US2918048A - Control valve arrangement for injection pumps - Google Patents

Description

Dec. 22, 1959 u. ALDINGER ETAL 2,918,048

CONTROL VALVE ARRANGEMENT FOR INJECTION PUMPS Filed June 2, 1954 2 Sheets-Sheet l 1 lfllllll-llllllllll I III was-wraps ULR /C h A L D/NGER am? 3'0 H A h'n E s LJEB ER Dec. 22, 1959 u. ALDINGER ETAL 2,918,048

CONTROL VALVE ARRANGEMENT FOR INJECTION PUMPS Filed June 2, 1954 2 Sheets-Sheet. 2

/NVNTOPS.' ULRIC Hl-Dl/YGGR A"? Talmud-ES WEBER injection pump for a combustion engine.

CONTROL VALVE ARRANGEMENT FOR INJECTION PUMPS Ulrich Aldinger, Stuttgart, and Johannes Weber, Stutt gart-Feuerbach, Germany, assignors to Robert Bosch G.m.b.H., Stuttgart, Germany Application June 2, 1954, Serial No. 434,038

Claims priority, application Germany June 3, 1953 16 Claims. (Cl. 123-140) The present invention relates to a control value arrangement for injection pumps supplying fluid fuel to combustion engines, and more particularly to a control valve arrangement for automatically controlling the amount of fuel injected by the injection pump.

It is known to produce an automatic regulation of injection pumps by a spring-loaded valve communicating with the pump pressure chamber, the arrangement being such that, as the number of revolutions of the combustion engine and of the injection pump is increased, a greater part of the fuel which is pumped by the injection pump is permitted to escape into a low pressure relief conduit.

In the known arrangement of this type the rotary speed is adjusted by adjusting the tension of the spring loading the control valve. However, since the pressure in the pump chamber increases and decreases according to a square function of the number of revolutions of the engine and of the strokes of the injection pump which is driven by the engine, whereas the tension of the spring is only a linear function of the length of the spring, the

adjustable range of injection pumps according to the prior art is small, and frequently insufficient.

It is one object of the present invention to overcome the disadvantages of the known injection pump arrangements, and to provide a control valve arrangement ootaining an injected amount of fuel corresponding to the number of revolutions of the combustion engine.

It is another object of the present invention to provide a spring-loaded valve which is operated by the fluid pressure produced by the injection pump and permits escaping of fuel surplus into a low pressure relief conduit, while a throttling passage between the inlet conduit of the combustion engine and the pump pressure chamber influences the pressure difference acting on the control valve.

It is a further object of the present invention to provide a turnable valve member having a throttling recess cooperating with a throttling recess in a valve body so that by turning of the valve member the effective cross section of the throttle passage formed by the two throttling recesses is adjusted.

With these objects in view, the present invention mainly consists in a control valve arrangement for use with an The control valve arrangement comprises a member formed with a conduit for connecting a pump chamber of an injection pump to the combustion engine driving the same; first valve means arranged in the conduit tending to close the same, the first valve means being adapted to be opened by fluid pressure in the pump chamber so as to permit fluid to pass from the pump chamber through the conduit to the combustion engine, the extent of opening of the first valve means depending upon the fluid pressure in the pump chamber means; adjustable throttling means associated with the first valve means for adjusting the amount of fluid passing therethrough; a relief conduit meansformed with a relief conduit; and second valve tnt means interposed between the pump chamber and the relief conduit and tending to move to 21 closing position for preventing escape of fluid from the pump chamber through the relief conduit, the second valve means being adapted to automatically open for establishing communication between the pump chamber and the relief conduit upon increase of the fluid pressure in the pump chamber to an extent increasing with the fluid pressure in the pump chamber. When the fluid pressure in the pump chamber increases due to an increase of the rotational speed of the combustion engine driving the pump, the result will be an increase of the amount of pressure fluid escaping through the relief conduit and a decrease of the amount of fluid passing through the first valve means and through the conduit to the combustion engine.

More specifically, the present invention refers to a control valve arrangement which comprises, in combina tion, a tubular valve body having an inner bore having a first open end adapted to communicate with the pressure chamber of an injection pump, and asecond open end adapted to communicate with the inlet conduit of a combustion engine driving the injection pump, the bore being formed with at least one first throttling recess communicating with one end of the bore, the tubular valve body being further formed with a relief conduit opening into the bore; a spring-loaded valve member arranged in the bore movable between a valve opening position and a valve closing position, the spring-loaded valve member tending to move to the valve closing position and being adapted to be moved to the valve opening position by fluid pressure produced by the injection pump, the movable valve member establishing in the valve opening position communication between the first open'end of the bore and the relief conduit to anextent depending on the fluid pressure of the injection pump, the valvemember being formed with at least one second throttling recess inthe outer surface thereof forming with the first throttling recess a throttling passage'communicating with the other end of the here when the" valve member is in the valve opening'position, the valve member being turnable' within the'bore'; and means for turning the valve member in the bore for adjusting the' effective cross-section of the throttling passage;

Preferably a throttling conduit shunting the throttling passage isprovided which permits passage of fluid fuel to a small extent before the two throttling recesses register during the movement of the valve member.

The valve member is preferably provided with a:

conical valve portion cooperating with a valve seat in the bore of the valve body.

The novel features which are considered as characteristi-c for the invention are set forth in particular in the appended claims. its construction and its method of operation, together with additional objects and advantages thereof, will be best' Fig. 4 is across sectional view taken on line IVIV in Fig. 3; V I

Fig. 5 isa fragmentary axial sectional view taken on lineV-V in Fig. 4; N Fig. 6 is'an axial sectional view of a modified embodi ment of the present invention;

Fig. 7 is'a cross sectional view taken on line VIIVII in Fig. 6;

The invention itself, however, both as to' Fig. 8 is an axial sectional view of another modified embodiment of the present invention; and

Fig. 9 is a cross sectional view taken on line inFig. 8.

Referring now to the drawings, and more particularly to Fig. 1, a pump piston 2 is movably arranged in the cylinder 1 of an injection pump, which is only partly shown. Piston 2 is driven in a known manner from the associated combustion engine. The piston 2 is provided with a helical control edge 3 and is arranged turnable about its axis within pump cylinder 1. A conduit 4 opens into the pump chamber 5 and serves for supplying fluid fuel to the pump chamber 5, and as an overflow means. In the illustrated lower dead center position of the pump piston 2, the port of the conduit 4 is opened so that fluid can flow into the chamber 5 of the pump.

A valve body 6 closes the pump cylinder 1, and is formed with a bore 7 connecting the pump chamber 5 with the inlet conduit portion 9' leading to the combustion engine formed in the pressure member 9 which presses the valve body 6 against the pump cylinder 1. a A packing ring 10 is arranged between members 6 and 9.

A valve member 8 is slidably arranged within the bore 7 of the valve body 6, and is movable in axial direction as well as turnable about its axis. The end of the valve member located at the end of bore 7 which communicates with the pressure chamber 5, has a conical valve portion engaging a valve seat 16 in the illustrated valve closing position of the valve member 8. Adjacent valve seat 16, an annular recess 17 is provided in the valve body 6 which cooperates with a narrower annular recess 18 in the valve member 8. Transverse conduits 19 lead to an axially extending conduit 20 which is closed at one end by a plug 21 and communicates through a transverse conduit 22 with a throttling recess 23 in the outer surface of the valve member 8. The throttling recess 23 cooperates with a throttling recess 24 in the bore 7 of valve body 6, the throttling recess 24 communicating with the inlet of the combustion engine.

In the illustrated valve closing position of the valve member 8, the throttling recesses 23, 24 do not communicate, but when the valve member 8 is moved into a valve opening position by fluid pressure in the pressure chamber 5 against the action of spring 11, the two throttling recesses 23 and 24 register so that they form a throttling passage in the path of the pumpedfluid fuel.

An operating member 13 is formed with a recess engaging a prismatic portion 12 of the valve member, and is a means for turning the valve member between a position in which the first throttling recess 24 is arranged opposite the second throttling recess 23, and another position in which the throttling recesses are peripherally spaced from each other so that the flow of fluid is interrupted. Intermediate these positions, the valve member -8 assumes a plurality of positions in which the throttling recesses 23, 24 only partly overlap, as for instance shown in broken lines in Fig. 2, whereby the effective cross section of the throttling passage formed by the throttling recesses 23, 24 is adjusted.

The valve body 6, and the pump cylinder 1 are formed with a relief conduit 26 which opens into the supply conduit 4, and has at the other end thereof a port 25 located adjacent the annular recess 17. The fluid pressure in relief conduit 26 is low and corresponds to the pressure in the supply conduit 4.

The effective stroke of the pump piston 2 starts with the closing of the supply conduit 4 by the piston. Thereupon the valve portion 15 is lifted from the valve seat 16 by the fluid pressure in chamber 5 against the action of the spring 11, and the fluid flows from the pump chamber 5 into the annular space formed by the two annular recesses. 17 and 18. From there the fluid passes to the conduits 19, 20, 22 into the throttling recess 23, and since in the valve opening position of the valve member 8 the throttling recesses 23, 24 communicate, the fluid passes into throttling recess 24 and from there into the inlet of the combustion engine. An inlet pipe, not shown, connects pressure member 9 with the injection nozzle of the combustion engine.

In the position illustrated in Fig. 2, the throttling passage formed by the two throttling recesses 23 and 24 has its greatest effective cross section. In this position the control valve arrangement regulates the maximum number of revolutions of the combustion engine. At a high number of revolutions of the engine, the pressure difference between the two openends of the bore 7 is suflicient to move the movable valve member 8 against the action of the spring 11 for such distance that the annular recess '18 reaches the port 25 of the relief conduit, and a part of the fluid fuel which is pumped by the piston 2 escapes through relief conduit 26 into conduit 4. At an increase of the number of revolutions, the fluid pressure in the chamber 5 increases, and consequently the annular recess 18 is fully registered with the port 25, and a greater part of the fuel escapes through the relief conduit 26. The number of revolutions of the combustion engine then decreases since a smaller amount of fuel reaches the cornbustion engine, and eventually a predetermined maximum number of revolutions is maintained.

Turning of the valve member 8 by the operating member 13 in the direction of the arrow 28 in Fig. 2 reduces the eifective cross section of the throttling passage since the throttling recesses 23 and 24 are partly staggered and overlap. In the position of the throttling recesses illustrated in Fig. 2 in broken lines the valve member 8 is turned into a position corresponding to the idle run of the combustion engine. In this position the eifective cross section of the throttle passage is so small that already at a low number of strokes of the pump piston a pressure difference is produced between the open ends of the bore 7 which is suflicient for moving the valve member 8 into a position in which the upper edge of the annular recess 18 reaches the port 25 so that a part of the pumped fuel can escape into the relief conduit 26.

When the valve member 8 is turned in the direction of the arrow 28 into a position in which the throttling recesses 23 and 24 are peripherally spaced so that they no longer communicate, the pressure in the pressure chamber 5 of the pump is suflicient to open the valve member 8 at any number of revolutions of the combustion engine driving the pump to a position in which the annular recess 18 registers with the port 25 so that the entire pumped fluid flows into the relief conduit 26 and from there to the supply conduit 4. In this position of the valve member 8, no fuel reaches the combustion engine.

The above description of the operation of the embodiment shown in Figs. 1 and 2 will make it apparent that the fuel passes from the pump chamber means 5 through a conduit in members 6 and 9 to the combustion engine. The faces 15, 16, and the conduits 19, 20, 22, constitute first valve means which are adapted to be opened by fluid pressure in the pump chamber means, and are associated with the adjustable throttling means 23, 24. The upper edge of the annular recess 18 and the port 25 of the relief conduit 26 constitute second valve means, both the first and the second valve means tending to close due to the action of the spring 11.

Referring now to Fig. 3, the structure of the embodiment shown therein corresponds to the embodiment of Fig. 1, the difference being that the throttling recess 23 is spaced a distance afrom the throttling recess 24 in the valve body 6. The portion 8 of member 8 between the recesses 23 and 24 acts as a plunger which in a known manner causes an increase of volume of the inlet conduit during closing of the valve and thereby effects a rapid lowering of the pressure in this conduit. In this embodiment the cylindrical valve portion 30 directly adjacent the valve portion 15 has a smaller diameter than the main portion of the cylindrical valve member 8. The portion 30 plunges into the bore 7 before the port 25 registers with the annular recess 18, so that the annular gap formed in this position between the bore 7 and the cylindrical portion 36 constitutes a second throttling passage. This throttling passage causes a more rapid increase of the pressure difference at an increased number of revolutions of the engine, as compared with embodiment of Fig. 1, so that the valve member 8 opens the port 25 already at a small increase of the number of revolutions of the combustion engine. The cross-section of the second throttling passage is not influenced by turning of member 8 and has an influence on the increase of number of revolutions required for opening the port 25. Consequently, the second throttling passage can be used for influencing the accuracy of regulation.

The valve body 6 is provided with a throttling conduit, best seen in Figs. 4 and 5, which in the closed position of the valve connects the throttling recess 23 in valve member 8 with the inlet conduit of the combustion engine. The throttling conduit consists of a bore 31 and a transverse bore 32 which is located opposite throttling recess 23 and communicates with the same when the valve member 8 is in valve closing position. The additional throttling conduit 31, 32 is closed when the valve member moves toward the position in which the throttling recesses 23 and 24 communicate. Consequently, the throttling conduit 31, 32 permits passing of the fuel to the combustion engine at a low number of rotations, for instance during starting, while the valve member performs only a very small stroke, so that during the closing of the valve member the above described reducing of the pressure does not take place in the inlet conduit. Due to this fact, the amount of fuel supplied to the combustion engine is increasedas compared with the normal operationfor an amount corresponding to the increase of volume of the inlet conduit during the valve closing stroke during normal operation. Consequently, the combustion engine is injected during the starting operation with an amount of fuel exceeding the normal full load amount.

As best seen in Figs. 1 and 3, the port 25 extends only through a very small peripheral portion of the bore 7 so that the valve member 8 is laterally pressed against the port 25 during operation so that the control valve operations are exact, and not influenced by play of the valve member 8 in the bore 7.

In the embodiments shown in Figs. 6-9, the conical valve portion is not arranged at the end of the valve member located adjacent the pump chamber, but at the other end. This change requires a different arrangement of the throttling recesses in the valve body and in the valve member.

In the embodiment shown in Figs. 6 and 7, the valve member 8 has a conical valve portion 35 which in the illustrated valve closing position engages a seat 36 of the valve body 6. Directly adjacent the conical valve portion 35, an annular recess 37 is provided from which transverse conduits 38 lead to an axially extending conduit 39 which is closed by a plug 40 at the end of the valve member 8 facing the pump chamber.

A segment-shaped throttling recess 41 is provided in the valve member 8 and communicates with the conduit 39. The throttling recess 4i cooperates with another throttling conduit 42 in bore 7 of valve body 6 to form with the same an adjustable throttling passage Whose effective cross section is adjusted by turning the valve member 8 in bore 7. The fluid fuel passes through the throttling passage 41, 4-2 and the axially extending conduit 39, 38 to the annular recess 37 and from there between the opened valve portion 35 and valve seat 36 into the conduit in the pressure member 9 to which the inlet of the combustion engine is connected.

In the position illustrated in Fig. 7, the throttling passage 41, 42 has its maximum effective cross section. Turning of the valve member 8 in the direction of the arrow 43 causes a reduction of the effective cross section of the throttling passage since the throttling recesses only partly overlap. In the position illustrated in Fig. 7 in broken lines, the throttling recesses 41, 42 are peripherally spaced so that no fuel can reach the combustion engine. In this position reciprocation of the pump piston 2 causes a stroke of the valve member 8 of such length that its front face 44 opens the relief port 25. When the port 25 is opened by the face 44, the entire pumped amount of fuel escapes through the relief conduit 26 into the low pressure conduit 4.

In the embodiment shown in Figs. 8 and 9, a means is provided for relieving the pressure conduit at the end of the injection, and a second throttling passage is provided for influencing the accuracy of the regulation similar to the embodiment shown in Figs. 3-5.

Adjacent the valve portion 35 an annular recess is provided which forms together with the annular recess 37, a cylindrical portion 46 having the shape of a flange. The valve member 8 must consequently make at least a stroke of the length b to open the passage of the fuel. During the closing movement of the valve member 8, the volume of the inlet conduit is correspondingly increased, and a lowering of the pressure in this conduit produced. As compared to the embodiment shown in Fig. 6, the movable valve member 8 must perform a longer stroke for opening the port 25.

As best seen in Fig. 8, the throttling recess 41 is narrower in axial direction than in the embodiment shown in Fig. 6. This construction obtains the result that the portion 48 of the valve member 8 plunges into the bore 7 when the port 25 is opened by the recess 41.

The portion 48 is flattened at 49 to form a recessed surface of the valve member 8 permitting passage of the fluid fuel. This recessed surface 49 forms together with the inner surface of the bore 7 a second throttling passage by which, in the manner described in detail in reference in the embodiment shown in Figs. 3-6, the accuracy of the regulation can be influenced. I I In all embodiments, the oblique control edge 3 of the pump piston 2 serves the purpose of adjusting by turning of the piston the maximum fuel amount for a particular combustion engine. This adjustment is only carried out once for each combustion engine with which the apparatus of the present invention is used, and the pump piston is not turned during operation. Consequently, an oblique control edge 3 is not necessary when the desired maximum fuel amount is determined by a suitable choice of the pump piston diameter and stroke. in this event, a smooth cylindrical piston is suflicient for the embodiments shown in Figs. 1 and 6, whereas the embodiments shown in Figs. 3 and 8 require a piston which effects at the end of the stroke communication between the pump pressure chamber 5 with conduit 4 so that the plunger portion of the movable valve member may rapidly effect a reducing of pressure in the inlet conduit.

Such communication could, for instance, be obtained by an annular groove in the piston connected by conduits to the pump chamber 5.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of control valve arrangements differing from the types described above.

While the invention has been illustrated and described as embodied in a control valve arrangement for injection pumps comprising a pressure responsive valve member controlling a relief conduit and an adjustable throttling conduit, 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 specific aspects of this inven tion and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of thefollowing claims.

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

1. A control valve arrangement comprising, in combination, a tubular valve body having an inner bore having a first open end adapted to communicate with the pressure chamber of an injection pump, and a second open end adapted to communicate with the inlet conduit of a combustion engine driving the injection pump, said bore being formed with at least one first throttling recess communicating with one end of said bore, said tubular valve body being further formed with a relief conduit opening into said bore; a spring-loaded valve member arranged in said bore movable between a valve opening position and a valve closing position, said spring-loaded valve member tending to move to said valve closing position and being adapted to be moved to said valve opening position by fluid pressure produced by the injection pump, said movable valve member establishing in said valve opening position communication between said first open end of said bore and said relief conduit to an extent depending on the fluid pressure at said first open end of said bore, said valve member being formed with at least one second throttling recess in the outer surface thereof forming with said first throttling recess a throttling passage communicating with the other end of said bore when said valve member is in said valve opening position, said valve member being turnable within said bore; and means for turning said valve member in said bore for adjusting the effective cross-section of said throttling passage.

2. A control valve arrangement comprising, in combination, a tubular valve body having an inner bore having a first open end adapted to communicate with the pressure chamber of an injection pump, and a second open end adapted to communicate with the inlet conduit of a combustion engine driving the injection pump, said bore being formed with at least one first throttling recess cornin said bore movable between a valve opening position and a valve closing position, said spring-loaded valve member tending to move to said valve closing position and being adapted to be moved to said valve opening position by fluid pressure produced by the injection pump, said movable valve member establishing in said valve opening position communication between said first open end of said bore and said relief conduit to an extent depending on the fluid pressure at said first open'end of said bore, said valve member being formed with at least one second throttling recess in the outer surface thereof forming with said first throttling recess a throttling passage communicating with the other end of said bore when said valve member is in said valve opening position, said valve member being turnable within said bore between one position in which said first and second throttling recesses are located opposite each other to fully open said throttling passage and another position in which said throttling recesses only partly overlap for constricting said throttling passage; and means for turning said valve member in said bore of said valve body between said positions thereof.

3. An arrangement as claimed in claim 2 wherein said valve member is turnable to a further position in which said throttling recesses are peripherally spaced from each other so as to interrupt communication between said open ends of said bore.

4. A control valve arrangement comprising, in combination, a tubular valve body having an inner bore having a first open end adapted to communicate with the pressure chamber of an injection pump, and a second i 8 open end adapted to communicate with the inlet conduit of a combustion engine driving the injection pump, said bore being formed with at least one first throttling recess communicating with one end of said bore, said valve body being formed with a throttling conduit communicatat one end thereof with the inlet conduit of the combustion engine, and opening at the other end thereof in said bore at a point spaced in axial direction from said first throttling recess, said tubular valve body being further formed with a relief conduit opening into said bore; a spring-loaded valve member arranged in said bore movable between a valve opening position and a valve closing position, said spring-loaded valve member tending to move to said valve closing position and being adapted to be moved to said valve opening position by fluid pressure produced by the injection pump, said movable valve member establishing in said valve opening position communication between said first open end of said bore and said relief conduit to an extent depending on the fluid pressure at said first open end of said bore, said valve member being formed with at least one second throttling recess in the outer surface thereof forming with said first throttling recess a throttling passage communicating with the other end of said bore when said valve memher is in said valve opening position, said throttling recesses being spaced from each other in axial direction in said valve closing position of said valve member so that said second throttling recess in said valve member communicates first with said throttling conduit and then with said first throttling recess during movement of said valve member from said valve closing position to said valve opening position.

5. A control valve arrangement comprising, in combination, a member formed with a conduit and adapted to connect a pump chamber of a pump to a combustion engine driving the pump; first valve means arranged in said conduit tending to close the same, said first valve means being adapted to be opened by fluid pressure so as to permit fluid to pass from the pump chamber through said conduit to the combustion engine so that the extent of opening of said first valve means depends upon the fluid pressure in the pump chamber; adjustable throttling means associated with said first valve means for adjusting the amount of fluid passing therethrough; a throttling conduit means formed with a throttling conduit shunting said adjustable throttling means and being associated with said first valve means in such manner said first valve means first open said throttling conduit means, and then close said first throttling conduit means and open said adjustable throttling means; a relief conduit means formed with a relief conduit; and second valve means adapted to be interposed between said pump chamber and said relief conduit and tending to move to a closing position so as to prevent escape of fluid from the pump chamber through said relief conduit, said second valve means being adapted to automatically open for establishing communication between the pump chamber and said relief conduit upon increase of the fluid pressure in the pump chamber to an extent increasing with the fluid pressure in the pump chamber whereby increase of fluid pressure in the pump chamber due to an increase of the rotational speed of the combustion engine will result in an increase of the amount of pressure fluid escaping through said relief conduit and in reducing the amount of fluid passing through said first valve means and through said conduit to the combustion engine.

6. A control valve arrangement comprising, in combination, a tubular valve body having an inner bore having a first open end adapted to communicate with the pressure chamber of an injection pump, and a second open endadapted to communicate with the inlet conduit of a combustion engine driving the injection pump said bore being formed with at least one first throttling recess communicating with one end of said bore, said tubular valve body being further formed with a relief conduit opening into, said. bore; a springrloaded valve member arranged in. said. bore. movable between a valve Opening position and valve closing position, said spring-loaded. valve member tending to move to said valve closing position and being adapted to be moved to saidvalve opening position by fluid pressure produced by the-injection pump, said valve member being formed with an, annular recess communicating with said' relief conduit in said valve opening position of said valve member for establishing communication. betweensaid other open end of said bore and said relief conduit to an extent depending on the fluid pressure at said first open end of said bore, said valve member being formed with at least one second throttling recess in the outer surface thereof forming with said first throttling recess a throttling passage communicating with the other end of said bore when said valve member is in said valve opening position, said valve member being formed With an axially extending conduit connecting said annular recess with said second throttling recess, said valve member being turnable within said bore; and means for turning said valve member in said bore for adjusting the effective cross-section of said throttling passage;

7. A control valve arrangement comprising, in combination, a tubular valve body havingan inner cylindrical bore having a first open end adapted to communicate with the pressure chamber of an injection pump and a second open end adapted to communicate with the inlet conduit of a combustion engine driving the injection pump, said bore being formed. with at least one first throttling recess located at said second open end of said bore and communicating with the inlet conduit of the combustion engine, said bore being further formed with a valve seat located at said first open end of said "bore, said tubular valve body being further formed with a relief conduit having a port opening into said bore; a springloaded valve member arranged in said bore and having a valve portion at one end thereof, said spring-loaded valve member being arranged movable between a valve opening position and a valve closing position in which said valve portion engages said valve seat, said springloaded valve member tending to move to said valve closing position and being adapted to be moved to said valve opening position by the fluid pressure at said first open end of said bore, said valve member being formed with an annular recess adjacent said valve portion communieating with said relief conduit in said valve opening position of said valve member, said valve member being formed with at least one second segment-shaped throttling recess in the outer surface thereof forming in said valve opening position with said first throttling recess a throttling passage communicating with the inlet conduit of the combustion engine, said valve member being formed with an axially extending conduit connecting said annular recess with said second throttling recess, said valve member being turnable within said bore; and means for turning said valve member in said bore for adjusting the relative angular position of said throttling recesses and thereby the effective cross section of said throttling passage.

8. An arrangement as claimed in claim 7 wherein said annular recess is spaced from said port of said relief conduit in axial direction a predetermined distance in said valve closing position of said valve member, and wherein said throttling recesses are spaced from each other in axial direction said distance in said valve closing position; and wherein a portion of said valve member located at the other end thereof is adapted to act as a plunger decreasing the pressure in the inlet conduit of the combustion engine when said valve member moves to said valve closing position.

9. An arrangement as claimed in claim 8 wherein said tubular valve body is formed with a throttling conduit adapted to communicate at one end with the inlet conduit, and opening at the other end thereof into said 19 bore at a. point spaced from said first throttling recess in axial direction, so that said second throttling recess first passes over said point, and then to said first throttling recess during movement of said valve member from said valve closing position to said valve opening position.

10. A control valve arrangement comprising, in combination, a tubular valve body having an inner cylindrical bore having a first open end adapted to communicate with the pressure chamber of an injection pump and a second open end adapted to communicate with the inlet conduit of a combustion engine driving the injection pump, said bore being formed with at least one first throttling recess located at said first open end of said bore and communicating, with the pressure chamber of the injection pump, said bore being further formed with a valve seat located at said second open end of said bore, said tubular valve body being further formed with a relief conduit having. a port opening into said bore; a springloaded valve member arranged in said bore and having a valve portion at one end thereof, said spring-loaded valve member being arranged movable between a valve opening. position and a valve closing position in which said valve. portion. engages said valve seat, said springloaded. valve member tending to move said valve closing position and being adapted to be. moved to said. valve opening position by the fluid pressure at said first open end of said bore, said valve member being formed with an annular recess located adjacent said valve portion and communicating with said second open end of said bore in said valve opening position, said valve member being formed with at least one second segment-shaped throttling recess in the outer surface thereof forming with said first throttling recess a throttling passage, said second throttling recess communicating with said port of said relief conduit in said valve opening position of said valve member, said valve member being formed with an axially extending conduit connecting said annular recess with said second throttling recess, said valve member being turnable within said bore; and means for turning said valve member in Said bore for adjusting the relative angular position of said throttling recesses and thereby the effective cross section of said throttling passage.

11. An arrangement as claimed in claim 10 wherein in said valve closing position of said valve member, said second throttling recess is spaced in axial direction from said port of the relief conduit, and said annular recess is spaced from said valve seat, and wherein said valve member is formed with a second annular recess intermediate said first-mentioned annular recess and said valve seat so that a flange portion is formed on said valve member intermediate said annular recesses and adapted for serving as a plunger.

12. An arrangement as claimed in claim 11 wherein said valve body is formed with a throttling conduit adapted to communicate at one end with said pressure chamber and opening at the other end thereof into said bore at a point spaced from said first throttling recess in axial direction so that said second throttling recess first passes over said point, and then to said first throttling recess during movement of said valve member to said valve opening position.

13. An arrangement as claimed in claim 10 wherein said second throttling recess is spaced in axial direction from said other end of said valve member, and wherein the portion of said valve member located between said other end of said valve member and said second throttling recess has a depressed surface constituting another throttling passage connecting said port of said relief conduit with said first throttling recess when said valve member is in said valve opening position.

14. A control valve arrangement, comprising, in combination, a valve body formed with a conduit for connecting a pump chamber of a pump to a combustion engine driving the pump, and with a relief conduit; a control valve arranged in the said conduit and including a movable valve member tending to close said control valve and being adapted to be moved to an opened position'by fluid pressure produced in said conduit by the pump chamber so as to permit fluid to pass from said pump chamber means through the conduit to the combustion engine so that the extent of opening of said movable'valve member depends upon the fluid pressure in the pump chamber, said control valve including relief valve means adapted to be interposed between said pump chamber and said relief conduit so as to prevent escape of fluid from said pump chamber means through said relief conduit, said relief valve means opening when said mov-. able valve member moves toward said opened position so as to establish communication between the pump chamber and relief conduit upon increase of the fluid pressure in the pump chamber; and an adjustable throttling means associated with said control valve means for adjusting the pressure difference between the pump chamber and the combustion engine.

15. A control valve arrangement, comprising, in com bination, a valve body formedwith a conduit for connecting a pump chamber of apump to a combustion engine driving the pump, and with a relief conduit; a control valve arranged in the said conduit and including a movable valve member slidably mounted in said valve body and tending to close said control valve and being adapted to'be moved to an opened position by fluid pressure so as to permit fluid to pass from the pump chamber through said conduit to the combustion engine so that the extent of opening of said movable valve member depends upon the fluid pressure in the pump chamber, said control valve including relief valve means adapted to be interposed between the pump chamber and said relief conduit so as to prevent escape of fluid from the pump chamber through said relief conduit, said relief valve means opening when said movable valve member moves toward said opened position so as to establish communication between the pump chamber and said relief conduit upon increase of the fluid pressure in said pump chamber, said valve body and valve member being formed with a pair of cooperating throttling recesses forming a throttling passage; and means for turning said valve member in said valve body for adjusting the effective cross-section of said throttling passage.

16. An arrangement as claimed in claim 15 wherein said valve member and said valve body together define another throttling passage for passage of fluid in any turned position of said valve member.

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