, application France, May 14, 1965 1o ciaims.(c1. nis-2) ABSTRACT F THE DISCLDSURE A throttle is provided in a supply conduit for connecting an auxiliary pump with the cylinder of a control valve controlling the relief conduit of a fuel pump so that axial oscillations of the control valve are .dampened and the regulation of the output of the main pump is improved since the movement of the control valve is delayed and the relief conduit is later opened as compared with an arrangement without the throttle.

The present invention relates to an output regulated pump, and more particularly to a fuel injection pump whose output is regulated so that the amount of fuel injected into a combustion motor docs not rise in proportion to the increased speed of the combustion motor.

Fuel injection pumps are known whose output is regulated in accordance with the liquid stop principle. In pumps of this type, a control piston is provided in a control cylinder for relieving at the proper moment the pressure of the fuel injection pump. The control piston is moved by fuel flowing through a supply conduit to a. relieving position, and is biased to return while pressing the fuel through a throttling conduit.

In fuel injection pumps of this type, the mass of the control piston, and the fuel in the regulating conduits, forms an oscillatable system which is excited by the mass `forces at each stroke of the control piston. The axial oscillations of the control piston disturb the accurate regulation and inuence the regulation of the amounts of fuel pumped by the injection pump.

lt is one object of the invention to improve regulated pumps, particularly fuel injection pumps, and to provide a reliably operating output regulated pump.

Another object of the invention, is to dampen oscillations of a iluid medium in the control conduit means of the pump.

Another object of the invention is to provide a pump whose output is automatically regulated.

Another object of the invention is to delay the relief action of the control piston so that the output of the injection pump at high speeds is influenced.

With these objects in View, the present invention re lates to an output regulated pump, comprising a main pump, an auxiliary pump operating in synchronism with the main pump, and control valve means including a cylinder located in a relief conduit of the main pump and having an output conduit, and a reciprocable valve mem ber biassed to move in one direction for closing the output and relief conduits.

Supply conduit means and throttling return conduit means connect the auxiliary pump with the control cylinder so that the auxiliary pump pumps a fluid, preferebly fuel, through the supply conduit into the cylinder for moving the valve member to open the relief conduit and to connect the supply conduit with the outlet conduit. The supply conduit has a check valve blocking flow into the auxiliary pump so that the fluid flows through the throttling return conduit into the auxiliary pump while the biassed valve member moving in one direction urges the fluid out of the cylinder. This results in shorter strokes 3,391,641 Patented July 9, 1968 ICC of the valve member at high speeds of the pumps so that the output of the main pump is reduced. In accordance with the invention, throttle means are provided in the supply conduit for delaying the movement of the valve member to the position in which the pressure of the main pump is relieved and its injection stroke terminated. Furthermore, oscillations in the supply conduit are suppressed and dampened.

In order to prevent that an unduly great part of the fluid flows through the throttling return conduit, the throttle means in the supply conduit has a greater open cross-section than the throttling conduit, and if the throttling conduit is provided with an adjustable throttle, the throttling means in the supply conduit has a greater open cross-section than the maximum cross-section of the adjustable throttle in the return conduit.

The supply conduit is provided `with a check valve which blocks flow from the control cylinder back into the auxiliary pump. In the preferred embodiment of the invention, the throttling means is disposed in the supply conduits between the control cylinder and the check valve so that the fluid pumped by the auxiliary pump first passes through the check valve and then through the throttle means.

The novel features which are considered as characteristie for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of a specific embodiment when read in connection with the single iigure of the accompanying drawing which is a schematic sectional view of an injection pump according to the invention.

Referring now to the drawing, a main pump has a piston .l mounted in a cylinder 2 for reciprocating axial movement, and for turning movement about its axis. During the turning movement, piston 1 acts as a distributor by supplying during its pressure stroke, amounts of fuel successively to a series of delivery conduits 3 which are angularly spaced equal distances around cylinder 2. The number of delivery conduits 3 is the same as the number of cylinders of a combustion engine into which fuel is injected by the main pump 1, 2. A check valve 4 is disposed in each of the delivery conduits 3.

The cylindrical surface of piston 1 has a groove 5 which connects the cylinder chamber 6 successively with one of the delivery conduits 3 when piston 2 is angularly displaced during cach stroke. Consequently, during successively pressure strokes of piston 2 into chamber 6, different delivery conduits 3 receive fuel which is sucked into cylinder 6 through an inlet 1U communicating with a suction chamber il filled with liquid fuel. Chamber 6 communicates with inlet it) through a duct 7, an annular chamber S and angularly spaced grooves 9, a different groove 9 communicating with inlet 1t) during successive suction strokes and angular displacements of main piston 1. A pump, not shown, lpumps fuel from a tank into the chamber 11. During the suction stroke of main piston 1, fuel flows from suction chamber 11, and passages 10, 9, 8, 7 into chamber 6, and during the pressure stroke, fuel is discharged through groove 5 and a delivery conduit 3 and check valve 4 into the cylinder of a combustion engine, not shown.

A relief conduit 13a, 13b connects cylinder chamber 6 with suction chamber 11, and includes a cylinder portion 22a of a control cylinder 22 located between two portions 12a, 12b of a control valve member 12 which has a reduced portion 12e located in cylinder portion 22a. A spring 14 abuts a flange 15 of control valve member 12 and urges the same to a position in which liangc i5 abuts a surface 16 of the supporting body of the apparatus. ln this normal position of control valve means 22, 12, relief conduit 13a, 13b is closed by valve portion 12b so that a certain amount of fuel is discharged during each pressure stroke of main piston 1 through the respective delivery conduit 3.

An auxiliary pump including a cylinder 18 and a piston 17 operates in synchronism with the main pump, since pistons 1 and 17 are connected. A rotary cam, not shown, acts on piston 17 to obtain synchronous reciprocation of pistons 17 and 1. The chamber formed in cylinder 18 by piston 17 communicates through axial, angularly spaced grooves 19 with an inlet 25 communicating with the suction chamber 11 so that the auxiliary pump 17, 18 pumps a liquid fuel. However, the auxiliary pump could also be operated with another liquid.

A supply conduit 20 connects auxiliary pump 17, 18 with a chamber in control cylinder 22 located on the left of piston portion 12a. A check valve 21 is located in supply conduit 20, blocking tiow from control cylinder 22 into cylinder 18 through one of the grooves 19, but permitting flow of iluid pumped by piston 17 into control cylinder 22. A return conduit 27 connects supply conduit 20 and control cylinder 22 with cylinder 18 of the auxiliary pump.

When piston 17 is reciprocated together with main piston 1, the fuel is pumped through supply conduit 20 into control cylinder 22 and moves control valve member 12 against the action of spring 14 to a position in which cylinder portion 22a connects relief conduit portions 13a and 13b so that the pressure in cylinder chamber 6 of the main pump is relieved, and delivery of fuel through the respective delivery conduit 3 to the combustion engine is terminated.

When auxiliary piston 17 moves downward in a suction stroke, inlet 2S communicates through one of the grooves 19 with cylinder 18 when piston 17 arrives at its lower dead center position, or already during the downward stroke.

The supporting body of the device has a bore in which a throttle member 28 is mounted for turning movement. Throttling member 28 has three portions 28a, 28b, and 28C, portion 28e separating two chambers. Portions 28a and 28h have slanted surfaces cooperating at throttling points 24 and 26 with an outlet conduit 23 and a return conduit 27.

During the upward pressure stroke of pistons 17 and 1, fuel is discharged through delivery conduit 3, and is also pumped through supply conduit it) into cylinder 22 so that cylinder chamber 6 is relieved when piston portion 12b of control valve member 12 opens relief conduit portion 13b so that the same can communicate through cylinder portion 22a with relief conduit portion 13a. While control valve member 12 moves further to the right against the action of spring 14, piston portion 12u assumes a position establishing communication between outlet conduit 23 and cylinder chamber 22 so that the pressure is relieved, and the force of spring 14 is sutiicient to return control valve member 12 toward the left as viewed in the drawing. As soon as outlet conduit 23 is again closed by piston portion 12a, discharge through outlet conduit 23 is no longer possible, and the fuel in cylinder chamber 22 is pressed by the action of spring 1li through throttling return conduit 27 over throttling point 26 into cylinder 18 of the auxiliary pump. Consequently, the movement of control valve member 12 toward the left as viewed in the drawing is braked and slowed down to an extent depending on the adjustment of the throttle point 26 by turning adjustment of throttling member 28.

When the speed of reciprocation of pistons 17 and 1 reaches a predetermined high speed, the so-called liquid stop effect takes place, and control valve member 12 cannot return to its left dead-center position before new fuel is pumped by auxiliary piston 17 through supply conduit 20 into cylinder chamber 22. Consequently, the length of the stroke of valve member 12 is shortened, and relief conduit portions 13a, 13b will be sooner connected to each other during the pressure stroke of auxiliary piston 17. As a result, a smaller amount of fuel is delivered through the respective delivery conduit 3 during each pressure stroke of main piston 1, since cylinder chamber 6 is relieved before the end of a full stroke of main piston 1.

In accordance with the present invention, a throttle means 29 is also provided in the supply conduit 26, and as shown in the drawing, downstream of the tlow of lluid from cylinder 18 into control cylinder 22. In other words, throttle means 20 is located between the check valve 21 and cylinder 22 in the preferred embodiment of the invention.

Throttle means 29 dampens axial oscillations of control valve member 12, reduces the amplitude of such oscillations, and consequently improves the stability of the regulation of the output of main pump 1.

Throttle means 29, which may also be made adjustable, produces a pressure drop which rises at increasing Speeds so that, depending on the speed of operation of the auxiliary and main pumps, the start of the movement of control valve member 12 toward the right is delayed. Due to this delay of the movement of control valve member 12, and a consequent later opening of the relief conduit 13a, 13b, the amount of fuel delivered to the injection nozzles of the combustion engine through delivery conduit 3 is increased.

The volumes of uid between auxiliary piston 17 and throttle means 29 on one hand, and between throttle means 29 and valve member 12 on the other hand, can be selected so that the ratio between these volumes causes a predetermined delay of the start of control valve member 12 toward its relieving position whereby at increasing driving speed, the amount of fuel delivered through delivery conduit 3 to the injection nozzles of the combustion engine rises to a desired extent. Consequently, throttle means 29 permits an adjustment in regulation of the amount of delivered fuel depending on the number of revolutions of the combustion engine, and of the drive cam means reciprocating pistons 17 and 1.

Different types of throttle means 29 may be used. Supply conduit means may be simply provided with a constricted portion, or a diaphragm with an opening may be inserted into supply conduit 20, or a stop may be provided for limiting the movement of the ball of check valve 21 so that the same forms a throttle means in the supply conduit 20 effective during pumping of fuel from cylinder 18 into control cylinder 22.

In the illustrated embodiment which provides an adjustable throttle 26, 28a in the return conduit 27, it is necessary that the open free cross-section of throttle means 29 is greater than the maximum opening of throttle 26. A greater part of the iluid which operates control valve member 12, must flow through supply conduit 20 then through return conduit 27.

In an actual embodiment of the invention, throttle means 29 has a free open cross-section of 0.78 mm2, while the free open cross-section of throttle 26 is adjustable between 9.03 mm2 and 0.46 mm2.

It Iwill be understood that each of the elements described above, or two or mo-re together, may also tind a useful application in other types of injection pumps differing from the types described above.

While the invention has been illustrated and described as embodied in an outlet regulated pump including a throttle means for delaying the relief of the pressure of a yfuel injection pump, it is not intended to be limited to the details shown, since various modifications and structural changes may be -made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specic aspects of this invention and, therefore, such adaptations should and are intended to be comprehended lwithin the meaning and range of aquivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. Output regulated pump comprising, in combination, main pump means having an inlet, at least one delivery conduit, and a relief conduit, control valve means including a control cylinder member located in said relief conduit and having an outlet conduit and a throttling return conduit, and a reciprocable control Valve member located in said cylinder member, one of said members being biassed to move in one direction to a position closing said outlet and relief conduits; auxiliary `pump means operating in synchronism with said main pump means and having an inlet for a duid; and supply conduit means connecting said auxiliary pump means Vwith s-aid cylinder member so that said auxiliary pump means pumps the Huid through said supply conduit means into said cylinder member for moving said biassed member opposite to said one direction for first opening said relief conduit and then connecting said supply conduit means 4with said outlet conduit so that when flow of Huid through said supply conduit means into said auxiliary pump means is blocked, the tiuid is pressed through said throttling return conduit means by said biassed member returning in said one direction whereby at high speeds of said pump means said biassed member moves shorter strokes so that the output of said main pump means is reduced; and throttle means in said supply conduit means for delaying the movement of said biassed member in said opposite direction and thereby the opening of said relief conduit.

2. A pump according to claim 1 and including an adjustable throttle means in said throttling return conduit means.

3. A pump according to claim 1 and including an adinstable throttle means in said throttling return conduit means; and wherein the open cross-section of said throttle means in said supply conduit means is greater than the maximum open cross-section of said throttle means in said return conduit means.

4. A pump according to claim 1 comprising a check valve in said supply conduit means for blocking flow into said auxiliary pump means; and wherein said throttle means in said supply conduit means is located between said cylinder and said check valve.

5. A pump according to claim 4 ywherein said throttling return conduit means has a smaller open cross section than said throttle means in said supply conduit means and 5 -is connected ywith said auxiliary pump means,

6. A pump according to claim 1 including means for supplying a liquid fuel to said in-lets of said main pump means and of said auxiliary pump means; wherein said main pump means includes a main piston mounted for axial -re-ciprocation and for angular movement; and including a plurality of delivery conduits, said main piston having an Vaxial groove successively communicating with said delivery conduits during angular movement of said main piston.

7. A pump according to claim 1 including a manually operated throttling member located in said outlet and return conduits, and being operable for adjusting the free cross-section of said outlet and return conduits.

8. A pump according to claim 4 wherein said throttle means is located adjacent said check valve between said check valve and said control cylinder, and wherein said check valve is located adjacent said auxiliary pump means.

9. A pump according to claim 1 wherein said control valve member forms a chamber in said control cylinder located on one side of said control valve member; and wherein said supply and return conduit means communicate with said chamber.

10. A -pump according to claim 9 wherein said control valve member has two piston end portions, and a reduced portion between said piston end portions, said reduced portion and piston end portions forming an annular chamber; -wherein said relief conduit has a first relief conduit portion communicating with said delivery conduit of said main pump means, and an other relief conduit portion, one of said relief conduit portions being normally closed by one of said piston end portions, and said annular cylinder chamber connecting said relief conduit portions when said control valve member is moved in said opposite direction out of its normal position.

References Cited UNITED STATES PATENTS 2,950,709 8/1960 Bessiere 103--41 X 3,011,489 12/1961 Bessiere 103-41 X 3,044,404 7/1962 Bessiere 103--41 3,090,314 5/1963 Bessiere 103-41 3,114,321 12/1963 Bessiere 103--41 3,122,100 2/1964 Bessiere 103-42 X 3,267,865 8/ 1966 Deininger 103--42 FRED C. MATTERN, IR., Primary Examiner.

-DONLEY J. STOCKING, Examiner.

W. I. KRAUSS, Assistant Examiner.

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