US3359962A

US3359962A - Distributing means for a fuel injection pump

Info

Publication number: US3359962A
Authority: US
Inventors: Jean G Cadiou
Original assignee: Andre Citroen SA
Current assignee: Automobiles Citroen SA
Priority date: 1965-06-24
Filing date: 1965-10-21
Publication date: 1967-12-26
Anticipated expiration: 1984-12-26
Also published as: DE1526739A1; BE672597A; LU49878A1; FR1448272A; ES320157A1; NL6516249A; SE328734B; GB1113610A

Description

Dec. 26, 1967 J. G. CADIOU 3,359,962

' DISTRIBUTING MEANS FOR A FUEL'INJECTION PUMP I Filed 06+. 21, 1965 2 Sheets-Sheet 1 f ELY Dec. 26, 1967 J. G. CADIOU DISTRIBUTING MEANS FOR A FUEL INJECTION'PUMP Filed Oct. 21, 1965 2 Sheets-Sheet 2 145 fig 6 United States Patent 9 Claims. (Cl. 123-139) ABSTRACT OF THE DISCLOSURE Distributing means for directing the flow of fuel from a primary supply pump to the injection pump of an internal combustion engine, then to a metering member and then successively to each of the cylinders of an engine, comprising three discs having passageways formed therein arranged coaxially in a fluid-tight casing, the

central disc being freely rotatable while the end discs.

are fixed against rotation. Upon rotation of the central disc fuel flowing from a primary fuel pump to the inlet of the distributing means is selectively passed through said three discs for injection into the individual cylinders of an engine.

The present invention relates to a distributing means for association with a fuel injection pump, for example in a petrol engine, the purpose of which is to dire-ct the circulating flow of petrol from a primary supply pump to the injection pump and then to a metering member and finally, will preferably be used with this distributing means.

There already exists, on this subject, numerous technical articles in which different terms are used for designating the same elements, which terms moreover are not always those which are retained by those skilled in this art. 7

To avoid any ambiguity, some of the terms which will be used in the following description for designating certain essential elements of the distributing means according to the invention will now be defined.

It is quite possible that one part of the surface of a face of one of the members of the distributing means of this invention will be allocated to a fuel flow circuit between two members and that another part of the same face will, at the same time, be allocated to the flow of fuel between two other members. In fact, as soon as relatively high pressures are present, two faces applied against one another are not in contact but are separated by a small gap or interface produced and filled by a thin film of oil instilled slowly between the two faces; the

pressurised fluid then exerts a force on the surface of the two faces between which it has beeninstilled. The term block will be used for that part of the surface of a face on which is exerted the predetermined pressure of the fuel coming from a flow circuit. Consequently, several blocks subjected to the pressure of fuel circulating along different circuits may also be present on the same face, which face is thus consequently subjected to different pressures.

The force which is exerted on two distributing blocks opposite one another, belonging respectively to two associated faces, tends to separate these faces from one another; consequently it will be referred to as the lift of the block. This effect of separation has often been prevented by applying a fixed, opposing force, which holds the faces one against the other.

With high fluid pressures, the application of this opposing force is not effected without difiiculty and since it is fixed, in those periods where the pressure of the fluid is lower than the opposing force provided, it uselessly 3,359,962 Patented Dec. 26, 1967 subjects the faces to a high unit pressure, which makes its movement, for the purposes of distribution, more difficult to produce and produces rapid wear in addition. This disadvantage becomes more awkward and more sensitive when the fuel to be distributed is petrol.

The invention has for an object a distributing means particularly adapted to its use on fuel flow circuits between difiierent members, in which there is practically no fixed opposing force holding the faces in contact against the effect of the pressure; this distributing means is however sealed whilst the risks of friction and wear are minimised or substantially eliminated. Its design and construction are simple; it forms a compact, low-bulk assembly which is easy to assemble.

A distributing means according to the invention comprises, in a casing, three distributing discs disposed coaxially to the control shaft of the injection pump; a first disc is fixed and annularly surrounds said shaft, a second disc is placed after the first and keyed in rotation on the end of said shaft; a third disc is placed after the second and is fixed against rotation but is movable in an axial direction and, finally, an axial compression spring is located between the rear cover of the casing and the third disc.

The distributing faces are each divided by a circular groove into two annular blocks, two blocks opposite two adjacent faces being associated with two blocks opposite two other adjacent faces, on either side of the second disc. A group of four blocks, thus associated, is exposed to the pressure of the petrol or other fuel discharged by the injection pump to the metering member and the other group of four associated blocks is exposed to the pressure of the fuel discharged from the metering memher to the cylinders.

In one embodiment of the invention, two of the opposed blockshave a series of apertures corresponding alternately to the circuit for the fuel passing from the primary pump to the injection pump and from the latter to'the metering member, whilst the two opposed blocks associated with the first are exposed to the pressure of the fuel discharged by the injection pump. Two more of the opposed blocks have a series of apertures corresponding successively to the circuits for the fuel passing from the metering member to each of the cylinders of the engine, whilst the two opposed blocks associated with the first are exposed to the pressure of the fuel coming from the metering member.

Moreover, a fraction of the end face of the third disc is exposed to the pressure of the fuel coming from the injection pump and/or to the pressure of the fuel coming from the metering member.

In order that the invention may be more readily understood reference will now be made to the accompanying drawings which show certain embodiments thereof by way of example, and in which:

FIGURE 1 shows a longitudinal section through a distributing means according to the invention, coupled to a fuelinjection pump,

FIGURE '2 shows a section along the line IIII of FIGURE 1 of the face of a distributing disc,

FIGURE 3. shows a section along. the line IIIIII of FIGURE 1 through the face associated with the preceding one,

FIGURE 4 shows a section along the line IVIV of FIGURE 1 through the face of another distributing disc,

FIGURE 5 shows a section along the line V-V of FIGURE 1 through the face associated with the preceding one,

FIGURE 6 shows a modification of a distributing disc,

FIGURE 7 shows a section along the line VII--VII of FIGURE 6 showing a modification of the face shown in FIGURE 3, and

FIGURE 8 shows a section along the line VIII-VIII of FIGURE 6 showing a modification of the face shown in FIGURE 4.

Referring now to the drawings, FIGURE 1 shows a complete distributing means according to the invention associated with a fuel injection pump, but the latter is only shown partially by its control shaft 1 on which a cam 2 is secured. The latter controls a rocker arm 3 pivotally mounted about a spindle 4 parallel to the shaft 1. The rocker arm 3 acts directly by one of its ends on a piston (not shown) of the injection pump. In the assembly, this pump is situated in a plane perpendicular to the shaft 1. Some of its members are protected or supported by a casing 5 in which is arranged a cylindrical housing designated by the general reference 6 where the end of the control shaft 1 of the injection pump penetrates.

In the housing 6 are located the following, successively from left to right:

A first distributing disc 7 held fixed against rotation by a pin 8 integral or secured to the casing 5; this disc is completely transversed by the shaft 1 and has an internal bearing 9 in which the shaft 1 freely rotates.

A second distributing disc 10 is applied by one of its faces against the disc 7 and rotates with the shaft 1 by means of a square 11 fixed to the end of the latter; shaft 1 does not completely traverse the disc 10.

A third distributing disc 12 is applied by one of its faces against the disc 10, and is fixed against rotation but free to move axially.

Finally, a cover 13 is fixed to the casing 5 by screws 13a which penetrate in part into the housing 6, surrounds the disc 12 and thereby holds and guides it.

A relatively weak compression spring 14 is interposed between the cover 13 and the disc 12; a large part of it extends into a groove 15 in the latter. This spring 14 holds, at the instant of stopping, by developing a slight force, the three successive discs against one another and against the base of the housing 6.

It will be observed that, during operation, when the shaft 1 is rotated (by means not shown), the cam 2 controls the rocker arm 3 which gives the piston of the pump its inlet and discharge movements, and that simultaneously the second disc 10 is rotated by the shaft 1 whilst the first disc 7 and the third disc 12 are fixed. The different fuel flow circuits will now be described, which are successively established and broken during operation.

The rocker arm 3 and the cam 2 are situated in a space 16 which communicates by means of a threaded opening 17 with a primary fuel supply pump (not shown); the latter continuously keeps the space 16 filled with fuel.

A radial hole 18 made in the shaft 1 connects the space 16 to an axial channel 19 formed in the same shaft; this channel 19 communicates in its turn by a second radial hole 20 with a space 21 provided in the second disc 10 about the shaft 1, in front of the. square 11.

Four conduits 22 extend from the space 21 into the mass of the second disc 10, said conduits being angularly spaced at 90, and being formed with radial and longitudinal portions at right angles to each other, so as to point in the direction of the face of the disc 10 which is in contact with the face of the first disc 7. The face 7a is shown in FIGURE 2 and the face 10a in FIGURE 3. The apertures of the four conduits 22 will be seen on the face 10a (FIGURE 3) and it will be observed that there also exists on this face four notches 23, of reduced depth, regularly disposed between the conduits 22, and which extend radially over a short distance from the periphery of the face 10a.

The face 7a (FIGURE 2) has a shallow port 24 which is slightly extended circumferentially, and which is situated, radially on a circumference such that it may coincide successively with each of the conduits or holes 22 and each of the notches 23.

A longitudinal channel opens out into the port 24,

which channel entirely transverses the first disc 7. This channel 25 opens out in the face of the disc 7 applied against the casing 5 and from there it is connected by means (not shown in the figure) to a single intake and discharge aperture of the cylinder of the injection pump.

It is thus seen that the rotation of the shaft 1 and of the second disc 10 periodically places the single intake and discharge aperture of the pump in communication with the space 16 by the channel 25, one of the conduits 22, the space 21, the hole 20, the channel 19 and the hole 18 during the intake phase of the pump, or with one of the notches 23 during its discharge phase. The circumferential length of the slot 24 determines the duration of the placing in communication of the channel 25 and the conduit 22 and notches 23.

It will be observed from FIGURE 2 that the face 7a has another slot 24- symmetrical with the first slot 24 with respect to the centre of said face. Thus an identical variation of the lift of the block 100 is symmetrically produced at the same instant.

FIGURE 1 shows the existence between the external diameter of the

discs

10 and 12 and the internal diameter of the housing 6, a difference such that an annular chamber 26 is created between the housing 6, the periphery of the disc 10 and the part of the periphery of the disc 12 which is not engaged in the cover 13.

The notches 23 of the slide valve 10a open out into the annular chamber 26, and a channel 27 is formed in the wall of casing 5 and is connected with a metering member (not shown) associated with the injection pump, and with the distributing means. The fuel which flows through the channel 27 after coming from the notches 23 and the channel 25 (as has been seen above) is passed directly from the pump and will be referred to as the discharged fuel. It will be noted that the annular chamber 26 is permanently filled with a discharged pressurised fuel.

The fuel returns from the metering member through a channel 28 which is also formed in the wall of the casing 5 and which communicates with a conduit 28 formed in the wall of the cover 13. The channel 28 opens out into a bore 29 made in the cover and into which penetrates a smaller disc end of the disc 12; a spring 14 is housed in a groove 15 formed in one end of the disc 12. This spring 14 is thus compressed on the one hand between the base of the bore 29 of the cover 13 and the base of the groove 15 of the disc 12.

A central conduit 30 concentric with the disc 12 traverses the whole of the thickness of the latter in order to open out on the face 12a of the disc 12 in contact with the surface or face 10b of the disc 10. These faces 12a and 1012 are shown respectively in FIGURES 5 and 4.

The face 10b has a central groove 31 of limited depth, situated opposite the central conduit 30 and extended by a radial groove 32 of limited length. The disc 12 is traversed at four channels 33, regularly spaced by presenting two parts at right angles, one longitudinal, the other radial. The longitudinal parts of the channels 33 open onto the face 12a at a distance from the axis which correspond to the length of the radial groove 32 so that the end of the latter may be successively located in line or register, with each of the channels 33. The radial part of this latter opens out on the lateral face of the disc 12, opposite the respective conduits such as 34, formed in the cover 13 and which are each finally connected to one of the cylinders of the engine.

The fuel coming from the metering member through the conduit 28 will be referred to as the metered fuel; it is seen that, due to the rotation of the shaft 1 and the second disc 10, it is sent successively through the bore 29, the central conduit 30 the central groove 31, the radial groove 32 and one of the channels 33, to each of the cylinders whilst the injection pump is inducing and discharging, as has been explained above.

Due to the relatively high pressure of the discharged fuel and the metered fuel (the latter being lower than the former), there is an infiltration between the faces 7a and 10a and between the faces 10b and 12a. The force (or lift) which is thus produced tends to separate them against the action of the spring 14, whose force is much too Weak to oppose it, if no measure were taken :for this purpose.

Referring to FIGURES 3 and 4, it will be observed that the face 10a is divided into two zones, one peripheral, the other central, by a central groove 75, and that the face 101; is similarly divided into two zones by a circular groove 37. These two grooves are connected by a longitudinal hole 36 which passes through the thickness of the slide valve 10, and communicate with a return pipe through a hole bored across the flat side valve 12 (not shown). The result is that the fuel in the

groove

35 and 37 is at zero pressure.

The peripheral zone of the face 10a, in which are situated the openings of the conduit 22 and the distributing notches 23 of the injection pump, is in fact the distributing block 100 of the pump. The pressurised fuel at the periphery of the flat disc 10a is infiltrated as far as the groove 35, causing forces to appear which correspond to the lift of the block 10c. The same applies to the block 10d situated on the other face, where the fuel flows from the periphery as far as the groove 37; the external diameter of this groove has been chosen so that the lift of the block 10d is equal to the lift of the block 100. These two blocks operate between the discharge pressure of the pump and zero pressure.

The central zone of the flat disc 10a (FIGURE 3) has a groove 39 which communicates through a bore 38 (FIG. 1) with the space 31 situated on the other face of the flat side valve 10 and fed with the gauged fuel. The pressurised fuel passes from this groove 39 as far as the groove 36 Where the pressure is zero and towards the center where the pressure is very low with respect to that of the metered fuel. The resultant of these pressure forces represents the lift of each block 10 the dimensions of the groove 39 have been selected so that the lift of the block 10f is equal to the lift of the block 10c. These two blocks operate between the pressure of the metered fuel and zero pressure.

It is thus seen that the forces on the two faces 10a and 10d of the flat disc 10 are equal: on the one hand the lifts of the blocks 10c and 1001 which are equal as a function of the discharge pressure of the pump (peripheral zone), on the other hand, the lift of the blocks 10 and me which are equal as a function of the pressure of the metered fuel (central zone).

In order to maintain the faces applied together, it will be sufficient to apply the flat disc 12 against the flat slide valve 10 with a force substantially equal to the lift of the blocks 10c and 10d on the one hand and with a force substantially equal to the lift of the blocks 10] and 10e on the other hand.

The disc 12, for its part, has balancing surfaces which counter-balance the lift of the blocks 10:; and 10d.

Referring to FIGURE 1, it may be observed that the end face 12b of the disc 12 introduced into tha bore 23 of the cover 13 is exposed to the pressure of the metered fuel arriving through the conduit 28 and preceding to the central conduit 30. The area of this face is determined so that the source which is applied thereto is equal and opposite to the'lift of the block 10a for distributing the metered fuel and consequently balances this lift.

On the other hand, there is a gap 40 between the internal end face of the cover 13 and an annular face located opposite, thereto, constituted by a shoulder 41 arranged on the disc 12. The total area of the shoulder 41 exposed to the pressure of the discharged fuel filling the annular chamber 26 is determined such that the resultant force which is applied thereto is equal and opposite to the lift of the block 10d for balancing the pump block 100, and consequently balances this lift.

No account has been taken in the preceding explanation of the pressure of the supply fuel arriving through the space 21 and the conduit 22; in practice, it is negligible compared with that of the discharged fuel. The port or slot 24, symmetrical with the port or slot 24 in the face 7a, is located opposite a notch 23 at the same time as the port 25; an identical variation of the lift of the block 10c is thus produced symmetrically and at the same moment, as the notches 23 coincide with the slots 24 and 24'; thus a lack of balance of the contacting faces is avoided.

It is thus seen that the forces which act upon the faces are always balanced and that the reactions are supported by the casing on the one hand, the flat disc 7 being applied to the base of the bore 6, and by the cover 13 on the one hand, which is itself fixed to the casing of the pump.

In the figures and in the course of the preceding descrip tion, it has been shown that the associated blocks for distributing and balancing the discharge fuel were situated on the peripheral zone of the casing whilst the associated blocks for distributing and balancing the shown fuel were located on the centralzone of the same faces. It will be apparent that this arbitrary allocation is not obligatory according to the invention. On the contrary, if desired, the central zone may be used as blocks for the discharged fuel which would circulate then through the central conduit 30 and the conduit 38 in the direction of the metering number, whilst the metered fuel would return through the channel 27 and would fill the annular chamber 26 in order to have access to the blocks for the metered fuel which would then be constituted by the peripheral zones of the faces.

This inverse arrangement is easily deducible from what has been illustrated and described, therefore no drawings showing this inverse arrangement are necessary.

In theory, as has been explained, by reason of the rapid fall in pressure which is produced in the blocks, the

grooves

35 and 37 which separate two blocks may be considered as zones of zero pressure. On the other hand, it is known that the pressure of the discharged fuel which will be referred to as P is greater than that of the gauged fuel which will be referred to as P by reason of the load losses inevitably created by the metering member. Thus, by taking the face 10b of FIGURE 4 as a reasonable example, it may be seen that the pressure in the block 10d is lowered from a valve P at its periphery to a value of nil when the groove 37 is reached, whilst the pressure in the block 10c is lowered from a value P at the center to a value of ni-l when the groove 37 is reached.

There is a moment when the pressure P during lowering, passes the value P This observation permits a modification to be made to the embodiment of the faces and blocks, this modification being shown in FIGURES 6, 7 and 8. In the latter the same elements as those in the preceding figures are designated by the same references plus 100.

FIGURE 6 shows the

discs

107, and 112 as Well as the cover 113. FIGURE 7 shows the face 110a of the disc 110; shown to the same scale as the face 10a, it presents a considerably reduced bulk. The face 110a has a groove which is submitted to the pressure P through a hole 136 which opens out into a groove 147 of the face 11%. The block 1 10c which ensures the distribution of the pump operates between the discharge pressure P of the pump and the pressure P of the metered fuel. The block 110 operates between the pressure P and the zero pressure of the axial zone.

On the face 110b, the groove 147 has a peripheral edge which is slightly offset with respect to the axis of the face; a notch 148 of small depth, communicating with the groove 147, is placed at a distance from the center such as to communicate with the holes 133 during its rotation.

The groove 147 is fed with metered fuel as will be seen later and the offsetting of the peripheral edge has for an 7 object diametrically to compensate for the modification of the lift given by the notch 148.

The block 110d which ensures the distribution of the metered fuel operates between the discharge pressure P of the pump and the pressure P of the metered fuel. This groove 147 is dimensioned so that the lift of the block 110d is equal to the lift of the block 1100.

The block 1160 which operates between the pressure P of the metered fuel and the axial pressure close to zero, is dimensioned so that it has the same lift as the block 110).

As in the preceding case, the stresses on the faces 116a and 11012 are equal. In order to maintain the faces applied together, it is sufficient to apply the flat slide valve 112 with a thrust defined by the discharge pressure P of the pump and exerting itself on the circular zone 140 on the one hand and by the pressure of this gauged fuel exerting itself on the cap 144 on the other hand.

As shown in FIGURE 6, a conduit 128 abuts on the lateral face of the disc 112 and communicates with a radial channel 143 which opens out into the groove 115 in which is housed the spring 114. An intermediate cap 144 is placed between the latter and the cap 113. The surface of the cap 144 is dimensioned such that the thrust due to the pressure P of the metered fuel balances the lift of the faces under the effect of the same pressure.

Of course, this modification has all the advantages of the preceding embodiment whilst allowing a much reduced bulk to be obtained. Moreover, in this solution, the square may traverse the distributing disc 110, thus producing a return collector which is at the compression pressure of the pump.

No mention has been made in the preceding description of the numerous joints such as 150 (FIGURE 6) visible in the drawings; it is obvious that the construction can be provided with joints, preferably of the toric or O- ring type, between all the contact surfaces between which the fuels must not be allowed to pass.

It will be also observed that the examples described relate to the particular case of a four cylinder engine. The invention is perfectly adjustable to a different number of cylinders: it is consequently sufficient to modify the number and the angular position of the channels, conduits and notches which depend upon the number of cylinders of the engine.

It is understood that the invention is not limited to the embodiments described but that it covers, on the contrary, all the modifications or equivalents which could be applied thereto without departing from its scope or its spirit, as defined by the appended claims.

I claim:

1. Distributing means for directing the flow of fuel from a primary supply pump to an injection pump, then to a metering member and then successively to each of the cylinders of an engine, said distributing means comprising: a casing having an inlet and a plurality of outlets; a control shaft extending into said casing; three distributing discs having passageways extending therethrough and arranged in said casing coaxially to said control shaft; a first one of said discs being fixed in said casing completely surrounding said shaft, but allowing said shaft to freely rotate therein; a second one of said discs having a first flat face placed against a fiat face of said first disc and being keyed on one end of said shaft for rotation therewith, the third one of said discs being placed against a second flat face of said second disc and having means preventing it from rotating in said casing but allowing movement in the axial direction; an axial compression spring located between said casing and said third disc for biasing said third disc against said flat face of said second disc; said second disc, when rotated, selectively controlling the flow of fluid from said inlet through said discs to said outlets.

2. The distributing means of claim 1, in which said first disc has only one passageway extending thcrethrough, one end of said passageway being adapted for connection to a fuel injection pump.

3. The distributing means of claim 2, wherein said second disc has a plurality of passageways and notches formed therein; said passageways and notches being periodically placed in communication with the other end of the single passageway of said first disc to allow fuel to alternately enter and exit from said single passageway.

4. The distributing means of claim 3, in which said passageways formed in said second disc are connected at one end to the first flat face and at their other end to a chamber formed in the central portion of said first disc; said chamber receiving fuel from a second chamber formed in said casing by means of a passageway formed in said control shaft and which is in continuous fluid communication with said chambers.

5. The distributing means of claim 1 further including at least one groove formed on the fiat faces of each of said discs, said grooves dividing said faces into annular blocks, each of said blocks on a given face being opposite the blocks on an adjacent face, whereby a group of four such blocks on one side of said second disc, thus associated, are subjected to the pressure of the fuel discharged from the injection pump and flowing to the metering member and the other group of four blocks on the other side of said second disc are subjected to the pressure of the fuel discharged from the metering member and flowing to the cylinders thus substantially balancing the force applied to the face of each of said discs.

6. The distributing means of claim 5, wherein a fraction of the end face of said third disc is subjected to the pressure of the fuel coming from the injection pump.

7. The distributing means of claim 5, in which a fraction of the end face of said third disc is subjected to the pressure of the fuel coming from the metering member.

8. The distributing means of claim 5 wherein two opposite blocks located on the opposite flat faces of the first and second discs are connected in series with the fuel flowing from the primary pump to the injection pump and then to the metering member, the remaining two opposite blocks associated with the opposite faces of the first and second discs being subjected to the pressure of the fuel discharged by the injection pump.

9. The distributing means of claim 5 in which two of the opposite blocks of the opposite fiat faces of the second and third discs are connected in series with the fuel passing to the cylinders of the engine, the remaining two opposite blocks associated with the opposite faces of the second and third discs being subjected to the pressure of the fuel coming directly from the metering member.

References Cited UNITED STATES PATENTS 3,046,894 7/1962 Machen l03-2.l 3,054,393 9/1962 Schmidt 123l39 3,124,116 3/1964 Morris 1032.1 3,238,934 3/1966 Morris et al 123139.11

LAURENCE M. GOODRIDGE, Primary Examiner.

Claims

1. DISTRIBUTING MEANS FOR DERECTING THE FLOW OF FUEL FROM A PRIMARY SUPPLY PUMP TO AN INJECTION PUMPS THEN TO A METERING MEMBER AND THEN SUCCESSIVELY TO EACH OF THE CYLINDERS OF AN ENGINE, SAID DISTRIBUTING MEANS COMPRISING: A CASING HAVING AN INLET AND A PLURALITY OF OUTLETS; A CONTROL SHAFT EXTENDING INTO SAID CASING; THREE DISTRIBUTING DISC HAVING PASSAGEWAYS EXTENDING THERETHROUGH AND ARRANGED IN SAID CASING COAXIALLY TO SAID CONTROL SHAFT; A FIRST ONE OF SAID DISC BEING FIXED IN SAID CADING COMPLETELY SURROUNDING SAID SHAFT, BUT ALLOWING SAID SHAFT TO FREELY ROTATE THEREIN; A SECOND ONE OF SAID DISCS HAVING A FIRST FLAT FACE PLACES AGAINST A FLAT FACE OF SAID FIRST DISC AND BEING KEYED ON ONE END OF SAID SHAFT FOR ROTATION THEREWITH, THE THIRD ONE OF SAID DISCS BEING PLACES AGAINST A SCOND FLAT FACE OF SAID SECOND DISC AND HAVING MEANS PREVENTING IT FROM ROTATING IN SAID CASING BUT ALLOWING MOVEMENT IN THE AXIAL DIRECTION; AN AXIAL COMPRESSION SPRING LOCATED BETWEEN SAID CASING AND SAID THIRD DISC FOR BIASING SAID THIRD DISC AGAINST SAID FLAT FACE OF SAID SECOND DISC: SAID SECOND DISC, WHEN ROTATED, SELECTIVELY CONTROLLING THE FLOW OF FLUID FROM SAID INLET THROUGH SAID DISCS TO SAID OUTLETS.